Abstract

1. Comparison of Aquatic Macroinvertebrates in Pool and Riffle Habitats of Blackburn Fork Michael Railling, Department of Biology, Undergraduate Student, Tennessee Technological University, Cookeville, TN 38505 USA Abstract Aquatic communities were quantitatively taken with artificial substrate samplers in pool and riffle habitats of the Blackburn fork. However one of the artificial samplers was lost during the five week collection period. The remaining samples were qualitatively used to show the richness, percent of EPT’s (Ephemeroptera, Plecoptera, Trichoptera), and percent Chironomidae present in the two habitats. Findings of both habitats were compared to show different macroinvertebrate compositions. Table 1. Taxa Comparison of Pools and Riffles of the Blackburn Fork Introduction The Blackburn Fork is a productive 4th order stream in Jackson and Putnam counties (Baker 1994). Macro invertebrates are good indicators of Stream Quality because they are closely associated with the conditions of the environment, They are easy to collect, they are relatively stationary, and they have a wide distribution (Early et al. 2002). Macroinvertebrate assemblages not only vary regionally they can also vary greatly at local levels (Heino et al. 2003). Abundance of the macroinvertebrates can be affected by many factors but habitat is the prime factor (Waters and Giovanni 2002). Organisms have adaptations to certain substrates especially invertebrates. Some may prefer the larger cobble and faster currents of a riffle and other may prefer the slower and bedrock substrate found in a pool (Cushing and Allan 2001). Pools generally have higher dissolved oxygen levels and a more neutral pH. Water Qualities In pH and dissolved oxygen can have a significant effect on the biota (Boto and Bunt 1981). Are the macroinvertebrate in pool and riffle composed of the same taxa or densities? In my research I plan to show that pool and riffle habitats have comparably different taxa and proportions of these taxa. Figure 1. % in pools Figure 2. % in Riffles Blue= % EPT’s Yellow= % Other Purple= % Chironomidae Discussion The lower water quality pools had higher percentage of Chironomidae, higher percentage of EPT’s, but had less richness. The higher water quality riffles had higher richness, less Chironomidae, but had lower percentage of EPT’s. Comparably the Richness and % EPT’s in both habitats is considerably low when compaired to other healthy streams. Percent Chironomidae was slightly higher. Human disturbance could be the factor influencing the numbers. Within my 100 meter sampling area is a popular swimming hole and a riffle commonly used for invertebrate sampling. In 2002 Weigel et al stated that perturbation can cause richness and percent EPT’s to decreases while % Chironomidae increased. Near the sampling site there is a residential area with numerous houses. The sample area also runs along side the road which is constantly traveled. I suspect that increased sedimentation through human disturbance has reduced habitats or made them unsuitable for aquatic life, especially in the riffle habitats (Roy et al. 2003). In conclusion both habitats are composed of different assemblages of organisms even though they are within meters of each other. The pools contain more EPT’s and total number of invertebrates while the riffles have more Taxa Richness. Neither are more important than the other, but both pools and riffles are essential to the survival of habitat specific organisms of Blackburn Fork. Results The pools had 655 invertebrates from 11 different taxa including Chironomidae. The riffles had 450 invertebrates from 17 taxa including Chironomidae. The percent of EPT’s was similar, the pools was composed of 3.97% EPT’s and the riffles had 3.78% EPT’s. The pools had 95.73% Chironomidae and the riffles had 92.44% Chironomidae. The pools had .03% of other taxa, however in the riffles other taxa made up 3.78% Table 2. % Comparisons of the Blackburn Fork