Ecological Archives A021-009-A5

Annika W. Walters and David M. Post. 2011. How low can you go? Impacts of a low-flow disturbance on aquatic insect communities. Ecological Applications 20:163–174.

Appendix E (TABLE E1). Linear model analysis results of insect community metrics and functional feeding group density for pool and riffle habitats.1

Riffle habitats Pool habitats
slope R2 P slope R2 P
Community metrics
Total density (individuals/0.1 m2) negative 0.27 0.02 positive 0.01 0.29
Family richness negative -0.07 0.84 positive -0.06 0.69
EPT richness negative -0.03 0.49 negative -0.06 0.77
Family diversity positive 0.64 <0.001 positive -0.06 0.66
Family dominance negative 0.25 0.03 negative -0.07 0.98
Functional feeding group density (individuals/0.1m2)
Collector-filterer negative 0.40 0.005 negative -0.05 0.59
Collector-gatherer negative 0.16 0.07 positive 0.13 0.09
Scraper negative 0.36 0.009 negative 0.03 0.26
Shredder positive -0.01 0.38 positive 0.12 0.10
Predator positive 0.16 0.07 positive 0.34 0.01


TABLE E2. Linear model analysis results of family insect density and average insect body size in pool and riffle habitats.2

      Density (individuals/m2) Size (mm)
Habitat Family Order slope R2 P slope R2 P
Pool Baetidae Ephemeroptera positive 0.00 0.31 positive -0.16 0.69
communities Capniidae Plecoptera negative 0.33 0.01 negative 0.5 0.11
Chironomidae Diptera positive 0.28 0.02 positive 0.13 0.09
Chloroperlidae Plecoptera positive -0.04 0.53 negative -0.12 0.50
Corydalidae Megaloptera positive 0.01 0.29 negative -0.08 0.56
(larvae) Coleoptera positive 0.18 0.06 positive -0.09 0.82
Ephemerellidae Ephemeroptera positive 0.27 0.02 negative 0.10 0.18
Gomphidae Odonata positive 0.18 0.05 negative -0.32 0.86
Heptageniidae Ephemeroptera negative 0.25 0.03 negative 0.05 0.20
Hydropsychidae Trichoptera positive -0.07 0.92 negative -0.04 0.50
Leptophlebiidae Ephemeroptera negative -0.05 0.60 negative -0.08 0.70
Leuctridae Plecoptera positive 0.25 0.25 positive 0.06 0.21
Perlidae Plecoptera positive -0.04 0.52 negative 0.12 0.16
Philopotamidae Trichoptera negative 0.25 0.03 negative 0.48 0.08
Polycentropodidae Trichoptera negative -0.07 0.88 negative 0.38 0.03
Psephenidae Coleoptera negative -0.07 0.95 positive 0.05 0.21
Sialidae Megaloptera positive 0.09 0.13 positive -0.14 0.72
Tipulidae Diptera positive 0.22 0.04 positive -0.02 0.42
Riffle Baetidae Ephemeroptera negative -0.07 0.82 negative 0.10 0.16
communities Chironomidae Diptera negative 0.05 0.21 negative 0.14 0.08
  Chloroperlidae Plecoptera positive 0.00 0.32 negative 0.17 0.09
  Corydalidae Megaloptera negative -0.07 0.82 negative -0.09 0.83
  (adult) Coleoptera negative -0.07 0.80 positive -0.07 0.74
  (larvae) Coleoptera positive 0.18 0.06 positive -0.08 0.87
  Glossomatidae Trichoptera positive 0.00 0.34 positive -0.11 0.54
  Heptageniidae Ephemeroptera negative 0.46 0.002 negative 0.06 0.19
  Hydropsychidae Trichoptera negative 0.04 0.22 negative 0.54 <0.001
  Leptophlebiidae Ephemeroptera negative 0.13 0.10 negative 0.07 0.17
  Leuctridae Plecoptera positive 0.12 0.10 positive 0.06 0.61
  Peltoperlidae Plecoptera negative 0.14 0.09 negative -0.05 0.45
  Perlidae Plecoptera positive 0.15 0.08 negative 0.17 0.06
  Perlodidae Plecoptera negative -0.06 0.68 negative 0.44 0.13
  Philopotamidae Trichoptera negative 0.65 <0.001 negative -0.01 0.39
  Polycentropodidae Trichoptera positive 0.04 0.23 negative 0.05 0.22
  Psephenidae Coleoptera negative -0.06 0.70 positive 0.01 0.32
  Rhyacophilidae Trichoptera negative -0.02 0.43 negative 0.19 0.16
  Sialidae Megaloptera positive -0.04 0.50 positive -0.07 0.59
  Simuliidae Diptera negative 0.41 0.005 negative 0.56 0.05
  Tipulidae Diptera positive 0.00 0.34 negative 0.07 0.16
  Veliidae Hemiptera positive 0.19 0.05 positive -0.07 0.95

1A positive slope means that the community metric or functional feeding group density increased at lower flow levels. All August 2005, 2006, and 2007 stream reaches with discharge data are included. Significant P values at the 0.05 level are denoted in bold.

2A positive slope means that insect density or body size increased at lower flow levels. All August 2005, 2006, and 2007 stream reaches with discharge data are included. Insect families that had density and body size data for fewer than five stream reaches are not included in the table. Significant P values at the 0.05 level are denoted in bold.


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