Upwelling
The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rich waters to the surface. There are at least five types of upwelling: coastal upwelling, large-scale wind-driven upwelling in the ocean interior, upwelling associated with eddies, topographically-associated upwelling, and broad-diffusive upwelling in the ocean interior.
Hudson River
The Hudson River estuary is the site of wetlands from New York City all the way up to Troy. It has one of the largest concentrations of freshwater wetlands in the Northeast. Even though the river can be considered brackish further south, 80 percent of the wetlands are outside the influence of the saltwater coming from the Atlantic Ocean. Currently, the river has about acres of wetlands, and rising sea levels due to climate change are expected to lead to an expansion of that area. Wetlands are expected to migrate upland as sea level (and thus the level of the river) rises. This is different from the rest of the world, where rising sea levels usually leads to a reduction in wetland areas. The expansion of the wetlands are expected to provide more habitat to the fish and birds of the region.