Photo of Lake Willoughby captured by Farrah Ashe
A Comprehensive Suitability Assessment of Vermont Waterbodies for Spiny
Water Flea (Bythotrephes longimanus), Zebra Mussel (Dreissena polymorpha),
and Starry Stonewort (Nitellopsis obtusa)
Authors: Farrah Ashe, Nikki Boudah, Kelsey Colbert, Kait Jones and Will Sutor
Partnered with:
Vermont Department of Environmental Conservation
Table of Contents:
Executive Summary
Page 2
Introduction
Page 2
Background
Page 3
Approach
Page 3
Findings
Page 6
Discussion and Recommendations
Page 11
Literature Citations
Page 15
Acknowledgements:
We would like to thank our partner Josh Mulhollem of the Vermont Department of
Environmental Conservation (DEC) for his guidance throughout the course of this project. He
provided our team with the waterbody data used in the report and answers to our many questions
during the entire process. We thank him for the time he dedicated to us and the resources which
he was able to provide for our team.
1
Executive Summary:
According to the Vermont Department of Environmental Conservation (Agency of
Natural Resources, 2017), the waterbodies of Vermont are vulnerable to invasion from zebra
mussels, spiny water flea, and starry stonewort. There is currently a lack of state-wide
knowledge on which waterbodies are hospitable to these three organisms. By understanding this,
the state can assess where the greatest needs are, and focus their efforts on prevention and
monitoring in those locations. If no action is taken to determine waterbodies at high risk for
invasion, more affordable preventative measures will no longer be an option. This is problematic
because invasive species can drastically alter ecosystems, resulting in the need of mitigation or
eradication efforts further down the road which can cost the state orders of magnitude more than
preventative measures or monitoring in the early stages of invasive species establishment
(USGS, 2017).
The goal of this project was to conduct a statewide analysis to determine which Vermont
waters are at the highest risk of introduction and establishment of these three invasives. This was
accomplished by reviewing relevant scholarly literature on the three focal species and the
environmental conditions they can tolerate. Tolerance information was then organized to
determine high, moderate, and low priority waterbodies at risk for invasion from each invasive
species. This data was compiled and used with the vessel travel data to create an ArcGIS map on
the state waterbodies for each invasive species. Using these tools, we were able to recommend to
the DEC the waterbodies that should be prioritized for monitoring and spread prevention.
Introduction:
Vermont’s waterbodies are currently inhabited by seventeen invasive species and
threatened by fifteen more invasives in neighboring watersheds (Agency of Natural Resources,
2016). The spiny water flea, starry stonewort, and zebra mussels are three of the seventeen
species currently found in parts of Vermont and all three are expected to continue invading
Vermont’s waterbodies. Preventing further spread of invasives is critical to conserving
Vermont’s biodiversity, as invasives can lack natural predators and therefore outcompete native
species. Spread of invasive species also poses a risk to human health as invasives can clog water
pipes and impact the quality of fish and water humans are consuming. It is also important to
recognize that most of these aquatic invaders are spread between waterbodies as a direct result of
human activity. Known invaders such as the zebra mussel, can easily cling to boats or trailers.
They can also be spread into new locations due to a lack of public knowledge around baitfish
regulations (Agency of Natural Resources, 2016). Mitigating the negative impact aquatic
invasive species impose can be aided with public education but if it is not addressed, more
extensive preventative measures must be implemented. The result of the high cost of eradication
can place a great fiscal burden on local communities.
The purpose of our project is to therefore determine which waterbodies in Vermont are
susceptible to invasion by one or all of these species, and the level of risk for invasion based on
water quality characteristics. The goal of this report is to help the reader better understand the
risk invasives pose on the areas they are inhabiting, and to emphasize the importance of
conducting a statewide analysis to determine which Vermont waterbodies are most at risk for
invasion of the spiny water flea, starry stonewort, and zebra mussel.
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Background:
Studies have shown that nonindigenous species pose a severe threat to the health of
waterbodies throughout the state of Vermont (Modley, 2008). The introduction of an invasive
species can change food webs by destroying native food sources, alter ecosystem functions such
as changing water chemistry, and degrade the habitat quality of other organisms. Furthermore,
the presence of a nonnative species can decrease native species biodiversity and even cause
localized extinction in an ecosystem (USGS, 2017). As a result, the spread of invasive species
throughout the state is not only detrimental to Vermont’s ecology but are also financially costly
to mitigate (Clavero and Garcia-Berthou, 2005).
The zebra mussel (Dreissena polymorpha), spiny water flea (Bythotrephes longimanus)
and starry stonewort (Nitellopsis obtusa), are three aquatic invasive species that have been
identified in waterbodies of Vermont. Each of these invaders has been known to cause harm to
the ecosystems that they infiltrate, and therefore present a serious concern to the state. Zebra
mussels, for example, can attach themselves to any surface in the water including other native
clams and mussels causing asphyxiation and eventually death (Johnson and Padilla, 1996). Due
to their aggressiveness, and also effective domination of ecosystems that they invade, zebra
mussels have been known to alter the structure and function of waterbodies around the world
(Karatayev et al., 2002). According to the USGS Ecological Survey, both the spiny water flea
and starry stonewort pose similar ecosystem-altering threats to aquatic ecosystems as the zebra
mussel. The spiny water flea has the capacity to completely shift the trophic structure of an
ecosystem through its insatiable appetite for crustacean and zooplankton. Such effects have
shown significant reductions in these two species, crucial to nutrient cycling within aquatic
systems (Kelly, 2013). Similarly the starry stonewort can have negative impacts on fish
spawning, foraging, and nesting habitat, altering the ecosystem and abundance of aquatic species
(Pullman, 2010; Midwood et al., 2016). As a result, many states have begun to require mitigation
and prevention efforts for these three aquatic invaders at the state and local level (e.g. analyses
and risk assessments of critical bodies of water) (Kipp et al., 2017).
Vermont has not formulated a comprehensive environmental suitability and vessel-based
introduction risk assessment for these three aquatic invasive species. Therefore, a statewide
analysis of these three invasives that are currently in and threatening the waters of Vermont is
needed. Our assessment will determine the waters in Vermont which are at the highest risk of
introduction by vessel travel and establishment in native suitable habitat. This will help the state
of Vermont determine which aquatic ecosystems should be prioritized for invasive prevention
planning, monitoring, and control measures in the future.
Approach:
We chose to focus on three invasive species for the main portion of this project. Zebra
mussels were chosen because of their severe negative impacts in Lake Champlain and Lake
Bomoseen in Vermont. Studies have shown that these invaders clog water intake pipes, pose a
hazard to recreationalists, and harm the native biota and natural food web of these lakes
(Modley, 2008). Due to its natural history, there are large amounts of scientific literature on
zebra mussels and the factors controlling their growth, reproduction, and subsequent spread
(Cohen, 2017; Feng & Papes, 2017; Karatayev et al., 1998; McMahon, 1996; Wu et al., 2010).
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We also chose this species from the request of our partner due to these reasons and the need for
prioritizing waterbodies to better focus prevention and monitoring efforts. The spiny water flea
was chosen because of its recent invasion into Vermont (first observed in Lake Champlain in
2014) (Voorhees et al., 2015). This lack of study poses a problem to the state water managers on
understanding the best control and prevention methods to use in Vermont, as well as,
understanding the spread paths of the species. Starry stonewort is also a relatively new invasive
species to the waters of Vermont found in 2015, with its most recent invasion into the waters of
Lake Derby of Derby, VT (VT DEC, 2016). The last two species presented the opportunity to
gather a wealth of scholarly information on these species to aid in the knowledge of our partner,
the VT DEC, and help in finding limiting factors to their survival in Vermont waters.
In order to best determine the level of risk for invasion of each waterbody in Vermont,
information on the habitat requirements of the three species was compiled and assessed. We
analyzed the scholarly literature on each of the three species in order to understand which lake
characteristics were necessary for survival, growth, and reproduction to determine population
establishment if the species were to be introduced into the ecosystem. This included research on
water pH, conductivity, salinity, hardness, depth, dissolved oxygen, chlorophyll-a concentration,
and total phosphorus, among the other water quality parameters that were pertinent to the
required habitat profile of the nonnative species. We then compiled the found tolerance ranges
from the literature into a spreadsheet. This allowed for easy comparisons of the lake data we
received from our project partner.
Our community partner gave us the lake data in groupings by the environmental
parameters. The averages that were not already found in this data were calculated to a daily,
yearly, and then overall average for each waterbody. Each of the parameters were set as “meets”
or “does not meet” for each of the three species. If the waterbody only had one measurement
which was taken to represent the whole, this was noted and marked with an asterisk. The
waterbodies that has no data were marked with “N/A”, indicating that the data was not available.
Some of the data that were collected were done so in the spring (e.g. total phosphorus and
hardness). This was used because spring is one of the times of the year in which dimictic lakes
(the lake type of most Vermont lakes) experience turnover and therefore the nutrients that were
previously layered throughout the water column are most evenly mixed (Nunberg, 1988). This
data was then compiled into one spreadsheet. The risk of an invasion occurring given successful
introduction was classified into three different categories: low risk, moderate risk, and high risk.
Here we defined this risk being the risk of establishment of the invasive species if introduction
were to occur. High risk waterbodies fall within two or more of the environmental tolerance
parameters or contain two or more parameters with “meets” for that species. Moderate risk
waterbodies contain one environmental tolerance parameter that was met, due to natural lake
fluxes. Low risk waterbodies do not have any of the parameters that were met. We also noted the
difference between waterbodies with low data (only one year of data) versus those which had
multiple years of data collection. These specific low data values are well marked so if they need
to be explored further on an individual basis, they can be considering the unknown variance that
the data could have with using only one year of data to represent the waterbody.
We utilized vessel travel data from the DEC’s greeter program, a program designed to
track boater behavior and inspect boats to better understand the transportation of invasives. The
greeter data was listed for two different risk factors: risk from last waterbody and risk from time
since in last waterbody. These two factors were first categorized on a 1-3 level of risk (1 being
low, 2 being medium, and 3 being high). For the risk of last waterbody: 3=The last waterbody
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visited contains at least one invasive species that is not currently found at the lake where the
inspection occurred. 2=It is unknown if the last waterbody visited contains any AIS of concern
consisting mostly of out-of-state waters. 1=The last waterbody visited does not contain any AIS
that are not already found in the lake where the inspection occurred. For the time since the last
launch the categories were: 3=the watercraft was last used in a lake other than the one where the
inspection occurred within the last 5 days. 2=the watercraft was last used in a lake other than the
one where the inspection occurred within the last 2 weeks but not within the last 5 days, or, it is
unknown when the watercraft was last used. 1= the watercraft was not used in a lake other than
the one where the inspection occurred within the last two weeks. This data was then summed and
recategorized as 2-3 being low risk, 4 being medium risk, and 5-6 being high risk vessels
launching. This data was then used to create an ArcGIS shapefile and subsequently a map. State
waterbody data (VT Priority Lake/Pond data from vtanrgis public access data) were added to a
map of Vermont. The calculated risk percentages attribute was then chosen to be represented as a
pie chart for the three risk categories. This map was created to provide a visual to aid in the
understanding of the overall risk including the boat travel introductory risk in addition to our
environmental suitability establishment risk.
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Findings:
Our team created a spreadsheet which contains the environmental parameters and the
waterbodies of Vermont listed by name and location (by longitude and latitude). In this
spreadsheet, chlorophyll-a concentrations, pH, alkalinity, hardness, and total phosphorus
concentrations are listed (refer to Table 1 for a sample of the chlorophyll-a data).
Table 1: This is a sample table of the type of results that were obtained from the
environmental parameters for each of the three invasive species. Here we are seeing
the partial results on whether or not starry stonewort could invade each waterbody.
“Meets” specifies that the concentrations of chlorophyll-a found in that waterbody are
allowable if starry stonewort were to be introduced to this waterbody. An asterisk
indicates that the chlorophyll-a concentration measurements are only based on one
year’s data. “Does not meet” indicates that the specific waterbodies are not capable of
hosting starry stonewort due to the concentrations of chlorophyll-a. “N/A” means that
there was no available data for that waterbody and therefore the test was not applied.
Lake_ID
AMHERST
ARROWHEAD MOUNTAIN
BEEBE (HUBDTN)
BERLIN
MEMPHREMAGOG
METCALF
NINEVAH
SHELBURNE
SILVER (BARNRD)
SOUTH (EDEN)
SOUTH BAY
SPRING (SHRWBY)
ST. CATHERINE
STAR
STRATTON
SUNRISE
SUNSET (BENSON)
SUNSET (BRKFLD)
TICKLENAKED
VALLEY
WAPANACKI
WILLOUGHBY
WINONA
WOODWARD
Chlorophyll-a limits in the environment for starry stonewort
meets
meets
meets
N/A
meets
meets
meets
does not meet
meets
meets
meets
meets
meets
meets
meets
meets*
meets
meets
meets
meets
meets
meets
meets*
meets
We chose not to include dissolved oxygen as one of the final environmental parameters,
because the dissolved oxygen varies with the water depth and the lake layers (Rao et al., 2008).
The hypolimnion could be anoxic, while the other more shallower layers are still able to contain
6
sufficient oxygen levels to sustain growth and reproduction of the invasive species. For example,
despite their temperature sensitivity, spiny water flea will move vertically in the water column to
find the optimal conditions suitable for dissolved oxygen concentration. Table 2 contains a list of
the Vermont waterbodies that are stressed due to low dissolved oxygen levels. This omission is
unlikely to affect our data, but in the future this parameter could be significant. Especially if
there is a moderate match in suitability, where one environmental parameter is not met while
others are.
Table 2: This table is a list of the Vermont waterbodies which are considered to have
“stressed” dissolved oxygen conditions.
Waterbody Name
Lake Eden
Elfin Lake
Ewell Pond
Fern Lake
Great Hosmer Pond
Lake Parker
Sabin Pond
(Woodbury Lake)
Shelburne Pond
Spring Lake
(Shrewsbury Pond)
Stiles Pond
Ticklenaked Pond
Valley Lake (Dog
Pond)
Walker Pond
Town
Eden
Wallingford
Peacham
Leicester
Craftsbury
Glover
Latitude
44.72
43.47
44.37
43.87
44.7
44.72
Longitude
72.5
72.99
72.17
73.07
72.37
72.23
Calais
Shelburne
44.4
44.38
72.42
73.17
Shrewsbury
Waterford
Ryegate
43.5
44.42
44.18
72.92
71.93
72.1
Woodbury
Hubbardton
44.43
43.74
72.43
73.14
Furthermore, it is important to note that depth was not assessed in our study because of
its variability within a lake’s profile. While we did acquire the maximum and mean depths of
each waterbody studied from the state, it wasn’t appropriate for any of our focal species. Depth
did not impact the spiny water flea, because conditions in the water column vary and the species
is able to move vertically. We also found that depth wasn’t appropriate for starry stonewort and
zebra mussel, because both species inhabit shallow waters that are present in all lakes.
Each of the environmental parameter records was then added to a master spreadsheet
categorized by each species separately. The number of waterbodies that met the species habitat
parameters allowed us to calculate a quantitative value for risk of establishment. This final
spread looks similar to Table 1, but instead contains a risk column with the waterbodies marked
as “low”,”moderate”, and “high”.
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Table 4: Denotes our tolerance range data gathered from the literature. All tolerance ranges are
listed next to their subsequent source. Ranges that did not possess maximum values were left
blank.
8
Table 5: Total counts of Vermont waterbodies from our data (n=374), separated into our
categories of population establishment risk for each invader. Risk is classified as low, moderate
or high in terms of the waterbody meeting either none, one or two of the water quality
parameters we previously identified as necessary for establishment (Table 1). Values within
parentheses represent percentages for each count.
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Figure 1: This is a map of Vermont with thirteen of the DEC’s greeter stations that had
sufficient data available. These are represented with pie charts for the high, medium, and
low risk vessels launching into those waterbodies. This risk metric is based on the previous
waterbody that the vessel was in and the time since that vessel was previously in another
waterbody.
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Discussion and Recommendations:
Spiny Water Flea:
The results of our literature review and subsequent data analysis of the abiotic/biotic
factors dictating the population establishment for spiny water flea (B. longimanus), largely
support the idea that it can spread to almost all of Vermont’s waterbodies. Past research has
indicated that the three most important habitat characteristics for this species are salinity, water
temperature, and lake area. These factors are important due to the life history of this species, as it
originated in the deep, cold water lakes of northern Europe and Asia (Kelly et al., 2013). We
omitted salinity from our consideration, because while it is a limiting factor for the spiny water
flea, all the lakes and ponds in Vermont are freshwater. Spiny water flea is known to tolerate a
temperature range of 4-30 degrees Celsius, which directly coincides to the seasonal temperature
variability within the waterbodies of Vermont (Weisz and Yan, 2010; Personal communication:
Josh Mulhollem). Although its optimal range for population growth has been repeatedly
identified as 10-24 degrees Celsius, recent studies have shown that temperatures outside of the
optimal range do not impose a significant source of stress on the development of populations
(Weisz and Yan, 2010). Additionally, when temperatures are too high or too low based on these
tolerance ranges, spiny water flea can move throughout the water column to find a suitable
environment that best fits its needs (Kerfoot et al., 2011). This movement capability directly
relates to the second most limiting factor for establishment of this species, lake area. Recent
research has shown that spiny water flea may perform better in large, deep lakes due to the wide
range of habitat availability. Larger lakes possess a wider range of temperatures and higher
availability of zooplankton, the main food source of this voracious predator (Kelly et al., 2013).
Unfortunately, we were unable to include these two variables in our analyses because of gaps in
the data. The waterbody data provided by the DEC did include temperature, but the values were
measured on or near the surface and did not encapsulate the variability within the entire water
column. For future research on the establishment of this species, we suggest a more in-depth
analysis of the temperature variability within Vermont’s waterbodies both seasonally and at
different levels of the water column.
For the other limiting water quality characteristics that the research identified, such as:
pH, hardness, water clarity and phosphorous content, we found that this species is capable of
establishment in most, if not all, of the waterbodies we analyzed (Table 3).
Zebra Mussel:
The results of our literature review and subsequent analysis of the factors controlling the
establishment of zebra mussels showed that it presents the least amount of establishment risk to
Vermont waterbodies. The two water quality factors that are most prominent to its establishment
are pH and hardness- a proxy for calcium content (Hincks and Mackie, 1997). These variables
operate in tandem with one another. As pH decreases, the calcium content of the water decreases
as well due to its relationship with the naturally-occurring buffer, CaCO3. Essentially, as cellular
respiration produces carbon dioxide within the aquatic ecosystem, it binds with the surrounding
H2O molecules to create carbonic acid(H2CO3). This weak acid is capable of dissolving
limestone, releasing mineral ions such as calcium. Due to its weak nature, carbonic acid degrades
over time, releasing two H+ ions and CO32-. The positively charged calcium ions then bind with
11
the newly formed carbonate ion to create CaCO3 (Hammes and Verstraete, 2002). The loss of
readily available calcium within the water column is especially detrimental to zebra mussels
because they are unable to use the mineral in order to form their shells (Hincks and Mackie,
1997). This delicate balance between hardness and pH renders a strict tolerance range that allows
this invasive species to become established. Our review of the literature returned a pH range of
7.4-9.4 and a minimal hardness concentration of 57.7 mg/L (Cohen, 2017; Hincks and Mackie,
1997). The literature did not provide a maximum range value for water hardness because it is not
applicable in this situation, as zebra mussels would be able to form their shells in aquatic
ecosystems with higher mineral content (Wu et al., 2010). These values of tolerance were then
applied to our waterbody data that we received from the DEC and returned relatively surprising
results. Zebra mussels returned the lowest count of waterbodies that are at high risk for invasion
(Table 4). We believe these findings are a consequence of the underlying bedrock geology of
Vermont affecting the pH of the waters (Prindle, 1932). Most of the waterbodies we examined
had a relatively acidic pH, which does not support the spread of this invasive bivalve.
In addition to pH and hardness, we examined the effects of chlorophyll-a and
phosphorous concentrations on the suitability of zebra mussel habitat. Chlorophyll-a was
considered as a surrogate for food availability as it needs a minimum amount of available
nutrients to filter feed efficiently (Wu et al., 2010). The presence of phosphorous in the aquatic
ecosystem operates in tandem with this variable; as phosphorous concentrations increase,
phytoplankton growth increases due to the availability of nutrients. Our literature review
returned a minimum chlorophyll-a concentration of 4.25 ug/L, which was only met in 34.59% of
the assessed waterbodies (Table 3). Although the effects of zebra mussel establishment are
extremely detrimental to the native ecosystem, we propose that they are the least threatening of
the three invasive species that we analyzed in terms of spread risk due to their relatively stringent
habitat requirements.
Starry Stonewort:
One of the main factors that influences the establishment of starry stonewort is water
velocity (Schloesser et al., 1986). Schloesser et al. found the species cannot tolerate a water
velocity of eleven centimeters per second, which is far above any water velocities that are
typically observed in lakes and ponds (1986). This is because of the way the plant ground itself
into the substrate, making waters with faster velocities uninhabitable for the plant (Schloesser et
al., 1986). Schloesser et al. also found that substrate had an influence on the waters where the
plant can be found, however, the DEC did not have the same robust data for each of their
waterbodies on substrate as they do on water quality data (1986). We therefore omitted these two
factors which could be the reason for the high risks to almost all of Vermont’s waterbodies (see
Table 5).
Overall there was a lack in invasive range tolerance studies done on starry stonewort,
because of the relatively recent invasion (Midwood et al., 2016; Brown, 2016; Escobar et al.,
2016). These studies were not using the large datasets and support as those seen in when
researching the zebra mussel tolerance ranges of environmental characteristics. Midwood et al.
was a field study of the characteristics in observed areas where the species were found, and the
characteristics of the area where the species was not observed (2016). This method is inherently
flawed to the other due to the possibilities of regional variation and small sample sizes affecting
the ranges that are seen. This also puts into question, is the range observed in the study
12
representative for the whole species and what different populations can tolerate. Escobar et al.
attempted to combat this unknown by using a model, however, the model is not perfect due to
the relatively small amount of knowledge in general available on this species (2016).
In Table 5, you can see that most Vermont waterbodies met the criteria that we set.
Although this material does not have strongly scientifically supported metrics like the zebra
mussel data, this is a representation of what the scientific community currently knows. We
conclude that starry stonewort has minimal limitation in Vermont’s waterbodies, and therefore
needs an increase in monitoring and vessel-checking programs to ensure that spread risk is low.
Further Discussion
After conducting a thorough review of the available literature, there are still significant
uncertainties surrounding the extent to which we can characterize risk for an invasion of each of
these species. When determining the water quality standards that allowed us to characterize
habitats as suitable for invasion, there was substantial variation among reported threshold values.
This was especially seen for starry stonewort since its invasion was more recent to North
America. For example, the pH tolerance range was found by Escobar et al. (2016) to be 7.548.37, while Midwood et al. (2016) reported 7.4-8.5; with the nature of pH being a logarithmic
scale, the difference between 8.3 and 8.5 is substantial. The literature is not in consensus, and
this therefore has error built into our methods. We also used the watershed data that the DEC has
stored in a database. Some of these values have extensive data stores with ten years of study,
while others only have one year of data. To make up for this uncertainty, we noted which
parameters only had one year’s worth of data and clearly labelled them in our data tables and
spreadsheets. We used averaged data to alleviate discrepancies and we confirmed our proposed
values with our community partner, Josh Mulhollem.
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Figure 2: This diagram shows the Ecological Risk Assessment (ERA) framework referred
to by the Environmental Protection Agency. Our project sits during the analysis and risk
characterization phases of the process.This image was obtained from material created by
Breck Bowden in a lecture on ecological assessment (Bowden, 2017).
Since our project is set in the analysis and risk characterization phases of the ERA
framework (see Figure 2), the primary focus was to provide information that could be used for a
future a monitoring plan or policy change, not go as far as to communicate risk management
techniques. We are only providing our partner with two different tools of risk characterization
(our spreadsheet in the supplemental data link and our map in Figure 1).
The alternatives that we have identified, aims to address areas for improvement that are
in the current invasive species monitoring program. The alternative that we believe to have the
highest merit is the implementation of new boat transport laws. These laws would attempt to
impose stricter regulations focused on a reduction of invasive transport between state
waterbodies. Neighboring states like New York have already implemented proactive policies,
which require boaters to clean and drain their boats before launching or leaving from waters
owned by the Department of Environmental Conservation (Constantakes, 2014). A simple
change in boating procedure would provide significant reductions in the spread of invasive
species throughout the state, as personal watercraft are one of the main vectors of invasive
movement.
To implement our proposed alternative we would need to focus on educating boaters
throughout the state. This can be accomplished by assigning members of our team to boat launch
points at the most popular waterbodies. By spreading the word about the consequences of not
draining and drying boating equipment, we could gain support for the initiative. To ensure
compliance, a state game warden could be assigned to focus on aquatic plant and animal
14
transport. His/her primary objective would be to understand which species pose a threat to the
aquatic ecosystems and to eliminate negligent boating practices. Perhaps a more extreme
alternative would be the implementation of mandatory boat inspections by the Warden or trained
volunteers upon entering or leaving waterbodies. The obvious caveat to this scenario is the sheer
number of waterbodies that exist within the state. It would take far too many people and too
much money to inspect every watercraft. Our hope is that by focusing on the most frequently
visited lakes, we can reach the largest number of people.
Literature Citations:
Agency of Natural Resources. (2016). Gallery of Invaders: Species Currently Found in Vermont.
Vermont Official State Website. (http://dec.vermont.gov/watershed/lakes-ponds/aquaticinvasives)
Bowden, B. (2017). Ecological Assessment: A Primer [PowerPoint slide]. Retrived from
https://bb.uvm.edu/webapps/blackboard/content/listContent.jsp?course_id=_104916_1&c
ontent_id=_2117880_1
Brown, W. (2014). Defining trophic conditions that facilitate the establishment of an invasive
plant: Nitellopsis obtusa. Master's thesis (natural resources and environmental sciences);
University of Illinois, Urbana Champaign, Illinois.
Clavero, M., & Garcia-Berthou, E. (2005). Invasive species are a leading cause of animal
extinctions. TRENDS in Ecology and Evolution, 20(3), 110-110.
Cohen, A., (2017). Potential Distribution of Zebra Mussels (Dreissena polymorpha) and Quagga
Mussels (Dreissena bugensis) in California Phase 1 Report. California Department of
Fish and Game.San Francisco Estuary Institute Oakland, CA.
http://www.sfei.org/sites/default/files/biblio_files/2007Dreissena_Potential_Distribution.pdf
Constantakes, P. (2014). New state regulations target aquatic invasive species [Press release]
Dodson, S. (1992). Predicting crustacean zooplankton species richness. Limnology and
Oceanography, 37(4), 848-856
Escobar, L. E., Qiao, H., Phelps, N. B., Wagner, C. K., & Larkin, D. J. (2016). Realized niche
shift associated with the Eurasian charophyte Nitellopsis obtusa becoming invasive in
North America. Scientific Reports, 6.
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Feng, X., & Papes, M. (2017). Physiological limits in an ecological niche modeling framework:
A case study of water temperature and salinity constraints of freshwater bivalves invasive
in USA. Ecological Modelling, 346, 48-57. doi: 10.1016/j.ecolmodel.2016.11.008
Hammes, F., & Verstraete*, W. (2002). Key roles of pH and calcium metabolism in microbial
carbonate precipitation. Reviews in environmental science and biotechnology, 1(1), 3-7.
Hincks, S. S., & Mackie, G. L. (1997). Effects of pH, calcium, alkalinity, hardness, and
chlorophyll on the survival, growth, and reproductive success of zebra mussel (Dreissena
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