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IDENTIFICATION OF PREDOMINANT ENVIRONMENTAL FACTORS STRUCTURING STREAM MACROINVERTEBRATE COMMUNITIES WITHIN A LARGE AGRICULTURAL CATCHMENT
Citation:
Richards, C., G. Host, AND J. Arthur. IDENTIFICATION OF PREDOMINANT ENVIRONMENTAL FACTORS STRUCTURING STREAM MACROINVERTEBRATE COMMUNITIES WITHIN A LARGE AGRICULTURAL CATCHMENT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/246 (NTIS PB94177722), 1993.
Description:
Patterns of macroinvertebrate community composition were examined in streams within a 40,000-km2 catchment in central Michigan, USA, to identify the major environmental gradients influencing community variation. griculture and associated clay and sandy soils predominated in much of the region. ighty macroinvertebrate taxa were collected from stream surveys conducted during May and August 1990. ommunity composition varied primarily by the proportions of Plecoptera and Ephemeroptera. enthic communities from the heaviest agricultural zones were most different from those at other sites. hemical composition among the sites varied most in relation to nutrients (NH3, NO3, PO4). ther parameters were relatively similar. hysical characteristics of the sites were scored in six habitat categories: (i) substrate characteristics, (ii) instream cover, (iii) channel morphology, (iv) riparian zone and stream-bank conditions, (v) riffle/run quality, (vi) pool quality. ost physical habitat scores were lowest in the intense agriculture zones. he relative importance of physical and chemical variables in explaining variation in macroinvertebrate communities was quantified using canonical correspondence analysis. ubstrate characteristics were most important tn both surveys. ignificant correlations (P < 0.05 and P < 0.10) were observed between substrate quality and total numbers ot Ephemeropteran, Plecopteran, and Trichopteran taxa. hese relationships reflected correlations from sites in the clay soil-type region (P < 0.01 and P < 0.10) which contrasted with non-significant results from the less impacted, sandy soil-type region. ffective stream restoration efforts in this region will require the alteration of ocal land-use activities that influence the physical habitat. urther development of empirical relationships between catchment activities and substrate and channel characteristics within natural geomorphic regions is essential for the evaluation of restoration projects.