HABITATS USED BY THE ENDANGERED FOUNTAIN DARTER (ETHEOSTOMA FONTICOLA) IN THE SAN MARCOS RIVER, HAYS COUNTY, TEXAS

We examined algae and macrophytes used as habitats by the endangered fountain darter Etheostoma fonticola through examination of six probable microhabitats. Rhizoclonium, Ludwigia repens, and Hydrilla verticillata had the greatest densities of fountain darters, although all six species of plants tested had fountain darters in >= 5% of samples. The smallest darters were in Rhizoclonium, and the largest were in Potamogeton illinoensis. This likely was due to differences in current velocity among microhabitats. In the San Marcos River, it is important for fountain darters to have vegetated areas with dense cover to provide food, reproductive habitats, and refugia.