REPRODUCTIVE ALTERATION AS INDICATOR FOR ENVIRONMENTAL HORMONAL DISRUPTION IN OREOCHROMIS NILOTICUS INHABITS LAKE MANZALA

K.M. Ahmed; M.A. Amer;

A.A. El-Gamal and M.F. Osman

Animal Production Department, Faculty of Agriculture, Ain Shams University, 68 Hadaek Shubra, 11241, Cairo, Egypt.

Received 17/ 8/ 2014

Accepted 15/ 10/ 2014

Abstract

The presence of testis-ova (TO) in gonochristic fish has been used as biomarker for detecting xenoestrogens exposure e.g. polyaromatic compounds (PAHs) and Polychlorinated biphenyl (PCBs). In late 2011, a pilot screening was performed to detect signs of estrogenic compounds on Nile tilapia O. niloticus inhabit Lake Manzala 31° 16′ 0″ N, 32° 12′ 0″ E; followed by other one in 2012.

Hepatosomatic index (HSI) and Gonadosomatic index (GSI) values variation were noted in both sexes and seasons in all subjected areas. The presence of oocytes within the testicular tissue of males were explicit. Hence, severity index ranking (0-4) was developed based on the number of oocytes per testicular tissue section. The number of histological section needed to clearly detect intersex in tilapia was statistically verified by using samples collected from 2011 to 2012.

Seasonal differences in severity and occurrence O. niloticus male were detected by calculating occurrence percentage in the two consecutive seasons. The TO percentages ranged from 30-60% in first season and 24-45% in second season in all sampling areas. The highest diffusion and severity were noted during postspawn – prespawn season, when compared with spawning season.

On the other hand, females’ gonads showed seasonal differences. In the first season, spent stage (V) was the common stage with 100% of the collected samples. While, in the second season mature stage (III) and ripping oocyte stage (IV) where detect.

Keywords: Xenoestrogens, Lake Manzala, Testis-ova, Endocrine disrupting chemicals (EDC), Oreochromis niloticus.