A field microcosm method to determine the impact of sediments and soils contaminated by road runoff on indigenous aquatic macroinvertebrates

A field-based microcosm method was used to determine whether sediments and soils that receive road runoff are toxic to indigenous aquatic macroinvertebrates present in the Greater Melbourne Area (GMA), Australia. Sediments and soils collected from areas draining three major highways were placed in 20 L microcosms along the littoral zone of a non-polluted wetland. Aquatic insects that emerge from the wetland randomly lay eggs in the microcosms. The occurrence and abundance of key taxa in these microcosms was measured to determine toxicity of the sediments. Several taxa responded in different ways to these sediments. The abundance of Paratanytarsus grimmii, Polypedilum leei, and Oxyethira columba significantly increased with increased concentrations of contaminants in sediments, and appeared to be most influenced by nutrient enrichment. The occurrence of Tanytarsus fuscithorax significantly declined with increased concentrations of zinc in surface waters that leached from sediments. Cricotopus albitarsis abundance was significantly higher in nutrient-enriched sediments, but significantly declined in high zinc concentrations in surface waters. There were significant negative correlations between the occurrence of Larsia albiceps, T. fuscithorax, and Procladius spp. and copper or total petroleum hydrocarbon (TPH) concentrations in sediments. This method provides unique information on the effects of contaminated soils and sediments on indigenous aquatic macroinvertebrates and can be used to determine the effectiveness of water sensitive urban designs in reducing sediment toxicity.