Effects of stream flow rate on caddisfly case building

Human disturbance has a negative impact on stream ecosystems and is an indicator of stream health. Disturbance of animal habitats can take many forms. For example, the increasing number of recreational hikers and trail runners results in a growing human influence on stream ecology. Additionally, climate change has created severe drought conditions in Southern California that are affecting water flow in local streams. Among the direct effects of drought for freshwater wildlife are habitat loss and disruption of stream connectivity. Caddisflies of the genus Lepidostoma are commonly found in freshwater streams in the Santa Monica Mountains. These insects are important to the ecology of streams as food for fish and as leaf shredders and decomposers. Because natural stream flow is changing, and correspondingly, the material composition of the streambed is also changing, we are investigating the effect of flow rates on the behavior of caddisflies. We predict that flow rate will have an effect on caddisfly case building success. To test this hypothesis we are simulating ecologically relevant flow rates observed in streams in the Santa Monica Mountains and measuring how these different water conditions affect case building. We constructed a flume to manipulate water velocity and are using caddisfly larvae collected from field sites in the Santa Monica Mountains. Our results will contribute to our understanding of how changing anthropogenic and climatic effects impact benthic macroinvertebrate behavior in a unique region of the world. More broadly, this study will promote knowledge about the ways degradation and alteration of habitats impact wildlife