PAWLIK, J. R.; Univ. of North Carolina at Wilmington: Is bad taste expensive? Resource allocation and chemical defenses of Caribbean sponges.

Sponges are a major component of the benthic fauna of Caribbean reefs, and are consumed by a few species of predatory fishes (e.g., angelfishes). We previously discovered that Caribbean sponge species could be divided into three groups: (1) those that are chemically defended and found openly on the reef, (2) those that are not defended, found openly on the reef, and are subject to fish grazing, and (3) those that are not defended and found only in cryptic locations because of fish grazing. We have been investigating whether there are trade-offs in resource allocation for sponges of the first 2 categories: Do chemically undefended sponges grow faster, heal faster, or reproduce more than sponges that invest in chemical defenses? Chemically undefended sponges regenerated simulated bite marks at much faster rates than chemically defended species. Holes were cut in 4 species of chemically undefended and 3 species of chemically defended, vase-shaped sponges, and regeneration of tissue was monitored over 12 days using digital photography. Rates of regeneration ranged from 6-8% of wound area per day for undefended species, and 0-2% per day for chemically defended species. These data, along with the results of on-going long-term predator-exclusion experiments, suggest that there are trade-offs between chemical defenses and sponge tissue regeneration and growth.