Make your own free website on Tripod.com

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 sampled with artificial substrate samplers in pool and riffle habitats of Blackburn fork, Jackson and Putnam counties, Tennessee.The pool and riffle habitays were qualitatively used to show taxa richness, percent EPT (Ephemeroptera, Plecoptera, Trichoptera) and percent Chironomidae.Findings of both habitats were compared to show different macroinvertebrate community compositions.

 

Keywords

 

Taxa, Richness, EPTís, Chironomidae, Macroinvertebrate, Dissolved Oxygen, Pool, Riffle, Hester-Dendy Artificial Samplers.

 

Introduction

 

††††††††††† The Blackburn Fork is a productive 4th order stream in Jackson and Putnam counties (Baker 1994).On 9/14/03 a sampling effort was conducted along a 100-meter stretch of Blackburn Fork to compare macroinvertebrate community structures between pool and riffle habitats.

Macroinvertebrates 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). Invertebrates have adaptations to certain substrates.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).Riffles generally have higher dissolved oxygen levels and a neutral pH.Water qualities including pH and dissolved oxygen can have a significant effect on the biota of a stream (Boto and Bunt 1981).

††††††††††† Pools and riffles are comparably different in water quality, but do they contain the same macroinvertebrate.Are the taxa and quantities different in pools and riffles.In my research I plan to prove that different taxa and quantities are found in these two habitats.

 

Methods and Materials

 

††††††††††† Six different sites were selected in the Blackburn fork in a 100-meter stretch.Three of these sites were in pool and three were in riffles.One Hester-Dendy artificial substrate samplers were placed in each of the six sites (TDEC 2002). Each sampler was composed of nine 3in by 3in plates.The samplers were left for five weeks.At the end of the five weeks, the samples were collected using a D-frame net.Only five were collected, one of the riffle samples was lost.Each sample was preserved in a 10% formaldehyde solution and a 3.785 liter bag.Each was labeled and placed in a cooler.

††††††††††† Four samplers were scrubbed, the two remaining riffle sample and two randomly selected from the pools.Invertebrates were separated from the substrate and identified to Genus.Chironomidae were left at family because identification is very time consuming (Wymer and Cook 2003).

 

Results

 

††††††††††† The pool samples had 655 organism from 11 different taxa, including Chironomidae.The riffles had 450 invertebrates from 17 taxa, including Chironomidae.Percent EPT and percent Chironomidae were similar in pool and riffle habitats. The pool samples were composed of 3.97% EPT and the riffles had 95.73% Chironomidae and the riffle had 3.78% EPT and 92.55% Chironomidae.However, the significant difference is other taxa.The pool habitat had 0.03% other taxa compared to the riffle with 3.78% other taxa.

 

 

†††††† Table 1.Taxa Comparison of Pools and Riffles of Blackburn Fork

Pool

 

 

 

Riffle

 

 

Genus

 

Score

 

Genus

 

Score

Cheumatopsyche

13

 

Cheumatopsyche

1

Ceratopsyche morosa

1

 

Lype diversa

1

Isonychia

 

1

 

Isonychia

 

5

Stenonema femoratum

6

 

Stenonema femoratum

1

Stenonema terminatum

2

 

Stenonema terminatum

9

Ephemerellidae

1

 

Psephenus herricki

1

Tricorythodes

1

 

Helichus basalis

1

Baetis

 

1

 

Macronychus glabratus

2

Libertia

 

1

 

Calopteryx

2

Antocha

 

1

 

Nigronia serricornis

2

Chironomidae

627

 

Antocha

 

3

 

 

 

 

Simulium

 

2

 

 

 

 

Gammarus

1

 

 

 

 

Hemerodromia

1

 

 

 

 

Ferressia rivularis

1

 

 

 

 

Orconectes

1

 

 

 

 

Chironomidae

416

†††††††† Total†††††††† †††††††††††††††††††††††655†††††††††† Total†††††††††††††††††††††††††††††††† 450

††

 

Table 2.

Pool And Riffle Comparison of Blackburn Fork

 

 

Taxa Richnes

EPT Score

% EPT's

% Chironomidae

% Other

Pools

11

17

3.97

95.73

0.03

Riffles

17

26

3.78

92.44

3.78

 

Figure 1.% Composition of Pools†††††††††††† Figure 2.% Composition of Riffles

†††††††††††††††††† in Blackburn Fork†††††††††††††††††††††††††††††††††††††††† in Blackburn Fork

 

Discussion

 

††††††††††† In all 17 taxa were found in riffles and 11 were found in pools (Table 1).Two of the taxa, Antocha and Nigronia serricornis were found in higher numbers in the riffle habitats.The presence of these genra is directly associated with higher dissolved oxygen concentrations (Weigel et al. 2003).

††††††††††† Seventeen EPTís were found in the riffle habitats for a total of 3.78% (Table 2, Figure 2).Surprisingly, the pool habitat had 26 EPTís for a total of 3.97% (Table 2, Figure 1).I agree with Marshall (2001) that taxa richness directly corresponds with water quality, however I disagree that percent EPT corresponds with the water quality in my research.

††††††††††† A total of 416 Chironomids were found in riffles; making up 92.44% of the total composition (Table 2, Figure 2).Table 2 and Figure 1 show that 627 Chironomids were found in the pool sites making up 95.73 percent of the total composition.The family Chironomidae usually has a greater abundance in poorer water quality (Marshall 2001).A more specific environmental assessment could be made if the Chironomidae were identified to genus (King and Richardson 2002).

††††††††††† Comparably the richness and percent EPTís in both habitats is considerably low when compaired to reference streams in Putnam County.Percent Chironomidae was slightly higher when compared to the Spring Creek reference stream.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 EPTís 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 sampling sites are within meters of each other.The pools contain more EPTís and Chironomidae, while the riffles has more taxa richness.Regardless of how much they differ, both pools and riffles are equally important for the survival of habitat specific organisms of Blackburn Fork.†††


††††††††††† Literature Cited

 

  • Baker, S. 1994.Morphometry and Benthic Macroinvertebrate Community Structure of the Blackburn Fork Drainage as a Function of Stream Order. Journal of the Tennessee Academy of Science 69: 27-31.
  • Boto, K.G., and J.S. Bunt. 1981.Dissolved Oxygen and pH Relationships in Northern Australia Waterways. Limnology and Oceanography 26: 1176-1178
  • Cushing, C.E., and J.D. Allan 2001. Streams: Their Ecology and Life, Abiotic Factors. Academic Press. San Diego, California.††
  • Early, S.K., R.L. Newell, and V.F. Medina 2002. Use of Macroinvertebrateand Chemical Indices to Assess Water Quality of an Irrigation Wasteway. Journal of Freshwater Ecology 17:191-198.
  • Heino, J., T. Muotka, and R. Paavola. 2003. Determinates of macroinvertebrate diversity in headwater streams: Regional and local influences. 2003. Journal of Animal Ecology 72: 425-434.
  • King, R.S., and C.J. Richardson. 2002.Evaluating subsampling approaches and macroinvertebrate taxonomic resolution for wetland bioassessment. Journal of the North American Benthological Society 21: 150-171.
  • Marshall, B.D. 2001. An Evaluation of the Sensitivity of a Macroinvertebrate biomonitoring Study in Headwater Streams of the New River Gorge National River. Journal of Freshwater Ecology 2001: 415-428.
  • Roy, A.H., A.D. Rosemond, D.S. Leigh, M.J. Paul, and J.B. Wallace. 2003. Habitat-specific responses of stream insects to land cover disturbance: biological consequences and monitoring implications. Journal of the North Americam Benthological Society 22: 292-307.
  • State of Tennessee. 2002. Quality System Standard Operating Procedure for Macroinvertebrate Stream Surveys.Department of Environment and Conservation. Journal of Freshwater Ecology 17: 223-232.
  • Waters, N.M., and C.R. San Giovanni. 2002. Distribution and Diversityof Benthic Macroinvertebrates Associated with Aquatic Macrophytes. Journal of Freshwater Ecology 17: 223-232.
  • Weigel, B.M., L. Wang, P.W. Rasmussen, J.T. Butcher, P.M. Stewart, T.P. Simon, and M.J. Wiley. 2003. Relative influence of variables at multiple spatial scales on stream macroinvertebrates in Northern Lakes and Forest ecoregion, U.S.A.. Freshwater Biology 48: 1440-1461.
  • Wymer, W.A., and S.B. Cook. 2003. Effects of Chironomidae (Diptera) taxanomic resolution on multivariate analysis of aquatic insect communities. Journal of Freshwater Ecology 18:179-186.