NESTLER, J.R.*; TRUEBLOOD, L.A.; WHEELING, R.J.; Walla Walla College, College Place WA; Walla Walla College, College Place WA; Walla Walla College, College Place WA: Effect of Increased Ocean Temperature on the Metabolic Rates of Tropical and Temperate Sea Cucumbers

Sea cucumbers (Phylum Echinodermata, Class Holothuria) are important in tropical and temperate ocean communities by affecting physical and chemical sediment characteristics through their deposit feeding activities. This study examined the effect of seasonal ocean temperature increases on the metabolic rates of tropical (Pearsonothuria graeffei, southern Philippines, summer 2001) and temperate (Parastichopus californicus, northwest US, summer 2002) sea cucumbers. Oxygen consumption of tropical organisms significantly decreased from 0.050 to 0.025 mg O₂/g/h as water temperature increased from 27.5°C to 30.0°C (r²=0.4243, p=0.0044, n=19). This 2.5°C increase in the Philippines during the 2001 summer is larger than the 1°C increase which occurs in most years, and may represent a stressful situation for tropical sea cucumbers. These organisms may be responding to the temperature stress by reducing metabolism and entering a dormant state. Oxygen consumption of temperate animals significantly increased from 0.020 to 0.050 mg O₂/g/h as temperature increased from 9.5°C to 12.0°C (r²=0.6117, p=0.0042, n=13). This 2.5°C increase is typical for the northwest US, and thus these temperate sea cucumbers should not have been influenced by a temperature stress as were the tropical organisms. Metabolic measurements in temperate sea cucumbers are continuing through the fall of 2002 as the northwest US is influenced by a weak El Niño system. The increasing frequency of changes in ocean temperature may affect tropical and temperate community structure by altering the integral role that sea cucumbers have in these environments.