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North Alabama watersheds. Flint River Indian Creek Greenway Flint Creek. Fig. 3. Percent (%) EPT in all sampling sites. Fig. 2. Total number of EPT collected from each sampling site.
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Flint River Indian Creek Greenway Flint Creek
Fig. 3. Percent (%) EPT in all sampling sites.
Fig. 2. Total number of EPT collected from each sampling site.
Fig. 4. Total number and percent chironomids (bars) and simuliids (line) in each sampling site.
Fig. 1. Dominant families in watersheds combined.
Fig. 5. Simuliid mass from Flint River
Allison at work
Benthic Macroinvertebrate Assemblages in Flint River, Indian Creek and Flint Creek Watersheds in North Alabama- Preliminary Study
R. Ward, L. White, A. Bohlman and T. Tsegaye
Department of Plant and Soil Science, Alabama A&M University
P.O. Box 1208, Normal, AL 35762
Benthic macroinvertebrates are excellent indicators of water pollution such as turbidity and nutrient loads. The assessment of aquatic biodiversity is widely used to strengthen continuing measures of water quality in north Alabama. This preliminary study was conducted to determine taxa richness (total number of taxa) and composition of aquatic insects occurring in Flint River, Indian Creek and Flint Creek. For this report, bioassessment was based mainly on the relative abundance of EPT and chironomid [percent Ephemeroptera-Plecoptera-Trichoptera (%EPT) and percent chironomids]. EPT are known to be highly sensitive to increasing perturbations; increase in their abundance suggest improved water health. The occurrence and dominance of chironomids, on the other hand, may indicate organic impairments of streams. Twenty seven families have been identified in our sample collections suggesting the rich diversity of biotic components in the watersheds under study. In this study, spring-summer aquatic insect samplings were done at monthly intervals in three locations along each tributary using surber, dip net, kick net and leaf pack methods. In addition, gastropod presence in the watersheds was also recorded. The sampling sites also represent the diverse riparian zones and land use of the surrounding areas. Our preliminary results showed high dominance of Ephemeroptera over stonefly and caddisfly populations in all watersheds. Chironomids and simuliids comprised the majority of the Dipterans collected. Likewise, Elmidae (riffle beetles) has a strong presence in all watersheds. Riparian and stream characteristics were described for each sampling location.
Each of the sampling sites is described in Table 1. On the Flint River, collection sites were near agricultural lands and expanding residential rural developments; most effluents were from adjacent agricultural farms. Indian Creek is situated in heavily populated urbanized sections of the City of Huntsville; two sites on this watershed bordered green space areas. Urban sprawl and sedimentation contribute significantly to the deterioration of water quality in this tributary. Flint Creek is a designated EPA cleanup site; it is heavily channelized through agricultural pasture lands but two of the collection sites are located in hardwood forested/wetlands. All of these reaches are intermittent; their flow slowed, developing into shallow pools during the dry season.
Twenty seven families in 7 orders were represented in our composite collections (combined watersheds) (Table 2). Among EPT, Ephemeroptera dominated other groups at 29% of total individuals collected (Figs. 1-3); families Heptageniidae and Hydropsychidae (Trichoptera) led the group in abundance across watersheds. Stoneflies were practically absent in the study sites; Plecoptera was represented by only one family (Perlidae) at 3.17%. Caddisflies (Trichoptera) had a healthy presence in the watersheds at 15.70%. Although combined EPT dominated all other insect groups, Diptera (17.82 %) closed in second to mayflies in abundance. Chironomids ranked fourth among top families in all watersheds suggesting organic stream impairment. Indian Creek (Providence) topped all other sites for number of chironomids. The site is in the center of a massive urban sprawl; adjacent areas are currently undergoing expansive business and residential development. The xylophagous riffle beetles (Elmidae) occurred in all watersheds. With Heptageniidae, Elmidae ranked first (at 14%) among top 11 families in the all watersheds (Fig. 1). Simuliids were predominant in Flint Creek (Fig. 4), occurring in moderate numbers elsewhere.
Flint River, Indian Creek and Flint Creek are major tributaries to the
Tennessee River which supplies drinking water and provides recreation areas to
residents of Madison and other counties in north Alabama. The quality of water
draining from these watersheds is of prime importance to the public. Benthic
macroinvertebrates vary in their sensitivity and tolerance of pollutants occurring
in bodies of water. These organisms respond to long term impairments of stream
water. Unlike chemical water parameters which are reflective of water condition
at time of sampling, population levels of aquatic fauna respond to long term
effects due to their stabilized water environment. Thus, as bioindicators,
aquatic insects are excellent and reliable determinants of the general health of
streams and rivers. Members of the orders Ephemeroptera (mayflies), Plecoptera
(stoneflies) and Trichoptera (caddisflies) are intolerant of pollutants; their
relative abundance indicates good water quality. Midges and blackflies [both are
in the order Diptera (flies)] are tolerant of pollution; their occurrence in high
numbers is indicative of water impairment.
Table 1. Description of sampling sites.
Dip Net – Both sides of the stream bank were sampled for aquatic
insects using 10 jabs of dip net along the stream within the sampling site.
Samples were combined for collections on each side of the stream.
Leaf Pack – Leaf packs were collected from each half of the stream
into a composite sample (300-500 g wet weight). Leaf packs provide suitable
habitat and nutrition for a variety of macroinvertebrates. Each collected leaf
pack was hand-picked for clinging invertebrates.
Kick Net - Three riffles were sampled with a 1-m kick net. The
substrate was disturbed approximately 3 meters upstream of the net.
The invertebrates were handpicked after each kick.
The general geophysical characteristics of the collection sites canopy
cover (%), riparian vegetation, stream disturbances, etc. were noted.
Field parameters recorded include stream depth (cm), water temperature
(°C), pH, turbidity (FAU), total dissolved solids (ppm) and dissolved oxygen
(mg/L). All macroinvertebrates were initially preserved in 75% ethyl
alcohol, brought back to the laboratory, sorted, identified to family, and placed in 90% ethanol in glass vials.
For this report, bioassessment was based on percent (%) EPT for each
sampling site and for all watersheds combined. Percent chironomids and
simuliids were measured similarly. Other parameters (e.g., total taxa,
diversity indices, etc.) will be used in subsequent data analyses.
Study Watersheds – Flint River, Indian Creek and Flint Creek
Three sampling sites, each 100 m long reach, were selected for each watershed. For Flint River , the sites were on Hwy 72, Buddy Williams Road, and 3 Forks. For Indian Creek, Old Madison Pike, Farrow Road, and Providence Main were chosen. Lacon, AL, Neel, AL, and the Bankhead National Forest were selected for Flint Creek.
Each site per watershed was sampled monthly. Sampling was based on EPA Rapid Bioassessment Protocol’s (RBP’s) multi-habitat methods (USEPA 2006). Macroinvertebrates were collected from a variety of microhabitats using different techniques. All sampling methods were begun downstream, moving up the reach to minimize disturbance.
Surber – Each site per watershed was divided into 3 sections with riffles along the length of the stream from which three samples were collected. Each sample was a composite of three sub-samples obtained by rubbing substrate (gravel and cobbles) for 1 minute to dislodge aquatic insects. Insects were individually picked using forceps or camel’s hairbrush from the mesh.
Table 2 . Major groups collected in study areas.
U.S. EPA. 2006. Rapid Bioassessment Protocols for use in Streams and Wadeable Rivers:
Periphyton, Benthic Macroinvertebrates, and fish.http://www.epa.gov/owow/monitoring/rbp/index.html