VITELLOGENIN (VTG) IN MALE CATFISH (Clarias gariepinus) FROM OSSE RIVER, BENIN CITY, NIGERIA: ASSESSEMENT OF REPRODUCTIVE ENDOCRINE STATUS

ABSTRACT

Globally, there has been growing environmental health concerns on account of the presence certain environmental contaminants known as endocrine disrupting chemicals (EDCs) with potential to disrupt endocrine functions, in humans and wildlife, in the environment. Fishes are considered as one of the primary risk organisms of EDCs because sex determination is fish is labile and can be disturbed or reversed when exposed to EDCS. Despite the weight of adverse     reproductive and developmental health effects of EDCs on wildlife, very little is known about the environmental occurrence of EDCs and their associated effects in developing countries. This study was therefore undertaken to access the effects of estrogenic EDCs on male C. gariepinus in Osse River using vitellogenin (VTG) as a biomarker of exposure. Sexually mature fish (31 male and 17 females) was sampled for four months (June to September, 2019) from two stations. Fish samples were grouped into four based on collection time; and blood samples were collected and analysed using Enzyme Linked Immunosorbent Assay (ELISA) for plasma VTG level. Plasma VTG (μg/ml) level ranged from 13.65 to 16.93 (Sample 1); 5.03 to 22.50 (Sample 2); 10.25 to18.80 (Sample 3) and 17.35to 17.95 (Sample 4). Whereas in female fish, the plasma VTG level ranged from 15.30 to 19.82 throughout the study period. Statistical analysis showed that the plasma VTG level in female fish was not significantly higher than the observed level in male fish overall. The results clearly revealed that C. gariepinus is exposed to EDCs with estrogenic mode of action in Osse River. It was concluded that further studies be carried out for the identification of the EDCs.