Journal of Environmental Biology

Differential response of Tilapia guineensis fingerlings to inorganic fertilizer under various salinity regimes

 

L.O. Chukwu¹ and H.A. Okpe²

¹Aquatic Toxicology and Ecophysiology Laboratory,

Department of Marine Sciences, University of Lagos, Akoka, Lagos, Nigeria

²Federal Department of Fisheries, Monitoring, Control and Surveillance Unit (MCS), Lagos, Nigeria

 

(Received: 6 April, 2005 ; Accepted: 08 December, 2005)

 

Abstract: The influence of salinity on the response of the estuarine teleost, Tilapia guineensis fingerlings to acute toxic effects of inorganic nitrogen-phosphorus-potassium (NPK) (15: 15: 15) fertilizer was investigated using semi-static bioassay.? The toxicity of NPK fertilizer was found to increase significantly with increase in the salinity level from 0.05 ? to 32.4 ?. The 96 hr LC₅₀ value at salinity of 32.4 ? was 0.11mg/l and was found to be significantly (p < 0.05) higher than the toxicity values at any other salinity level of media evaluated. The implication of the findings is that pollution control standards and/or safe limits for brackish water ecosystem should consider variations in salinity regimes for greater relevance and reliability.

 

Key words: Response, Tilapia, Toxicity, Fertilizer, Salinity.

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