Effects of global warming on fish reproductive endocrine axis, with special emphasis in pejerrey Odontesthes bonariensis.

MIRANDA LA; ELISIO M; CHALDE T

GENERAL AND COMPARATIVE ENDOCRINOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2013 vol. 192 p. 45 - 54

0016-6480

The ongoing of global warming trend has led to an increase in temperature of several water bodies.Reproduction in fish, compared with other physiological processes, only occurs in a bounded temperature range; therefore, small changes in water temperat ure could significantly affect this process. This review provides evidence that fish reproduction may be directly affected by further global warming and that abnormal high water temperature impairs the expression of important genes throughout the brain?pitu-itary?gonad axis. In all fishes studied, gonads seem to be the organ more readily damaged by heat treat-ments through the inhibition of the gene expression and subsequent synthesis of different gonadal steroidogenic enzymes. In view of the feedback role of sex steroids upon the synthesis and release of GnRH and GtHs in fish, it is possible that the inhibition observ ed at brain and pituitary levels in treated fish is consequence of the sharp decrease in plasma steroids levels. Results of in vitro studies on the inhi-bition of pejerrey gonad aromatase expression by high temperature corroborate that ovary functions are directly disrupted by high temperature independently of the brain?pituitary axis.  For the reproductive responses obtained in laboratory fish studies, it is plausible to predict changes in the timing and magnitude of reproductive activity or even the total failure of spawning season may occur in w arm years, reducing annual reproductive output and affecting future populations.