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F I N A L R E P O RT
Mapping and Monitoring Submerged Aquatic
Vegetation in Ichetucknee
and Manatee Springs
Submitted to:
Suwannee River Water Management District
9225 County Road 49
Route 3, Box 64
Live Oak, FL 32060
Submitted by:
2803 Fruitville Road, Suite 130
Sarasota, FL 34237
(941) 954-4036
University of Florida
Department of Fisheries and Aquatic Sciences
7922 NW 71st Street
Gainesville, FL 32653
(352) 392-9617
June 2003
05704-sw-03
Mapping and Monitoring Submerged Aquatic
Vegetation in Ichetucknee and Manatee Springs
Final Report
June 2003
Prepared for:
Suwannee River Water Management District
9225 County Road 49
Rout 3, Box 64
Live Oak, FL 32060
Prepared by:
R. C. Kurz, P. Sinphay, W. E. Hershfeld, A. B. Krebs, A. T. Peery
2803 Fruitville Road
Suite 130
Sarasota, FL 34237
(941) 954-4036
And
Debra C. Woithe, M.S.
5115 Palmetto Point Drive
Palmetto, FL
And
S.K. Notestein, T. K. Frazer, J. A. Hale, and S.R. Keller
Department of Fisheries and Aquatic Sciences
University of Florida
7922 NW 71st Street
Gainesville, Florida 32653
(352) 392-9617
FOREWORD
This report was prepared for the Suwannee River Water Management District (SRWMD)
by Post, Buckley, Schuh & Jernigan (PBS&J) under Contract No. 02/03-180.
ACKNOWLEDGEMENTS
Mr. Rob Mattson of the SRWMD was instrumental in coordinating the administrative
aspects of the project with the various Park staff and provided direction and technical
guidance throughout the project. Mr. Sam Cole, Park Biologist for the Ichetucknee
Springs State Park, provided invaluable assistance in coordinating field mapping and
sampling within the Ichetucknee Springs and River. He also provided much of the data
used in the recreational impact analysis. The Center for Taxonomy and Systematics (Mr.
Michael Milligan) conducted all of the SAV-associated macroinvertebrate identification.
EXECUTIVE SUMMARY
This report describes the mapping and monitoring of submerged aquatic vegetation (SAV) and
associated biota and water quality for the Ichetucknee Springs and Manatee Springs systems,
located in north-central and west Florida, respectively.
The specific tasks for this project were:
1. To map the spatial distribution of SAV in the Ichetucknee Springs and River and Manatee
Spring and its spring run;
2. To conduct monitoring and sampling of SAV in the Ichetucknee and Manatee Spring systems
to document existing vegetation health and identify the relationships between water flow,
velocity, canopy cover, and SAV plant community structure;
3. To conduct SAV-associated macroinvertebrate sampling in the Ichetucknee River to better
understand the importance of SAV as a substrate/habitat for other organisms; and
4. To conduct a recreational use impact analysis for the river using SAV data collected by
Ichetucknee Park staff and available hydrologic data. Relationships between water levels and
changes in SAV coverage were analyzed after periods of heavy recreational use to determine
if damage is greater during drought years.
The most common species encountered (in order of percent cover) in the Ichetucknee Springs and
River were Sagittaria kurziana, Zizania aquatica, Vallisneria americana, Chara sp.,
Myriophyllum heterophyllum, Ludwigia repens, and Hydrocotyle sp. Only sparse patches of
Sagittaria kurziana were found in Manatee Springs, mainly at the periphery of the headsprings.
Approximately 78% of the Ichetucknee River bottom is covered by SAV compared to
approximately 1% coverage in the shorter Manatee Springs run. In comparison to a previous
mapping effort by Dutoit in 1979, SAV coverage in the Ichetucknee River has increased by
approximately 23 acres or 353% over the past 24 years.
Field monitoring was conducted to measure SAV coverage, biomass, water quality, stream
velocity, canopy coverage, and periphyton abundance along 31 evenly distributed transects in the
Ichetucknee River. The results of field monitoring show that SAV biomass in the river is higher
than several spring-fed rivers in north-central and west Florida. The Ichetucknee River has
optimal sediment and flow characteristics suitable for SAV growth. Changes in SAV biomass
along the river appears to be largely a function of location, depth, and canopy cover, with greater
percent cover and biomass in the lower Floodplain reach where light limitations (greater tree
canopy cover over the river) may be causing a response in the growth of longer blades.
Periphyton abundance was greatest in areas of low canopy cover (Rice Marsh reach).
The spatial distribution, abundance, and diversity of SAV and associated epibenthic
macroinvertebrate communities, are often utilized to assess the heath of aquatic ecosystems.
SAV-associated macroinvertebrates were sampled in the Ichetucknee River along the same 31
transects where SAV field monitoring was performed. A total of 31,539 individuals representing
47 species of macroinvertebrates were identified during this sampling effort. Chironomids
dominated the samples and represented approximately 91.8% of all samples combined, followed
by Hydracarina sp. (4.3%), Petrophilla sp. (1.2%), Hydroptila sp. (0.7%), and Oxyethira sp.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
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(0.5%). Based on the diversity and abundance of SAV-associated macroinvertebrates, the
Ichetucknee River would be considered “healthy” compared to other streams and rivers in
Florida.
Macroinvertebrate abundance and number of taxa were negatively correlated with canopy cover the greatest canopy cover occurred in the Headspring and Floodplain reaches compared to the
Rice Marsh which had little to no canopy cover over the main river channel. This relationship
may be related to the abundance of periphyton, which was also greatest in areas of low canopy
cover. Both macroinvertebrate abundance and number of taxa were positively correlated with
periphyton abundance. There were no significant differences in the number of macroinvertebrate
taxa or abundance with respect to stream flow velocity, water depth, SAV species, or SAV wet
weight.
Recreational activity has probably been the most important factor affecting the health of the
Ichetucknee River and associated SAV beds from the 1970s to present. Monitoring by Park staff
has indicated a relatively consistent trend of declining SAV coverage during the high use summer
period, followed by an increase in coverage through the spring. The rate of decline in SAV
coverage was determined to be significantly correlated with headspring water levels at one of four
monitoring stations, and weakly correlated with groundwater levels and park usage (number of
people).
The following recommendations are presented based on the results of this study:
1) Continued monitoring of SAV and associated fauna and water quality should be
conducted periodically (annually or biennially) to assess and compare future conditions
with those found in this and previous studies. This information will be extremely useful
in the future management of surface and groundwater resources in the area and the
development of Minimum Flows and Levels (MFLs).
2) Enforcement of more restrictive park management guidelines for the Ichetucknee Springs
and River may be necessary during drought conditions since it appears that greater SAV
loss occurs during periods of lowered water levels in the headspring. Water levels at the
headspring should be used as the primary management tool, since these values often lag
behind local rainfall conditions/patterns.
3) SAV in Manatee Springs and spring run appear to be affected by both long term and
seasonal changes in water quality (highly tannic waters from the Suwannee River) and
grazing by manatees. Restoration of SAV in this spring system will be problematic,
especially since most of the headspring area is open to swimming and recreational use.
However, protection (e.g., through the use of exclusion zones) of existing, albeit sparse
SAV may result in future increases and persistence of this important habitat.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
iii
Table of Contents
page
FOREWORD ....................................................................................................................... i
ACKNOWLEDGEMENTS................................................................................................. i
EXECUTIVE SUMMARY ................................................................................................ ii
1.0 Introduction................................................................................................................... 1
2.0 SAV Mapping ................................................................................................................ 2
2.1 Materials and Methods ............................................................................................. 2
2.1.1 Study Area ..................................................................................................... 2
2.1.1.1 Ichetucknee Springs and River.................................................................... 2
2.1.1.2 Manatee Springs ......................................................................................... 4
2.1.2 Mapping Methodology................................................................................... 5
2.1.2.1 GPS and GIS Specifications........................................................................ 5
2.1.2.2 Field Mapping............................................................................................. 6
2.1.2.3 Preparation of Digital and Hard Copy Maps............................................. 9
2.1.2.4 Quality Control Process ............................................................................. 9
2.2 Results and Discussion ........................................................................................... 10
2.2.1 SAV Maps.................................................................................................... 10
2.2.2 SAV Coverage ............................................................................................. 11
2.2.2.1 Ichetucknee Springs and River.................................................................. 11
2.2.2.2 Manatee Springs ....................................................................................... 12
3.0 SAV Sampling ............................................................................................................ 15
3.1 Introduction............................................................................................................. 15
3.2 Materials and Methods ........................................................................................... 15
3.2.1 Data Summaries and Statistical Analyses............................................................ 17
3.3 Results and Discussion ........................................................................................... 17
4.0 Macroinvertebrate Sampling....................................................................................... 33
4.1 Introduction............................................................................................................. 33
4.2 Materials and Methods ........................................................................................... 33
4.3 Results and Discussion ........................................................................................... 34
5.0 Recreational Use Impact Assessment ......................................................................... 40
5.1 Introduction............................................................................................................. 40
5.2 Methods................................................................................................................... 40
5.3 Results and Discussion ........................................................................................... 41
6.0 References ................................................................................................................... 49
Appendices
Appendix A - Metadata for Ichetucknee and Manatee Springs SAV Maps
Appendix B - Ichetucknee Springs and River and Manatee Springs and Springs Run SAV Maps
Appendix C - Reprints of Dutoit (1979) Ichetucknee River SAV Maps and Cover Estimates
Appendix D - Data and Statistical Summaries from SAV Transect Sampling
Appendix E - Field Notes from SAV-Associated Macroinvertebrate Sampling
Appendix F - SAV-Associated Macroinvertebrate Data for 31 Ichetucknee River Transects
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
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1.0 Introduction
The spring systems of Florida are a treasured natural resource. They provide a significant source
of freshwater, create unique environmental conditions for rare aquatic habitats and biota, and are
important recreational attractions for visitors from around the world. However, the springs, their
recharge basins, and their downstream spring runs are fragile ecosystems and have been impacted
by human development during the past century, particularly through excess nutrient loading and
groundwater withdrawals. Recognizing the importance of these unique systems, the Florida
Springs Task Force was formed by various state and local agencies and private interest groups in
1999 to develop management strategies for preserving and protecting the state’s springs.
The following study was managed by the Suwannee River Water Management District
(SRWMD) and funded by the Florida Department of Environmental Protection’s (FDEP) Florida
Springs Initiative to address the Task Force’s Information Strategy, which was developed to
implement monitoring programs to detect and document long-term trends in spring conditions.
This project involved the mapping and monitoring of submerged aquatic vegetation (SAV) in two
spring systems, Ichetucknee Springs and Manatee Springs. SAV-associated macroinvertebrates
were also collected in the Ichetucknee Springs system. This information will be useful to evaluate
trends in ecological conditions in the springs and lead toward the better management of these
aquatic ecosystems.
The specific tasks for this project were:
5. To map the spatial distribution of SAV in the Ichetucknee Springs and River and Manatee
Spring and its spring run;
6. To conduct monitoring and sampling of SAV in the Ichetucknee and Manatee spring systems
to document existing vegetation health and identify the relationships between water flow,
velocity, canopy cover, and SAV plant community structure;
7. To conduct SAV-associated macroinvertebrate sampling to better understand the importance
of SAV as a substrate/habitat for other organisms; and
8. To conduct a recreational use impact analysis for the river. Using SAV data collected by
Ichetucknee Park staff and available hydrologic data, relationships between water levels and
changes in SAV coverage were analyzed after periods of heavy recreational use to determine
if damage is greater during drought years.
This report is divided into four sections (mapping, monitoring, SAV-associated
macroinvertebrates, and recreational use impact analysis) which address each of the above tasks.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
1
2.0 SAV Mapping
Submerged aquatic vegetation (SAV) was mapped
in both the Ichetucknee Springs and River and
Manatee Springs and its spring run.
This
information was gathered to document the
existing spatial distribution and coverage of SAV
in each spring system. Comparisons to previous
SAV mapping in Ichetucknee Springs were made
based on a study by Dutoit in 1979.
2.1 Materials and Methods
2.1.1 Study Area
2.1.1.1 Ichetucknee Springs and River
The Ichetucknee Spring and River are located
approximately three miles west of Fort White,
Florida. The river crosses U.S. 27 and also
defines a portion of the county boundary between
Suwannee and Columbia County (Figure 2-1).
The Ichetucknee River is fed by nine named
springs located along the upper 2.5-miles of the
river. The northernmost spring forms the head of
the river and is known as Ichetucknee Spring or
Head Spring (Figure 2-2). Flow from this spring
travels southward and forms the Ichetucknee
Figure 2-1 (above). Aerial of Ichetucknee River.
River proper. The remaining eight named springs
Figure 2-2 (below). Ichetucknee head spring.
of the group are, in downstream order, Cedar
Head Spring, Blue Hole Spring, Roaring Springs,
Singing Springs, Boiling Spring, Grassy Hole Springs, Mill Pond Spring, and Coffee Spring
(Figure 2-3). Flow characteristics for the Ichetucknee Springs group are shown in Table 2-1.
The springs are within the confines of the Ichetucknee Springs State Park, which occupies 2,241
acres in Columbia and Suwannee Counties and was established in 1970. Historically, the area was
used by local residents for swimming, watering of livestock, and phosphate mining. The average
river width is 6 to 10 m and average depth is approximately 1 m in the upper reaches of the river.
At approximately 550 m downstream, the river meets the southward flow of Cedar Head Spring
and Blue Hole Spring. The river then flows about 4800 m south, then 6400 m southwest and
discharges into the Santa Fe River. Depth increases in the middle and lower reaches of the river
to approximately 2 to 4 m.
The Ichetucknee River lies within an ancient basin called the Ichetucknee Trace along the 50 ft
contour line of USGS topographic maps (Dutoit, 1979). The contributing basin or spring-shed of
the Ichetucknee Springs includes an area north toward Lake City and includes surface flows from
several sinkholes including Rose Sink near the city of Columbia. Local recharge occurs in the
vicinity of the headsprings through various sinkholes and percolation through limestone outcrops
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
2
and sandy soils. The SRWMD is currently evaluating the groundwater basin of the springs
through a separate Springs Initiative grant from the FDEP.
Table 2-1. Spring characteristics for Ichetucknee and Manatee Springs.
Mean
Discharge
Spring/Run
Ichetucknee**
Manatee***
3
(ft /sec)*
360
181
Max.
Discharge
3
(ft /sec)*
578
238
Min.
Discharge
3
(ft /sec)*
241
110
Length of
Spring Run
Studied (ft.)
17,388
1,148
*from: Florida Geological Survey (1977)
**period of record 1917-1974, n=375 measurements
***period of record 1932-1973, n=9 measurements
Figure 2-3. Map of Ichetucknee Springs System (from Florida Geological Survey, 1977).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
3
The mapping area in the Ichetucknee system was
located entirely within Ichetucknee State Park
extending from the head spring downstream to the
U.S. 27 Bridge. This represents a distance of
approximately 5300 m. There are three distinct
zones within the mapping area representing different
canopy coverages, river widths, and depths. The
upper zone from the head spring to approximately
1050 m downstream is characterized by heavy tree
canopy, relatively narrow channel width (10 to 15
m) and shallow depths (1 to 2 m) and was originally
identified as the Headsprings Reach in a previous
study by Dutoit (1979). The middle zone or Rice
Marsh area is much wider (approximately 60 m
wide) and is characterized by thick Zizania aquatica
marshes along the shoreline, moderate depths (2 to 3
m) and open canopy.
The river channel is
approximately 15 to 20 m wide and a few small tree
islands occur in this middle zone. Like the upper
zone, the lower zone or Floodplain Reach (Dutoit,
1979) is characterized by heavy tree canopy,
however, the average width is approximately 15 to
20 m and depth is approximately 2 to 3 m. This
zone lies within a flatter topography than the upper
zone and is flanked by extensive floodplain forest
(primarily bald cypress, Taxodium distichum).
2.1.1.2 Manatee Springs
Manatee Springs is located in Levy County, west of
Chiefland, along the lower reaches of the Suwannee
River. Unlike the Ichetucknee Spring systems,
Manatee Springs has a much shorter spring run of
only 350 m before entering the Suwannee River
(Figures 2-4, 2-5). The area surrounding the spring
is also a state park and is used for recreation
including camping, swimming and SCUBA diving.
A sinkhole (Catfish Hotel) exists approximately 25
m from the Manatee head spring and the two are
connected via a cave network.
The mapping area in the Manatee Spring system
extends from the headspring for approximately 350
m (1,148 ft) downstream to the confluence with the
Suwannee River.
Figure 2-4 (above). Aerial photograph of Manatee
Springs. Figure 2-5 (below.) Manatee Springs
State Park location map (source: FDEP).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
4
2.1.2 Mapping Methodology
A combination of mapping methods was used for the Ichetucknee and Manatee Springs. Field
mapping methods were selected after an initial field reconnaissance and refined through several
trial mapping efforts. Where Global Positioning System (GPS) signals were reliable and met or
exceeded minimum standards, integrated GPS/GIS on a handheld computer was used for field
mapping. These areas of GPS mapping cover all of Manatee Springs and roughly half of
Ichetucknee Springs. In the narrow, heavily canopied areas of the Ichetucknee River where GPS
signals were obstructed, transect mapping was performed. SAV was classified according to the
percent coverage of each species present. Following completion of field mapping, a seamless
coverage of SAV bed polygons was created for the Ichetucknee Springs and River. For Manatee
Springs, a shoreline boundary and point coverage were created as separate layers. All coverages
were prepared using ESRI’s ArcView GIS software. All field mapping was performed during
March, April, and early May 2003. Details describing the GIS software, GPS equipment, field
mapping methods, final map preparation, and the quality control process for both spring systems
follow.
2.1.2.1 GPS and GIS Specifications
The primary field mapping computer hardware was a Compaq iPAQ, model number 3850,
running Windows PocketPC. ESRI ArcPad Version 6.01.5 GIS software was used along with a
Teletype World NavigatorTM GPS, CF v2.0, Card #1651. The ArcPad mapping software
automatically retrieved positions from the GPS as the outline of the SAV bed (polygon) was
traced and produced mapped features in the field. The ArcPad graphical user interface was
customized with ArcPad Studio using VBScript and XML programing languages.
The custom interface provided data entry forms specifically designed for this mapping effort. A
standard Dell laptop computer running Windows 2000 and ArcView 3.2 was used to reference
information as needed. The laptop was operated using a 9 volt battery and power inverter. The
final map was prepared in ESRI ArcView 3.2. The Florida State Plane, North Zone, Datum
HPGN (NAD 83/90) with units in Feet projection was used. The minimum mapping unit was 30
square feet. Metadata documentation is provided in Appendix A.
Based on the FDEP Mapping Standards for GPS, the following minimum settings were used for
all mapping:
•
•
•
•
•
•
•
PDOP <6.0
Signal to Noise Ratio >6.0
Elevation Mask = 15 deg.
Minimum positions = 25
Minimum number of satellites = 4
Logging interval of point features = 1 second
Coordinate system = latitude/longitude
A deviation of no more than 5 meters was deemed acceptable. For the Ichetucknee River, a
Florida Department of Transportation (FDOT) benchmark at the U.S. 27 bridge was used to
verify the accuracy of the GPS units used for mapping. Plots of verification points are shown in
Figure 2-6 for each of the dates mapping was performed. Quality control and quality assurance
were conducted by periodic point feature collection at several locations, including the U.S. 27
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
5
bridge, the concrete/rock wall at the head springs, and the Ichetucknee headsprings staff gage.
GPS accuracy checks met the 5 meter deviation standard in open canopy areas where PDOP
values typically ranged between 1.0 and 3.0 (< 6.0). Measured horizontal accuracy was typically
within 1 to 2 m of the FDOT benchmark position.
The images used as a base map were one meter resolution, 1:24,000 scale, 1999 USGS color
infrared Digital Orthophoto Quarter Quads (DOQQ). Quad number Q4823 Northeast was used
for Ichetucknee Springs and Q4424 Northwest was used for Manatee Springs. During
preliminary shoreline mapping using GPS, it was determined that the aerial photography for the
Ichetucknee
River
was
shifted
approximately 25 feet to the north. The
known benchmark at the U.S. 27 bridge
also confirmed the need to shift the
DOQQ.
Using the GPS mapped
boundary of the headsprings and the
benchmark location on the U.S. 27
bridge, the image was shifted to the
north along with the digitized shoreline
boundary described below.
The
imagery for Manatee Springs did not
appear to be shifted and was used in
native format for shoreline and SAV
mapping. A staff gage at the springs
Figure 2-6. GPS verification/QC check points at the U.S.
was used as a reference point.
27 bridge on the Ichetucknee River. Note pixel size of
2.1.2.2 Field Mapping
DOQQ basemap is 1 m.
A shoreline feature was created for each spring run to delineate the boundary of the mapping
areas. The shoreline boundary was demarcated at the interior edge of dry land, dense wetland
hardwood forest, and/or emergent wetland vegetation. Where conditions allowed for GPS
mapping, the shoreline was followed with the GPS, in a canoe or on foot, sometimes using an
extended pole for a receiver mount. Where GPS signals were obstructed by dense tree canopy,
the shoreline was photo-interpreted from aerial photography. The photo-interpreted shoreline
was field checked and edited to create a more accurate delineation. Where feasible, ground
truthing was done using a GPS reference and edited in the field. In other cases, the width of the
river was measured with a tape and the shoreline edited later during map preparation.
SAV was evaluated according to the percent coverage of all species present. The classification
system, a modified Braun Blanquet cover estimate, follows the methods of Woithe and
Sleszynski, (1996), for the nearby Rainbow River in Dunnellon, Florida. Cover categories used
were 0%, 0-25%, 25-50%, and 50-100%. To simplify the recording of information in the field,
the cover categories were represented by a 0, 1, 2 or 3, respectively. A systematic reconnaissance
of an area was first performed to assess the species present, their cover categories, and how they
should be delineated. Additional data collected for each spring run were bottom feature type
(SAV, bare, or emergent), date, and comments. Some of the information in the comments field
includes substrate type (rock or sand), algae coverage, and species present in quantities less than
the minimum mapping unit. Vegetation patches as small as 30 square feet were individually
mapped for the Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
6
Portions of the Ichetucknee River where the GPS was used for SAV mapping are: 1) from the
head spring to the end of the broad, open rice marsh, and 2) approximately 2000 ft of river
upstream from the downstream take out point near U.S. 27. In these areas, SAV was mapped by
following the perimeter of the bed with the GPS unit. This was done while observing the SAV
from the canoe, or with a diver in the water guiding the canoe. The GPS receiver was either
mounted to a telescoping pole, or on the bow of the canoe. SAV polygons were checked for
positional and dimensional accuracy using the aerial photography, visible landmarks, and
previously mapped features. A point feature was placed within each SAV polygon, and attributed
using the customized forms.
Transect mapping was performed as an alternative to
GPS mapping in three general sections of the
Ichetucknee River: 1) the confluence of the Mill Pond
Spring to Dampier’s Landing Dock, 2) Dampier’s
Landing to the power lines, and 3) the U.S. 27 bridge
to the take out point. A 100-foot floating transect was
devised using polyethylene rope, floats and weights.
Weights were used to anchor the beginning and end
points of the transect, which had large floats. Smaller
floats were used to mark 25 foot segments.
The beginning transect point of each of the three
sections was a fixed point with a location determined
using GPS. The transect line was shifted down or up
river by moving one of the weights. GPS points were
taken at the beginning and endpoints of each transect
to assist in locating transects within the river during
the GIS desktop mapping. SAV polygons were hand
drawn relative to the transect onto waterproof paper
from the canoe, or while snorkeling. Notes and
sketches were made regarding the location of the
transect relative to bends in the river. SAV polygons
were drawn onto field sheets with lines representing
the relative distance between transect line and river
boundary.
During the rise in water levels in late March 2003,
water lettuce (Pistia stratiotes) formed a dense mat
across the entire river at several oxbow locations in
the lower portions of the river (Figure 2-7). Little to
no light could penetrate this mass of plant material for
several weeks. Volunteer crews organized by the
Center for Aquatic Studies at the University of
Florida’s Institute of Food and Agricultural Sciences
were led by the Park staff to clear much of this
vegetation during late March and early April 2003.
Flow and river stage in the Ichetucknee River and in
Manatee Springs (the lower Suwannee River) changed
significantly during the field mapping period. Santa
Figure 2-7. Water lettuce mat at oxbows in
lower Ichetucknee River in March 2003 (above)
and effect of vegetation on water column light
penetration (below).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
7
Fe River levels rose approximately 2 to 3 m from late February through late March and this rise
was most pronounced in the downstream section of the Ichetucknee River. Ichetucknee River
stage is directly affected by rises in the Santa Fe River and a plot of river stage in the Santa Fe
and in Manatee Springs is shown in Figure 2-8.
Figure 2-7. Changes in river stage immediately downstream of the Ichetucknee River at the Santa Fe
River USGS gaging station and at Manatee Springs near the Suwannee River (source: USGS, 2003).
In the Ichetucknee River, several larger Zizania aquatica beds that were emergent during initial
field reconnaissance trips in February 2003 became submersed during the field mapping and then
became emergent again as the river level declined. Since the rise in stage was known prior
mapping, these Zizania beds were delineated as shoreline/emergent areas versus SAV beds. In
addition to changes in river stage, shoreline vegetation was pruned during the mapping period.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
8
Private interest groups removed downed trees from the main channel to clear obstructions for
tubers, sometimes exposing areas of bare substrate.
In the Manatee Spring run, water clarity declined significantly with
the rise in river stage – this was due to the more tannic and tidallyinfluenced Suwannee River backflowing into the spring run in
March 2003 (Figure 2-8). The lower portion of the spring run is
flanked by cypress floodplain forest which also drained tannic waters
into the spring run, even during the May 2003 mapping period where
river levels had declined. As a result, light and water quality
conditions in this area are extremely variable. The endangered westIndian manatee (Trichecus manatus) also uses the spring run as a
source of freshwater and forages on SAV during the early spring.
Due to the poor conditions for SAV growth and intense predation by
manatees, SAV in the Manatee Springs run is very sparse. As a
result, a point coverage of SAV beds was created instead of polygons
to identify the location of SAV. Braun Blanquet coverage was
recorded at each point along with approximate dimensions of each
bed, which were typically less than the 30 square feet minimum
mapping unit.
2.1.2.3 Preparation of Digital and Hard Copy Maps
After each field mapping session, the information was transferred
and compiled into the comprehensive, geographically referenced GIS
database using ArcView 3.2. The GPS field delineation was
essentially redigitized "heads up" (traced) in the comprehensive layer
to create clean, complete polygons with their associated attributes.
For the transect mapping, the locations of the 100 foot transects lines
were first digitized onto the basemap, using the GPS points as
supplemental information. The SAV polygons and their attributes
were then digitized "heads up" relative to transect lines from the field
notes, just as they had been in the field. The straight, fixed width
transects of the field sheets were fit into the sinuous, changing width
of the river with the aid of notes and sketches drawn onto the field
sheets.
Figure 2-8. Manatee Springs
run in Feb (above) and May
(below) 2003. Note change in
water clarity (increase in
tannic color).
2.1.2.4 Quality Control Process
SAV mapping data was checked using a rigorous quality control process. Quality control of the
GIS map was performed to verify that all polygons were correctly labeled and that no polygons
were smaller than the minimum mapping unit. The field data were thoroughly reviewed to assure
that information was correctly transferred from the GIS file. The GIS files were checked to
assure that all polygons were labeled, that adjacent polygons did not have the same attributes, and
that attributes in all fields were feasible (for example, that a polygon with Sagittaria kurziana
coverage of 50-100% did not have a bottom feature type of "bare").
The completed GIS map was downloaded onto the handheld computer with GPS for field
verification. This allowed for tracking and viewing one's location on the map while navigating
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
9
the river. The map was verified at 70 locations (Figure 2-9) and the overall accuracy was
determined to be 94.2%. This field checking was done both by selecting random individual
points in the river and by navigating upriver and observing approaching polygons. As the canoe
approached a polygon, its characteristics (size and shape, species present, and cover category)
were identified from the map, and verified by visual observation. Though the GPS signals were
sometimes inadequate to delineate small polygons, they were sufficient to determine relative
location of most polygons in the river. Additional quality control was performed by comparing
field sampling information from the State Park biologist (Sam Cole) taken at 10 transects and also
SAV monitoring data taken by UF in the spring of 2003 at 31 transects.
Figure 2-9. SAV polygon quality control
checkpoints on the Ichetucknee River.
(checkpoints = green box with check mark)
2.2 Results and Discussion
2.2.1 SAV Maps
As described earlier, SAV mapping in the Ichetucknee River was conducted using both GPS and
transect field techniques followed by heads up digitization and editing. The most common
species encountered (in order of percent cover) in the Ichetucknee Springs and River were
Sagittaria kurziana, Zizania aquatica, Vallisneria americana, Chara sp., Myriophyllum
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
10
heterophyllum, Ludwigia repens, and Hydrocotyle sp.
(photographs of the more common species are shown below).
Chara is an algae which grows along the river bottom in large
mats, typically in deeper areas south of the Headspring Run.
Zizania was present mainly in the shallower areas of the
Headspring Run and along the shoreline and in shallow areas
within the Rice Marsh. Sagittaria was present throughout the
river but became mixed with Vallisneria in the lower Rice
Marsh and Floodplain Reach areas.
Myriophyllum was
mapped on only nine occasions, all within the Floodplain
Reach area. Ludwigia and Hydrocotyle were present as small
coverages along much of the river shoreline, but these areas
were typically too small to map (less than 30 ft2 minimum
mapping unit).
Maps of SAV and unvegetated bottom for the Ichetucknee
Springs and River are presented in Appendix B. The shoreline
and SAV point coverage for Manatee Springs are also
presented in Appendix B.
2.2.2 SAV Coverage
2.2.2.1 Ichetucknee Springs and River
The total area of submerged habitat surveyed and classified
during this study was approximately 150,658.22 m2 or 37.23
acres. A breakdown of area by bottom type is presented in
Table 2-1 below. The coverage for emergent bottom type
represents only a small percentage of the actual emergent
marsh vegetation within the river floodplain since emergent
vegetation was only mapped in a few isolated areas
immediately adjacent to SAV beds. This was most prevalent
within the middle “Rice Marsh” area where SAV and
emergents were intermixed within the river boundary. By far,
the dominant habitat features in the river are SAV beds.
A total of 305 separate SAV beds (polygons) were mapped
with a total coverage of 118,035 m2 or 29.2 acres (see Table 21). Table 2-2 represents the coverage of each species within
the river, which results in a greater total number of acres than
reported in Table 2-1. In some cases, an individual polygon
may have more than one species present at a lesser percent
cover than the dominant species. These calculations were
performed by summing the area for each SAV bed (polygon)
by each species present in a given bed.
Sagittaria kurziana was the most prevalent species within the
river representing over 50% of the total SAV cover. The
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
11
second most dominant species was Zizania aquatica at approximately 19%, followed by
Vallisneria americana at approximately 18%. The algae Chara sp. represented about 10% of the
total cover, followed by sparse patches of Myriophyllum heterophyllum, Ludwigia repens, and
Hydrocotlye sp. which each represented less than 1% of the total cover.
Table 2-1. Coverage of bottom types at Ichetucknee Springs and River.
Bottom Type
Sq. Meters
4970.70
27652.07
118035.45
150658.22
Bare
Emergent
SAV
Total
Acres
1.23
6.83
29.17
37.23
%
3.30%
18.35%
78.35%
100.00%
Table 2-2. Coverage of SAV by species in the Ichetucknee Springs and River.
SAV Species
Sagittaria kurziana
Zizania aquatica
Vallisneria americana
Chara sp.
Myriophyllum heterophyllum
Ludwigia repens
Hydrocotyle sp.
Sq. Meters
Acres
76317.06
27199.58
25801.89
14821.98
876.69
499.08
28.78
% of Total
18.86
6.72
6.38
3.66
0.22
0.12
0.01
Mean Braun
Blanquet Cover
52.44%
18.69%
17.73%
10.18%
0.60%
0.34%
0.02%
3
2
3
3
2
2
1
Braun Blanquet Cover Categories 0 = 0%, 1= 0-25%, 2= 25-50%, and 3= 50-100% cover within 1 m2 quadrat.
2.2.2.2 Manatee Springs
The total area of submerged habitat surveyed and classified at Manatee Springs was
approximately 9,040.53 m2 or 2.23 acres. A breakdown of area by bottom type is presented in
Table 2-3 below. The majority of the head spring and spring run are currently bare. Of the SAV
beds present, the dominant species in Manatee Springs and spring run was Sagittaria kurziana.
This species typically occurred as small (<10 m2) patches, typically along the shallower (<2 m)
fringes of the headspring and also in small (<1 m2) clumps in the main spring run. Blade lengths
were typically less than 15 cm. The furthest downstream SAV observation was 215 m from the
headspring. Using coverage estimates gathered during the point coverage mapping, estimates of
SAV cover were calculated and are presented in Table 2-4 below.
Table 2-3. Coverage of bottom types at Manatee Springs and Spring Run.
Bottom Type
SAV
Bare
Total
Sq. Meters
124.24
8916.28
9040.53
Acres
0.03
2.20
2.23
%
1%
99%
100%
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
12
Table 2-4. Coverage of SAV by species in Manatee Springs and Spring Run.
SAV Species
Sq. Meters
Sagittaria kurziana
Ludwigia repens
Potamogeton sp.
Total
Acres
116.492
2.385
5.366
124.24
% of Total
0.0288
0.0006
0.0013
0.03
93.76%
1.92%
4.32%
100%
Mean Braun
Blanquet Cover
1
1
2
Braun Blanquet Cover Categories 0 = 0%, 1= 0-25%, 2= 25-50%, and 3= 50-100% cover within 1 m2 quadrat.
In 1979, Dutoit mapped SAV in the Ichetucknee Springs and River (see Appendix C for copies of
these maps). SAV coverages at that time totalled 26,036 m2 or 6.43 ac. The boundaries of
Dutoit’s mapping effort appear to be smaller than the boundaries used in this study and did not
include several short spring runs at Boiling, Grassy Hole, or Mill Pond Springs. Park use in 1979
had reached over 250,000 visitors per year and stricter regulations to limit environmental abuse
had only recently been implemented. A 3,000 user per day limit had just been established by the
Park to reduce further degradation of the river ecosystem. As a result, SAV was just beginning to
recover after years of unrestricted recreational use during the time of Dutoit’s study.
SAV coverage in the spring of 2003 was much higher than in 1979 at approximately 29 ac and
98% SAV cover of the river bottom versus only 33% coverage in the late 1970s. This increase in
SAV is due to a number of factors, most notably the implementation of the above-mentioned park
regulations and carrying capacity limits for recreational use on the river. Between 1979 and
2003, SAV coverage is estimated to have increased by approximately 74% in the Headspring
Reach, 59% in the Rice Marsh, and 86% in the Floodplain Reach (Table 2-5).
Table 2-5. Estimated Changes in SAV Coverage at Ichetucknee Springs and River between
1979 and 2003.
Area
Headspring Reach
Rice Marsh
Floodplain Reach
Year
1979
2003
1979
2003
1979
2003
Sq. Meters
1872.00
7230.49
12685.00
30799.70
11479.00
80005.26
Acres
0.46
1.79
3.13
7.61
2.84
19.77
% Change
286%
143%
597%
Low coverage of SAV in Manatee Springs is likely due to the flood stage conditions which
occurred immediately prior to mapping. These conditions resulted in the movement of highly
colored water from the Suwannee River into the spring run. Park staff reported dark water
conditions along the entire length of the run to the head spring. This phenomenon occurs
periodically, resulting in low light conditions and poor conditions for SAV growth. Grazing by
manatees also occurs during the spring, further reducing SAV coverage.
For comparative purposes, the following discussion describes conditions in the nearby Rainbow
Springs and River where SAV mapping was recently completed in 2000 (PBS&J, 2000).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
13
Rainbow Springs, located in the southwest Marion County community of Dunnellon, is the fourth
largest of the twenty-seven first magnitude spring runs in Florida. It shares many ecological
features and species with the Ichetucknee Springs and River. Some notable differences include
the Rainbow’s size (width and length), adjacent development, and relatively constant water
levels. The Rainbow River is both a State Aquatic Preserve and an Outstanding Florida Water.
Its average discharge at the headsprings is 700 ft3/second, and average river velocity is 0.5
miles/hour. Mean depth of the Rainbow River is approximately seven feet and maximum depth
15 feet, while roughly half of the river is between 3 and 5 feet deep (Childs, 1999). The river
flows about 6 miles from its source at the head spring to its confluence with the Withlacoochee
River, varying in width from about 100 to 300 feet. In general, the Rainbow is less heavily
shaded than the narrower Ichetucknee and has a greater overall area between the fringing tree
canopies.
Spring discharge for the Rainbow River accounts for 97% to 99% of the volume of the river, and
as a result water contributions from its watershed are insignificant (Water and Air Research,
1991). Spring discharge varies seasonally in response to rainfall, though regulation by the Inglis
dam (located downstream on the Withlachochee River) keeps the Rainbow River stage levels
held relatively constant (Jones, 1996). The constant water levels seem to have several effects on
the vegetation of the river. Trees endure much less stress without widely fluctuating water levels
and therefore tree falls appear to be much less frequent than in the Ichetucknee River. Nonwoody emergent and submersed vegetation do not appear to be in transition because they
experience constant water depths. Only very slight changes in the size and shape of emergent
vegetation beds appear to occur over time. A few, more noticeable changes in emergent beds
appear to be caused by recreational impacts. Like the Ichetucknee, the Rainbow is a very popular
recreational resource, with concessions providing for tube and canoe rental, as well as swimming
and boat launch. The river also used for fishing and SCUBA diving. Motorized boats are
allowed on the river, though only idle speed is permitted. Several abandoned phosphate mines
are present within the banks of the Rainbow River.
The vast majority of the Rainbow River’s west bank is occupied by residential development.
Activities associated with this development have a significant potential to impact SAV through
both direct clearing of SAV as well as general access and use. Between the 1996 and 2000
vegetation mapping efforts, all changes in aerial coverage were less than 10%. At the time of the
2000 mapping, the most dominant SAV species of the Rainbow River were Sagittaria kurziana
(strap-leaf sagittaria), Hydrilla verticillata (hydrilla), and Vallisneria americana (eelgrass),
occurring in 52%, 37%, and 18% of the river respectively. With the exception of hydrilla, these
percentages are nearly identical to the percentages of Sagittaria and Vallisneria in the
Ichetucknee River. The invasive exotic hydrilla has roughly doubled its coverage since 1990 and
is a substantial concern to resource managers. Ceratophyllum demerseum (coontial), Najas
guadalupensis (southern naiad), and Chara sp., each occur in less than 5% of the river. Ludwigia
repens (red ludwigia), Myriophyllum sp., Utricularia sp., and Nasturitium sp. cover less than 1%
of the river each and are confined to the headspring area. Eleven percent of the river is bare
substrate which is much less than in Manatee Springs, but higher than the approximately 3% bare
area in the Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
14
3.0 SAV Sampling
3.1 Introduction
Sampling of SAV in the Ichetucknee Springs and River was conducted to document existing
vegetation conditions and to identify relationships between stream velocity and SAV cover,
biomass and community structure. Due to the paucity of SAV in Manatee Springs, no SAV
sampling was performed. Water quality data for Manatee Springs is presented in Appendix D.
The sampling protocol for SAV provided a statistically rigorous database that was used to assess
multiple relationships between flow velocity, stage, water chemistry, physicochemical parameters
(temperature, pH, conductivity, dissolved oxygen), and light availability (e.g., canopy cover) and
SAV species presence and cover. The sampling protocol followed similar methods developed by
Frazer et al. (2001) for the sampling of five coastal rivers along west-central Florida (four of
which were spring-fed).
3.2 Materials and Methods
For the Ichetucknee River system, 31
evenly distributed transects were selected
for sampling and included a range of
flows and terrestrial canopy coverage
(Figure 3-1). Physical, chemical, and
biological samples were collected on April
30th, 2003 between approximately 9 AM
and 6 PM. These sites were distributed
(approximately 150 m between transects)
in three areas: the Headspring Reach; Rice
Marsh area; and the Floodplain Reach.
The transects were oriented perpendicular
to stream flow and began near the head
spring canoe launch and ended near the
last take-out point near U.S. 27. Several
of these transects were adjacent to
permanent sampling locations utilized by
the park.
Figure 3-1. SAV sampling locations (in green).
At each transect, five stations were sampled, with one in the middle of the river and two to either
side, approximately one-third and two-thirds the distance to the shoreline. Mid-stream sampling
locations were documented with a Garmin WAAS enabled GPS receiver. The sampled
parameters included: stream width (Transects 1-8 only), water column depth, stream flow, canopy
cover, temperature, specific conductance, dissolved oxygen, pH, water column light attenuation,
submersed aquatic vegetation (SAV) biomass and coverage (selected transects), periphyton
abundance, and substrate type.
Stream widths were measured with a 50 m fiberglass tape measure. Water column depth was
measured with a telescoping fiberglass survey rod. Stream velocities were measured at 60% of
water column depth with a Marsh-McBirney Model 2000 portable flow meter reporting 5-second
average values. Terrestrial canopy cover directly above each station was categorized visually as
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
15
0 to 100%. Measures of temperature (deg. C), specific conductivity (µS/cm), dissolved oxygen
concentration (mg/L), and pH were measured in situ with a Yellow Springs Instrument Company
model 650 hand-held meter. Li-Cor Instruments Inc. quantum light sensors were employed to
simultaneously collect surface and downwelling light intensity (umole photons/s/m2 of
photosynthetically active radiation, PAR) with a data logger at selected locations. Light
attenuation (Kd) was determined from the equation: Kd = [ln (Io / Iz)] / z, where Io is incident
irradiance at the water surface and Iz is light intensity at depth z (m) (Kirk 1994). Divers visually
determined the substrate type and assigned it to one of 10 categories: mud, mud/sand, mud/shell,
mud/rock, sand, sand/shell, sand/rock, shell, shell/rock, or rock.
Estimates of SAV coverage (%) were made at all sampling locations (n = 155). Measures of
SAV biomass (kg/m2) were collected along 10 of the 31 regularly spaced transects, so that each
of the three river zones was adequately represented. This resulted in 50 individual measures of
biomass. Along each transect, five stations were sampled for submersed vegetation, with one in
the middle and two to either side approximately one-third and two-thirds the distance to the
shoreline. At each of the resulting stations, a 1-m2 quadrat was placed on the river bottom and the
SAV contained within was visually estimated by its coverage. Although this was done for each
SAV species, total coverage is approximately equal to the most abundant SAV species contained
within the quadrat.
At those transects where SAV biomass was harvested, a 0.25 m2 quadrat was placed on the
bottom and the above-ground biomass contained within the quadrat removed by divers and
transported to the surface. SAV was separated by species and the different fractions were spun in
a nylon mesh bag to remove excess water. Samples were then weighed with calibrated hand-held
Pesola scales. Weights were recorded to the nearest 10 g for samples less than 1 kg and to the
nearest 100 g for samples greater than 1 kg. All types of vegetation present in the quadrat were
recorded and ranked according to their biomass.
Periphyton associated with submersed macrophytes were sampled along the ten transects where
SAV biomass measures were made. Along these transects, a representative sample of the most
abundant macrophyte species was carefully removed and placed in a 1-L Nalgene jar with
deionized water and stored in a cooler with ice until processed (within 24 hours of collection).
Periphyton abundance was quantified with a method used by Moss (1981) and modified by
Canfield and Hoyer (1988a).
Periphyton removal was accomplished by vigorously shaking each bottle for 30 seconds and the
resultant slurry was poured though a 1.0 mm screen into a Nalgene beaker. Fresh deionized water
was then added to the plant sample and the process repeated a total of three times. The total
slurry volume (ca. 1 to 1.5 L) was thoroughly mixed and a sub-sample (ca. 50 to 400 ml) filtered
through a Gelman type A/E 47 mm glass-fiber filter. Filters were stored frozen in wide-mouth
Nalgene jars that contained desiccant until analyzed for chlorophyll.
Periphyton abundance was expressed as mg chlorophyll/g of host macrophyte weight.
Macrophyte weights were expressed either as wet or dry weights (wet wt and dry wt,
respectively). Wet and dry weights for each macrophyte sample were determined by weighing
the plants to the nearest 0.001 g on a Mettler Toledo AG204 scale. Wet (fresh) weights were
measured after the macrophyte samples had been gently blotted with paper towels. Dry weights
were measured after the macrophyte samples had been placed in a forced-air-drying oven
maintained at 65 deg. C for approximately 48 hours.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
16
3.2.1 Data Summaries and Statistical Analyses
All raw data used in summary figures and tables are available in electronic format. Mean transect
values, where appropriate, were used to summarize physical, chemical and vegetative measures.
For correlation analyses and model development, all variables were log10-transformed to
accommodate heterogeneity of variances (Sokal and Rohlf 1981). When aquatic vegetation
biomass estimates were equal to 0.0 kg wet wt/m2, a negligible value of 0.001 kg wet wt/m2 was
used for subsequent statistical analyses. All statistical computations were performed with the JMP
statistical software package (SAS Institute, Inc. 2000). Statements of statistical significance
imply p < 0.05.
3.3 Results and Discussion
Raw data and statiscial summaries of the SAV transects are presented in Appendix D. Summary
results of each parameter sampled are discussed below.
Sampled depth values ranged from 0.3 to 3.0 m, with the sampled river average depth being 1.47
m. Mean mid-channel depth was 1.9 m and mean transect depth generally increased with
distance downstream (Figure 3-2), however, variability in depth at each transect was generally
lower downstream from transect 15. In the upper river, from the main spring boil to the
confluence with Blue Spring run, shallowest average transect depths were encountered. In the
Rice Marsh reach, where the river was widest, shallow depths were common as the river widens,
but a deeper channel was also present. In the lower river section, stream width narrowed and a
concomitant increase in stream depth was noted.
Water depth can potentially influence the abundance and distribution of SAV through several
processes. First, hydrostatic pressure can be directly inhibitory. In fact, Huchinson (1975) noted
that angiosperms in freshwaters are not generally observed deeper than 8 to 11 m. Such depths,
however, do not occur in our study area within the Ichetucknee River.
Second, increased light attenuation and reduced light availability with depth can negatively affect
SAV growth and may, in many instances, prohibit plant colonization. Light levels at all sampling
locations in the Ichetucknee River were sufficient, however, for SAV to occur (see below).
Third, SAV that occurs in shallow water can be subject to physical damage (tearing or uprooting)
by recreational users that walk or drag their feet along the river bottom. The likelihood of
recreational users touching the bottom is a function of the height of the water column (and users’
leg lengths). Shallow water in the upper sections of the Ichetucknee River are likely more
susceptible to recreational damage, while the more consistently deep sections of the river further
downstream may provide a depth refuge for SAV. It is worth noting that SAV in the upper most
river (see historical data for station 4.1 from 1989 to 2002) increased as the daily limit of
recreational users declined.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
17
ICHETUCKNEE RIVER
2.5
2.0
DEPTH (m)
1.5
1.0
0.5
0.0
0
5
10
15
20
25
30
TRAN SECT
Figure 3-2. Mean transect depth (m) for the Ichetucknee River on April 30th 2003.
Measured stream velocity rates ranged from –0.01 to 0.56 m/s, with the a mean of 0.20 m/s. The
negative flow value was encountered in an eddy along a bend of the river at transect 24. Mean
flow velocity gradually increased with distance downstream as a consequence of additional spring
discharge (Figure 3-3). However, variation between transects was often large and may simply be
reflective of the differences in stream widths and depths.
Stream velocity strongly influences the composition of the substrate (Butcher, 1933) which can,
in turn, influence the SAV community. Favorable sediments for macrophyte growth, such as
sandy clays, may be scoured away at velocities greater than 0.30 m/s (Hynes, 1970) and sand
substrates begin to give way to gravel and large rocks at stream velocities of 0.60 m/s or greater
(Butcher, 1933). Thus, a stream bed consisting of large stones or bare rock that are continually
being rolled or scoured will have little submersed aquatic vegetation, while a river bed that is
comprised largely of mud, silt and sand has the potential to support abundant aquatic vegetation
(Allan 1995). Additionally, large amounts of continuously shifting sand may bury established
macrophyte communities while remaining too unstable to allow re-colonization. Therefore,
detrimental aspects of flow are generally encountered at high stream velocities.
Within the Ichetucknee River, the average observed flow rate was 0.20 m/s, with only 10% of the
measured flow rates exceeding 0.33 m/s. These values appear to be well below those necessary
to scour the substrate or dislodge rooted plants (see Butcher, 1933) and correspond closely with
the velocity values for peak macrophyte diversity reported by Nilsson (1987). Streams with these
velocities may be expected to have mud or sand substrates, which agree with our observations
that the substrate in the Ichetucknee River is mostly composed of about 39% sand and 47% mud
(see Figure 3-13 below). While we modeled significant relationships between SAV biomass and
SAV coverage with stream velocity, only a small amount of the variation in these parameters
(13% and 4%, respectively) could be explained by stream velocity (see Figures 3-4 and 3-5).
Thus, current velocity is not a strong predictor of the abundance and distribution of submersed
aquatic vegetation in this river.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
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ICHETUCKNEE RIVER
0.30
0.25
FLOW (m/s)
0.20
0.15
0.10
0.05
0.00
0
5
10
15
20
25
30
TRANSECT
Figure 3-3. Mean transect flowvelocity (m/s) for the Ichetucknee River on April 30th 2003.
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
0
.1
.2
.3
.4
.5
.6
Flow (m/s)
Figure 3-4. Relationship between SAV biomass and flow in the Ichetucknee River on April 30th 2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
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Mean SAV Percent Coverage
100
80
60
40
20
0
.10
.15
.20
.25
Mean Flow (m/s)
Figure 3-5. Relationship between SAV coverage and flow in the Ichetucknee River on April 30th 2003.
Measured canopy cover values ranged from 0 to 100%, with an average of 40% (Figure 3-6). As
previously noted, SAV is dependent on adequate light availability. Shading from terrestrial
vegetation has been linked to SAV abundance and distribution in stream systems (Canfield and
Hoyer 1988). We observed no such relationships between terrestrial canopy coverage and SAV
biomass or coverage (Figures 3-7 and 3-8, respectively). While there was a subtle decline in
SAV as terrestrial canopy cover increased, it was not statistically significant.
Although the presence of a terrestrial canopy certainly can reduce incident surface light, other
environmental parameters such as stream orientation or angle of sun inclination may give better
estimates of SAV cover or biomass at fixed stream locations. We noted that large amounts of
SAV were often measured in shaded portions of the river, but it is possible that the plant growth
(production) is reduced in these shaded areas relative to more open areas in the river. If so, then
plants occurring in these areas may be more susceptible to further reductions in the light field or
other disturbances.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
20
ICHETUCKNEE RIVER
100
TERRESTRIAL CANOPY COVER (%)
80
60
40
20
0
0
5
10
15
20
25
30
35
TRANSECT
Figure 3-6. Mean transect canopy cover (%) for the Ichetucknee River on April 30th 2003.
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
0
20
40
60
80
100
Terrestrial Canopy Cover %
Figure 3-7. Relationship between SAV biomass and canopy cover in the Ichetucknee River on April 30th
2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
21
SAV Coverage (per m)
100
80
60
40
20
0
0
20
40
60
80
100
Terrestrial Canopy Cover %
Figure 3-8. Relationship between SAV coverage and canopy cover in the Ichetucknee River on April 30th
2003.
Measured values for the vertical light attenuation coefficient at transects 1, 5, 6, and 7 ranged
from 0.49 to 0.71 (Kd/m) with an average of 0.59 (Kd/m). These values suggest that Kd values
increase with distance downstream, potentially as a result of an increase in suspended particles in
the water column. Light attenuation coefficients are integrated measures of the amount of light
reduction with depth. In the aquatic environment, light is absorbed and reflected by suspended
particles (algal and non-algal), dissolved material (humics) and by the water itself. If any one of
these light-attenuating factors is increased, then the light available for SAV photosynthesis will
be reduced.
Using our minimum and maximum estimates of light attenuation (Kd of 0.49 to 0.71/m), SAV in
the Ichetucknee River should have sufficient light (>10% of incident irradiance) to a depth of 3.2
to 4.7 meters. The euphotic depth is the depth beyond which light levels are less than some
percentage of surface irradiation (approximately 1% for phytoplankton and 10% for
macrophytes). Below this level, it is generally accepted that net positive photosynthesis by plants
and algae does not occur (Scheffer 1998) and, if the low light environment is persistent, plants
and algae should not be expected to occur. Given that the present euphotic depth is greater than
the water column depth, light limitation of SAV should not occur in the Ichetucknee River unless
water clarity declines.
Temperatures, at the time of sampling, ranged from 21.8 to 23.8 deg. C, with an average of 23.1
deg. C. Mean transect temperature values gradually increased with distance downstream from the
head spring until approximately transect 14, at which point they remained relatively stable
(Figure 3-9). The mean temperature for transects 14 through 31 was 23.6 deg. C. These gradual
increases in temperature were expected as a result of increasing solar heating within the less
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
22
canopied Rice Marsh, and also the lack of significant spring flows in the lower reaches of the
river.
Specific conductivity values ranged from 309 to 348 uS/cm (at 25 deg. C), with an average of 327
µS/cm. Mean transect specific conductivity values generally increased with distance downstream
(Figure 3-10).
IC H E T U C K N E E R IV E R
24 .0
23 .5
TEMPERATURE (°C)
23 .0
22 .5
22 .0
21 .5
21 .0
0
5
10
15
20
25
30
T R AN S E C T
Figure 3-9. Mean transect temperature(°C) for the Ichetucknee River on April 30th 2003.
ICH ETU CKN EE RIVER
345
340
SPECIFIC CONDUCTIVITY (µS/cm)
335
330
325
320
315
310
305
0
5
10
15
20
25
30
T R AN SEC T
Figure 3-10. Mean transect specific conductivity (µS/cm at 25 °C) for the Ichetucknee River on April
30th 2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
23
Dissolved oxygen (DO) values ranged from 3.6 to 8.1 mg/L, with an average of 6.4 mg/L. In the
upper river, dissolved oxygen concentrations rapidly increased with distance downstream from
the main spring. At transect 14, values declined (Figure 3-11). These observed trends in
dissolved oxygen concentration are consistent with other vegetated spring-fed rivers (Frazer et al.
2001), in which the ground water emanating from spring vents has low DO values, and rapidly
increases due to photosynthesis by SAV and atmospheric diffusion.
IC HETUC KN EE R IV E R
9.0
8.0
DISSOLVED OXYGEN (mg/L)
7.0
6.0
5.0
4.0
3.0
2.0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
TR AN SEC T
Figure 3-11. Mean transect dissolved oxygen (mg/L) for the Ichetucknee River on April 30th 2003.
Measured pH values ranged from 7.2 to 7.9, with an average of 7.7. A gradual increase in pH
was noted (Figure 3-12). Given the abundance of SAV in the river and the trend of dissolved
oxygen and pH values simultaneously increasing downstream, we attribute the changes in pH to a
decline in carbon dioxide as SAV utilizes this gas during photosynthesis.
Eight SAV species of submersed aquatic vegetation were observed within sample quadrats. In
order of rank abundance they were as follows: Sagittaria kurziana (strap-leaf sagittaria) at 54%,
Zizania aquatica (wild rice) at 17%, Vallisneria americana (tape grass) 10%, Chara sp.
(muskgrass) at 6%, Vaucheria sp. (filamentous algae) at 5%, Fontinalis sp. (watermoss) at 3%,
Ludwigia repens (red ludwigia) at 2%, and Hydrocotle sp. (dollar weed) at 1% (Figure 3-13).
These values for the dominant species are nearly identical to the values calculated from the SAV
maps, and provide further quality assurance for the mapping effort. Two species Nasturtium
officinale (watercress) and Myriophyllum heterophyllum (foxtail) were observed outside of
sampled quadrats. The three dominant species Sagittaria kurziana, Zizania aquatica, and
Vallisneria americana, together comprised 81% of the observations, indicating that relatively few
species contribute to the majority of the SAV cover present in the Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
24
ICHETUCKNEE RIVER
8.0
7.8
pH
7.6
7.4
7.2
7.0
0
5
10
15
20
25
30
TRANSECT
Figure 3-12. Mean transect pH for the Ichetucknee River on April 30th 2003.
IC H E T U C K N E E R I V E R
Z iz a n ia a q u a t ic a
FREQUENCY OF OCCURRENCE BY SPECIES
V a u c h e r ia
V a llis n e r ia a m e r ic a n a
S a g it t a r ia k u r z ia n a
L u d w ig ia r e p e n s
H y d r o c o t y le
F o n t in a lis
C h a ra
None
0
10
20
30
40
50
60
PERCENT
Figure 3-13. Frequency of occurrence for the dominant SAV species sampled in the Ichetucknee River
on April 30th 2003.
Within the sampled quadrats, SAV coverage ranged from 5 to 100 %, while mean cover values
for transects ranged between 44 and 100 %. The sampled river had a mean SAV coverage value
of 71 %. Mean transect SAV coverage gradually increased with distance downstream (Figure 3Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
25
14). Mean SAV coverage (by transect) and mean depth (by transect) were positively correlated
(Figure 3-15, r2 = 0.26), further suggesting that depth is not limiting SAV growth in the
Ichetucknee River. We observed a weak positive correlation between stream flow and SAV
coverage (r2 = 0.10; p = 0.09) (Figure 3-5). However, as flow rates are moderate in the
Ichetucknee River (see above), it is not likely that the abundance and distribution of SAV would
be largely affected by naturally occurring variations in stream flow rates. When comparing SAV
coverage to canopy cover, we observed a decline in SAV coverage with increasing canopy cover,
but the relationship was not statistically significant (Figure 3-8).
ICHETUCKNEE RIVER
120
SAV PERCENT COVERAGE
100
80
60
40
20
0
0
5
10
15
20
25
30
T RAN SEC T
Figure 3-14. Mean transect SAV percent coverage for the Ichetucknee River on April 30th 2003.
Within sampled quadrats, SAV biomass values ranged from 0.14 to 13.8 kg/m2 wet weight, while
mean values (by transect) ranged between 2.4 and 8.0 kg/m2 wet weight. The sampled river
average was 4.7 kg/m2 wet weight. SAV biomass generally increased with distance downstream
(Figure 3-16). SAV biomass was positively correlated with depth (r2 = 0.20, Figure 3-17), largely
because SAV leaf (blade) length tended to be greater in the lower river where depths were also
generally greater. The potential for a reduction in SAV biomass as river depths decline may exist
based on this empirical relationship. SAV biomass and stream flow were positively correlated (r2
= 0.13) (Figure 3-18), suggesting (as above) that stream flow does not reach velocities which are
inhibitory to SAV biomass in the Ichetucknee River. Finally, we observed a qualitative decline in
SAV biomass as terrestrial canopy coverage increased, but the relationship was not statistically
significant (Figure 3-7).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
26
Mean SAV Percent Coverage
100
80
60
40
20
0
1.0
1.5
2.0
2.5
Mean Depth (m)
Figure 3-15. Relationship between SAV coverage and depth in the Ichetucknee River on April 30th 2003.
ICH ETUCKNEE RIVER
10
9
7
6
2
SAV BIOMASS (kg/m wet weight)
8
5
4
3
2
1
0
0
5
10
15
20
25
30
TR AN SEC T
Figure 3-16. Mean transect SAV biomass (kg/m2 wet weight) for the Ichetucknee River on April 30th
2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
27
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
.0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Depth (m)
Figure 3-17. Relationship between SAV biomass and depth in the Ichetucknee River on April 30th 2003.
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
0
.1
.2
.3
.4
.5
.6
Flow (m/s)
Figure 3-18. Relationship between SAV biomass and flow in the Ichetucknee River on April 30th 2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
28
Twenty-seven samples from 10 different transects were collected to estimate periphyton
abundance (mg chlorophyll per g of host macrophyte wet weight). Periphyton abundance ranged
from 0.01 to 0.37 mg chl/g host plant wet weight, with the sampled river average equal to 0.106
mg chl/g host plant wet weight. Mean transect periphyton abundance generally declined with
distance downstream, although peak abundance was observed at transect 11 (in the Rice Marsh
zone of the river) (Figure 3-19).
Periphyton abundance has commonly been correlated to water column nutrient concentrations,
stream flow and light availability (e.g., Notestein et al. 2003 and references therein). Although
nutrient data were not collected, we may assume that water column nutrient concentrations were
highest at the spring vents and declined with distance downstream, as we have observed in other
spring-fed river systems (Frazer et al. 2001). A decline in water column nutrients with distance
downstream may result in a decline in periphyton abundance. A negative correlation between
stream flow and periphyton abundance (r2 = 0.46) was observed when comparing mean transect
values (see Figure 3-20). This suggests that as stream flow increases, periphyton may be
dislodged at higher rates. Reductions in stream flow could, in turn, facilitate higher periphyton
abundance, and negatively impact the SAV community.
A negative correlation between terrestrial canopy cover and periphyton abundance (r2 = 0.45) was
also observed when mean transect values were compared (Figure 3-21), suggesting that
periphyton abundance may be correlated with light availability, as has been reported in other river
systems (e.g. Hill and Harvey 1990). Greatest light availability was found in the Rice Marsh
reach.
ICHETUC KNEE RIVER
0.12
PERIPHYTON (mg chl/g host plant wet wt.)
0.10
0.08
0.06
0.04
0.02
0.00
0
5
10
15
20
25
30
T R AN SEC T
Figure 3-19. Mean transect periphyton abundance (mg chl/g host plant wet weight) for the Ichetucknee
River on April 30th 2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
29
Mean Periphyton Abundance (mg chl/g host wet weight)
0.30
0.25
0.20
0.15
0.10
0.05
0.00
.10
.15
.20
.25
Mean Flow (m/s)
Mean Periphyton Abundance (mg chl/g host wet weight)
Figure 3-20. Relationship between periphyton abundance and flow in the Ichetucknee River on April
30th 2003.
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
25
50
75
100
Mean Canopy Cover (%)
Figure 3-21. Relationship between periphyton abundance and canopy cover in the Ichetucknee River on
April 30th 2003.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
30
Six different categories of river substrate were observed. By order of abundance they were: mud,
sand, rock, shell fragments, mud/sand and sand/rock (Figure 3-22). In general, the substrate was
dominated by mud (47%) and sand (39%). The prevalence of mud and sand suggests that most of
the river bottom is suitable for SAV colonization and growth.
ICH ETUCKNEE RIVER
Shell
SEDIMENT TYPE
Sand/R ock
Sand
R ock
M ud/Sand
M ud
0
5
10
15
20
25
30
35
40
45
50
PER C EN T
Figure 3-22. Histogram of sediment types in the Ichetucknee River on April 30th 2003.
Ichetucknee SAV in comparison to other Florida spring-fed rivers
A comparison between the SAV community within the Ichetucknee River and four other springfed rivers was made possible based on prior research (Frazer et al. 2001) conducted during the
summers of 1998, 1999 and 2000. The other four rivers, Crystal, Homosassa, Chassahowitzka
and Weeki Wachee, like the Ichetucknee, are primarily spring-fed. Each of the four latter rivers,
however, discharges directly into the Gulf of Mexico and all are tidally influenced. As the
spring-fed coastal rivers were sampled during three consecutive summers, we report (as
appropriate) mean values by river and ranges within each river over the three year time period.
Within the Ichetucknee River, approximately 98% of the stations sampled had at least some SAV
present. Within the other spring-fed rivers, we observed that the percentage of sampled river
bottom with SAV was less: 42% in the Crystal River, 72% in the Homosassa River, 85% in the
Chassahowitzka River and 84% in the Weeki Wachee River. The Ichetucknee River has a high
prevalence of SAV and the majority of the SAV is due to two species, Sagittaria kurziana and
Vallisneria americana, which had a combined frequency of occurrence of 74%. In the
comparative systems, Sagittaria kurziana and Vallisneria americana were rarely dominant. In
fact, the combined occurrences of these two species were only 19%, 6%, 32% and 19% (three
year average, 1998 to 2000) for the Crystal, Homosassa, Chassahowitzka and Weeki Wachee
Rivers, respectively.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
31
In comparison to these four coastal spring-fed rivers, the Ichetucknee River can be characterized
as highly vegetated with a relatively small number of dominant native submersed aquatic species.
It is worth noting also, that in the four coastal spring-fed rivers, filamentous algae (e.g., Lyngbya,
Enteromorpha and Chaetomorpha) were common and frequently abundant to the point of
nuisance levels. Additionally, non–indigenous species such as Hydrilla verticillata and
Myriophyllum spicatum were commonly observed, and at times were the dominant
representatives of the SAV community. This is in stark contrast to the Ichetucknee River.
Although SAV coverage was not estimated in the four coastal rivers, biomass was measured at all
sampling stations. The mean biomass of SAV within the Ichetucknee River was higher than the
four comparative rivers (Table 4-1), and the maximum observed biomass within an individual
sampling quadrat in the Weeki Wachee River was the result of a dense bed of Hydrilla
verticillata (Frazer et al. 2001). These data suggest that factors which are known to influence the
abundance and distribution of SAV, i.e. available light, stream flow, sediment type, grazing
and/or salinity, are relatively favorable within the sampled portions of the Ichetucknee River
compared to other nearby spring-fed rivers.
Table 4-1. A comparison of SAV biomass between five Florida spring-fed rivers. Ichetucknee River
statistics are derived from data collected on April 30, 2003 (N = 155), while the other four rivers statistics
are from data collected during August of 1998, 1999 and 2000 (N = 300).
Mean SAV
Biomass
(kg/m2)
Minimum SAV
Biomass
(kg/m2)
Maximum SAV
Biomass
(kg/m2)
Ichetucknee
4.66
2.4
8.0
Crystal
0.42
0.0
2.6
Homosassa
0.71
0.0
4.4
Chassahowitzka
1.44
0.0
5.5
Weeki Wachee
3.86
0.0
21.4
River
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
32
4.0 Macroinvertebrate Sampling
4.1 Introduction
Springs and spring-fed rivers provide important habitats for diverse biological communities. A
summary describing the current body of research regarding freshwater macrofauna in Florida’s
karst habitats was recently prepared by Walsh (2001). The FDEP and researchers at the
University of Florida have conducted benthic macroinvertebrate sampling at Ichetucknee Springs
and several other spring systems throughout the state (FDEP, 1997; Woodruff, 1993). However,
few studies exist which describe the epibenthic or SAV-associated macroinvertebrate
communities in spring-fed systems. The most recent monitoring results by FDEP indicate that
stream health in the Ichetucknee River system falls midway between Fair and Healthy on the
stream index scale with water quality data indicating elevated levels of nitrates (FDEP, 2002).
The spatial distribution, abundance, and diversity of SAV and associated epibenthic
macroinvertebrate communities, are often utilized to assess the heath of aquatic ecosystems
(Thorp, 1997). Benthic macroinvertebrates and SAV are strong indicators of environmental
health as they are sensitive to ambient stress imposed by fluctuations in water quality, water
quantity, and temperature. Stress tends to reduce the number of different types of organisms
present in aquatic systems. Additionally, special emphasis is given to certain taxa that are known
to be highly sensitive to pollution (FDEP, 1996). Studies have been conducted identifying the
roles of certain taxa within the trophic dynamic of aquatic systems. SAV typically supports a
more diverse and higher density population of macroinvertebrates when compared with other
open water habitats in the same vicinity (Balci, 2003). Additionally, taxa richness and taxa
abundance fluctuate between different species of SAV. In the Ichetucknee River, the SAV
community is primarily comprised of Vallisneria americana, Sagittaria kurziana, Zizania
aquatica, and Chara sp.
SAV-associated macroinvertebrate sampling was conducted throughout the Ichetucknee River
concurrently with the SAV mapping effort. This biological data will be used to assess the current
health of the macroinvertebrate community and for comparisons between SAV species, river
reach (Headspring vs. Rice Marsh vs. Floodplain), flow, and depth.
4.2 Materials and Methods
This study was conducted at 31, evenly distributed stations along the Ichetucknee River,
beginning at the headsprings of the Ichetucknee State Park down to the most downstream canoe
take out point near the U.S. 27 bridge. SAV-associated macroinvertebrate sampling was
conducted at the same stations described in the SAV sampling section described above. The
sampling stations are the same as shown in Figure 3-1 above. The river was divided into the
following three reaches, which corresponds to the different levels of shading created by the
canopy: Headspring Reach (heavily canopied), Rice Marsh (little to no canopy), Floodplain
Reach (heavily canopied). Sampling was performed by canoe, snorkeling, and SCUBA in
deeper reaches of the river.
At each of the 31 sites (transects), the total width of the stream was measured. From the total
width, three stations where chosen and labeled: one in the middle, and two equidistant between
the middle and far edges. The stations were labeled A, B, and C, respectively, with A always
occurring on the left side of the river while facing upstream (typically the west side of the river),
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
33
all B stations in the middle of the river, and all C stations on the right side of the river. At each
transect, ambient weather conditions were recorded along with a brief description of the shoreline
on either bank. At each station (A, B, and C) that was vegetated, SAV/macroinvertebrate
samples were collected using an elongated nitex mesh bag with a square metal frame at the open
end and a sample collection jar at the closed end. The bag was lowered quickly over each site.
The vegetation that occurred within the squared open end were cut approximately one inch above
the substrate and allowed to float up into the mesh bag. The sample was then brought to the
canoe for processing.
SAV blades were carefully transferred to pre-weighed, labeled sample containers. The remaining
biota in the net was rinsed down to the sample jar at the closed end. The excess water was
drained through the net and the sample added to the labeled sample container. Any remaining
sample was rinsed down with a squirt bottle using as little water as possible. The sample was
than weighed in grams to obtain a wet weight. The sample was then preserved immediately in
10% formalin.
At each A, B, and C station, an underwater photograph was taken prior to sample collection.
Subsequently, an estimate of the percent cover at each station was conducted using the BraunBlanquet index of vegetation cover. This index includes identifying all species represented in a
standardized area, then assigning each one of the following codes: 0: species not present, 1:
species <5 percent of total, 2: species = 5-10 percent of total; 3: species = 10-25 percent of total;
4: species = 25-50 percent of total; 5: species 50-90 percent of total; 6: species = >90 percent of
total. Ranges of percent cover are expressed as numerical values. Also noted at each station was
the presence or absence of epiphytes and any other pertinent observations. Copies of field notes
are provided in Appendix E.
In the lab, all macroinvertebrates were subsequently rinsed from the SAV blades and transferred
to glass jars and preserved in ethanol. Subsequently they were sorted, enumerated, and identified
to the lowest possible taxon. However, due to the high abundance of macroinvertebrates,
subsampling was conducted. A glass pan, (approx. 13” x 9” x 2”) was sectioned into identical
squares labeled 1 through 40. Individuals were removed and enumerated from a randomly
chosen square until 100 animals were counted. Once 100 animals were counted, the remainder of
the square was enumerated. If 100 animals were not present within the area of one square, a
second would be randomly selected etc., until a count of 100 was reached. A different
subsampling method was used for oligochaetes. Due to large numbers of individuals,
oligochaetes were subsampled by randomly selecting at least 6 individuals from each sample and
identifying to genus and/or species. Three SAV blades (excluding Chara) were measured to
calculate an average blade length for each sample. No B samples were collected at stations 13 or
18 due to a lack of SAV in the middle portion of the river. All statistical comparisons were
conducted at the 95% confidence level (p<0.05).
4.3 Results and Discussion
Results are presented for all mid-river or B sampling stations. A total of 31,539 individuals
representing 69 species of macroinvertebrates were identified during this sampling effort.
Chironomids dominated the samples and represented approximately 91.8% of all samples
combined, followed by Hydracarina sp. (4.3%), Petrophilla sp. (1.2%), Hydroptila sp. (0.7%),
and Oxyethira sp. (0.5%). A list of all macroinvertebrate species identified from B stations for
the 31 transects is provided in Appendix F. Chironomid taxa are presented in Appendix G.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
34
The results indicate that the number of individual macroinvertebrates and the number of different
macroinvertebrate taxa vary between the three river segments (Headspring reach, Rice Marsh,
Floodplain reach) (Table 4-1, Figure 4-1). The lowest number of taxa represented within the
samples occurred in the Floodplain reach, ranging from 3 to 15 individuals (Figure 4-2). Due to
the large number of individual chironomids, this group is represented as one taxa. The
Floodplain reach includes transects 15 through 31, and is the furthest downstream and the longest
portion of study area. This segment of the river also had the highest percent canopy cover, the
highest temperature, the highest flow velocities, and the lowest periphyton abundances. The
number of individual macroinvertebrates within the Floodplain reach was as low as 19 animals
and as great as 3,319 animals, with an average of 701 individuals.
Table 4-1. Mean values for SAV-associated macroinvertebrate abundance and taxa for the Ichetucknee
River.
River Reach
Headspring
Rice Marsh
Floodplain
Range of Abundance
65-890
369-5337
19-3319
Mean Abundance
376
2364
701
Range of Taxa
5-12
6-18
3-15
Mean # of Taxa
8
12
8
The Rice Marsh segment of the river included transects 5 through 14, and is the most open reach
with respect to canopy cover. The number of individuals was consistently higher within this
segment (Figure 4-1). The mean abundance was 2,364, and the greatest number of individuals in
a transect was 5,337. The mean abundance and mean number of taxa were significantly higher
within the Rice Marsh reach, compared to the other two river segments The highest periphyton
abundance was also found within this segment of the spring run.
6000
5000
4000
3000
2000
1000
0
Transect
Figure 4-1. SAV-associated macroinvertebrate abundance at transects along the Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
35
The Headspring reach included transects 1 through 4 and is the shortest segment of the river
reach, as defined by this study. This area is also heavily canopied and had the lowest
temperatures and depths. The mean number of taxa was the same as the floodplain reach though
the mean number of individuals was lower than the other two river segments. This may be due to
a lower sample size compared to the Rice Marsh and Floodplain reaches which had between 10 to
15 transects each.
20
18
16
14
12
10
8
6
4
2
0
Transect
Figure 4-2. Numbers of SAV-associated macroinvertebrate taxa at transects along the Ichetucknee
River.
As previously stated, the Chironomids were not identified to family or genus; however
approximately six, randomly selected, individuals were identified to the lowest practical taxon
and include the following: Chironomus sp. (gatherer), Cricoctopus sp. (grazer/gatherer),
Dicrotendipes sp. (gatherer), Labrundinia sp. (predator), Labrundinia pilosella (predator),
Paratanytarsus sp. (gatherer), Pentaneura sp. (predator), Polypedilum convictum (gatherer),
Polypedilum illinoesnse gatherer), Procladius sp. (predator), Pseudochironomus sp. (gatherer),
Tanytarsus sp. (gatherer), and Thienemanniella sp. (grazer). Of the individuals identified,
Dicrotendipes sp. was the dominant taxa, comprising 42% of the total.
Macroinvertebrate abundance was negatively correlated with canopy cover (p=0.026) (Figure 43). The greatest canopy cover occurred in the Headspring and Floodplain reaches compared to
the Rice Marsh which had little to no canopy cover over the main river channel. Mean abundance
was significantly greater in the Rice Marsh compared to the Headspring (p=0.0006) and
Floodplain (p=0.0003) reaches, but was not significantly different between the Headspring and
Floodplain reaches (p=0.87). Mean number of taxa was also negatively correlated with canopy
cover (Figure 4-4) and was significantly greater at the Rice Marsh than at the Floodplain reach
(p=0.01, n=24). However, there were no significant differences between the Rice Marsh and the
Headspring (p=0.11), nor between the Headspring and Floodplain reaches (p=0.76).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
36
Scatterplot (Ichetucknee.STA 11v*27c)
y=1932.007-18.78*x+eps
6500
5500
ABUND
4500
3500
2500
1500
500
-500
-10
10
30
50
70
90
110
AVGCANOP
Figure 4-3. Relationship between macroinvertebrate abundance and average canopy cover (%) in the
Ichetucknee River.
Scatterplot (Ichetucknee.STA 11v*27c)
y=11.489-0.056*x+eps
20
16
TAXA
12
8
4
0
-10
10
30
50
70
90
110
AVGCANOP
Figure 4-4. Relationship between number of macroinvertebrate taxa and average canopy cover (%) in
the Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
37
Both abundance (r2 = 0.68, p= 0.006) and number of taxa (r2 = 0.48, p= 0.04) were also correlated
with periphyton abundance (mg chl/g host plant wet weight) (Figures 4-5 and 4-6). As described
in the previous section, greatest periphyton abundance was found in the Rice Marsh area
compared to the Headspring and Floodplain reaches.
The Ichetucknee River is classified as a first-magnitude Florida spring, which is defined as
having a discharge of greater than 100 cubic feet per second (cfs). Water velocity is considered
to be critical to this type of lotic freshwater community, which is usually dominated by
rheophyllic organisms (DEP, 1998). Although there were no significant differences in the
number of taxa or abundance with respect to flow velocity, certain species of the following
groups are considered to be “current loving”, all of which were observed during this study:
Colleoptera, Emphemeroptera, Plecoptera, Tricoperta, Odonata, and Diptera, Oligochaeta
(Naididae).
The general morphology of SAV influences the colonization and the type of epiphytic
macroinvertebrate community that will coexist. However, other factors such as epiphyton
biomass, predation pressure, and seasonal variations can affect the distribution and abundance of
macroinvertebrates (Balci, 2003). Interestingly, there were no significant differences in the
number of taxa (p=0.10) or abundance (p=0.94) with respect to SAV species (Vallisneria,
Zizania, Sagittaria, or Chara) or wet weight, indicating that macroinvertebrates were widely
distributed among the in-stream vegetation.
Several previous studies have shown that Chironomids are one of the most abundant and diverse
macroinvertebrate groups that exist within SAV communities of Florida streams (Warren et al.,
2000; FDEP, 1998). Chironomid larvae area an important food source for many freshwater fish
and other invertebrate species and their role within aquatic systems has been well established
(Menzie, 1980). The trophic functions of a majority of the species within this group have been
identified as grazers and gatherers. This invertebrate community structure is generally associated
with desirable species of SAV, indicative of sufficient water velocity and water quality (Warren
2000). Though an increase in % percent Diptera generally implies lower water quality, diversity
among the chironomids is indicative of good stream conditions (FDEP, 1997).
Though diversity within the Chironomids was only subsampled, the abundance of animals present
was high. The relationship between the dominant SAV-associated taxa (Chironomids), their
predicted feeding types (grazer/gatherer), and periphyton abundance (periphytic algae) was
statistically significant. As percent canopy cover decreased within the different reaches of the
river, periphyton increased along with the macroinvertebrate abundance. Periphyton was more
abundant in the Rice Marsh reach where there is less canopy cover and greater light availability.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
38
Scatterplot (Ichetucknee.STA 12v*27c)
y=-215.234+12459.7*x+eps
6500
5500
ABUND
4500
3500
2500
1500
500
-500
0.00
0.06
0.12
0.18
0.24
0.30
PERIPHYT
Figure 4-5. Relationship between macroinvertebrate abundance and periphyton abundance in the
Ichetucknee River.
Scatterplot (Ichetucknee.STA 12v*27c)
y=-291.338+161.716*x+eps
6500
5500
ABUND
4500
3500
2500
1500
500
-500
0
4
8
12
16
20
TAXA
Figure 4-6. Relationship between number of macroinvertebrate taxa and periphyton abundance in the
Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
39
5.0 Recreational Use Impact Assessment
5.1 Introduction
Recreational activity has probably been the most important factor affecting the health of the
Ichetucknee River and associated SAV beds from the 1970s to present. Monitoring by Park staff
has indicated a relatively consistent trend of declining SAV coverage during the high use summer
period, followed by an increase in coverage through the spring. The rate of decline in SAV
coverage may be due to combination of recreational use and other factors such as long-term
changes in surface and groundwater levels.
Daily limits on the number of recreational users are set at 750 for the Upper tube launch, and
2250 for the Midpoint tube launch; an unlimited number of tubers may enter the river at the
Dampier’s Landing tube launch. These limits were established on the basis of studies which
evaluated the kinds and amounts of damage that swimming, canoeing, diving, and tubing had on
the aquatic communities (Dutoit, 1979; MacLaren and Younker, 1989).
Using SAV and park use data collected by Ichetucknee Park staff and available hydrologic data,
relationships between water levels and changes in SAV coverage were analyzed after periods of
heavy recreational use to determine if damage is greater during times of drought and/or low water
levels.
5.2 Methods
The Park Service at Ichetucknee
Springs has collected transect data
since 1989 at 17 transects in the
park to evaluate recreational
impacts. These locations are
shown and labeled by transect
number in Figure 5-1. These data
are
typically
collected
in
April/May, prior to the start of the
high use summer period, and in
late fall following the peak use
period. This information allows
the park staff to evaluate impacts
caused by heavy use in the
summer and then recovery of
vegetation during the winter.
Changes in vegetation cover for
the dominant species at each
transect were calculated for each
spring and summer monitoring
period.
Long term rainfall data were
obtained for the Lake City
Figure 5-1. Ichetucknee Park transect locations (in blue).
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
40
precipitation station to evaluate trends in the recharge area of the springs. Long term
groundwater level data (Tin Lizzie well) provided by the District in the vicinity of Ichetucknee
Springs was also evaluated to determine if relationships exist with respect to trends in SAV
coverage. Park staff has also collected water level data at the head spring since the 1990s.
The Park staff has also collected depth soundings along each transect and stage data at the
headsprings and headsprings run. The intensity of disturbance with respect to changes in stage
was evaluated using this data. Trends were analyzed to determine if relationships exist between
stage, water depth, and vegetation cover changes along each spring run along with changes in
recreational use (park use statistics). Park use statistics are collected and analyzed by Park staff
annually to determine if the carrying capacity of the river has been exceeded and if closings are
needed to allow recovery of SAV. Carrying capacity, in this case, can be defined as the rate of
use at which damage is equal to the natural ability of each plant community to recover (Dutoit,
1979).
5.3 Results and Discussion
Heaviest park use occurs between June and August - this pattern has been consistent since the
1980s (Figure 5-2). Park use declined at the north river area of the park from over 85,000 visitors
in the late 1980s to as low as approximately 40,000 visitors in the early 1990s. North river use
has been relatively stable at approximately 50,000 to 60,000 visitors since 1995 (Figure 5-3). In
the south river area, park use has slowly risen since 1991 from approximately 65,000 visitors to
over 100,000 visitors in 1999. A slight declining trend has occurred in both the north and south
river since 1999/2000 and 2002.
Ichetucknee State Springs Park Visitors 1987-2000
70,000
60,000
# People
50,000
40,000
30,000
20,000
10,000
JU
L
AU
G
SE
P
O
C
T
N
O
V
D
EC
JA
N
FE
B
M
AR
AP
R
M
AY
JU
N
0
Months
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Figure 5-2. Changes in park use over between January and December annuall at Ichetucknee Springs
State Park.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
41
Yearly Total of River Users at North and South End
(Apr 1987 - Sep 2002)
120,000
# People
100,000
80,000
60,000
40,000
North River Total
20,000
South River Total
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
0
Year
Figure 5-3. Changes in river use at Ichetucknee Springs and River since 1987.
Long term rainfall trends from the Lake City gage appear to have declined since the El Nino
period between 1997 and 1998 (Figure 5-4). Droughty conditions were observed throughout the
state during most of 1999 through 2002. These declining rainfall trends resulted in declining
water levels measured at the headspring run of the Ichetucknee River (data provided by Sam
Cole, Ichetucknee State Park) (Figure 5-5). It appears that the heaviest park usage has also
occurred during the declining limbs of the seasonal peaks in water level at the headspring.
Declines in vegetation cover for the headspring transects (4-1, 4-2, 5-1, 5-2) also appear to suffer
the greatest declines during the drought conditions beginning in 1998/1999. As a result, these
transects were selected for further analysis with respect to water level fluctuations.
Lake City
14
12
10
8
6
4
Oct- 02
Oct- 01
Oct- 00
Oct- 99
Oct- 98
Oct- 97
Oct- 96
Oct- 95
Oct- 94
Oct- 93
Oct- 92
Oct- 91
0
Oct- 90
2
Figure 5-4. Trends in rainfall at Lake City, Florida.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
42
Park usage also peaked in 1999 which coincides with the steepest decline in water levels (blue
line, dashed blue line indicates trend line) and the most severe decline in SAV (Sagittaria)
percent cover at transect 5-1 (red line in bottom graph). Figure 5-6 shows that the trend in SAV
percent cover over time at this transect has declined since 1996, but has recently increased to predrought conditions in 2003. This may be due to the recent rainfall increases and headspring water
levels observed in the early spring of 2003. SAV percent cover (primiarily Sagittaria) at transect
4-1 (light blue line in bottom graph), however, has not shown a similar response to transect 5-1
and, in fact, has increased significantly since 1997, in spite of the drought and lowered water
levels (Figure 5-7). This transect may be located in an area where tubers or swimmers are less
likely to touch the bottom or walk.
26000
27
26.5
16000
26
11000
25.5
Apr-02
Oct-02
Oct-01
Apr-01
Oct-00
Apr-00
Apr-99
Oct-99
Oct-98
Apr-98
Oct-97
Apr-97
Oct-96
Apr-96
Oct-95
Apr-95
Apr-94
Oct-94
Oct-93
Apr-93
Oct-92
24.5
Apr-92
1000
Apr-91
25
Oct-91
6000
Water Level (ft, NGVD)
21000
Oct-90
# of People
Park Usage
Head Spring Run
Poly. (Head Spring Run)
Poly. (Park Usage)
-4000
24
Oct-02
Apr-02
Oct-01
Apr-01
Oct-00
Apr-00
Oct-99
Apr-99
Oct-98
Apr-98
Oct-97
Apr-97
Oct-96
Apr-96
Oct-95
Apr-95
Apr-94
Oct-94
Oct-93
Apr-93
Oct-92
Apr-92
Oct-91
-10
Apr-91
0
Oct-90
% Change in Vegetation Cover
10
-20
-30
-40
-50
4-1 Veg Change
4-2 Veg Change
5-1 Veg Change
5-2 Veg Change
2 per. Mov. Avg. (5-1 Veg Change)
2 per. Mov. Avg. (5-2 Veg Change)
-60
Figure 5-5. Trends in park usage and water levels (above) and change in vegetation coverage (below) in
the Headspring Reach at Ichetucknee Springs.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
43
S03
S02
S01
S00
S99
S98
S97
S96
S95
S94
S93
S92
S91
S90
100
90
80
70
60
50
40
30
20
10
0
S89
SAV % Cover
Ichetucknee Springs State Park
Spring/Fall Vegetative Cover, Transect 5-1
Season/Year
Figure 5-6. Trends in SAV percent cover at transect 5-1 in the Ichetucknee State Park..
S03
S02
S01
S00
S99
S98
S97
S96
S95
S94
S93
S92
S91
S90
50
45
40
35
30
25
20
15
10
5
0
S89
SAV % Cover
Ichetucknee Springs State Park
Spring/Fall Vegetative Cover, Transect 4-1
Season/Year
Figure 5-7. Trends in SAV percent cover at transect 4-1 in the Ichetucknee State Park.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
44
Changes in SAV cover were analyzed with respect to headspring water level, groundwater levels
(Tin Lizzie well), and park usage (number of people) (Table 5-1). The only significant (p<0.05)
correlation was observed between headspring water level and percent change in vegetation at
transect 5-2 (Table 5-2, Figure 5-8). However, similar non-significant trends were also observed
at transects 4-1 and 5-1 (Figure 5-9). Relationships between groundwater levels and vegetation
change were not significant for any of the headspring transects, however, trends were typically
similar to those for headspring water levels at transects 4-2 and 5-2 (Figure 5-10).
Table 5-1. Water level, park usage, and Ichetucknee Park monitoring transect vegetation change data
used for regression analysist.
Year
Head Spring
Tin Lizzie
Run Stage Park Usage
4-1 Veg
4-2 Veg
5-1 Veg
5-2 Veg Water Level
(ft. NGVD) (# of people) Change % Change % Change % Change % (ft. NGVD)
1989
1990
1991
No Data
24.57
25.40
62,424
50,872
42,105
-1.4
-2.6
-0.2
No Data
No Data
No Data
6
-26.4
-30.6
No Data
No Data
No Data
20.46
18.78
23.29
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
25.09
24.98
25.35
25.03
24.94
25.27
25.16
25.11
25.03
24.70
24.51
48,685
51,606
45,424
49,654
53,881
53,859
55,308
58,053
60,694
56,676
55,230
-7.2
-10.4
-6
0.3
-7.9
2.3
-0.5
-6.9
-11.2
-6.2
2.9
No Data
No Data
No Data
No Data
No Data
No Data
No Data
-29
-2.8
-17.7
-39
-12.6
-12
-12.6
-37.3
-50.6
-9.1
-27.5
-18.5
-0.9
-34.7
-33.6
No Data
No Data
No Data
No Data
No Data
No Data
No Data
-4.6
-8.3
-14.6
-23.3
24.01
20.74
22.94
20.84
20.58
19.97
22.77
19.89
19.61
19.8
18.84
Table 5-2. Regression statistics (p-values) between water level and park usage variables against percent
change in vegetation at Ichetucknee Park monitoring transects.
Transect
Independent Variable
Headspring Water Level
Groundwater Level (Tin Lizzie Well)
Park Use (No. of People)
4-1
0.84
0.90
0.62
4-2
0.46
0.18
0.14
5-1
0.21
0.85
0.25
5-2
0.02
0.14
0.22
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
45
Head Spring Stage vs. % Change in SAV Cover at Transect 5-2
% Change in SAV Cover
24.40
0
24.50
24.60
24.70
24.80
24.90
25.00
25.10
25.20
-5
y = 28.697x - 725.44
2
R = 0.9682 (p=0.02)
-10
-15
-20
5-2 Veg Change
Linear (5-2 Veg Change)
-25
Stage (ft NGVD)
Figure 5-8. Relationship between change in SAV percent cover at transect 5-2 and headspring water
level in the Ichetucknee State Park.
Head Spring Stage vs. % Change in SAV Cover at Transect 5-1
24.40
24.60
24.80
25.00
25.20
25.40
25.60
% Change in SAV Cover
0
-10
-20
-30
-40
-50
y = 36.404x - 937.94
5-1 Veg Change
Linear (5-1 Veg Change)
2
R = 0.2433
-60
Stage (ft NGVD)
Figure 5-9. Relationship between change in SAV percent cover at transect 5-1 and headspring water
level in the Ichetucknee State Park.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
46
T in Lizzie Well Level vs. % Change in SAV Cover at T ransect 5-2
% Change in SAV Cover
18.6
0
18.8
19
19.2
19.4
19.6
19.8
20
-5
-10
y = 14.701x - 299.89
2
R = 0.7367 (p=0.14)
-15
-20
5-2 Veg Change
Linear (5-2 Veg Change)
-25
Stage (ft NGVD)
Figure 5-10. Relationship between change in SAV percent cover and groundwater level at transect 5-2 in
the Ichetucknee River State Park.
Park usage was also not significantly related to vegetation change at any of the transects. This
lack of trend may be due to the high numbers of park visitors during the last several years and
also the lack of sufficient data for transects 4-2 and 5-2 to make adequate statistical inferences.
For example, in 1989 approximately 62,424 people used the north run of the river yet only a
slight change in vegetation cover was observed at transects 4-1 and 5-1. In fact, an increase in
cover was observed at transect 5-1. The following year, fewer visitors were recorded, yet a large
change in percent cover was observed at transect 5-1 and this appears to be more related to head
spring stage than park usage. This pattern is also present during 1996, 2001, and 2002. Based on
the table below, it appears that the greatest percent change in vegetation cover occurs when
headspring water levels drop below 25.0 ft. NGVD, regardless of park usage.
Future trend analysis may be more easily analyzed through the use of SAV and depth contour
maps. Although extremely useful, the transect information may not provide sufficient data to
estimate widespread changes in SAV coverage over time with respect to water levels or park
usage. Based on the SAV map for the headspring area, it is obvious that losses occur
immediately adjacent to and downstream of the north tube launch area (Figure 5-11). Mapping of
SAVin this area over time, in conjunction with transect sampling, would allow the calculation of
changes in total SAV acreage and percent cover within different zones of the headspring run and
also the extent downstream (e.g., linear feet) of losses or gains.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
47
Figure 5-11. SAV map (2003) showing all SAV species (in green) in the upper headspring reach of the
Ichetucknee River.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
48
6.0 References
Allan, J.D. 1995. Stream ecology: structure and function of running waters. 1st Edition.
Chapman and Hall, London, England.
Balci, P., Kennedy, J. H. 2003. Comparison of chironomids and other macroinvertebrates
associated with Myriophyllum spicatum and Heteranthera dubia. Journal of Freshwater
Ecology, Volume 18.
Butcher, R. W. 1933. Studies on the ecology of rivers. I. On the distribution of macrophytic
vegetation in the rivers of Britain. Journal of Ecology. 21: 58-91.
Canfield, D. E. and M. V. Hoyer. 1988. The nutrient assimilation capacity of the Little Wekiva
River, Final Report. Department of Fisheries and Aquaculture. IFAS, University of Florida,
Gainesville.
Childs, D.L. 1999. Spatial Evaluation of Factors Influencing Hydrilla on the Rainbow River.
M.S. Project. Center for Wetlands, University of Florida. Gainesville, FL.
Dutoit, C. H. 1979. The carrying capacity of the Ichetucknee Springs and River. Masters Thesis,
University of Florida, Gainesville, Florida. 176 pp.
FDEP. 1996. Ichetucknee trace baseline monitoring, 1996. Florida Department of Environmental
Protection, Chemistry Section, Central Laboratory. 15 pp.
FDEP. 1997. Biological assessment of the Ichetucknee River Columbia County. Florida
Department of Environmental Protection, Biology Section. 15 pp.
FDEP. 1998. The Role of Ecological Assessments in Environmental Management. Florida
Department of Environmental Protection, Bureau of Laboratories.
FDEP. 2000. Ichetucknee Springs State Park approved unit management plan. Division of
Recreation and Parks, Tallahassee, FL.
FDEP. 2002. EcoSummary of Ichetucknee Springs.
Protection, Bureau of Laboratories.
Florida Department of Environmental
Frazer, T.K., M.V. Hoyer, S.K. Notestein, J.A. Hale and D.E. Canfield, Jr. 2001. Physical,
Chemical and Vegetative Characteristics of Five Gulf Coast Rivers. Final Report.
Southwest Florida Water Management District, Brooksville, Florida
Hill, W.R. and B.C. Harvey. 1990. Periphyton responses to higher trophic levels and light in a
shaded stream. Canadian Journal of Fisheries and Aquatic Sciences. 47: 2307-2314.
Hutchinson, G. E. 1975. A treatise on limnology: Vol. III. Limnological botany. John Wiley &
Sons, Inc. New York. 660 pp.
Hynes, H.B.N. 1970. The ecology of running waters. University of Toronto Press.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
49
Jones, G.W., S.B.Upchurch, and K.M.Champion. 1996. Origin of Nitrate in Ground Water
Discharging from Rainbow Springs, Marion County, Florida. Ambient Ground-Water
Quality Monitoring Program, Southwest Florida Water Management District. Brooksville,
FL.
Menzie, Charles A, 1980. The Chironomid (Insecta: Diptera) and Other Fauna of a
Myriophyllum picatum L. Plant Bed in the Lower Hudson River. Estuarine Research
Federation
Moss, B. 1981. The effect of fertilization and fish on community structure and biomass of
aquatic macrophytes and epiphytic algae populations: An ecosystem experiment. Journal
of Ecology. 64: 313-342.
Nilsson, C. 1987. Distribution of stream edge vegetation along a gradient of current velocity.
Journal of Ecology. 75 (2): 513-522.
Notestein, S.K., T.K. Frazer, M.V. Hoyer and D.E. Canfield, Jr. 2003. Nutrient limitation of
periphyton in a spring-fed, coastal stream in Florida, USA. Journal of Aquatic Plant
Management. 41: 57-60.
PBS&J. 2000. Rainbow Springs Aquatic Preserve 2000 Vegetation Mapping and Change
Analysis Report. Florida Department of Environmental Protection, Bureau of Coastal and
Aquatic Managed Areas. Dunnellon, Forida.
Rosenau, J. C., G. L. Faulkner, C. W. Hendry, Jr., and R. W. Hull. 1977. Springs of Florida.
Florida Geological Survey - Geological Bulletin No. 31, revised. From
http://www.flmnh.ufl.edu/springs_of_fl/aaj7320/content.html.
Thorp, A. G., R. C. Jones, D. P. Kelso. 1997. A comparison of water-column macroinvertebrate
in beds of differing submersed aquatic vegetation in the tidal freshwater Potomac River
communities. Estuaries 20: 86-95.
Walsh, S. J. 2001. Freshwater macrofauna of Florida karst habitats. In: Eve L. Kuniasky, editor,
U.S. Geological Survey Karst Interest Group Proceedings, Water-Resources Investigations
Report 01-4011, p. 78-88.
Walsh, S. J., and J. D. Williams. 2003. Inventory of fishes and mussels in springs and spring
effluents of north-central Florida state parks. USGS Final Report submitted to the Florida
Park Service.
Warren, G.L., Hohlt, D.A., Cichra, C.E., VanGenechten, D. 2000. Fish and Aquatic Invertebrate
Communities of the Wekiva and Little Wekiva Rivers: A Baseline Evaluation in the
Context of Florida’a Minimum Flows and Levels Statutes.
Water and Air Research, 1991. Diagnostic Studies of the Rainbow River. Southwest Florida
Water Management District. Brooksville, FL.
Woodruff, A. 1993. Florida springs chemical classification and aquatic biological communities.
Masters Thesis, University of Florida, Gainesville, Florida. 117 pp.
Mapping and Monitoring SAV in Ichetucknee and Manatee Springs
50
Appendix A
Metadata for Ichetucknee and Manatee Springs SAV Maps
Appendix B
Ichetucknee Springs and River and Manatee Springs and
Springs Run SAV Maps
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Vallisneria americana 0-25%
ch
Rea
Sagittaria kurziana 50-100%
ring
dsp
Hea
Legend
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Blue Hole Spring
Ludwigia repens 50-100%
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
Sagittaria-Chara Mix, 0-25%
Sagittaria-Chara Mix, 25-50%
Vallisneria-Chara Mix, 0-25%
Vallisneria-Sagittaria Mix, 50-100%
Bare
Emergent
Other
Out
50 100
Rice Marsh
Reach
0
200
Feet
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_1.mxd
Legend
Sagittaria kurziana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
h
eac
sh R
Vallisneria americana 0-25%
Mar
Sagittaria kurziana 50-100%
e
Ric
Sagittaria kurziana 25-50%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Roaring Spring
Ludwigia repens 50-100%
Bare
Emergent
Other
Singing Spring
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
Sagittaria-Chara Mix, 0-25%
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
0
50 100
200
Feet
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_2.mxd
Boiling Spring
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Rice Marsh Reach
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
0
50 100
Vallisneria-Chara Mix, 0-25%
200
Feet
Sagittaria-Zizania Mix, 0-25%
Sagittaria-Chara Mix, 0-25%
Sagittaria-Chara Mix, 25-50%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_3.mxd
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Mill Pond Spring
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
Sagittaria-Chara Mix, 0-25%
Sagittaria-Chara Mix, 25-50%
0
50 100
200
Feet
Flood Plain Reach
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_4.mxd
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 0-25%
200
Feet
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_5.mxd
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
Sagittaria-Chara Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 25-50%
200
Feet
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_6.mxd
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 0-25%
200
Feet
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_7.mxd
Coffee Spring
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
200
Feet
Sagittaria-Chara Mix, 0-25%
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_8.mxd
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 0-25%
200
Feet
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_85.mxd
Legend
Sagittaria kurziana 0-25%
Flood Plain Reach
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
Bare
Emergent
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 0-25%
200
Feet
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_9.mxd
Flood Plain Reach
Legend
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Vallisneria americana 0-25%
Vallisneria americana 25-50%
Vallisneria americana 50-100%
Chara sp. 0-25%
Chara sp. 25-50%
Chara sp. 50-100%
Zizania aquatica 0-25%
Zizania aquatica 25-50%
Zizania aquatica 50-100%
Hydrocotyle sp. 0-25%
Myriophyllum heterophyllum 50-100%
Ludwigia repens 50-100%
U.S.
27 B
ri
Bare
Emergent
dge
Other
Out
Chara-Myriophyllum Mix, 0-25%
Ludwigia-Hydrocotyle-Zizania Mix, 0-25%
Vallisneria-Chara Mix, 0-25%
Sagittaria-Zizania Mix, 0-25%
0
50 100
Sagittaria-Chara Mix, 0-25%
200
Feet
Sagittaria-Chara Mix, 25-50%
Vallisneria-Sagittaria Mix, 50-100%
Submerged Aquatic Vegetation
in Ichetucknee Springs and River
Spring 2003
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/figure_10.mxd
Headspring
Su
wa
nn
Boat Ramp
R
ee
Legend
Ludwigia repens 0-25%
r
ive
Ludwigia rpens 25-50%
Potamogeton sp. 0-25%
Potamogeton sp. 25-50%
Sagittaria kurziana 0-25%
Sagittaria kurziana 25-50%
Sagittaria kurziana 50-100%
Bare
0
Submerged Aquatic Vegetation
in
Manatee Springs and Spring Run
Spring 2003
50
100
200
Feet
2803 Fruitville Road, Suite 130
Sarasota, Florida 34237
Phone: 941.539.4036
Fax: 941.951.1477
G:\Projects\SRWMD_Spring_Veg\DraftGISDeliverables\MXD/report.mxd
Appendix C
Reprints of Dutoit (1979) Ichetucknee River SAV Maps and
Cover Estimates
Appendix D
Data and Statistical Summaries from SAV Transect Sampling
Table D- 1. Sampling coordinates for the Ichetucknee River as sampled by Frazer et al. on April 30,
2003.
Transect
Latitude
Longitude
1
29.98310
-82.76071
2
29.98207
-82.76027
3
29.98079
-82.75928
4
29.97948
-82.75875
5
29.97825
-82.75927
6
29.97680
-82.75886
7
29.97541
-82.75895
8
29.97412
-82.75938
9
29.97228
-82.75999
10
29.97115
-82.75998
11
29.96992
-82.76015
12
29.96885
-82.76086
13
29.96770
-82.76151
14
29.96697
-82.76173
15
29.96511
-82.76192
16
29.96445
-82.76287
17
29.96383
-82.76447
18
29.96320
-82.76574
19
29.96188
-82.76811
20
29.96154
-82.76797
21
29.96069
-82.76931
22
29.96031
-82.77084
23
29.95987
-82.77306
24
29.95926
-82.77319
25
29.95922
-82.77435
26
29.95931
-82.77556
27
29.95913
-82.77627
28
29.95842
-82.77834
29
29.95774
-82.77968
30
29.95653
-82.78011
31
29.95537
-82.78222
Table D-2. Ichetucknee River mean values from data collected on April 30, 2003. N = 5 for depth, flow and canopy and N = 3 for each of the remaining
parameters. Asterisk width values were estimated from adjacent FDEP SAV monitoring transects.
TRANSECT
WIDTH
(m)
DEPTH (m)
FLOW (m/s)
CANOPY
(%)
TEMPERATURE
( C)
SPECIFIC
CONDUCTIVITY (µS/cm)
DISSOLVED
OXYGEN
(mg/L)
pH
LIGHT
ATTENUATION
(Kd/m)
1
17
0.98
0.11
78
21.9
320
4.3
7.46
0.49
2
21
0.98
0.18
20
21.8
320
4.5
7.46
.
3
15
0.98
0.22
90
21.8
320
4.7
7.57
.
4
16
1.18
0.26
86
21.9
312
3.7
7.27
.
5
26
1.00
0.23
0
21.9
311
4.1
7.45
0.58
6
45
0.82
0.20
0
22.1
309
5.0
7.49
0.58
7
54
1.12
0.23
10
22.2
314
4.9
7.50
0.71
8
50
1.00
0.24
2
22.3
315
5.2
7.59
.
9
.
1.00
0.15
5
22.5
323
5.2
7.67
.
10
.
1.04
0.17
0
22.6
322
6.2
7.61
.
11
.
1.03
0.13
0
23.0
321
6.7
7.75
.
12
.
1.44
0.13
0
23.2
322
7.4
7.70
.
13
.
1.20
0.14
33
23.3
321
7.6
7.79
.
14
.
1.16
0.15
0
23.5
321
7.8
7.84
.
15
.
1.48
0.17
30
23.6
329
7.4
7.61
.
16
22.7*
1.80
0.23
90
23.6
332
7.2
7.63
.
17
25.8*
1.82
0.21
80
23.6
335
7.1
7.67
.
18
.
1.32
0.23
0
23.6
334
7.2
7.72
.
19
.
1.94
0.15
36
23.6
334
7.2
7.75
.
20
.
1.80
0.18
61
23.6
334
7.2
7.77
.
21
19.7*
2.10
0.24
64
23.7
334
7.2
7.74
.
22
.
1.48
0.26
68
23.7
335
7.2
7.75
.
23
.
1.82
0.26
78
23.7
335
7.1
7.68
.
24
21.2*
1.80
0.14
100
23.7
336
7.1
7.74
.
25
21.2*
1.72
0.23
0
23.6
339
7.0
7.73
.
26
.
1.60
0.24
60
23.6
336
7.0
7.71
.
27
21.2*
2.06
0.27
50
23.7
336
7.1
7.70
.
28
.
1.76
0.18
58
23.6
336
6.9
7.70
.
29
.
2.28
0.22
50
23.6
334
6.9
7.70
.
30
.
1.84
0.22
40
23.5
340
6.6
7.71
.
31
19.7*
1.98
0.17
60
23.6
337
6.9
7.76
.
1.47
0.20
40
23.1
327
6.4
7.65
0.59
Sampled River Mean
Table D-3. Ichetucknee River mean transect values (N = 5) for SAV data collected on April 30, 2003.
TRANSECT
SAV PERCENT
COVERAGE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Sampled River Mean
47
52
44
67
61
74
51
69
51
57
44
81
72
82
77
52
59
90
54
92
88
82
82
80
100
84
100
78
70
72
82
71
SAV BIOMASS
(kg/m2 wet weight )
PERIPHYTON
(mg chl/g host wet wt.)
3.32
0.11
3.26
0.11
4.49
0.12
2.43
0.27
8.04
0.14
4.06
0.07
3.46
0.05
5.73
0.08
5.98
0.02
6.48
0.05
4.66
0.11
DOMINANT
SAV SPECIES
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana
Zizania aquatica
Zizania aquatica
Zizania aquatica
Sagittaria kurziana
Sagittaria kurziana
Zizania aquatica
Zizania aquatica
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana & Vallisneria americana
Sagittaria kurziana
Sagittaria kurziana & Vallisneria americana
Sagittaria kurziana
Chara sp.
Sagittaria kurziana
Sagittaria kurziana
Sagittaria kurziana
Chara & Fontinalis
Vallisneria americana
Sagittaria kurziana
Sagittaria kurziana
Chara & Sagittaria kurziana
Vallisneria americana
Sagittaria kurziana
Chara sp.
TABLE D-4. Manatee Spring mean values from data collected on May 8, 2003. N = 3 for the transect mean values.
TRANSECT
WIDTH (m)
1
2
3
4
5
.
26
.
.
.
Sampled Area Mean
FLOW (m/s)
TEMPERATURE ( C)
SPECIFIC
CONDUCTIVITY (uS/cm)
DISSOLVED
OXYGEN (mg/L)
pH
1.87
1.87
1.87
2.20
0.11
0.10
0.08
0.09
22.4
22.4
22.5
22.7
22.9
498
488
482
419
410
2.0
2.0
1.8
1.7
1.9
6.97
7.03
7.10
7.06
7.05
0.43
1.03
1.95
2.43
2.80
1.95
0.09
22.6
453
1.8
7.05
1.92
DEPTH (m)
Light Attenuation (Kd/m)
SAV Biomass (kg/m2) By Depth (m)
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
.0
.5
1.0
1.5
2.0
2.5
3.0
3.5
Depth (m)
Linear Fit
Linear Fit
SAV Biomass (kg/m2) = 1.36 + 2.34 Depth (m)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.20
0.18
3.34
4.75
48
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
129.07
129.07
Error
46
512.72
11.15
C. Total
47
641.80
Parameter Estimates
Term
Estimate Std Error
Intercept
1.36
1.11
Depth
2.34
0.69
(m)
F Ratio
11.58
Prob > F
0.001
t Ratio Prob>|t|
1.23
0.22
3.40
0.001
Figure D-1. Empirical relationship between stream depth and submersed aquatic
vegetation (SAV) biomass for the Ichetucknee River on May 30th 2003.
Mean SAV Percent Coverage By Mean Depth (m)
Mean SAV Percent Coverage
100
80
60
40
20
0
1.0
1.5
2.0
2.5
Mean Depth (m)
Linear Fit
Linear Fit
Mean SAV Percent Coverage = 41.526713 + 19.911519 Mean Depth (m)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.26
0.24
14.28
70.77
31
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
2117.84
2117.84
Error
29
5910.01
203.79
C. Total
30
8027.85
Parameter Estimates
Term
Estimate Std Error
Intercept
41.53
9.43
Mean Depth
19.92
6.18
(m)
F Ratio
10.39
Prob > F
0.003
t Ratio Prob>|t|
4.41 0.0001
3.22
0.003
Figure D-2. Empirical relationship between stream depth and submersed aquatic
vegetation (SAV) coverage for the Ichetucknee River on May 30th 2003.
SAV Biomass (kg/m2) By Flow (m/s)
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
0
.1
.2
.3
.4
.5
.6
Flow (m/s)
Linear Fit
Linear Fit
SAV Biomass (kg/m2) = 2.19 + 12.06 Flow (m/s)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.13
0.11
3.50
4.66
49
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
84.73
84.73
Error
47
575.56
12.25
C. Total
48
660.29
Parameter Estimates
Term
Estimate Std Error
Intercept
2.19
1.06
Flow (m/s)
12.06
4.59
F Ratio
6.92
Prob > F
0.01
t Ratio Prob>|t|
2.06
0.05
2.63
0.012
Figure D-3. Empirical relationship between stream flow and submersed aquatic
vegetation (SAV) biomass for the Ichetucknee River on May 30th 2003.
Mean SAV Percent Coverage By Mean Flow (m/s)
Mean SAV Percent Coverage
100
80
60
40
20
0
.10
.15
.20
.25
Mean Flow (m/s)
Linear Fit
Linear Fit
Mean SAV Percent Coverage = 49.059242 + 109.85366 Mean Flow (m/s)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.096
0.065
15.82
70.77
31
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
768.23
768.23
Error
29
7259.62
250.33
C. Total
30
8027.85
Parameter Estimates
Term
Estimate Std Error
Intercept
49.059
12.714
Mean Flow
109.854
62.709
(m/s)
F Ratio
3.069
Prob > F
0.090
t Ratio Prob>|t|
3.86 0.0006
1.75
0.090
Figure D-4. Empirical relationship between stream flow and submersed aquatic
vegetation (SAV) coverage for the Ichetucknee River on May 30th 2003.
SAV Biomass (kg/m2) By Terrestrial Canopy Cover Percentage
14
SAV Biomass (kg/m2)
12
10
8
6
4
2
0
0
20
40
60
80
100
Terrestrial Canopy Cover %
Linear Fit
Linear Fit
SAV Biomass (kg/m2) = 5.10 - 0.012 Terrestrial Canopy Cover %
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.02
-0.0002
3.71
4.66
49
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
13.63
13.63
Error
47
646.66
13.76
C. Total
48
660.29
Parameter Estimates
Term
Intercept
Terrestrial Canopy Cover
%
F Ratio
0.99
Prob > F
0.32
Estimate Std Error
5.10
0.69
-0.012
0.013
t Ratio Prob>|t|
7.35 <.0001
-1.00
0.32
Figure D-5. Empirical relationship between terrestrial canopy cover and submersed
aquatic vegetation (SAV) biomass for the Ichetucknee River on May 30th 2003.
SAV Coverage (per m) By Terrestrial Canopy Cover Percentage
SAV Coverage (per m)
100
80
60
40
20
0
0
20
40
60
80
100
Terrestrial Canopy Cover %
Linear Fit
Linear Fit
SAV Coverage (per m) = 72.59 - 0.045 Terrestrial Canopy Cover %
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.003
-0.003
33.43
70.77
155
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
594.52
594.52
Error
153
170937.12
1117.24
C. Total
154
171531.64
Parameter Estimates
Term
Intercept
Terrestrial Canopy Cover
%
F Ratio
0.53
Prob > F
0.47
Estimate Std Error
72.59
3.67
-0.045
0.062
t Ratio Prob>|t|
19.80 <.0001
-0.73
0.47
Figure D-6. Empirical relationship between terrestrial canopy cover and submersed
aquatic vegetation (SAV) coverage for the Ichetucknee River on May 30th 2003.
Mean Periphyton Abundance (mg chl/g host wet wt.) By Mean Flow (m/s)
Mean Periphyton Abundance (mg chl/g host wet weight)
0.30
0.25
0.20
0.15
0.10
0.05
0.00
.10
.15
.20
.25
Mean Flow (m/s)
Linear Fit
Linear Fit
Mean Periphyton Abundance (mg chl/g host wet weight) = 0.3249848 1.0868469 Mean Flow (m/s)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.46
0.39
0.05
0.10
10
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
0.020
0.020
Error
8
0.023
0.003
C. Total
9
0.044
F Ratio
6.86
Prob > F
0.03
Parameter Estimates
Term
Estimate Std Error t Ratio Prob>|t|
Intercept
0.325
0.087
3.76
0.006
Mean Flow
-1.087
0.415
-2.62
0.03
(m/s)
Figure D-7. Empirical relationship between stream flow and periphyton abundance (mg
chl/g host plant wet weight) for the Ichetucknee River on May 30th 2003.
Mean Periphyton Abundance (mg chl/g host wet weight)
Mean Periphyton Abundance (mg chl/g host wet wt.) By Mean
Terrestrial Canopy Cover
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
25
50
75
100
Mean Canopy Cover (%)
Linear Fit
Linear Fit
Mean Periphyton Abundance (mg chl/g host wet weight) = 0.1511356 0.0013761 Mean Canopy Cover (%)
Summary of Fit
R Square
R Square Adjusted
Root Mean Square Error
Mean of Response
Observations
0.45
0.38
0.06
0.10
10
Analysis of Variance
Source
DF Sum of Squares Mean Square
Model
1
0.020
0.020
Error
8
0.024
0.003
C. Total
9
0.043
Parameter Estimates
Term
Intercept
Mean Canopy Cover
(%)
Estimate Std Error
0.151
0.026
-0.0013
0.0005
F Ratio
6.477
Prob > F
0.034
t Ratio Prob>|t|
5.87 0.0004
-2.54
0.034
Figure D-8. Empirical relationship between terrestrial canopy cover and periphyton
abundance (mg chl/g host plant wet weight) for the Ichetucknee River on May 30th 2003.
Appendix E
Field Notes from SAV-Associated Macroinvertebrate Sampling
Appendix F
SAV-Associated Macroinvertebrate Data for 31 Ichetucknee
River Transects
Appendix G
SAV Occurrence Comparisons and Additional SAV-associated
Macroinvertebrate Data
Errata:
The methodology for enumerating SAV-associated macroinvertebrates was misstated in
the original report. The correct methodology is stated below:
“In the lab, all macroinvertebrates were subsequently rinsed from the SAV blades and transferred
to glass jars and preserved in ethanol. Subsequently they were sorted, enumerated, and identified
to the lowest possible taxon. However, due to the high abundance of macroinvertebrates,
subsampling was conducted. A glass pan, (approx. 13” x 9” x 2”) was sectioned into identical
squares labeled 1 through 40. Individuals were removed and enumerated from a randomly
chosen square until 100 animals were counted. Once 100 animals were counted, the remainder of
the square was enumerated. If 100 animals were not present within the area of one square, a
second would be randomly selected etc., until a count of 100 was reached. A different
subsampling method was used for oligochaetes. Due to large numbers of individuals,
oligochaetes were subsampled by randomly selecting at least 6 individuals from each sample and
identifying to genus and/or species. Three SAV blades (excluding Chara) were measured to
calculate an average blade length for each sample. No B samples were collected at stations 13 or
18 due to a lack of SAV in the middle portion of the river. All statistical comparisons were
conducted at the 95% confidence level (p<0.05).“