ORDINATION OF MACROINVERTEBRATE 

 COMMUNITIES IN A MULTISTRESSED 

 RIVER SYSTEM 



DAVID C. BECKETT 



Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio 



ABSTRACT 



The macroinvertebrate communities of the Great Miami River system (south- 

 western Ohio) were studied over a wide range of environmental conditions and 

 stresses. Stations ranged from relatively undisturbed locations to areas subjected 

 to flood-control modification, power-plant thermal discharges, municipal 

 sewage-treatment-plant discharges and industrial-wastewater outfalls. 



Similarity indices and subsequent polar ordination showed that river passage 

 through the city of Dayton did not prohibit high biotic similarity between some 

 sites below Dayton and undisturbed upstream locations. Stations showed varying 

 patterns of affiliation (based on similarity indices), which correlated well with 

 changes in river discharge. Two types of faunal homogeneity were apparent: 

 during relatively high river- discharge periods a high degree of faunal similarity 

 occurred between far upstream and far downstream stations, and during low 

 flow conditions a biotic homogeneity was evident among all downstream 

 stations as a result of the maximization of pollutional influences and the 

 subsequent domination of euryecious species. Ordination of stations during high 

 flow conditions did not produce an ordering along any gradients. During low 

 flow conditions, however, stations ordered well along a gradient of pollutional 

 disturbances. Pollutional effects seemed to overwhelm the effect of normal 

 environmental variables on faunal composition during these low flow conditions. 



A comparison of the relatedness of macroinvertebrate communities 

 was used by Burlington (1962) to assess the effect of a point source 

 pollutant on benthic macroinvertebrates. His analysis suffered, 

 however, from a paucity of stations (7) and was taken over just one 

 time period. Grossman, Kaesler, and Cairns (1974) used cluster 

 analysis, based on community similarity to assess the effect of two 

 acute stresses (caused by major industrial spUls) on the benthic 



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