July finds our wetland biologist, Heather Pankurst, visiting 18 coastal wetlands, monitoring water quality and collecting macroinvertebrate samples (bugs). The coastal wetlands are located along the shore of Lake Ontario and provide unique ecological functions including settlement and retention of sediments and contaminants, filtration of nutrients, and the provision of habitat for wildlife. They also provide recreational and educational opportunities, and protect shorelines from erosion. This makes the protection of these ecosystems especially important.
During the May to September growing season, water quality measurements are taken each month, and Heather and her assistant will record this data at a minimum of three sample sights (inlet, middle, outlet) per wetland. Examples of what is recorded are weather conditions (air temperature, wind direction and strength, cloud cover and rainfall within the last 48 hours); barrier beach condition (i.e., open or closed); general location within the marsh (e.g., inlet, middle, outlet); water depth, turbidity, temperature, conductivity and pH. Heather will also comment on any wildlife observations.
Macroinvertebrates or creatures that you can see without a microscope, are biological indicators in aquatic environments. Heather uses a sweep net method to collect the aquatic invertebrates that are found within the water column around emergent vegetation such as cattails. Once she has collected enough creatures into a bin, they move to the next location as a minimum of three wetland samples are required. Each bin is later subsampled where 150 individual invertebrates are collected into a vial of 70 per cent ethanol. The vials are sent to a lab for analysis and identification.
Water quality data for 2019 showed improvements overall in most coastal wetlands, likely due to increased water levels in Lake Ontario and subsequently these coastal wetlands. There does not appear to be any clear trends in the macroinvertebrate community in any of our wetlands; some years they meet the established goal and other years they do not. Consistently, the Westside Marsh in Bowmanville is the only wetland that meets the goal, which is referred to as the Index of Biological Integrity (IBI). To find out more about the water quality and macroinvertebrate populations in coastal wetlands in our watershed, check out Central Lake Ontario Conservation's Integrated Watershed Monitoring Program StoryMap.