Endocrine Disruption in Laguna Lake Assessed through Histopathology of Tilapia (Oreochromis niloticus) Gonads

Abstract

The aim of the study is to investigate the presence of endocrine disrupting compounds (EDCs) in Laguna Lake through analysis of male and female tilapia (Oreochromis niloticus) gonads for possible EDC- induced abnormalities. Other parameters such as the effect of distance from source of effluent (San Pedro River) and the effect of length of exposure time to the degree of disruption of the gonads were also considered. To assess the effect of distance, 15 O. niloticus per site ranging from 4 to 6 months of age, with fork lengths 13-16 cm, were randomly sampled from sites 150 m (Site A), 600 m (Site B), and 1,000 m (Site C) away from San Pedro River. Effect of time exposure was assessed using tilapias reared in Laguna Lake for one month, four-six months and approximately 12-15 months. All gonad samples were dissected and processed for histopathology. Laguna Lake tilapia ovaries manifested degeneration of oocytes, and brown bodies scattered in the connective tissue stroma. Laguna Lake tilapia testes exhibited atrophy of seminiferous tubules, detachment of spermatocytes from basement membrane and from sertoli cells. Type II atresia were found exclusively in the ovaries of site A females and perinuclear oocytes were found in the testes of site A males and 12-15 month-old group. These results indicate the presence of endocrine disruption in gonads of Laguna Lake tilapia, the histological abberations being influenced by both distance and time factors.