Identification of predominant environmental factors structuring stream macroinvertebrate communities within a large agricultural catchment

• Published in: Freshwater biology 1993-04, Vol.29 (2), p.285-294
• Main Authors: RICHARDS, CARL, HOST, GEORGE E., ARTHUR, JOHN W.
• Format: Article
• Language: English
• Subjects: Chironomidae; Ephemeroptera; Freshwater; Insecta; Plecoptera; Trichoptera
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1111/j.1365-2427.1993.tb00764.x

SUMMARY 1  Patterns of macroinvertebrate community composition were examined in streams within a 40000‐km2 catchment in central Michigan, U.S.A., to identify the major environmental gradients influencing community variation. Agriculture and associated clay and sandy soils predominated in much of the region. 2  Eighty macroinvertebrate taxa were collected from stream surveys conducted during May and August 1990. Community composition varied primarily by the proportions of Plecoptera and Ephemeroptera. Benthic communities from the heaviest agricultural zones were most different from those at other sites. 3  Chemical composition among the sites varied most in relation to nutrients (NH3, NO3, PO4). Other parameters were relatively similar. Physical 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. Most physical habitat scores were lowest in the intense agriculture zones. 4  The relative importance of physical and chemical variables in explaining variation in macroinvertebrate communities was quantified using canonical correspondence analysis. Substrate characteristics were most important in both surveys. Significant correlations (P