AN ASSESSMENT OF THE BIOLOGICAL INTEGRITY OF THE
EASTERN RED RIVER BASIN IN TEXAS

Red River Authority of Texas, Wichita Falls, TX 76301

April 1998

Abstract. This paper gives insight into the biological health of streams located in the eastern Red River Basin in Texas. Little information exists on the biological communities of this geographical region, which hinders long-term comparisons. Hence, both fish and aquatic macroinvertebrates were collected the summer of 1997 for 1. to enable the calculation of biological indices and 2. to provide a biological survey for future reference. Rapid Bioassessment methodologies were used for the quantification of biological integrity at 10 monitoring stations in this region. Results show good overall biological health of the selected streams in this region, with some moderate impairment. Both fish and macroinvertebrate indices showed similar results, in most cases. Detected impairment is most likely due to physical habitat limitations, rather than water quality problems.

INTRODUCTION

This paper presents the results of a bioassessment study of the eastern Red River Basin in Texas. The study was performed under a monitoring plan developed under the Texas Clean Rivers Program (CRP). Under this plan, biological monitoring plays a major role in supplementing chemical and physical data to provide a complete assessment of water quality in the Red River Basin.

          The primary objective of this study was to assess the water quality of streams within the eastern Red River drainage in Texas. Collections of fish (Appendix A) and aquatic macroinvertebrates (Appendix B) were collected at 10 sampling stations, which encompass the entire eastern region of the Red River Basin. These biological collections were then used to calculate a biological integrity score, using Rapid Bioassessment Protocols (Plafkin et al., 1989). By performing habitat assessments at these stations, it is possible to determine biological impairment due to water quality, as opposed to natural habitat characteristics.

          Table 1 provides a description of these stations and Figure 1 shows a map of the stations. These stations are exposed to several different land uses having potential to impair water quality.

Table 1

Description of Monitoring Stations Sampled for Biological
Communities in Eastern Region of Red River Basin

U–Urban activity
F–Farming activity
R – Ranching activity

These include urban activities, such as wastewater effluent discharges and stormwater runoff carrying excess nutrients and pollutants. Secondly, these stations ( to a varying degree) encounter the potential degradation from farming activities, including sedimentation and excess runoff carrying various pollutants. Lastly, these stations are exposed to ranching activities, which results in sedimentation, introduction of fecal pathogens, and deterioration of the riparian zone/stream banks. Table 1 displays which of these activities are predominant at each of the monitoring stations.

Regional description

The eastern portion of the Red River watershed is from the Texas-Arkansas state-line upstream to the confluence of Cache Creek and Red River (Bowie County to Montague County).

There are five subwatersheds in the reach totaling 7,698 square miles of contributing drainage area in Texas, Arkansas and Oklahoma (3,600 square miles in Texas). Average annual rainfall for this region is approximately 30 to 40 inches a year.

The streams of this region are generally low-gradient and possess clay/silt substrates. Vegetation presence is moderate, dominated by hardwoods and grasses. Overall physical habitat in this region is supporting for biological communities to thrive. Limiting habitat characteristics for aquatic life in this region includes the lack of suitable habitat and poor bank stability.

METHODS AND MATERIALS

Rapid Bioassessment Methodology - Macroinvertebrates

Pollution tolerance values for macroinvertebrates were assigned based on values established by the Texas Natural Resource Conservation Commission (personal communication - Bill Harrison), the EPA (Plafkin, 1989) or from Lenat, 1993. Functional feeding groups for macroinvertebrate families were assigned based on classifications obtained from Merritt and Cummins (1996). Several insect families have been assigned multiple functional feeding group classifications by Merritt and Cummins (1996). In order to clarify these classifications, organisms were further identified to genus, and when possible, to species (Merritt and Cummins, 1996, Parrish R.K., 1975, and Thorp and Covich, 1991). The data thus recorded was used to score seven metrics for a slightly modified Rapid Bioassessment Protocol II (RBP II) (Plafkin et al., 1989 and Barbour et al., 1992).

Data Analyses

The following metrics were scored in the study:

Structure metrics:

1. Taxa Richness = total number of taxa collected at the site.

2. EPT Index = number of genera belonging to the Orders Ephemeroptera, Plecoptera, and Trichoptera which were collected.

3. Community Loss Index = (taxa richness at the reference site - taxa common to reference and sampling sites)/taxa richness at the sampling site.

Community balance metrics

4. Family Biotic Index (modified) = S (xi ti)/n, where:

xi = number of individuals within  a genus,     

ti = tolerance value for the taxa,

n = total number of organisms in  the sample.

5. Percent Contribution of Dominant Taxa = percent contribution of the dominant taxa to the total number of organisms collected.

Functional feeding group metrics:

6. Ratio of Scrapers/Filtering Collectors = number of scrapers/(number of scrapers + number of filtering collectors).

7. Quantitative Similarity Index = (Functional Feeding Groups or FFG’s) - compares two communities in terms of presence or absence of FFG’s, also taking relative abundance into account.

Each metric value obtained was given a Biological Condition Score of 0, 3, or 6, based on its percent comparison to the metric value obtained from reference station data. Scoring criteria for the Percent Contribution of Dominant Family was expressed as the actual percent contribution, not percent comparability to the reference station. The Community Loss Index and Quantitative Similarity Index (FFGs) were not given a percent comparability to the reference station, because a comparison to the reference station is incorporated into these indices. The metric scores for each sampling site were totaled, and compared to the total metric score for the reference site to obtain the Percent the reference site to obtain the Percent Comparability to Reference Site value. The reference site in this study was Mud Creek, due to it’s superior biological and physical health, as well as minimal environmental disturbances.

A habitat assessment matrix was completed for each sampling site using forms taken from Plafkin et al., 1989. The matrices were evaluated to determine percent comparability of habitat between the sampling sites and the reference site. The percent comparability was used to judge the potential for each sampling site to support a similar level of biological health compared to its reference site.

Sampling methodology

The sampling methodology for this study consisted of using a D-framed kick net to sweep woody habitat, vegetation, and to perform kick samples within riffles. Due to inconsistencies in the amounts and types of habitat between the sampling sites, a perfectly consistent sampling method could not be implemented. Therefore, the sampling method consisted of performing 5 minute sweeps, partitioning the 5 minutes between the most suitable macroinvertebrate habitats. The different habitats are sampled approximately the same percentage as they are present. For example, if the habitat consisted of approximately 60 percent bank woody habitat and 40 percent channel woody habitat, then the bank woody habitat would be sampled for 3 minutes and the channel woody habitat would be sampled for 2 minutes. If less than 100 macroinvertebrates are collected after the 5 minutes, then another 5 minutes of sampling was conducted.       

Rapid Bioassessment Methodology – Fish

Fish species were identified and assigned origin groups, tolerance values, and trophic levels (Plafkin et al, 1989; Hubbs, et al, 1991). This information was used to score 11 RBP V (or IBI) metrics (Plafkin et al, 1989). RBP V allows for some discretion in selecting individual metrics for analysis. The metrics used to calculate an IBI score for these stations was a modified version developed for fish in the Subhumid Agricultural Plains of Texas (Ecoregions 27, 29, and 32) (Linam, personal communication).

Data analyses

The 11 metrics which were evaluated in this study were:

All metrics, except "total number of individuals" were scored according to the previously cited references. The "total number of individuals" metric was changed due to different seine mesh sizes being used in this study as compared to mesh sizes used at stations at which the metric scoring criteria were calculated. Smaller mesh sizes were used at stations used in calculating the metrics, resulting in a greater number of fish to be collected (i.e. western mosquitofish). A score of 1 would have been obtained for this metric at all stations, therefore, an alternate methodology was used. The total number of individuals from each of the 10 stations were ranked and the value at the 90^th percentile was deduced. This number was split into thirds, giving the three ranges for the metric scoring. This is consistent with the methodology used for the calculation of other metrics.

The metric scoring consists of each metric receiving a 1, 3, or a 5, based on its numeric value. The 11 metric scores for each sampling site were totaled to obtain an Index of Biotic Integrity score. Each sampling site was classified as being in Limited (<35), Intermediate (35-40), High (41-48), or Exceptional (>48).

Sampling methodology

Fish were sampled at each site, using a backpack electroshocking unit and/or seining techniques. Due to differing conductivity levels and habitat, a consistent fish sampling methodology could not be implemented. The normal protocol for fish sampling calls for 15 minutes of seining and 7 seine hauls. However, if electroshocking could not be conducted, then 10 seine hauls were performed. Additional seine hauls were performed if a new species was collected in the final seine haul until a seine haul with no new species occurred. Sampling gear consisted of a Model 12-B Backpack Electrofisher, a 10 foot seine with ¼ inch mesh, and a 25 foot bag seine with ¼ inch mesh.

All habitats, such as snags, rootwads, riffles, and undercut banks were sampled if present, in order to maximize the capture of different fish species. A representative of each species was preserved in 10% Formalin solution and returned to the lab for identification. All other fish collected were released, unless identification could not be performed in the field. All fish were identified to species and the number of each species was recorded

RESULTS AND DISCUSSION

The overall biological integrity for this geographical region falls into moderately impaired category. The results shown in Table 2 indicate good overall biological health for the streams of the eastern region of the Red River Basin. RBA (invertebrates) scores range from 57.1 to 100, with the majority showing moderate impairment. RBA (fish) scores ranged from 29 to 49, with most scores falling into the intermediate – high categories. It is evident that anthropogenic activities are not extensively degrading the biological health in this region. However, impairment was detected in using these protocols. It is also evident that physical habitat conditions at these stations are far less than optimal, namely due to the lack of favorable substrate and varying flow regimes for both fish and macroinvertebrates.

Table 2

RBA and Habitat Scores for Stations Sampled in
Eastern Portion of Red River Basin

The flows at stations Bois D’Arc Creek @ FM 100, Pine Creek @ FM 2648, Choctaw Ck @ Hwy 69, and Big Mineral Creek @ FM 901 are heavily influenced by municipal wastewater discharge. The results of this study show that the water quality of these streams are supporting aquatic life communities similar to creeks not heavily influenced by wastewater effluent. Wastewater discharge from the city of Whitesboro sustains the healthy biological community at Big Mineral Ck @ FM 901 (as compared to Big Mineral Ck off of US 377).

The station Big Mineral Ck off of US 377 scored poorly (Limited) for the health of fish communities. The poor RBA (fish) score for this station can be attributed to natural conditions. The flow at this site is intermittent with perennial pools. The perennial pools are usually small shallow pools and would explain the poor biological integrity. The benthic community at this station showed only moderate impairment with a score of 64.3. This contrast is most likely due to the fact that macroinvertebrates can sustain healthy communities more easily in these low flow conditions, as compared to fish. It is also noted that it took twice the sampling effort (10 minutes) to get an adequate number of macroinvertebrates to calculate a valid RBA score. This low abundance is not considered in the score, however it can be a sign of impairment.

The station Red River @ I-35 also scored poorly for the health of its fish community. This is attributed to natural conditions. It is obvious that the fish communities inhabiting the waters at Red River @ I-35 will not be similar to those found in the fresh water tributaries sampled in this study. The environment of the Red River is characterized by saline water and poor habitat to sustain a diverse aquatic ecosystem.

The station Pine Creek approx. .75 miles downstream of US 27 showed interesting results. The RBA (invertebrates) had the lowest score (57.1) of all stations, while the RBA (fish) scored "High" (41). The habitat assessment score was relatively high among all the stations, which gives evidence that natural habitat conditions should be able to sustain healthy macroinvertebrate communities. Not only was the Pine Ck score the lowest, it also took twice the sampling effort to collect only 45 individuals. This gives question to 1. the validity of the calculated RBA score and 2. the macroinvertebrate health at this station. All water quality data in the TNRCC Surface Water Quality Management database for stations on Pine Creek and in the near vicinity was scanned with no evidence of poor water chemistry. Future collections for macroinvertebrates at this station will provide additional information in determining the cause of this uncertainty.

          The metric "Number of Macroinvertebrate Taxa" ranged from 14 to 31, which is good to moderate for this region. Most of these taxa are relatively tolerant, which is indicated by the metric, "Family Biotic Index". This metric ranged from 6.0 to 7.7, which is characteristic for waterbodies located in this area. Taxa belonging to the "intolerant" orders of Ephemeroptera, Plecoptera, and Trichoptera were very limited, as would be expected. The number of genera belonging to these orders ranged from 0 to 3.

All stations scored high for the metric "Scraper to Filterer Ratio". This is due to the lack of taxa belonging to the "Filterer" Functional Feeding Group (FFG). Elevated percentages of taxa belonging to this group is indicative of enrichment to the stream. The only two stations that had any substantial numbers of filterers were Pine Creek @ FM 2648 and Big Mineral Creek @ FM 901. Both have base flows heavily influenced by wastewater effluent. The consistent presence of taxa and percentages of functional feeding groups indicates moderate to good health, as indicated by the two metrics, "Community Loss Index" and "Quantitative Similarity Index – Functional Groups". Streams exhibiting impaired water quality conditions would most likely possess different taxa (and FFG percentages), as compared to the reference site.

CONCLUSION

Good overall biological integrity characterizes the eastern Red River Basin in Texas. Detected impairment obtained through the calculation of Rapid Bioassessments can be attributed mostly to natural conditions (i.e. poor natural habitat). Anthropogenic activities do play major roles in water quality and quantity in this area, however not in a negative manner. In some cases, man’s activities actually sustain flows needed for healthy biological communities to flourish.

These stations will be revisited at a later date, in order to detect long-term trends in quality for this region of the Red River Basin.

BIBLIOGRAPHY

Barbour, M.T., J.L. Plafkin, B.P. Bradley, C.G. Graves, and R.W. Wisseman. 1992. Evaluation of EPA’s Rapid Bioassessment Benthic  Metrics: Metric Redundancy and Variability Among Reference Stream Sites. Environmental Toxicology and Chemistry. 2:437-449.

Harrison, Bill. 1997. Personal communication through handout. Texas Natural  Resources Conservation Commission.

Hubbs, Clark, Robert J. Edwards and Gary P. Garrett. 1991. An Annottated Checklist of  the Freshwater Fishes of Texas, with Keys to Identification of Species. The Texas Journal of Science. 43(4): Special Supplement.

Lenat, David R. 1993. A Biotic Index for the Southeastern United States: derivation and list of tolerance values, with criteria for assigning water-quality ratings. Journal of North American Benthological Society. 12(3): 279-290.

Linam, Gordon. 1998. Personal communication. Texas Parks and Wildlife Department.

Merritt, R.W. and K.W. Cummins. 1996. An Introduction to the Aquatic Insects of North America. Second Edition. Kendall/Hunt Publishing Company. Dubuque, Iowa.           722 pp.

Parrish, Fred K. 1975. Keys to Water Quality Indicative Organisms of the Southeastern United States. United States Environmental Protection Agency. 2^nd Ed.   Cincinnati.

Plafkin, J.L., M.T. Barbour, K.D. Porter, S.K. Gross and R.M. Hughes. 1989. Rapid  Bioassessment Protocols for use in Streams and Rivers: Benthic Macroinvertebrates and Fish. EPA/444/4-89-001.

Thorp, James H. and Alan P. Covich. 1991. Ecology and Classification of North American Freshwater Invertebrates. Academic Press, Inc. San Diego. 911 pp.

APPENDIX A

FISH SPECIES LIST

APPENDIX B

MACROINVERTEBRATE SPECIES LIST

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