Factors affecting selenium bioconcentration at the base of aquatic food webs

Selenium is a naturally occurring element and an essential micronutrient for many organisms; however, at high concentrations it can become toxic. Currently, the mechanisms underlying selenium accumulation remain unclear, resulting in uncertainty in the prediction of selenium transfer from water to primary producers at the base of the food web – a process referred to as enrichment. This study assesses how varying concentrations of selenium and sulphate in water affect enrichment. Using reported concentrations of selenium, in water and periphyton collected from three mining regions in British Columbia, Canada, we show that enrichment is inversely related to exposure concentration. The effect of sulphate on enrichment was explored by comparing the fit of multivariate regression models (with and without sulphate) with Akaike’s Information Criterion (AIC). Models without sulphate were significantly better at predicting enrichment than models with sulphate (∆AICc = 2.29); however, conclusions were limited due to collinearity between selenium and sulphate.