Toxicity of Sediments From Urban Playa Wetlands: Hyalella azteca Survival and Growth

On the Southern High Plains (SHP) surface water typically collects in depressional areas called playas.  In urban centers, such as Lubbock, TX, these are often a central point for recreational areas (e.g., parks) and for water storage/conveyance.  These water bodies are an important resource for aquatic life and used by both invertebrate and vertebrate species. Urban playas may serve as centers of biodiversity and potential source populations for agricultural and grassland playas. They are often encompassed by residential areas and receive surface runoff via irrigation and precipitation.  Through this process they may receive insecticides and fungicides, which are used for urban lawns and landscaping and may be toxic to aquatic invertebrates. Further compounding this issue is the potential for homeowners to exceed recommended chemical application rates. The objective of this study was to examine the occurrence and toxicity of sediment-bound pesticides from urban playas. In addition, toxicity was assessed over a diurnal temperature range, which for the SHP can be greater than a 10C change over 24 h. Sediment was collected at input locations within playas and aliquots were used for chemical analysis and toxicity testing. Each sample was analyzed for common urban pesticides and were normalized by OC and assigned a toxic unit value. Standardized sediment toxicity methodology was followed to examine effects on Hyalella azteca survival and growth.  Results may suggest that insecticide and fungicide use in urban areas on the SHP may present a stressor to aquatic organisms within these habitats.