Limited functional responses of plankton food webs in northern lakes following diamond mining

Abstract

There is limited understanding of the impact of diamond mining on the aquatic communities of lakes that receive mining activity residue. For aquatic communities, assessing the response to mining, which can affect multiple variables concurrently, is not trivial, especially when a species-by-species approach is used. Thus, we assessed diamond mine impacts using changes in plankton functional composition, enabling an integrated evaluation of the ecological responses of aquatic ecosystems. Using a 19-year data set, we evaluated the functional responses of lake phytoplankton and zooplankton to water quality changes associated with mining activities in five downstream lakes of the Ekati Diamond Mine (Northwest Territories, Canada). Our results demonstrate that mining activity shifted phytoplankton functional composition toward edible diatoms and more recently the rotifer communities toward parallelepiped types, while for crustacean zooplankton we observed a reinforcement of the original functional composition. Following functional rather than taxonomic changes enabled a more mechanistic understanding of the processes behind the impacts and should facilitate the generalization of impacts to other sites, permitting comparison of community shifts caused by other types of mining.