Stoner and Waite: Habitat associations of Strombus gigas within seagrass meadows 



579 



A one-way ANOVA and a Newman-Keuls multiple 

 range test were used to test for differences in log 

 transformations of conch biomass among stations for 

 all date-site samples. There was a significant difference 

 in the log of conch biomass across stations. Conch 

 biomass increased from 13.4 g wet weight (±44.5) at 

 station 1 to 851 g wet weight ( ± 766) at station 5. The 

 log of conch biomass at stations 1 and 2 were not dif- 

 ferent from one another but were each significantly dif- 

 ferent from stations 3, 4, and 5. Stations 3 and 5 were 

 each significantly different from all stations but sta- 

 tion 4 (Newman-Keuls, jo<0.05). 



Relationships between 



conch and the independent variables 



There were highly significant correlations between 

 both density and biomass of conch in the field and the 

 depth and macrophyte characteristics of the habitat 

 (Table 6). Tested by individual date at Children's Bay 

 Cay, correlations between conch density and depth, 

 shoot density, and seagrass biomass were high and 

 relatively similar (r values between 0.753 and 0.910), 

 while correlations with detritus were significant but 

 lower. Similar patterns held for conch biomass. At 



Shark Rock in July, conch numbers and biomass were 

 highest at station 5 (Fig. 2) and did not increase over 

 the entire range of seagrass shoot density or biomass. 

 Therefore, linear regressions of conch density and 

 biomass with depth and macrophyte characteristics did 

 not yield high or significant correlations in most cases 

 when data from all seven stations were included (Table 

 6). Highly significant correlations were found using the 

 first five stations; all of the habitat characteristics 

 yielded correlation coefficients between 0.701 and 

 0.863 (Table 6). 



In regression models including data from all dates, 

 sites, and stations 1-5, all of the environmental 

 variables yielded significant correlations with conch 

 density and biomass (Table 6). Highest correlations oc- 

 curred between seagrass shoot density and both conch 

 density and conch biomass. Lowest correlation coeffi- 

 cients occurred with detritus. 



Two stepwise multiple regressions were run to deter- 

 mine the best multiple regression models for conch den- 

 sity and conch biomass using all of the data for stations 

 1-5 (all dates and sites combined). Alpha to enter and 

 remove from the models was set at 0.150. The regres- 

 sion model for conch density included first shoot den- 

 sity followed by detritus standing crop, and yielded a 



