Impact of water quality at different locations of Alexandria mediterranean coast on the pituitary-ovarian axis of gilthead seabream Sparus aurata

Abstract

Environmental pollutants such as metals, pesticides and other organics pose serious risks to aquatic organisms. Impact of pollution of Alexandria coast on gonadotrophs cells (GTC), ovarian structure and steroid hormones level in female S. aurata were evaluated in fish collected from four sites along Alexandria coast. The El Max Bay (EMB), Abu Qir Bay (AQB), Eastern Harbor (EH) and Abu Talat Region (ATR) sites were chosen representing regions with variable sources of pollution and compared to reference site (REF). Results showed that the physicochemical characteristics of water from sites EMB and AQB exhibited significant levels of heavy metals (Cd, pb, Cu, Zn and Fe) as well as pesticides that have a toxic impact on fish ovarian structure was revealed in the form of increased percentage of follicular atresia and deformed vitellogenic oocytes. Reduction in level of 17 β-estradiol and progesterone to significant values in both EMB and AQB sites compared to the reference site (REF). Also gonadosomatic index (GSI) of fish in both EMB and AQB sites showed significant decreased values. The gonadotrophs cells number decreases in EMB and AQB sites compared to reference site. The percentage of deformed cells with picnotic nuclei increased in AQB and EMB sites. The present study clearly demonstrated that pollution in EMB and AQB sites exhibits an endocrine disruptive action on the reproduction axis of S. aurata affecting quantity of GTC and/or ovaries structure, which could have a detrimental effect on population existence under prolonged exposure to pollution.