Effects of a Textile Mill Effluent and a Low Water Dam on Benthic Macroinvertebrate Community Structure of the Guadalupe River in Comal County, Texas

Nine sites were sampled monthly from December 1993 through November 1994 to assess the impacts of treated wastewater from a textile mill and a low water dam on the benthos of the Guadalupe River in New Braunfels, Texas. A Hess bottom fauna sampler and a ponar dredge were used to take samples of benthic macroinvertebrates and population densities were expressed in numbers per square meter. Water temperature and oxygen concentrations were also measured. The 59 benthic macroinvertebrate taxa found were dominated by Hyalella azteca (Hyalellidae), Chironomids, and Dubiraphia (Elmidae). More taxa and greater number of individuals were present downstream from the effluent than upstream at all times during the study period. The fewest taxa and individuals were present at sites located in the effluent canal. Rapid Bioassessment (RBA) Protocol III was used to assess the impact of the effluent on the community structure of the Guadalupe River. Although the results of the RBA showed that the sites within the effluent were moderately to severely impaired, the effluent had little if any impact on sites downstream from the point of discharge. Seasonal variation in distribution and abundance was noted for some macroinvertebrates, but was absent for most taxa analyzed. Other effluent effects were increased temperatures and reduced oxygen concentrations at sites in and directly downstream of the effluent. Some changes in taxonomic composition were noted at sites upstream and downstream from Old Mill Dam. A Jaccard Coefficient of Community Similarity showed that sites upstream from the dam were more similar to the reference site than those downstream. The differences in the Jaccard Coefficients upstream and downstream from the dam were significant (ANOVA 4 — 995). At all times more taxa were collected downstream than upstream of Old Mill Dam. Of the sampling sites located on the Guadalupe River, the fewest taxa were collected at the reservoir site. Recovery of both community structure, water temperature and oxygen concentrations was facilitated by the presence of a dam located downstream from the effluent. The effluent had little impact on community structure, water temperatures, and dissolved oxygen concentrations beyond 50m of the discharge source, mainly because of dilution.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Biology

Grantor

Southwest Texas State University

Year dc:date.issued

1995

Author dc:creator

• Kane, Sondra A.

Advisor dc:contributor.advisor

• Arsuffi, Thomas Lee

Committee members dc:contributor.committeemember

• Groeger, Alan W.
• Whiteside, B. G.

• water pollution
• Comal County
• Guadalupe River Watershed
• benthos
• invertebrates
• textile factories

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10877/19822

OAI identifier oai:identifier

oai:digital.library.txst.edu:10877/19822