Differences in the metabolism of two morphospecies Munida gregaria and M. subrugosa (Anomura: Galatheidae) from Beagle Channel

AVALOS, CECILIA; HEILMAYER, OLAF; GUSTAVO ALEJANDRO LOVRICH

Coquimbo, Chile

Congreso; Mid-Year Meeting The Crustacean Society; 2007

Universidad de Coquimbo / The Crustacean Society

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Munida gregaria and M. subrugosa are closely related galatheid crabs of 5-7 cm total length that play a key role in the coastal sub-Antarctic ecosystem of South America. Both morphospecies are sympatric in the Beagle Channel. Although as adults both morphospecies are benthic, M. gregaria is known to perform migrations in the water column, whereas M. subrugosa is always on the sea-bottom. Due to the different activity patterns, we expect to find differences in the aerobic metabolism of both morphoespecies. Here we study differences in the metabolism of these two morphospecies at the austral summer temperature. Animals were caught in Beagle Channel (54º 50´S; 68º 17´W) by means of an epibenthic trawl. Twelve individuals per morphopecies were acclimated to 8ºC in individual flasks during four to eight weeks. Oxygen consumption of crabs was measured using an intermittent flow-through system. After obtaining values for standard metabolism (defined as oxygen consumption of unfed, unstressed animals) Specific Dynamic Action (SDA) was evaluated. A different set of crabs (n=4 per morphospecies and sex) was dissected after acclimation, and gills and muscles were frozen to determine activity of Citrate synthase (CS) and pyruvate kinase (PK) as well as Arrhenius breakpoint temperatures. The mean standard metabolic rate for both morphospecies at 8°C was 61,65 ± 11,05 µl O2· l-1·h-1·gWM-1. No significant differences of standard metabolic rates were found in M. gregaria and M. subrugosa or between sexes (F=3.1; p=0.13 and F=1.4; p=0.67, respectively). Peaks of O2 consumption after feeding were different between both morphospecies, being significantly higher in M. subrugosa. Moreover, the pospandrial increase (SDA) was also higher in M. subrugosa than in M. gregaria. Our results show no differences in the standard metabolism between both morphospecies, however significant differences were found in SDA showing possible differences on phisiological answers. This study was funded by the CENSOR project – European Union Contract 511071   ORAL