Variation in Response of Laboratory-Cultured Freshwater Macroinvertebrates to Sediment from Streams with Differential Exposure to Agriculture

Abstract

Agricultural land use is widely accepted to elicit changes on surrounding environment and neighboring ecosystems. Meanwhile, the impact of different types of agricultural land use likely cause a variety of impacts on nearby ecosystems and the organisms that inhabit them. Freshwater systems support a wide range of organisms—from infaunal or epifaunal invertebrates to mobile pelagic and littoral fish species. The focus of this study was to determine how agricultural activity in the upstream catchment influences sediment properties and the resulting ability of three distinct invertebrate species to survive and reproduce in these different sediments. This will be the first study that evaluates the utility of the sediment quality triad when assessing the impact of agricultural activity on invertebrate growth, reproduction, and survival. In analyzing sediment and water chemistry, as well as metal and pesticide levels, none of the predictor variables were able to adequately explain the variation seen in any of the biological endpoints (reproduction, mortality, growth, or biomass). Although none of the factors measured in this experiment could explain the variation seen in biological endpoints, the experimental approach was informative in delineating biological trends between sediments subject to varying levels of agricultural activity. Although an experiment of this nature was not able to identify a causal mechanism to explain the variation in invertebrate biological endpoint, it is still extremely useful as an exploratory approach to assess relative sediment toxicity.