Evaluating macroinvertebrate community shifts in the confluence of freestone and limestone streams

  • Jennifer K. Hellmann | hellmann.13@osu.edu The Ohio State University Messiah College, United States.
  • Jeffrey S. Erikson Messiah College, United States.
  • Simon A. Queenborough The Ohio State University, United States.

Abstract

Aquatic macroinvertebrates are critical to ecosystem functioning through their regulation of many essential top-down and bottom-up ecosystem processes such as energy translocation, nutrient flow, and detrital decomposition. However, specific preferences by macroinvertebrates for certain ranges of abiotic and biotic characteristics mean that changes in these factors often create large differences in benthic community structure. Investigations into drivers of community structure have found distinct patterns of variation between ecosystems, but drivers of macroscale variation may differ from drivers of microscale variation. Such microscale variation in macroinvertebrate community structure as a function of abiotic conditions may be found in the confluence of two geologically distinct freshwater streams. Variation in the origin, underlying bedrock, and watershed of a stream results in drastically different physical and chemical characteristics and correspondingly distinct macroinvertebrate community structures. In areas where water from geologically distinct streams flows together, a mixing zone emerges with unique chemical and physical characteristics. There is little information on how invertebrate communities are structured within this mixing zone. To investigate this, we examined how the structure of the macroinvertebrate community changed downstream of the confluence. Up to thirty metres downstream, we found distinct stream sections that mirrored physical and chemical conditions found in limestone and freestone streams, and a mixing zone with emergent properties. These physical and chemical changes between sites were accompanied by shifts in macroinvertebrate community composition. Diversity indices indicated significantly higher diversity in freestone sites than in limestone sites or the mixing zone and there was a unique composition of genera in the mixing zone that were distinct from both limestone and freestone sites. Factors driving variation in communities on a small-scale may be distinctly different from those influencing large-scale patterns and this study highlights the need for the continued exploration of the microscale variation in community structure. 

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Author Biographies

Jennifer K. Hellmann, The Ohio State University Messiah College

Evolution, Ecology, and Organismal Biology

PhD Candidate

Jeffrey S. Erikson, Messiah College

Biology Department

Assistant Professor

Simon A. Queenborough, The Ohio State University

Department of Evolution, Ecology, and Organismal Biology

Assistant Professor

Published
2014-07-30
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Section
Original Articles
Supporting Agencies
Messiah College
Keywords:
Geology, diversity, microscale, abiotic, emergent, freshwater stream, limestone.
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How to Cite
1.
Hellmann JK, Erikson JS, Queenborough SA. Evaluating macroinvertebrate community shifts in the confluence of freestone and limestone streams. J Limnol [Internet]. 2014Jul.30 [cited 2020Jul.10];74(1). Available from: https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2014.935