Meeting Abstract
67.2 Sunday, Jan. 6 Microhabitat temperature profiles and stress protein levels in a high intertidal tropical marine snail, Cenchritis muricatus BOTTON, M. L.**; JUDGE, M. L.; HAMILTON, M. G.; Fordham Univ., New York; Manhattan Coll., New York; Fordham Univ., New York botton@fordham.edu
The knobby periwinkle (Cenchritis muricatus) inhabits the rocky coastline of St. John, US Virgin Islands, occupying a niche in the extreme upper intertidal and supralittoral zones (up to 14.5 m above mean water level). Very few snails <12 mm in length were found in any supralittoral microhabitat, but occurred primarily at the lower tidal heights. Overall, size differences among snails from different microhabitats were modest; the smallest individuals were collected from crevices in black rocks, and the largest snails were found on tree roots or branches. To quantify temperature stresses among microhabitats, we deployed clay-filled shells ("snail mimics") with temperature probes and a data logger at four locations: exposed white rock, exposed black rock, crevices, and grass stems. During the period of study, the daily low air temperatures averaged 24.3 C, and the daily high air temperatures averaged 30.0 C. Thermal stress was considerably higher on substrates, but it varied significantly with microhabitat. Each substrate exceeded 36 C for 4.5 h or more per day. However, snails occupying black rocks and crevices were exposed to temperatures above 44 C for ca. 2 h daily, whereas temperatures rarely exceeded 42 C on white rocks or grass stems. Levels of two classes of stress proteins, Hsp70 and Hsp 90, were measured in "control" snails that were hydrated and kept at a constant temperature of 26 C, and in snails that were placed on white rocks, black rocks, crevices, and grass stems at 0800 and then sampled at 1300 and 1700. Amounts of Hsp70 were similar between treatments and controls. However, levels of Hsp90 were higher among snails deployed in all four microhabitats compared to controls, suggesting that there was additional synthesis of this stress protein as a consequence of thermal stress.
