Wetlands: Monitoring Aquatic Invertebrates
Macroinvertebrates are useful indicators of wetland health for several reasons. As in streams, invertebrates found in wetlands integrate the entire spectrum of available aquatic wetland habitats and conditions. They are found in the sediment, in the water column, on and amongst the submerged and emergent vegetation. They are found in abundance in large and small, and permanent and seasonal wetlands.
Wetland macroinvertebrates are somewhat different from stream macroinvertebrates in their greater tolerance of low dissolved oxygen concentrations, but they are still sensitive to a variety of physical and chemical factors. Unnaturally high levels of nutrients, such as phosphorus, and chemicals, such as chloride, have been shown to have negative impacts on the invertebrate community. Unstable hydrology and a lack of invertebrate habitats can also have negative impacts.
MPCA staff evaluating invertebrate samples.This is a relatively new tool for monitoring wetland health, and Minnesota has been at the forefront of developing sampling protocols and analytical tools. In 1992 the MPCA began the process of developing an Index of Biological Integrity as a tool for monitoring wetland health using macroinvertebrates. In 1999, the process was refined for depressional wetlands in the North Central Hardwood Forest Ecoregion of Minnesota and is currently being refined for other areas of the state. It is possible that the same methodology could be applied for monitoring the health of lakes as well as other types of wetlands.
Hand-held dipnets are used to sample the invertebrate community in wetlands. Additionally, activity traps are used to collect the very fast swimming organisms, and those that are more active at night. Samples are picked in their entirety. Organisms are generally identified to genus.
Invertebrate community data and IBIs can be used for various wetland management needs and decisions, including:
- Condition monitoring (status and trends)
- Problem investigation monitoring
- Wetland mitigation effectiveness monitoring
- Permit issuance, and
- TMDL investigations, including listing, delisting, and effectiveness of implementation.
Reports
-
Status and Trends of Wetlands in Minnesota — Depressional Wetland Quality Baseline (wq-bwm1-06) 
Survey Design of Minnesota's Depressional Wetland Quality Assessment (November 2007)- Assessing the Quantity and Quality of Depressional Wetlands in the Redwood River Watershed Utilizing a Probabilistic Sampling Design (June 2006)
- Development and Validation of Indices of Biological Integrity (IBI) for Depressional Wetlands in the Temperate Prairies Ecoregion (April 2006)
- Defining Wetland Condition Assessment Processes (December 2004) For subsequent information regarding this process, see also 2008 Wetland Assessment Documentation.
- Indexes of Biological Integrity for Large Depressional Wetlands in Minnesota (May 2002)
Maps
Omernik Level II Ecoregions and MPCA Wetland Monitoring Sites
Searching for wetland invertebrates on a misty morning.
