Meeting Abstract

134-6  Sunday, Jan. 8 11:30 – 11:45  Transparency and Depth Effects on Metabolic Rates in Hyperiid Amphipods ELDER, L.E.*; SEIBEL, B.A.; Yale University; University of South Floridia leanne.elder@yale.edu http://people.earth.yale.edu/profile/leanne-elder/about

This study sought to determine what environmental and ecological factors influence the rate of metabolism in marine amphipods. We examined species from a range of environments and with diverse morphologies. The mean metabolic rate for marine hyperiid amphipods was significantly lower in the deep-living clade Physosomata (1.54±0.67 µmol O2 g^-1hr^-1 ) than in the shallow-living clade Physocephalata (7.27±0.85 µmol O2 g^-1hr^-1). Within the clade Physocephalata metabolic rates of transparent species were significantly lower (3.74±0.88 µmol O2 g^-1hr^-1) than non-transparent species (12.00±1.38 µmol O2 g^-1hr^-1). The variation in metabolic rates is discussed in relation to environmental factors, including habitat depth and temperature as well as biotic factors such as transparency and body mass. Our results are consistent with the visual interactions hypothesis, which postulates that decreasing selection for locomotory capacity (by transparency or living permanently below the photic zone) limits predator-prey detection distance among visually oriented organisms and allows for reduced energy expenditure for locomotion. The use of gelatinous zooplankton as substrate, food or protection will also be discussed.