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Evidence for Substrate Influence on Artificial Substrate Invertebrate Communities.
Iain D Phillips1,2,3, Kate S Prestie2,3,4
1Water Quality and Habitat Assessment Services, Water Security Agency, 101-108 Research Dr., Saskatoon, Saskatchewan, S7N 3R3, Canada.
Environmental Entomology
|July 7, 2017
Summary
Cobble basket placement significantly impacts benthic macroinvertebrate communities. Placing baskets on cobble habitats, not soft substrates, provides a more accurate representation of lake biodiversity for monitoring.
Area of Science:
- Aquatic Ecology
- Benthic Macroinvertebrate Ecology
- Freshwater Monitoring
Background:
- Cobble baskets are standard tools for assessing benthic macroinvertebrate communities in water bodies.
- Substrate type differences can bias macroinvertebrate colonization in cobble baskets, potentially misrepresenting community structures.
- Understanding substrate influence is crucial for accurate ecological assessments.
Purpose of the Study:
- To test the hypothesis that cobble basket placement influences benthic macroinvertebrate community composition.
- To determine if substrate type (cobble vs. soft sediment) affects macroinvertebrate colonization in deployed baskets.
- To provide recommendations for optimizing cobble basket deployment in lake monitoring.
Main Methods:
- Deployed cobble basket arrays (n=4) in Dog Lake, Saskatchewan, during 2011 and 2012.
- Placed baskets on both cobble habitats and adjacent soft/sandy substrates (approx. 100m apart).
- Analyzed macroinvertebrate communities using diversity indices (Shannon-Weaver), % EPT, total density, and Nonmetric Multidimensional Scaling (NMDS).
Main Results:
- Baskets on cobble substrate showed significantly higher Shannon-Weaver diversity than those on soft substrate in both years.
- Higher % EPT (Ephemeroptera, Plecoptera, Trichoptera) was observed on cobble in 2011; total density did not differ significantly.
- NMDS revealed distinct community compositions, with specific taxa like Gammarus lacustris dominating soft substrates and Aeshna sp./Mystacides sp. (2011) and Helobdella stagnalis/Glossophinia complanata (2012) favoring cobble.
Conclusions:
- Cobble basket placement significantly influences benthic macroinvertebrate community colonization, supporting the study's hypothesis.
- Cobble substrates yield more representative community data compared to soft substrates due to habitat complexity.
- Recommend deploying cobble baskets on comparable substrate types and prioritizing cobble beds for accurate lake monitoring and assessment.
