translate English to French: Thus, while determination of the causal factor(s) of toxicity in situ may be difficult, assessments conducted in the receiving water offer the advantage of identifying responses under natural conditions of caged test species (i.e., in situ toxicity tests) or native communities (i.e., in situ monitoring and observation).
Par exemple, la marée peut inverser l’écoulement du cours inférieur du Fraser (C.-B.) et ainsi provoquer la concentration des effluents à proximité des SE d’Annacis et de Lulu, de sorte que les poissons subissent de multiples expositions aux effluents (Churchland et al.,1982; Birtwell et al., 1988).