Benthic macroinvertebrates
overview
What are Benthic Macroinvertebrates?
Benthic Macroivertebrates are small aquatic animals and insect larvae that inhabit the bottom substrates (stones, logs, sediment and aquatic plants) of streams, rivers, and lakes for at least part of their life cycles. They are large enough to see with the naked eye (macro) and have no backbone (invertebrate). Why are Benthic Macroinvertebrates Important? Benthic Macroinvertebrates are relatively immobile and can not escape polluted water or unfavorable stream conditions. Granted their wide range of pollution sensitivity, the abundance and diversity of macroinvertebrates in an aquatic ecosystem can serve as an excellent indicator of stream conditions. Healthy macroinvertebrate communities typically coincide with ideal chemical and physical stream conditions. |
methodology
Benthic Macroinvertebrates were sampled and identified using modified procedures from the EPA's Rapid Bioassessment Protocol.
Samples were collected from a 1' by 1' target habitat using a 20 jab method and D-frame dipnet. A single jab consists of an aggressive kick, disturbing the substrate, followed by 2-3 hand sweeps, guiding the dislodged macroinvertebrates downstream towards the net. A total of eighteen samples were collected: six from above and below the pipeline crossing on Buck Creek, and six from each isolated site. After being transferred into sample containers, samples were taken to the Brown Lab (VT Biological Sciences), sieved (125 micron) and preserved using 70% ethanol. Macroinvertebrates were sorted and identified to the family level using a 30 grid pan (6 cm x 6cm), forceps, and a compound microscope. Raw biological data was aggregated using various stream condition metrics (PTI score, abundance, diversity) to quantify change between the upstream and downstream sites.
Samples were collected from a 1' by 1' target habitat using a 20 jab method and D-frame dipnet. A single jab consists of an aggressive kick, disturbing the substrate, followed by 2-3 hand sweeps, guiding the dislodged macroinvertebrates downstream towards the net. A total of eighteen samples were collected: six from above and below the pipeline crossing on Buck Creek, and six from each isolated site. After being transferred into sample containers, samples were taken to the Brown Lab (VT Biological Sciences), sieved (125 micron) and preserved using 70% ethanol. Macroinvertebrates were sorted and identified to the family level using a 30 grid pan (6 cm x 6cm), forceps, and a compound microscope. Raw biological data was aggregated using various stream condition metrics (PTI score, abundance, diversity) to quantify change between the upstream and downstream sites.
results
Taxa Diversity
There was minimal variation in Shannon Diversity (H) and family Evenness (E) from upstream to downstream. |
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conclusion
While both the upstream and downstream reaches of Buck Creek are considered healthy streams from the metrics analyzed, there are still many potential concerns about the health of the downstream site moving forward. Despite minimal change in other metrics, a moderate decrease in PTI Scores demonstrates mild environmental stresses on benthic macroinvertebrate communities downstream of the pipeline crossing. Further monitoring of stream biological conditions should be conducted as pipeline construction progresses and environmental reclamation plans are implemented.
References
EPA Rapid Bioassessment Protocol:
Barbour, M. T., J. Gerritsen, B. D. Snyder & J. B. Stribling, 1999. Rapid Bioassessment Protocols for Use in Wadeable Streams and Rivers. Periphyton, Benthic Macroinvertebrates, and Fish, second edition. EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
Diversity Indices:
Beals, M., L. Gross, and S. Harrell. “DIVERSITY INDICES,” 2000. http://www.tiem.utk.edu/~gross/bioed/bealsmodules/shannonDI.html.
Benthic Macroinvertebrates:
“Benthic Macroinvertebrates - Hoosier Riverwatch.” State of Indiana, n.d. https://www.in.gov/idem/riverwatch/files/volunteer_monitoring_manual_chap_5.pdf.
Barbour, M. T., J. Gerritsen, B. D. Snyder & J. B. Stribling, 1999. Rapid Bioassessment Protocols for Use in Wadeable Streams and Rivers. Periphyton, Benthic Macroinvertebrates, and Fish, second edition. EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
Diversity Indices:
Beals, M., L. Gross, and S. Harrell. “DIVERSITY INDICES,” 2000. http://www.tiem.utk.edu/~gross/bioed/bealsmodules/shannonDI.html.
Benthic Macroinvertebrates:
“Benthic Macroinvertebrates - Hoosier Riverwatch.” State of Indiana, n.d. https://www.in.gov/idem/riverwatch/files/volunteer_monitoring_manual_chap_5.pdf.