A fish and benthic invertebrate community survey in support of a pre-design investigation

OUR CHALLENGE

Contaminated substrate in an urban river required excavation to achieve the risk-based cleanup objectives. This remedial process would eliminate all fish and benthic invertebrates from the affected areas. To understand the pre–remedial biodiversity, Integral performed comprehensive baseline surveys upstream of and within the river reaches designated for remediation.  These surveys provided the data to establish a foundation for assessing the natural repopulation and recovery of fish and benthic invertebrate communities post–remediation.  

OUR APPROACH

Integral collected fish and benthic invertebrates from several impoundments and river reaches as part of the predesign investigation.  We counted, measured, and identified each fish to the species level and catalogued benthic invertebrates to the lowest-possible taxonomic level at each sampling site. We used these data to calculate the fish and benthic invertebrate index of biotic integrity (IBI) scores for each location and study area. These scores, reflecting species richness, diversity, abundance, population structure, and trophic dynamics, provided a comprehensive baseline of the fish and benthic invertebrate communities present under pre–remediation conditions.  

OUR IMPACT

The IBI scores helped summarize complex community parameters to evaluate the two aquatic communities between site-affected study areas versus upstream reference study areas, and across time (i.e., pre–remediation versus post–remediation). Our findings revealed a substantial similarity between the fish and benthic invertebrate communities in the site-affected and upstream references areas.  The results also provided the baseline conditions for use in a long-term monitoring program to help quantify the recovery of the post–remediation aquatic ecosystems in the river.