Using traits-based ecology to inform aquatic insect assemblage structure in relation to environmental flows
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Date
2014
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University of New Brunswick
Abstract
Benthic macroinvertebrate taxonomic data is the foundation of freshwater
biomonitoring programs.around the world. Biological trait information has been proposed
as an effective alternative or supplement to taxonomic data for ·biomonitoring purposes.
Traits are simply measurable, heritable properties of an organism that interact with the
environment. Trait data can expand the geographical scope of assessments as well as
describe mechanistic relationships between environmental conditions and the biological
community to diagnose impact severity and type of stressor. In riverine ecosystems, a
change in the flow regime or hydrological alteration is considered the most significant
environmental stressor because of the detrimental effects on biological communities and
habitats as well as interactions with other stressors. To maintain ecological integrity, trait
data can inform the benthic macroinvertebrate assemblage response to flow properties to
support environmental flow management criteria. My objective was to define and
evaluate traits and trait metrics that could be linked to hydrological conditions.
Specifically, I investigated intra- and inter-tax on trait properties for body size and body
shape, which are predicted to respond strongly to hydraulic and hydrologic scale
variables. Multiple field sites were sampled several times over a five-year period in the
unregulated Miramichi River Basin, New Brunswick, Canada to resolve the relationships
between flow and ecology. I was able to demonstrate the importance of intraspecific trait
variation and trait properties for characterizing the benthic assemblage. By measuring
specimen body sizes and establishing body shape criteria using geometric morphometric
analysis, I improved the accuracy of traits-based metrics and demonstrated a sizedependent
bias in current taxonomic-based metrics. Using both traditional categorical trait states as well as high-resolution trait data, I was able to characterize relationships
among aquatic insects and hydrological properties at nested spatial scales. Then I tested
the performance of taxonomic and trait metrics to assess hydrological data over short
(two-year) to moderate (five-year) temporal scales. High-resolution trait metrics
demonstrated equal or greater association with hydrological factors than taxonomic or
other trait metrics at these timescales. Trait information can add value to biomonitoring
approaches by accurately describing trait expression, enabling stronger statistical
inference, and increasing sensitivity and interpretability, which are essential for
evaluating the complex relationship between benthic assemblages and their hydrological
environment.