Search results
Results from the WOW.Com Content Network
The coastal upwelling zones diminish as well since they are wind driven systems, and the wind is no longer a very strong driving force in these areas. As a result, global upwelling drastically decreases, causing a decrease in productivity as the waters are no longer receiving nutrient-rich water.
The Great South Australian Coastal Upwelling System is a seasonal upwelling system in the eastern Great Australian Bight, extending from Ceduna, South Australia, to Portland, Victoria, over a distance of about 800 kilometres (500 mi). Upwelling events occur in the austral summer (from November to May) when seasonal winds blow from the southeast.
It is also one of six major coastal currents affiliated with strong upwelling zones, the others being the Humboldt Current, the Canary Current, the Benguela Current, the Oyashio Current, and the Somali Current. The California Current is part of the North Pacific Gyre, a large swirling current that occupies the northern basin of the Pacific.
There are two main upwelling zones in the system that vary in intensity throughout the year; The Western Upwelling Zone (WUZ); And the Eastern Upwelling Zone; (EUZ). The western the WUZ is situated between 74-71°W and generates mainly seasonal upwelling and high offshore transport due to intense winds.
While upwelling promotes abundant primary and secondary production in the upper parts of the water column and near the coast, deeper waters with limited oxygen exchange create hypoxic areas called oxygen minimum zones at the coastal shelf and upper coastal slope. The Benguela oxygen minimum zone starts around a depth of 100 m and is a few ...
Natural causes include coastal upwelling, changes in wind, and water circulation patterns. Other environmental factors that determine the occurrence or intensity of a dead zone include long water residence times, high temperatures, and high levels of sunlight penetration through the water column.
A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Worldwide there is about 620,000 kilometres (390,000 mi) of coastline. Coastal habitats extend to the margins of the continental shelves, occupying about 7 percent of the ocean surface area.
Near coastal zones, winds blowing parallel to the coast can generate wind-driven currents that create an Ekman transport away from the coast. [21] This moves the upper water mass away from the coast and leads to upwelling of cooler water from depth, [9] also termed coastal upwelling.