Temperature effects on metabolic responses of two galatheids from South America: Munida gregaria and Pleuroncodes monodon

AVALOS, M. CECILIA; FLORENTÍN, OLGA; ROMERO, M. CAROLINA; LOVRICH, GUSTAVO A.

Qingdao

Congreso; 7th International Crustacean Congress; 2010

Munida gregaria and Pleuroncodes monodon are two species of squat lobsters inhabiting the South American coasts. Both species have similar ecological roles, being the direct trophic link between the detritus and the top predators. Animals were acclimated to: 4, 8, 12 and 16ºC (M. gregaria) and to 12, 16, 20, 24ºC (P. monodon). Oxygen consumption of squat lobsters was measured in individual chambers using an intermittent flow-through system. Animals were dissected and gills and muscles used to determine activity of citrate synthase (CS) and pyruvate kinase (PK). In M. gregaria the mass specific metabolic rate (MSMR) increased with temperature in all the temperature range (4 to 16ºC). In P. monodon, oxygen consumption increased from 12 to 20ºC, but decreased in 24ºC, suggesting the animals were far beyond their optimal temperature. MSMR in umol O2*l1*h*g were as follows: 4ºC: 1.62±0.4; 8ºC: 2.55±0.5; 12ºC: 2.98±0.8 and 16ºC: 4.4±0.9 for M. gregaria and 12ºC: 2.46±0.9; 16ºC: 3.53±1.0; 20ºC: 4.7±1.7 and 124ºC: 3.17±0.7 for P. monodon. Q10 values showed that the preferred temperatures for M. gregaria are between 8 and 12 ºC and for P. monodon between 12 and 20ºC. Activities of CS and PK were measured in a temperature range between 0 and 28ºC and were found to increase with temperature with no signs of thermal inactivation, in neither of the species or tissues.In all cases M. gregaria showed higher enzymatic activity than P.monodon. In general these findings are in agreement with metabolic temperature compensation which suggests that animals adapted to warmer waters (in this study P. monodon from North Chile) will have a lower metabolic rate and enzyme activities ant any given temperature that their colder –adapted counterparts (in this study M. gregaria from Beagle Channel). It is important to be noted that the concept of metabolic compensation is the focus of much controversy and that is very difficult to find close related species with similar ecology and life styles to choose as model for these studies.