Meeting Abstract

S3.6  Monday, Jan. 4  The peril of the plankton VAUGHN, D.*; ALLEN, J.D.; Univ. of Washington, Friday Harbor Laboratories; College of William and Mary dvaughn@u.washington.edu

The pelagic environment is characterized by unevenly distributed resources and risks. Such unpredictability presents adaptive challenges to diverse planktonic organisms including the larvae of benthic invertebrates. Estimates of mortality during planktonic development are highly variable, ranging from 2% to 100% per day. Predation is considered a significant source of this mortality, but what explains the variability in estimates of the mortality of marine invertebrate larvae? While differential exposure of larval prey to predators may explain these widely variable estimates, adaptations that reduce vulnerability of marine larvae to predators may also be important. Although there are excellent reviews of larval mortality, predation and defenses, nearly 15 years have elapsed since the topic was formally reviewed. In this talk, we will highlight recent advances in understanding the behavioral, chemical and morphological defenses that larvae possess and assess their effectiveness in reducing predation risk. While recent work confirms that larval mortality is generally high, it also demonstrates that larvae can reduce their risk of predation in several ways including 1) temporarily escaping the benthos during vulnerable early stages, 2) producing chemical compounds that reduce palatability, 3) possessing morphological defenses such as spines and shells, and 4) exhibiting induced defensive responses whereby larvae can alter their behavior, morphology and life histories in the presence of predators. Taken together, these studies indicate that marine larvae are not hapless victims but instead possess a sophisticated suite of defensive phenotypes that have allowed them to persist in the life cycle of benthic invertebrates for eons.