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A short-term sublethal feeding inhibition assay, using zebra fish Danio rerio

2011A short-term sublethal feeding inhibition assay, using zebra fish Danio rerio.ABDEL-MONEIM Ahmed (Egypt)a.elmehrezy@yahoo.com
Organisation: University of Coimbra, Coimbra (PT)Supervisor :Rui Ribeiro & Matilde Santos
Summary: Feeding is a vital physiological function to all organisms, disrupted by contaminants, often at very low concentrations. This disruption is expected to be quantified, thus, used as a toxicity test endpoint. Sublethal effects measured at the organism level can be extrapolated to population, community and to ecosystem structure and function in a time-delayed process. In addition, feeding was found to have direct and immediate effects on ecosystem functions (as grazing), thus, making an unequivocal ecologically meaningful response.

The present study intended to contribute to develop a sensitive and ecologically relevant short-term in situ assay with the small freshwater fish species Danio rerio based on feeding, to evaluate secondary production impairment due to pollution. For this, a methodology to easily and precisely quantify feeding of D. rerio was first optimized. Secondly, the sensitivity of feeding relatively to survival and growth, after exposure to the reference chemical copper, was evaluated. The feeding endpoint was revealed to be slightly more sensitivity than both other endpoints. Also, feeding and lethality were integrated in a single parameter, to determine median population consumption inhibitory concentration for contaminants eliciting both lethality and feeding depression. Thirdly, the influence of the environmental parameters on the background variability in feeding rates was assessed, and no differences in feeding were found among the fish exposed to the different waters. Fourthly, the integration of feeding depression and mortality was evaluated with natural contaminated waters, showing that feeding was a responsive measurement to contamination and that the integration of lethality and feeding are pertinent to estimate contaminant effects at the population level. And fifthly, the proposed in situ assay chambers and procedures were found suitable to assess contamination by deploying it at uncontaminated replicated mesocosms, while a laboratory feeding test was simultaneously performed to control for all factors associated to the field manipulations.
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