Deep Sea Currents
Upwelling zones
In some parts of the world, the prevailing wind drives the surface water of the ocean away from the shore. This forces deeper water to well up from below to take its place. The water contains chemicals and minerals that fuel the growth of plankton, providing food for fish. Similar upwelling events create food rich zones over submerged seamounts. Deep ocean water is full of rich minerals and nutrients that are carried by the deep ocean currents in a unique pattern. The submerged extinct volcanoes are covered with nutrient-rich sediments. Ocean currents flowing over the seamounts pick up the nutrients and carry them to the surface, creating local upwelling zones. These isolated hotspots often have their unique wildlife.
If upwelling stops, it has a big impact on ocean life. Sometimes the trade winds over the Pacific weaken, allowing warm surface water to flow east and smother an upwelling zone off tropical South America. known as the El Nino effect, this stops the plankton growth, so the fish vanish - a disaster for fish-eating birds such as the blue footed boobies.
Article - Upwelling
Deep-water Currents
Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation. In cold regions, such as the North Atlantic Ocean, ocean water loses heat to the atmosphere and becomes cold and dense. When ocean water freezes, forming sea ice, salt is left behind causing surrounding seawater to become saltier and denser. Dense-cold-salty water sinks to the ocean bottom. Surface water flows in to replace the sinking water, which in turn becomes cold and salty enough to sink. This "starts" the global conveyor belt, a connected system of deep and surface currents that circulate around the globe on a 1000 year time span. This global set of ocean currents is a critical part of Earth’s climate system as well as the ocean nutrient and carbon dioxide cycles.
Article - Ocean currents
Together the deep-water currents and the surface currents carry ocean water all around the world.
The global conveyor carries the ocean water around the world along with dissolved oxygen and nutrients that are vital to oceanic life. A lot of these nutrients are scoured from the ocean floor by the deep-water currents, which eventually carry them up to the sunlit surface. Here, they nourish the plankton that feed animals like humpback whales.
I personally really liked researching this area. It was important to look into this part as a lot of life around seamounts exist because of deep-water currents as they bring all the nutrition and dissolved oxygen from across the oceans. Deep-water currents collide with seamounts and due to the occurrence of upwelling, the nutrition spreads all around the seamount, making it a hot-spot for marine life to flourish.
