Overview

Zooplankton are heterotrophic animals (prey on other plants and animals) found in the plankton, and are critical components to the functioning of marine ecosystems, serving as a link between lower trophic level production and upper trophic level consumption (Johnson et al. 2011).

Overview

Marine ecosystem productivity depends on the amount of primary production by phytoplankton, unicellular photosynthetic algae and cyanobacteria suspended in the water column that form the base of the marine food web. Measurements of the primary photosynthetic pigment, chlorophyll a (CHL), are commonly used as a proxy for phytoplankton biomass. Near-surface CHL can be measured remotely by ocean color sensors on satellites and then incorporated into integrated models to estimate primary production (PP).

Salinity

There is strong geographic variation in salinities across the northwest Atlantic. Input from fresh, cold Scotian shelf water and warmer, saltier slope water flowing through the Northeast Channel at depth result in three distinct water masses in Gulf of Maine. The saltiest and deepest is Maine Bottom Water, while the overlying Maine Intermediate Waters and Maine Surface Waters are fresher and warmer (Townsend et al. 2004).

Overview

Commercial fisheries in New England and the Mid-Atlantic have storied histories, which have been forced to come to terms with the realities of overfishing and stock collapse in the past century (Fogarty et al., 1998). Interestingly, the collapse of traditional groundfish and pelagic fisheries has coincided with a surge in the value of invertebrates, to the extent that the system is grossing the highest revenue since at least the 1970’s.

Upwelling is the upward movement of colder, nutrient-rich bottom water driven by the displacement of the surface layer. In the Mid-Atlantic, input of nutrients to the surface layer drives phytoplankton blooms, and results in high concentrations of particulate organic matter in the water column, where it is broken down through microbial respiration. Recurrent hypoxia regimes along the New Jersey coast are thought to be driven by this process (Glenn et al., 2014).

Gulf Stream & Warm Slope Water

The Gulf Stream is a major component of ocean circulation in the Northwest Atlantic. Propagation of Gulf Stream meanders and resulting eddies can create favorable conditions for high primary productivity throughout the Mid-Atlantic Bight and northwards to the Georges Bank shelf break (Townsend et al., 2006, Ryan et al., 1999).

Sea-surface temperature

Sea-surface temperatures (SST) in the U.S. Northeast Shelf Large Marine Ecosystem (NES-LME) are increasing at a faster rate than the majority of the world’s oceans, and these changes will undoubtedly affect the economy and ecology of the region over the next century.

Air temperatures in the Northeast US are warming more slowly than sea-surface temperatures (SST), with regional long-term trends in air temperature increasing with latitude. Air-sea heat exchange is the dominant factor driving interannual variability of Northeast US SST in the spring (Chen 2018). Summer SSTs are not related to air temperature and are more strongly associated with ocean dynamics.

Climate change and variability occur due to both human influences and natural processes on a global scale. In the Northeast Large Marine Ecosystem (NE-LME), large-scale climate oscillations are reflected in the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO). The position of the Gulf Stream and indices like the Atlantic Meridional Overturning Circulation (AMOC) also affect regional climate and oceanography. Greenhouse gas emissions are the driving component of human contribution to climate change.