Introduction to Winter 2015 Ecesis, Volume 25, Issue 4
Organisms serve as indicators of the health of the environment they inhabit. Bioassessment refers to studies that utilize species presence, number, and condition as indicators of ecological community quality. The developing science of bioassessment has focused on rating the condition of streams and other aquatic ecosystems by assessing the composition and abundance of insects and fish found in the water body. Bioassessment serves a role in restoration by allowing biologists and regulators to identify aquatic systems in need of restoration, determine restoration goals, measure or estimate response to change, and gauge restoration success. In this issue of Ecesis, we highlight bioassessment as an element of restoration, clearly demonstrating the value in applying bioassessment techniques into restoration efforts.
Biological integrity, defined by an unimpaired state, was included in the Water Pollution Control Act of 1972, more commonly known as the Clean Water Act (CWA). Bioassessment has been used in ecological evaluations since the early 1980s, when the concept of an Index of Biological Integrity (IBI) was first developed. In 1986, the U.S. Environmental Protection Agency (EPA) began a program to accelerate the development of cost-effective biological monitoring techniques, which led to the EPA’s Rapid Bioassessment Protocols for macroinvertebrates and fish. California has incorporated the EPA’s bioassessment approach and adapted protocols into aquatic habitat assessment and water quality control regulations. To a great degree, California has advanced the science and policies of bioassessment.
At the state level, bioassessment is being led by the California State Water Board through their Surface Water Ambient Monitoring Program (SWAMP), and the California Department of Fish and Wildlife through their Aquatic Bioassessment Laboratory (ABL). These two programs have determined that benthic macroinvertebrates (BMIs) are to be used as the primary biological indicators for bioassessments due to their sensitivity to changes in water quality, ease of collection and identification, and primarily-aquatic life histories. They have adapted the EPA’s Rapid Bioassessment Procedures to the state and they have established regional IBIs, which have been advanced statewide to the current California Stream Condition Index (CSCI). The California Aquatic Bioassessment Workgroup (CABW) has met annually since 1994 to present and discuss bioassessment research and the latest policy issues.
There can be a number of metrics used in aquatic bioassessments with the basic metrics being species richness, composition, and trophic structure of the macroinvertebrate community in a water body. Some of the commonly used metrics include: taxonomic richness (the total number of unique taxa); EPT richness (the number of taxa in the Ephemeroptera, Plecoptera, and Trichoptera orders); % EPT abundance (percent of the organisms that are EPTs); % Chironomidae (percent of the organisms that are in the Chironomidae family); % dominant taxon (percent of total abundance that is a single taxon); and % non-insect (percent of the organisms which are not insects). The metrics are scored combined into a single index score, then compared and rated against standardized reference conditions. Index scores can indicate whether a water body is subject to physical or chemical degradation, or if it has a relatively high water quality, all of which is based upon the structure of the BMI community.
The protocols for bioassessments were initially developed as rapid and inexpensive measurements of biological integrity. They can also be used in citizen science monitoring programs. Schools and local environmental organizations can learn and implement bioassessment programs to educate students and evaluate ecological health within the watersheds of concern to those groups.
Bioassessments can serve to track the status and trends of sensitive invertebrate populations, some of which may be in need of special status species protections. In addition, bioassessments can be used to evaluate environmental changes, including changes resulting from invasive species introductions to a site.
In this issue of Ecesis, we are bringing bioassessment to the forefront as an element of restoration. This article attempts to provide an introduction and summary of how bioassessment is structured in California. The contributed article by Michelle Tang and collaborators showcases the state’s bioassessment website with its very useful database of evaluated water bodies. Joan Demerow presents the UC Berkeley Calbug project — a beautiful and thorough catalog of California’s invertebrate collections — and she describes research documenting changes in Odonate populations since the early 1900s. Denise Knapp and her collaborators present a meta-analysis of plant invasion effects on invertebrate richness and provide a captivating summary of how invertebrates can be effective indicators of environmental change due to their unique role in ecosystem dynamics. A great way for restoration specialists and resource managers to learn more about bioassessment practices in California would be to follow the annual meetings of the CABW, typically held at UC Davis in the fall. I hope you will learn something from these articles and consider using bioassessment as a tool for restoration. — by Gregory Andrew, Fishery Program Manager, Marin Municipal Water District, and SERCAL Northern California Wetland & Riparian Guild Chair. firstname.lastname@example.org