There is growing interest in the use of freshwater macroinvertebrate species traits as an assessment tool for monitoring human impacts on stream ecosystems, but what exactly is a species trait?
A species trait is defined as a measurable property of an organism, measured in individuals and applied comparatively across species and at broad geographical scales. Biological traits of a species include life-history characteristics, physiological and functional roles, and examples include egg laying, feeding guild, mode of locomotion, respiration, dispersal capability, reproduction and longevity.
Species traits can provide an effective alternative to biomonitoring methods for examining ecosystem responses to environmental impacts than more traditional taxonomic-based measures.Traits may be more consistent across spatial and seasonal scales than macroinvertebrate community composition or biotic indices because traits have evolved as a consequence of selective environment pressures. Trait composition should therefore be similar under comparable environmental conditions, regardless of biogeographical differences in taxonomic composition. Traits can be useful for establishing mechanistic linkages between biotic responses and environmental conditions as certain suites of traits allow species to be successful in a given environment and, conversely, species that do not have the required traits do not survive or are absent.
Trait information for nearly 500 New Zealand macroinvertebrate taxa can be found in the New Zealand Freshwater Macroinvertebrate Trait Database. This extensive database was first developed in 2004 with the most recent and comprehensive update occurring in 2017. Trait data for New Zealand’s aquatic macroinvertebrates were derived from an extensive review of New Zealand and overseas literature, personal observations and expert opinion. This database includes 16 biological traits that represent 59 states or modalities nestled within life history, morphology, mobility and resource acquisition that describe different aspects of an organism’s life history (e.g. size, number of reproductive cycles) or features that confer resilience or resistance beyond that provided by life history traits (e.g. body shape), as well as more general biological and physiological features (e.g. feeding habits, respiration).
A spreadsheet of the New Zealand Freshwater Macroinvertebrate Trait Database and a report summarising species traits and the modalities used, as well as how trait data was scored, are available.
Funding
This project is in the Rehabilitation and Protection Programme, supported by NIWA through the Strategic Science Investment Fund.
