334 
Fishery Bulletin 113(3) 
labile 2 
Mean species density (individuals/m 2 ), mean number of species captured, and F-values and P-values from generalized linear 
mixed models run, by site for species collected in summer and fall 2010 at actively harvested (AH) and nonharvested (NH) 
oyster reefs in Louisiana. Degrees of freedom for F-values are provided in parentheses. Significant differences (P<0.05) be- 
tween harvest treatments are indicated by asterisks (*). Only species that contributed to more than 1% of the total catch 
were analyzed statistically. Note that n refers to the number of trays successfully sampled for abundance data. Standard 
errors of the mean are provided in parentheses. 
Summer Fall 
Scientific name 
Sabine 
Lake 
(NH) 
71=14 
Sister 
Lake 
(AH) 
71=12 
F( 1,4) 
P-value 
North 
Calcasieu 
Lake (NH) 
tz=15 
South 
Calcasieu 
Lake (AH) 
72 = 17 
F (1, 4) P-value 
Gobiosorna bosc 
9.4 (1.6) 
102.8 (21.4) 
19.26 
0.01* 
49.7 (6.2) 
51.9 (2.8) 
0.06 
0.82 
Hypsoblennius ionthas 
7.8 (2.1) 
18.2 (5.0) 
0.08 
0.8 
1.5 (0.6) 
0.8 (0.4) 
0.27 
0.63 
Gobiesox strumosus 
3.3 (0.9) 
10.6 (2.9) 
1.32 
0.31 
3.9 (0.9) 
0.8 (0.6) 
6.17 
0.07 
Chasmodes bosquianus 
0.7 (0.4) 
2.3 (1.0) 
1.5 (0.6) 
0.8 (0.4) 
Opsanus beta 
3.3 (1.2) 
1.5 (0.9) 
0 
0.3 (0.3) 
Myrophis punctatus 
0 
2.7 (1.6) 
0 
0 
Lutjanus griseus 
0 
0.4 (0.4) 
0.6 (0.4) 
0 
Chaetodipterus faber 
0.3 (0.3) 
0.4 (0.4) 
0 
0 
Gobionellus boleosoma 
0.3 (0.3) 
0.4 (0.4) 
0 
0 
Paralichthys lethostigma 
0.3 (0.3) 
0 
0 
0 
Fish density 
25.4 (3.4) 
139.2 (26.0) 
10.17 
0.03* 
57.3 (6.2) 
54.6 (2.8) 
0.17 
0.7 
Number of fish species 
2.8 (0.3) 
3.5 (0.4) 
1.16 
0.34 
2.5 (0.2) 
1.5 (0.2) 
11.69 
0.03* 
Eurypanopeus depressus 
74.8 (12.1) 
106.9 (15.3) 
1.96 
0.23 
173.5 (17.9) 
171.0 (14.3) 
0.03 
0.87 
Palaernonetes spp. 
207.7(28.8) 
103.9 (36.3) 
2.02 
0.23 
132.6 (17.0) 
65.6 (12.7) 
8.98 
0.04* 
Panopeus simpsoni. 
22.4 (2.8) 
13.7 (2.7) 
4.91 
0.09 
0.9 (0.7) 
15.8 (2.4) 
5.97 
0.07 
Callinectes sapidus 
0 
14.0 (5.2) 
3.28 
0.14 
13.9 (4.2) 
15.5 (5.2) 
5.33 
0.08 
Rhithropanopeus harrisii 
0.7 (0.4) 
20.1 (6.3) 
19.26 
0.01* 
0 
0 
Alpheus heterochaelis 
0.7 (0.4) 
9.1 (2.6) 
0.3 (0.3) 
4.6 (1.7) 
Menippe adina 
0.3 (0.3) 
4.6 (1.3) 
2.1 (0.8) 
5.6 (1.4) 
Farfantepenaeus aztecus 
0.3 (0.3) 
1.5 (1.0) 
0 
0.8 (0.6) 
Petrolisthes armatus 
0 
0 
0 
0.3 (0.3) 
Clibanarius uittatus 
0 
0.8 (0.8) 
0 
0 
Invertebrate density 
306.8 (29.8) 
274.5 (37.8) 
0.41 
0.56 
323.4 (22.9) 
279.2 (22.3) 
1.34 
0.13 
Number of invertebrate 
species 
3.4 (0.2) 
5.5 (0.4) 
14.26 
0.02* 
3.2 (0.3) 
3.4 (0.2) 
4.87 
0.09 
Total density 
332.2 (29.4) 
413.7 (55.9) 
0.1 
0.77 
380.7 (21.0) 
333.8 (24.5) 
1.82 
0.25 
Total number of species 
6.2 (0.3) 
9.0 (0.5) 
23.9 
0.008* 
5.7 (0.3) 
6.3 (0.3) 
1.69 
0.26 
in nekton assemblage (eigenvalue=0.11), was highly 
correlated with reef integrity (coefficient of correla- 
tion [?-]--0.69) and distinguished species that prefer 
fragmented reef habitats. Species, such as the big- 
claw snapping shrimp ( Alpheus heterochaelis ) and the 
estuarine mud crab, were associated with reefs with 
low integrity values (<50%). The vertical axis, which 
accounted for 27.7% of the variation (eigenvalue=0.05), 
was negatively associated with volume of loose shells 
(r=-0.70) and positively associated with total number 
of live oysters (r=0.70), and this axis distinguishes spe- 
cies that prefer live oyster habitats. Species, such as 
the freckled blenny {H. ionthas) and skilletfish, were 
strongly positively associated with the number of live 
oysters. 
Stable isotopes 
For the summer sampling, results from a 2-source mix- 
ing model indicated that pelagic basal food sources (i.e., 
FPOM) contributed more to the food web of the resi- 
dent community on the sampled oyster reefs than the 
nonpelagic sources (i.e., marsh plant) regardless of har- 
vest treatment (all values of source fractions of FPOM 
were >0.50; Table 3). The pelagic source contribution 
was higher for flatback mud crabs at the nonharvested 
site (0.65 [SE 0.03]) than at the harvested site (0.53 
[SE 0.04]). The trophic positions of the hooked mus- 
sel, eastern oyster, grass shrimp, skilletfish, and naked 
goby were elevated at the harvested site compared to 
the nonharvested site (Fig. 5). 
