Aquatic invertebrate diversity in isolated and permanent pools along an urban ephemeral stream in Central Texas.

Aquatic invertebrate community composition was sampled over 10 months in ephemeral and permanent pools along the upper segment of an ephemeral stream in Central Texas. A total of 67 total taxa were documented during this study. The highest numbers of taxa by total count found during the study were Hyalella, Chironomidae, Physa, and Caenis with total counts ranging from 1957 to 7437 individuals. Taxa with total moderate counts ranging between 209 and 856 individuals were Oligochaeta, Helobdella, Corbicula, Cyclopoida, Planorbis, and Berosus. Twelve different functional feeding groups were observed with collector-gathers-shredder accounting for 29.1%. The Pollution Tolerance Level was highest from 6 to 9 and peaked at 8 for both permanent and ephemeral pools indicating poor water quality. Based on the Hilsenhoff Family Biotic Index (FBI), the FBI was estimated to 7.47 and 7.53 for permanent and ephemeral pools, respectively, indicating poor water quality high in organic matter. Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa were represented by 5.3 and 18.2% of the total counts in permanent and ephemeral pools, respectively. All other taxa, excluding EPT taxa, represented 94.7 and 81.8% of the total counts in permanent and ephemeral pools, respectively. Our results indicate the runoff from adjacent urban areas resulted in reduced water quality within the pools based on aquatic invertebrate taxa. With reduced protection of ephemeral streams under the 2023 Supreme Court WOTUS decision, water quality and biodiversity will continue to decline and impact perennial river water quality longitudinally during flow events. [ABSTRACT FROM AUTHOR]