石油および環境バイオテクノロジージャーナル

概要

Effect of Crude Oil Water Soluble Fraction Toxicity on Tilapia Guineensis Fingerlings Using Histology of the Kidney as a Bioassay Indicator

Ebonwu BI* and Ugwu LLC

Histological studies is well established as a fundamental relationships between pollutants and exposure to living organisms. The various biological responses and changes observed with such histological alterations can be used as a tool to detect toxic effects of pollutants in the organs of living organism making it a good environmental stressor indicator for bioassay. Tilapia guineensis fingerlings were collected at acute toxcity and after 98 days recovery period. Bonny-light crude oil (BLCO) and Benin River crude oil (BRCO) Water soluable fraction (WSF) were used as pollutant with different concentration from 0.00, 0.25%, 0.55%, 0.85% and 1.25% for acute toxicity and recovery period. The kidney tissue samples of the fish at acute toxicity (4 days) and recovery period (98 days) was collected for different WSF concentration, fixed, and sectioned. The histological sections of 5μg thickness of each sample were prepared and fixed on slide. This was observed (M x 400) under a light microscope (Olympus Model QC pass 02) linked to ACER LCD monitor with an Integrated Digital Scope photo (Model DCM 35). The experiment showed that crude oil water soluble fraction (WSF) as a the pollutant resulted in cytoplasmic vascuolation of the epithelial cells, leading to degeneration of the cytoplasm and enlarged tubule of the kidney of Tilapia guineensis fingerlings for both BLCO and BRCO as concentration increased. The 98 days recovery period showed larger increase in cytoplasmic vacuolization of the kidney cytoplasm tissue for both crude oil WSF. The effect of Bonny-light and Benin River crude oil on the kidney of Tilapia guineensis showed true reflection of effect of pollution with swelling of the renal tubules. The response of the kidney tissue of Tilapia guineensis as observed in this work is an indication that Tilapia guineensis is a good candidate for bioassay test serving as a pollution indcator species.