Great Lakes coastlines support complex blends of habitats, such as wetlands, streams, estuaries, dunes, and more. Coastal wetland complexes are also junctions where nutrients coming from upland watersheds, including nitrogen and phosphorus, meet the Great Lakes.
Michigan Sea Grant Graduate Research Fellow Erin Eberhard from Michigan Technological University and her advisor, associate biology professor Amy Marcarelli, are investigating how nutrients move through coastal ecosystems where wetlands, streams, and lakes meet.
Coastal ecosystems, including wetlands, help manage water quality by acting as sponges. Wetlands absorb high levels of nutrients that run off from land, such as nitrogen or phosphorus, and prevent them from entering major bodies of water, such as lakes and rivers. Researchers from Michigan Technological University (Michigan Tech) are studying nutrient processes in this wetland near Peepsock Trail in Houghton, Michigan. Credit: Sarah Atkinson/Michigan Tech
In this photo, researchers Erin K. Eberhard and Amy M. Marcarelli from Michigan Tech are taking samples at 1 of 15 study locations in five areas around Lake Superior and Lake Huron. This wetland is located in Houghton, Michigan, along the portage canal that connects to Lake Superior. They are investigating areas where wetlands, lakes, and streams come together to better understand how different characteristics of this interface regulate the nitrogen cycle. Credit: Sarah Atkinson/Michigan Tech
Understanding how nutrients, particularly nitrogen, are cycled through these coastal ecosystems is important. High levels of nutrients can cause an overgrowth in algae, which can in turn reduce levels of dissolved oxygen in water bodies, reducing water quality and harming human and aquatic life. This research could help determine how and where extra nutrients may be removed as they enter the system. Credit: Sarah Atkinson/Michigan Tech
Each area of a coastal ecosystem has its own set of environmental characteristics that help facilitate complex biogeochemical cycling, such as nutrient cycling. In this photo, researchers Erin K. Eberhard and Amy M. Marcarelli are collecting a sediment core sample from a wetland mesocosm, or experimental water enclosure, that has been enriched with nitrogen and phosphorus to take back to the laboratory for analysis. Credit: Sarah Atkinson/Michigan Tech
Nitrogen fixation is the chemical processes by which nitrogen is made available to plants for growth; denitrification is the process by which nitrogen is removed from the water environment and released to the atmosphere. In streams and lakes, nitrogen fixation occurs primarily on macrophytes, which are aquatic plants (above). In wetlands, nitrogen fixation occurs primarily in sediment. In all three habitats, denitrification occurred exclusively in sediments. Understanding these processes better in these areas will help us protect large waterbodies such as lakes and rivers. Credit: Sarah Atkinson/Michigan Tech
Spatial patterns of environmental variables may drive the occurrence of nitrogen fixation and denitrification across wetland–stream–lake interfaces. In this image, the researchers have taken a sediment core taken from a wetland that clearly shows layers of sand, organic matter, and algae. Depending on the material and microbial community of each core, nutrients can be cycled differently across interfaces. Credit: Sarah Atkinson/Michigan Tech