Taxonomic composition and spatio-temporal variability of macroinvertebrates inhabiting snags were examined from an 8-km segment of the Elm Fork of the Trinity River. Seventy-seven macroinvertebrate taxa were collected from submerged wood during the study. Assemblages were highly variable spatially and temporally, especially among seasons. An ordination of species and environment did not find snag taxa to have striking correlations with many of the selected environmental variables, although there were some trends in flow-mediated species distributions. There were significant seasonal differences in the abundances of some taxa, particularly among the Chironomidae (Diptera). The Tribe Orthocladiini was numerically abundant during the winter, while the Tribes Chironomini and Tanytarsini dominated the summer and autumn. Additionally, this study included a secondary production and microdistribution analysis of a population of the caddisfly Cyrnellus fraternus. Distributions of C. fraternus were restricted to snags, the most stable substratum for retreat building and for resisting periodic high waters. Larvae were not found in the soft sand and mud benthic habitats near submerged wood. The insects were multivoltine with a minimum of three generations per year. Pupae were collected July through September and adults emerged from May through October. The population overwintered as larvae. Estimated annual production was 1,015.4 …

This report describes the findings of a study conducted on the watersheds of "Lake Lewisville, Lake Ray Roberts, Lake Grapevine and the Elm Fork of the Trinity River between Lake Lewisville and Frazier Dam," which are all part of the upper Trinity drainage basin (p. 31). The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in and around Dallas, Texas (p. i).

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; white internal coloring; tan external coloring; no external sculpturing. The specimen measures between 0 - 60 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; brown external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 60 - 100 mm in length and was assessed to be very-long dead when collected.

One preserved mussel specimen including the left valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 0 - 60 mm in length and was assessed to be subfossil when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Guadalupe basin. The specimen measures between 60 - 100 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits a rhomboidal shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 60 - 100 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including the left valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; brown external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; brown external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 0 - 60 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; brown external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 0 - 60 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including the left valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; brown external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 100 - 120 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 60 - 100 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 60 - 100 mm in length and was assessed to be long dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits an elliptical shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Nueces basin. The specimen measures between 60 - 100 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including the left valve only. The specimen exhibits a rhomboidal shape; thin shell; double looped beak sculpturing; white internal coloring; brown external coloring; no external sculpturing. The specimen measures between 0 - 60 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including both the left and right valves. The specimen exhibits a round shape; moderately thick shell; white internal coloring; brown external coloring; external sculpturing in the form of pustules. Collected in the Brazos basin. The specimen measures between 60 - 100 mm in length and was assessed to be relatively-recently dead when collected.

One preserved mussel specimen including the right valve only. The specimen exhibits a round shape; moderately thick shell; white internal coloring; tan external coloring; no external sculpturing. Collected in the Trinity basin. The specimen measures between 0 - 60 mm in length and was assessed to be recently dead when collected.