Assessing the impact of fish cage culture on Taal Lake (Philippines) water and sediment quality using the Zebrafish embryo assay
2009
Hallare, A.V. | Factor, P.A. | Santos, E.K. | Hollert, H.
The present study investigated the impact of fish cage aquaculture on the quality of lake water and sediment using a contact assay with Zebrafish (Danio rerio) embryos. Fertilized Zebrafish embryos were exposed to surface waters and whole sediments collected from three sites of varying levels of stress from Taal Lake, Philippines. Gonzales was the reference site, while Banaga and Balakilong were sites of heavy aquaculture. No significant developmental differences were observed in water samples collected from all sites. Very high survival rates, high hatching success rates, and few abnormalities were observed in all water samples. All values did not differ significantly from the reference site and from sediment control also developed normally and showed no significant defects. However, a significant reduction in both survival and hatching success rates, and a considerable increase in rates of abnormalities were recorded from sediments obtained from the aquaculture sites. The observed embryotoxic responses were discussed in relation to the presence of contaminants such as ammonia and copper which have settled in the sediments from unconsumed feeds. Results of the study clearly demonstrate that fish cage culture has a harmful impact on lake quality (particularly the sediment phase). The authors also recommend the use of an effect-directed analysis as a next-level approach to identify specifically other individual toxicants responsible for the teratogenic effects.
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