LIVE-DEAD FIDELITY OF MOLLUSCAN ASSEMBLAGES IN ANTHROPOGENICALLY IMPACTED SEAGRASS HABITATS, NORTH CAROLINA
At each site, bulk sediment samples were collected from the upper 40 cm of the substrate at 10m intervals along three 30m transects. Spearman’s rank correlation was used to compare the rank-order abundance of genera within the living and death assemblages at and among sites. When bivalve and gastropod assemblages are pooled, there are significant rank correlations between living and dead assemblages at all sites (OC: rs=0.3492, p<0.0004; BS: rs=0.4288, p<0.0008; CB: rs=0.2801, p<0.0006). Death assemblages for each site are also significantly correlated to one another (OC vs. BS: rs=0.6962, p<<0.0001; OC vs. CB: rs=0.4438, p<<0.0001; BS vs. CB: rs=0.3212, p<0.0014). Living assemblages are not significantly correlated among sites. Rarefaction analyses indicate that living and dead assemblages at Chadwick Bay are enriched compared to the other sites and that Oyster Creek yields the lowest diversity and abundance (95% confidence interval). Death assemblages at all sites are enriched in comparison to corresponding living assemblages. Significant live-dead fidelity contradicts our hypothesis. However, similarity of death assemblages and disparity of living communities among the three sites suggest that different anthropogenic pressures may yield specific ecologic responses by and consequences for molluscan assemblages. Field observations suggested that Chadwick Bay is the most stable, least impacted environment and Oyster Creek is the most stressed. Significant rank correlations and rarefaction results support these inferences.