Meeting Abstract
P3.62 Saturday, Jan. 5 Growth Rate Determinations for Lepas anatifera (Cirripedia:Lepadidae) in the Tropical Pacific Using Shell Growth Patterns and In-situ Temperature Records STEMPKO, T*; VENN, C; Bloomsburg University of PA; Bloomsburg University of PA cvenn@bloomu.edu
Many pedunculate barnacles of the species Lepas anatifera, including both subspecies L. anatifera anatifera and L. anatifera striata, collected from a mooring in the tropical Pacific Ocean bore shells with one or more distinct variations in shell thickness. The mooring was in place at 57°N, 95°W from February 1998 until May 1999, during which time a sensor recorded sea surface temperature (SST). In mollusks, variations in shell thickness often correlate to periods of stress, particularly temperature stress. In the present study, 126 of 240 barnacle specimens exhibited 1 distinct shift in shell thickness on both tergum and scutum. If the variations in shell thickness of barnacles in the present study are related to temperature changes, then the SST record can be used to infer the growth rate of the barnacles during the period of �new growth� (deposition of the post-thickened part of the shell). SST during the mooring deployment ranged over about 4°C, from above 30°C in May 1998 (end of El Niño) to near 26.5°C in January 1999. During the last 28 days of the buoy deployment, SST exhibited rapid cooling. Assuming that this temperature change triggered a change in growth rate and shell thickness, we estimated growth rates by dividing total �new growth� (scutum plus tergum) by 28 days, resulting in growth rates ranging from 0.2 to 0.5 mm/day for both subspecies of L. anatifera.
