Endocrine-disruptor molecular responses, occurrence of intersex and gonado-histopathological changes in tilapia species from a tropical freshwater dam (Awba Dam) in Ibadan, Nigeria.

In the present study, the occurrence of endocrine disruptive responses in Tilapia species from Awba Dam has been investigated, and compared to a reference site (Modete Dam). The Awba Dam is a recipient of effluents from University of Ibadan (Nigeria) and several other anthropogenic sources. A total of 132 Tilapia species (Sarotherodon malenotheron (n=57 and 32, males and females, respectively) and Tilapia guineensis (n=23 and 20, males and females, respectively)) were collected from June to September 2014.

Seasonal dynamics of phytoplankton in two tropical rivers of varying size and human impact in southeast Nigeria.

Phytoplankton occurrence and dynamics in rivers are mainly shaped by hydrophysical conditions and nutrient availability. Phytoplankton main structuring factors have been poorly studied in West African rivers, and this study was undertaken to identify these conditions in two tropical rivers that vary in size and human impact. For this, environmental variables and phytoplankton monthly samples were collected from the middle reaches of Asu and Cross rivers during an 18 months survey from March 2005-July 2006.

Condition factor and diet of Chrysichthys nigrodigitatus and Chrysichthys auratus (Siluriformes: Bagridae) from Aiba Reservoir, Iwo, Nigeria.

Chrysichthys nigrodigitatus and C. auratus are important, highly valued and threatened freshwater species. To contribute with their ecological knowledge, the condition factor and diet of these two congeneric species were studied between April 2005 and April 2006.

Cyanobacteria abundance and its relationship to water quality in the Mid-Cross River floodplain, Nigeria.

The physicochemical variables and cyanobacteria of Mid-Cross River, Nigeria, were studied in six stations between March 2005 and August 2006 to determine the relationship between water quality and cyanobacteria abundance. Canonical Correspondence Analysis (CCA) showed that biological oxygen demand (BOD), dissolved oxygen, pH, water velocity, width and depth were important environmental factors that influenced cyanobacteria abundance. Trace metals, phosphate and nitrate increased significantly from values of previous studies indicating increased eutrophication of the river but were weakly correlated with cyanobacteria abundance and could be scarcely regarded as regulating factors.