Meeting Abstract

6.3  Sunday, Jan. 4  Context-dependency of growth rate and vulnerability to predators of Caribbean coral reef sponges WULFF, Janie; Florida State University wulff@bio.fsu.edu

Sponges play key functional roles on coral reefs, including filtering the water column, gluing live corals to the reef frame, protecting exposed carbonate skeletons from excavating organisms, and facilitating regeneration of damaged reefs. Concerns that these roles could be lost due to declines in sponges, or, conversely, that sponges could overgrow reef surfaces with detrimental effect, impel understanding of factors that control sponge distribution and abundance. Relative importance of top down versus bottom up trophic factors was evaluated by comparing size changes and survival of 12 common species of Caribbean coral reef sponges in three linked habitats that differ in spongivore abundance and taxa and in water column productivity. Sponge pieces of the same size and genotype were attached to stable solid substrata inside cages and next to, but outside of, cages on the reef and in the seagrass, and on PVC pipes suspended among mangrove roots. Growth and survival were monitored at intervals for 1-3 years. For most sponge species, growth and survival were indistinguishable inside and outside of cages on the coral reef, but in the seagrass most species did not survive outside of cages. Curiously, both growth and survival of the coral reef sponges were highest among the mangrove prop roots.