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How does the upwelling affect global fisheries? Behind this is a stunning story!
In the depths of the vast ocean, there is a silent phenomenon happening, which is the uprising of the ocean.This wind-driven pushes denser, colder and nutrient-rich deep water to the sea.Whenever this stream of water comes out of the water, they replace the warm, usually nutrient-deficient surface water.These nutrient-rich ups not only drive growth in primary producers, but also have a profound impact on global fisheries.
"About 25% of global marine fish catches come from five upwelling areas, although these areas account for only 5% of the entire ocean area."
The deep water sources brought by the upstream are rich in nitrates, phosphates and silicone acids, which are nutrients formed by the decomposition of the settled organic matter.These nutrients are absorbed by phytoplankton, which are converted into organic compounds and form a complete food chain through photosynthesis.When phytoplankton flourishes, the entire ocean’s food chain will benefit from it, and various fish, seabirds and marine mammals will receive a continuous supply of food.
Operational mechanism of upstream
The causes of upflow are mainly caused by three elements: wind, Coriolis and Eckman transportation.When the wind blows on the sea surface, the water surface will change due to the action of the wind, further triggering interaction between the water layers.As water moves, water molecules move at an angle of about 90 degrees, which is the influence of Coriolis forces.Meanwhile, Eckman transport causes the water layer to move at an angle of about 45 degrees in the direction of the wind, causing the continuous flow of water to expand outward, thereby forming an upward flow.
"If the water flow is dispersed, the reduction in the upper water will trigger the rise of deep water to replenish the lost water."
Different types of upstream
According to different marine geographical environments, upstreams can be divided into various types, the most well-known ones include coastal upstreams, wide-area wind-driven inland sea upstreams, and upstreams related to eddy currents.
Among them, coastal upwelling has an important relationship with human activities. It not only supports the world's richest fisheries, but also has a profound impact on local ecosystems.In the northern hemisphere, when the wind direction is parallel to the coast, the surface water flow will shift to the right, and in the southern hemisphere it will shift to the left, allowing cold water to flow to the sea.
Climate Effects
Coastal upwelling also plays an important role in affecting the local climate.As heavy cold water rises, the sea surface temperature drops, causing cooling of its upper air.This process not only forms thick sea fog, but may also affect the formation of clouds, thereby changing the distribution of rainfall and making some areas drier.
The impact of upflow on fisheries
The health of global fisheries is closely related to upward flows.Due to the extremely high productivity of these areas, many commercial fisheries focus on these fish-rich waters.However, overfishing has also become a major threat.
"In an upstream ecosystem, a significant reduction in any species will affect the entire ecological chain."
For example, if a certain fish is overfished, this may lead to a shortage of food for other predators dependent on the species, which in turn puts the entire ecosystem at risk of collapse.In addition, climate change can also significantly affect the intensity and frequency of the upstream.During some extreme climate events such as El Niño, a weakening of upwelling can relieve fishes of access to nutrients and put the entire ecosystem at risk.
Therefore, protecting upstreams and their associated ecosystems is of great significance not only to fishing communities, but also to global food security and biodiversity.How can we balance economic interests with ecological protection in the future to ensure that this important ecosystem is not destroyed?
