Freshwater mussels are an important component of freshwater ecosystems. They can filter a large amount of water, affecting both water clarity and water chemistry. Their shells provide physical habitat for other organisms, they re-direct necessary nutrients to the bottom of the water column, and their excreted material can enhance the growth of algae and macroinvertebrates. However, dramatic declines of freshwater mussels have occurred due to habitat loss, destruction and modification, pollution, and invasive species. One mussel species in Texas (Texas Hornshell) has been listed as endangered under the Endangered Species Act and several other species are candidates for listing.
Changes in precipitation patterns and extremes, such as drought and floods, can also be detrimental to mussels. Freshwater mussels are particularly sensitive to drought events because they are relatively sessile and cannot easily escape to wetter areas. Mussels can also be washed out of suitable habitat during flooding or become stranded in habitat that later dries out. Rapid weather shifts from one extreme to another, such as rainfall “whiplash” (rapid wet-dry or dry-wet transitions) and “boomerang” (wet-dry-wet or dry-wet-dry transitions) events are therefore particularly harmful to these species.
This project is focused on examining the occurrence of “whiplash” and “boomerang” events in Central Texas, along the San Saba and Llano River within the Colorado River basin and understanding how these episodes impact freshwater mussels. Through analysis of rainfall and river data and models, and with knowledge of mussel ecology, the project researchers will provide stakeholders with a set of outlooks and information that can be used directly to inform decisions for short-term use and long-term planning during times of large precipitation variability. The scientific outcomes of this work will be useful to resource managers tasked with protecting freshwater mussel species in Central Texas and could be applied to other regions or species.