TESTING THE UTILITY OF MOLLUSK LIFE AND DEATH ASSEMBLAGES FOR DELINEATING SPATIAL DISTRIBUTION OF SEAGRASS HABITATS ALONG FLORIDA’S GULF COAST

Seagrass habitats support a broad suite of ecologically and economically important taxa, but are diminishing around the world at alarming rates due, in large part, to human related activities. Here, we examine living mollusk communities and sympatric death assemblages associated with seagrass habitats. Our goal is to evaluate live-dead agreement of mollusk assemblages as a proxy for assessing long-term changes in the distributional patterns of seagrass meadows.

We collected 48 suction core samples of live and dead mollusks from 12 sampling stations that represent three distinct habitat types: (1) “Static vegetated” (temporally unchanged with macrophyte cover); (2) “Static unvegetated” (temporally unchanged without macrophyte cover); and (3) “Transition localities” (temporally changing macrophyte cover). Specimens were identified to the lowest taxonomic level possible. Preliminary multivariate analyses (nMDS based on Bray-Curtis similarity) of data processed thus far indicate that, for both live and dead mollusks, samples from static vegetated stations grouped separately from static unvegetated stations (p < 0.001, MANOVA). Pilot nMDS analysis also indicates that death assemblages from transition stations ordinate in-between samples of vegetated and unvegetated stations suggesting that dead mollusks from transition areas reflect the temporal dynamic in seagrass cover.

Preliminary results indicate distinctive assemblages of live mollusks for both static vegetated and static unvegetated localities and distinct death assemblages for all three locality types. These findings suggest that mollusk assemblages may be useful in distinguishing between localities with different macrophyte cover dynamics. In addition, live-dead comparisons may provide insights into historical changes in spatial distribution of seagrass habitats.