SNYDER, M.J.*; ROSSI, S.: Alterations in Stress Proteins Correlate with Space Competition in Sessile Marine Invertebrates.

Competition for space among sessile marine invertebrates, following larval settlement, can involve aggressive behaviors and the production of biologically active substances. These strategies have been widely studied in benthic cnidarians, for which the destructive nature of such responses to competing species is well known. In this work, we have chosen two nearshore subtidal cnidarians, the anemone Anthopleura elegantissima and the corallimorpharian Corynactis californica. We tested whether stress proteins (HSP70) could be useful indicators of intra- and interspecies competition intensity in these species. In A. elegantissima, HSP70 was concentrated in the tentacles while in C. californica, there was no difference between tentacles and body. HSP70 levels were similar between C. californica inside and outside polyps when different clones interact, and were fairly constant in the corallimorpharian in the different interspecies encounters. All C. californica individuals appear prepared to war as exhibited the high constant polyp HSP70 expression. When interacting with other clones or specific competitors, A. elegantissima outside polyps (warriors) express significantly higher HSP70 levels than interior polyps. A. elegantissima distributes the defensive efforts with high warrior tentacle HSP70 levels correlating with the clonal responsibility for interactions against many different sessile competitors. Our results demonstrate that biochemical measurements such as stress protein levels may provide interesting clues about the in situ intensity and destructive nature of interactions between sessile benthic marine species. (Funded by NOAA California Sea Grant R/A-108)