Meeting Abstract

P3.107  Saturday, Jan. 5  The effects of salinity and temperature on hemolymph methyl farnesoate levels and testicular development in Carcinus maenas GANJI, PURNACHANDRA N*; BORST, DAVID W; University of Central Florida, Orlando; University of Central Florida, Orlando dborst@mail.ucf.edu

Methyl farnesoate (MF) is produced by the mandibular organ of crustaceans and may control a number of physiological processes including reproduction. We studied how environmental factors (salinity and temperature) affect hemolymph MF levels in male crabs (C. maenas). This crab has two color (green and red) phases. Red phase animals are more robust (thicker carapace, larger chela muscles) and have higher mating success while green phase crabs grow more quickly, until they transform into red phase animals. We compared MF levels in crabs maintained in seawater at two temperatures (11� and 18�C) and two salinities (5 and 33 ppt). In seawater at 11�C/33 ppt, about 30% of the red phase males had detectable MF in their hemolymph. This percentage increased to nearly 50% when red phase animals were place in 18�C/33 ppt seawater and to nearly 100% in lower salinity seawater at either temperature. In contrast, few green phase males had detectable MF when placed in 33 ppt seawater at either temperature and only had increased MF levels when placed in low salinity seawater at the higher temperature. To test the effects of MF on reproduction, we used green phase males which have a low testicular index (TI). These animals were treated to increase hemolymph levels of MF (exposure to 18�C/5ppt seawater, removal of eyestalks, or injection of MF). These treatments significantly increased their TI over a two week period. These results suggest that environmental factors such as temperature and salinity can enhance MF levels which in turn can stimulate testicular development. (Supported by NSF grant 0611447).