Generation and Field-Validation of Chronic Biotic Ligand Models for Fish
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Abstract
Biotic ligand modelling (BLM) has shown great promise for predicting metal toxicity in aquatic animals. However, most BLM development has been conducted under tightlycontrolled laboratory conditions and acute metal-exposure scenarios that are unlikely to exist in nature. The primary objective of MITHE Project A1 is to develop chronic BLMs in wild fishes inhabiting soft, sensitive waters typical of the Canadian Shield in order to improve the ecological relevance of ecological risk assessments. To do this, we are taking a threepronged approach by studying metal dynamics at three distinct biotic ligands: (i) gill epithelium, (ii) gut epithelium, and (iii) olfactory epithelium. Most BLM development has focused on metal dynamics at the gill, which represents the benchmark against which gut and olfactory epithelium models will be compared. The gut represents a major site for metal uptake that has, until recently, been largely ignored by gill-based BLMs. Consequently, if BLMs are to predict metal effects in wild fishes, all major uptake pathways must be considered. Moreover, metal binding to the olfactory epithelium results in chemosensory impairment, which could lead to large-scale ecological effects. Together, knowledge of metal dynamics at binding epithelia coupled to ecologically-relevant effects will allow us to make meaningful predictions about metal effects in aquatic ecosystems.