April 23rd, 2019
Between each spring and fall, a layer of cold ocean water travels along the seafloor along the length of the Mid-Atlantic Bight (MAB), a region that extends from Cape Cod, MA to Cape Hatteras, NC. This phenomenon is called the Mid-Atlantic Bight Cold Pool. The Cold Pool forms at the start of spring when there is less mixing within the water column, a greater input of less dense freshwater into marine environments, and more intense sunlight at the sea surface. These factors create a stratified water column. This means that cooler, denser water exists at greater depths, and warmer, less dense water exists at shallower depths in distinct layers.
The MAB seasonal cycle expresses one of the greatest changes in sea temperature throughout the year, compared to other regions around the world. This cycle is responsible for the formation of the Cold Pool, which can only persist if a stratified water column continues to exist above it. The Cold Pool is more defined throughout spring and summer when surface waters begin heating and freshwater enters the MAB. As summer transitions into fall, the water column becomes mixed, and the Cold Pool begins to disappear.
The structure of the MAB food web largely depends on the seasonal patterns of the Cold Pool. Its richness in nutrients supports the growth of phytoplankton at the base of the food web. The success of fish and other larger marine organisms within the MAB depends on the success of these phytoplankton. The migratory patterns, reproductive behaviors, and community structures of certain species of fish also depend on the Cold Pool. For instance, Yellowtail Flounder use scallop beds at bottom sediments as nursery grounds. The resulting population and geographical distributions of juvenile flounders is dependent on variations in temperature and stratification of the Cold Pool.
By accessing MARACOOS data, researchers can monitor the Cold Pool. Using satellite imagery, high-frequency radars, and oceanic gliders, MARACOOS partners create 3-D models to predict the physics of the MAB. By monitoring the Cold Pool, researchers understand its seasonal impact on the marine ecosystems in the Mid-Atlantic Bight.
Story By: Jessica Ganim