Variability of benthic macroinvertebrate biomass in two contrasting streams in southern Chile

Organism biomass, a continuous quantity, may be useful for general community and diversity assessment. Body length and biomass of benthic macroinvertebrates from two aquatic environments with different impact levels are determined in this study, classifying organisms using functional and taxonomic characteristics. Lyophilized benthic macroinvertebrate biomass was quantified to test for significant differences between an impacted and reference (less environmental impact) site. Results show that macroinvertebrate assemblages from the less impacted stream had higher average biomass than the assemblage from the perturbed site, and significant differences in biomass of Plecoptera, Trichoptera, predators, filterers and gills breathers were found between sites. The biomass signature was calculated for each analyzed scenario, weighting the presence of all specimens sampled considering the total biomass in a single regression curve equation. The cubic polynomial model had the best fit to the data. More background from theory to practice should be considered in biomonitoring research; hence we propose the application of macroinvertebrate biomass as an additional metric that will help evaluate the ecological status of streams, thus contributing to the knowledge of community-based biomonitoring of benthic macroinvertebrates.

Automated summary

This study determined the body length and biomass of benthic macroinvertebrates in two aquatic environments with different impact levels, finding that the disturbed site had lower biomass. Significant differences in biomass between sites were observed by calculating biomass signatures, suggesting a new method for biomonitoring research.