In the Great Lakes, communities of plants and animals vary depending on where and when you look. They are dispersed up and down and all around in the water, making it tricky to collect them for research studies. To answer questions about these organisms and how they interact in the Great Lakes ecosystem, scientists from NOAA’s Great Lakes Environmental Research Laboratory (GLERL) and CIGLR (Cooperative Institute for Great Lakes Research) are using a new high tech sampling tool called a MOCNESS (Multiple Opening and Closing Net and Environmental Sensing System).

GLERL’s MOCNESS is the first of its kind to be used in a freshwater system. Scientists are hopeful that this technology will lead to new discoveries about the Great Lake ecosystem, such as where plankton (microscopic aquatic plants and animals) live and what causes their distributions to change over space and time. The MOCNESS will also help scientists learn more about predator-prey interactions that involve zooplankton (microscopic aquatic animals), phytoplankton (microscopic aquatic plants), and larval and juvenile fishes.

Keeping track of changes in plant and animal communities in the Great Lakes over time is important, especially with changes in climate, the onslaught of invasive species, and land use practices causing increased nutrient runoff into the lakes.

The MOCNESS is a big improvement over the traditional single mesh sized sample collection nets. The sampling system provided by this new tool has a series of nets of different mesh sizes to collect different sized organisms (see a few examples in the gallery below). The operator can remotely open and close these nets, much like an accordion. At the heart of the system is a set of sensors that measure depth, temperature, oxygen, light levels, and the green pigment found in algae, Chlorophyll-a. Because this data can be viewed in real time on the vessel, the operator can better determine what is going on below the water surface and choose where and when to sample different sized organisms.

Here are some of the key questions that the scientists hope to answer using this advanced technology:

• How do plankton and larval fish respond to environmental gradients (water temperature, dissolved oxygen, UV radiation) over the course of the day, season, and across years?
• What are the major causes for changing distributions of the animals across space and over time (long-term, seasonal, 24-hour cycle)?
• How do these changes in affect reproduction, survival, and growth of individuals and their communities?

The MOCNESS has been tested in the waters of lakes Michigan and Huron for the past three years. The team, led by Dr. Ed Rutherford, is supporting GLERL’s long term study of the Great Lakes food webs and fisheries. “The MOCNESS will enhance the ability of our scientists to more effectively observe the dynamics of Great Lakes ecosystem over space and time—a critical research investment that will pay off for years to come,” says Rutherford.

This year, the team is actively processing samples that were collected in the spring and will continue to collect more samples through the fall. The MOCNESS will support ongoing ecological research on the Great Lakes and the results will be shared with others around the region who are working to make decisions about how to manage Great Lakes fisheries and other water resources.

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