Stream and riparian ecosystems can be strongly connected via the emergence of adult aquatic insects, which form an important prey subsidy for a wide range of terrestrial consumers. Consequently, human perturbations affecting stream ecosystems may propagate across habitat boundaries. Here I present a case study demonstrating how human activities may influence stream and riparian invertebrates. Streams impacted by mining supported less benthic insect and riparian arachnid biomass than reference sites, whereas streams in forest fragments surrounded by agricultural land uses were seemingly more productive, with greater standing crops of stream and riparian invertebrates. Structural equation modelling (SEM) indicated negative indirect effects of mining on riparian arachnids mediated through reduced subsidies of stream insects. In contrast, the SEM suggested both direct and indirect positive effects of agriculture on arachnids. These findings highlight how multiple anthropogenic pressures affecting stream habitats may contribute to productivity gradients determining the trophic connectivity between aquatic and terrestrial ecosystems.
Burdon, F. J. (2020). Agriculture and Mining Contamination Contribute to a Productivity Gradient Driving Cross-Ecosystem Associations Between Stream Insects and Riparian Arachnids. In Contaminants and Ecological Subsidies (pp. 61–90). Springer International Publishing. https://doi.org/10.1007/978-3-030-49480-3_4