Contrasting high and low relief
fishery habitats of the northeastern
Gulf: habitat delineation, food web
components and spatial
demographics
Doug DeVries1 Chris Gardner1, Gary Fitzhugh1,
and Thomas Harrah2
1NOAA
Fisheries Service
Southeast Fisheries Science Center
Panama City Laboratory
2Florida
State University
Goals
•
Provide spatially-explicit demographic and biological information linked to
habitat parameters for important reef fishes in N. Gulf, to improve
understanding of structure, function, and linkages of the various fishery
ecosystems in the region and enhance fishery ecosystem model
development and management.
•
Delineate and quantify hard bottom habitat on the inner- and mid-shelf in
the NE Gulf
•
Expands community survey and mapping efforts to very different, much
higher relief (10 m) habitat and to Apalachee Bay – provides increased
spatial and habitat contrasts
Objectives
•
Compare community structure, demographics, and trophic patterns between
high- and low-relief habitats
•
Compare growth and condition of fishes between high- and low-relief
habitats, and examine effect of scale of a species’ movements (or site
fidelity) on these parameters
•
Map and characterize hard bottom habitats in 10 - 30 m in the Big Bend,
focusing on our FSU collaborators’ study area, and in an area of very high
relief known as the “3x5’s” about 40 nm S. of Panama City
Species composition, abundance, and size data
•
Video data using ROV with parallel scaling lasers
– 2-4, 25-40m transects
– 20-30 min random search for cryptic species and additional size data
Age, food habits, and stable isotope samples
•
standardized hook-and-line sampling at nearby sites
Growth and condition comparisons
•
Standard age and growth studies, bioelectrical impedance analysis (BIA)
Panama
City
Apalachee Bay
Three-by-fives
Three-by-fives
High relief
Low relief
Video
Video
High relief
Low relief
3.4
Shannon-Weiner diversity indices + standard error
(√ transformed)
3.3
3.2
3.1
3
2.9
2.8
2.7
3x5 high
3x5 low
Inshore
Midshelf
Offshore
120
3x5 high
3x5 low
100
Midshelf and Offshore
Mean # fish / ha
80
60
40
20
0
Gray Snapper
Gray Triggerfish
Red Grouper
Red Snapper
Scamp
ROV transect counts
350
Mean number of fish / ha
USNPS
Bigeye
300
250
TPWD
High Relief
Low Relief
200
150
Creolefish
100
50
0
Spotfin hogfish
800
Purple Reeffish
Yellow tail Reeffish
Purple reeffish
Frequency
600
400
Yellowtail reeffish
200
0
High
Low
42
Laser
Frequency
35
3x5's
28
Midshelf and Offshore
21
14
7
0
125 175 225 275 325 375 425 475 525 575 625 675 725
Total length (mm)
60
Hook & line
Frequency
50
40
30
20
10
0
125 175 225 275 325 375 425 475 525 575 625 675 725
Total length (mm)
Red
snapper
Vermilion snapper
hook & line
20
3x5's
Offshore 2011
Frequency
16
12
8
4
0
100
125
150
175
200
225
250
275
300
FL (mm)
325
350
375
400
425
450
Bioimpedance
30
3x5's High relief
Old CI Low relief
3x5's Low relief
Phase angle
25
20
15
10
5
0
Gray
triggerfish
Red
porgy
Red
snapper
Vermilion
snapper
FSU
Marine
Lab
West
East
Gulf of
Mexico
Cape
San Blas
Cedar
Key
75 m
75 m
Ledge
Sponge/gorgonian
Pavement
Scattered
Sand or
Shell Hash
95%
Total area : 1.9 x 106 m2
80000
2
Scattered
3%
Total area (m )
Gorg/Sponge
1%
Western
Pavement
1%
Mean patch:2200 m²
Gorg/Sponge
Pavement
60000
Scattered
40000
20000
0
11
13
15
17
19
21
23
25
Depth (m)
Eastern
Sand or Shell
Hash
92%
<1%
Mean patch:1400 m²
80000
2
Scattered
5% Ledge
Total area (m )
Pavement
2%
Gorg/Sponge
1%
Total area : 3.3 x 106 m²
Ledge
Gorg/Sponge
60000
Pavement
Scattered
40000
20000
0
11
13
15
17
19
Depth (m)
21
23
25
Key Points
• Fish diversity was similar on high and low relief reefs within the
3x5’s and between those and low relief midshelf reefs ~50 km NW.
• Community structure did differ noticeably between the high and low
relief reefs within the 3x5’s area.
• Modal sizes of red snapper and vermilion snapper were ~100 mm
larger on 3x5’s reefs than on the earlier NGI study low relief reefs.
• Preliminary BIA analyses hinted at higher condition in fishes on
high relief 3x5’s reefs than on the earlier NGI study low relief reefs.
• About 5% of 2 cross-shelf (11-25 m) transects in central Apalachee
Bay was hard bottom reef habitat, but distribution varied between
the two.
Acknowledgements
Jeff Chanton - FSU
Jimmy Nelson - FSU
David Naar - USF
Brian Donahue - USF
Capt. Gary Buholm
LT Justin Keesee
John Brusher
Patrick Raley
Bill Walling