Effects of warm water pulses on sexual steroids and thyroid hormones during pejerrey Odontesthes bonariensis vitellogenesis

TOMÁS CHALDE; LEANDRO ANDRÉS MIRANDA

Buenos Aires

Simposio; 7th International Symposium on Fish Endocrinology; 2012

It has been demonstrated that exposure of pejerrey, a multiple-spawner fish, to elevated water temperature during the spawning season impairs its reproductive performance. In this study it was evaluated the effect of high temperature during vitellogenesis and the role of sexual steroids and thyroid hormones on this process. Four groups of fish of both sexes were kept under natural conditions until spawning. The fish were exposed during 4 days to warm water pulses during early vitellogenesis (June), mid-vitellogenesis (July), or final vitellogenesis (August), and a control group without warm pulses. In all groups subjected to warm pulses spawning was advanced compare to control fish, however fertilization and hatching rate were negatively affected in fish exposed during mid and late vitellogenesis. In these groups it was also observed that E2 levels in females, measured immediately after treatments, were lower than control fish, while T3 increased only after June treatment. In males, T3 levels increased by temperature pulses in all treatments, while 11-KT decreased in June. The results obtained showed that warm water during early reproductive stages impair the reproductive performance, diminishing eggs and larvae quality, being this damage more evident in females at late vitellogenesis.