Monitoring macroinvertebrates, or small aquatic insects and other creatures without backbones, is crucial for assessing the health of freshwater ecosystems and the quality of the water they inhabit. These organisms serve as bioindicators, meaning they can provide a snapshot of the overall health of the ecosystem, including water quality. By monitoring the types and abundance of macroinvertebrates in a water body, scientists and resource managers can detect changes in water quality that may be caused by pollution, habitat loss, or other environmental stressors. This information can then be used to inform decisions about water management, such as setting and enforcing water quality standards and developing strategies for protecting and restoring freshwater ecosystems. Overall, monitoring macroinvertebrates is an effective and important tool for maintaining and improving the health of our freshwater resources.
Thanks to Kevin Misner who coordinates a group of volunteers, several creeks in Montgomery County, MD are monitored regularly for water quality by assessing macroinvertebrates, measuring salinity, and sometimes phosphate and nitrate levels. One of the study sites is located on Riffle Ford Road ~ 1 mile downstream of a sewage processing plant.
We used a GaiaXus probe, submerged in the creek at ~ 50cm depth. A strong current necessitated tethering the probe and weighing it down with river rocks. We put the probe into “Buoy” mode and set the recording interval to 5 minutes. We did not expect significant changes over the few hours we were on-site and a single grab sample would have resulted in the same data. The Buoy Mode allows leaving the probe in the freshwater for up to 36h and recording changes during snow/rainstorms, a very important feature especially downstream of sewage plants.
The data from the probe showed relatively low salinity (TDS), in line with measurements taken with conventional “sticks”. Maryland has experienced an unseasonably warm Winter and while the absence of road salt in the creek is encouraging, the relatively high water temperature (11C) is concerning. Little precipitation resulted in a very clear stream with low turbidity (25NTU). Plotted below is the time course of TDS during our visit.
Overall, using the GaiaXus probe alongside in-depth ecosystem assessments is feasible, it is easy to deploy, use and recover and adds nearly no operational burden on the team but provides contextual data for the study of (in this case) macroinvertebrates.
Photos (c) Tim Mewes