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  • Simplifying Benthic Macroinvertebrate Collection and Analysis

    Using Multivariate Statistics

    by

    Autumn S. Pickett

    A Thesis Submitted in partial fulfillment

    of the requirements for the degree Master of Environmental Studies

    The Evergreen State College June 2012

  • ©2012 by Autumn S. Pickett. All rights reserved.

  • This Thesis for the Master of Environmental Studies Degree

    by

    Autumn S. Pickett

    Has been approved for

    The Evergreen State College

    By

    _______________________________________________

    Carri LeRoy, Ph.D.

    Member of the Faculty

    ______________________________________

    Date

  • ABSTRACT

    Simplifying benthic macroinvertebrate collection and analysis using multivariate statistics

    Autumn S. Pickett

    Biological assessment (bioassessment) is a direct way to evaluate, track changes and prioritize management actions in ecosystems. Benthic macroinvertebrates are often subjects of bioassessment because they are relatively easy to collect and identify, and have been studied extensively. Bioassessments involve a variety of statistical models that integrate the information collected using different methods. In particular, multivariate models compare the expected occurrence with observed, or ordinate species data to express the observed occurrence of taxa in “species space." The purpose of this thesis investigation is to use multivariate statistical models to see if there may be meaningful but simpler ways to characterize patterns found in a large macroinvertebrate dataset, and if these summary patterns might simplify the way biological data collection can be conducted in the future. A large dataset of benthic macroinvertebrates in the Wenatchee Basin was analyzed using multivariate ordination software (PC-ORD 5.32) to compare reference to non-reference sites. The data were examined as abundance and richness of species, higher taxonomic levels and functional feeding groups to see if patterns emerged when compared against selected environmental gradients. It appeared there were several characterizations that did no worse in distinguishing between reference and test sites than the full analysis of raw species. These characterizations were of richness and abundance of functional feeding groups and richness, abundance and presence/absence at higher taxonomic levels. Importantly, simplifying the classification of macroinvertebrates could allow for identification in the field so that insects could be returned alive to their habitat. Simplified methods may also prove more efficient, less costly and less time-intensive while maintaining the quality of results. More investigation is needed to determine if these simplified methods can be applied to other streams and datasets prior to widespread use.

  • iv

    Contents

    ABSTRACT ........................................................................................................................................ 4

    Contents .......................................................................................................................................... iv

    Figures and Images .........................................................................................................................vii

    Tables ............................................................................................................................................. viii

    Acknowledgements ......................................................................................................................... xi

    Introduction ..................................................................................................................................... 1

    Bioassessment .................................................................................................................................. 1

    Stream Communities ................................................................................................................... 2

    Integrity and reference sites ........................................................................................................ 3

    Stream macroinvertebrates ......................................................................................................... 4

    Macroinvertebrate Assemblages and Ecosystem Integrity .......................................................... 4

    Simple Community metrics .......................................................................................................... 5

    Tolerance measures ..................................................................................................................... 8

    Rare species ................................................................................................................................. 8

    Ephemeroptera, Plecoptera and Trichoptera: %EPT and EPT richness ........................................ 9

    Functional Feeding Groups .......................................................................................................... 9

    Multimetric and Multivariate analysis ........................................................................................... 14

    Multimetric Indices of Biological Integrity (IBI) ......................................................................... 14

    Metric assignment ..................................................................................................................... 15

    Mulitivariate Models .................................................................................................................. 16

    Observed vs. Expected (O/E) Models (RIVPACS) ........................................................................ 18

    Ordination .................................................................................................................................. 19

    Non-metric Multidimensional Scaling (NMDS) ...................................................................... 20

    Multivariate Models: Important Considerations ....................................................................... 21

    Distance measures ................................................................................................................. 21

    Transformation and relativization .......................................................................................... 22

    Hypothesis testing .................................................................................................................. 23

    Materials and Methods .................................................................................................................. 25

    Study Area .................................................................................................................................. 25

    Washington State Bioassessment .............................................................................................. 28

    Data acquisition ..................................................................................................................... 28

    Data collection methods ........................................................................................................ 29

    Descriptive Attributes of Sites ................................................................................................ 30

  • v

    Community data..................................................................................................................... 31

    Data analysis .............................................................................................................................. 31

    Functional Feeding Group and Tolerance .............................................................................. 31

    Richness measures ................................................................................................................. 32

    Data characterization and transformation ............................................................................. 32

    Considerations of Characterizations ...................................................................................... 33

    Ordination .............................................................................................................................. 33

    MRPP and summary statistics ................................................................................................ 35

    Results ............................................................................................................................................ 36

    Physical and community metrics ............................................................................................... 36

    Physical, temporal and community characteristics of the 3 smaller studies ............................. 37

    Reference vs. non-reference, wilderness vs. non-wilderness .................................................... 39

    Reference sites within studies ................................................................................................... 39

    Comparison of community metrics between reference and wilderness designations ............. 41

    Functional Feeding Group (FFG) Richness ................................................................................. 41

    Comparison of community me

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