What Is The Impact Of Coastal Upwelling On Biological Productivity?

Upwelling along oceanic eastern boundaries has been a topic of interest due to its profound effects on ocean productivity and associated biological and socioeconomic factors. A high-resolution coupled physical–biological model was developed to assess coastal upwelling in the Central Caribbean Sea (CCS) region, which is characterized by its proximity to land, nutrient sources, shallow seafloor interception, and propensity for coastal upwelling.

Coastal upwelling is an important aspect of fisheries management due to its impact on biological productivity. In eastern boundary current systems (EBCSs), coastal upwelling fuels high productivity, supporting vast and diverse marine populations. Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a nutrient-rich flow that brings cold, nutrient-rich waters to the surface, encouraging seaweed growth and supporting phytoplankton blooms. These phytoplankton blooms form the ultimate energy base for large animal populations higher in the food chain, including fish, marine mammals, and seabirds.

Productivity in coastal ecosystems is often distinct from that of the open ocean. Changes in upwelling are only one driving factor that regulates marine ecosystems. Changes in nutrient concentrations and ratios have also been found to be crucial for productivity. Waves in the interior of the ocean play a crucial role for productivity, causing cold, nutrient-rich water to move up and down on seasonal time. This results in a weaker offshore export of nutrients and organic matter, increasing local nutrient recycling and reducing spatial variability.

Coastal upwelling leads to high biological productivity because it brings cold, nutrient-rich water to the surface, where phytoplankton reside.

Why is the open ocean so less biologically productive than the coastal zone?

The presence of a thin buoyant surface layer and other processes in the ocean contribute to nutrient limitation, limiting ocean productivity. The export of organic matter to depth depletes the surface ocean of nutrients, causing them to accumulate in deep waters where there is no light available for photosynthesis. Ocean circulation can only slowly reintroduce dissolved nutrients to the euphotic zone, driving nutrients out of sunlit, buoyant surface waters.

This limits ocean productivity. Phytoplankton growth limitation is traditionally interpreted in the context of Liebig’s Law of the Minimum, which states that plant growth will be as great as allowed by the least available resource, the “limiting nutrient”. However, interactions among nutrients and between nutrients and light can also control productivity. In polar regions, higher iron supply can increase the efficiency of phytoplankton in capturing light energy. Generally, phytoplankton should seek co-limitation by all the chemicals they require, including trace metal nutrients.

What is the biological productivity of the ocean?

Ocean productivity is primarily the production of organic matter by phytoplankton, which are photoautotrophs that convert inorganic to organic carbon. These plants supply this organic carbon to diverse heterotrophs, such as bacteria, zooplankton, nekton, and benthos. Ocean productivity is characterized by various nested cycles of carbon, including gross primary production (GPP), net primary production (NPP), secondary production (SP), and net ecosystem production (NEP).

GPP refers to the total rate of organic carbon production by autotrophs, while respiration refers to the energy-yielding oxidation of organic carbon back to carbon dioxide. Net primary production (NPP) is GPP minus the autotrophs’ own rate of respiration, indicating the rate at which the full metabolism of phytoplankton produces biomass. Secondary production (SP) typically refers to the growth rate of heterotrophic biomass, with only a small fraction of organic matter used for growth. Fisheries rely on SP and depend on both NPP and the efficiency of organic matter transfer up the foodweb.

Net ecosystem production (NEP) is GPP minus respiration by all organisms in the ecosystem, with the value depending on the boundaries defined for the ecosystem. For example, NEP for the entire ocean is roughly equivalent to the slow burial of organic matter in sediments minus the rate of organic matter entering from the continents.

Productivity in the surface ocean is connected to nutrient cycling, with the blue cycle representing net ecosystem production (NEP), the red cycle representing the fate of organic matter produced in the surface ocean, and the green cycle representing internal respiration of phytoplankton. These nested cycles result in gross primary production (GPP) representing gross photosynthesis and net primary production (NPP) representing phytoplankton biomass production, which forms the basis of the food web. While new nutrient supply and export production are ultimately linked by mass balance, there may be imbalances on small scales of space and time, allowing for brief accumulations of biomass.

How does upwelling affect biological productivity?

Upwelling is defined as the phenomenon whereby colder, nutrient-rich waters rise to the surface, where they fertilize the surrounding waters, leading to high biological productivity and the formation of ideal fishing grounds.

How does the upwelling of water enhance the primary productivity in coastal ecosystems?

Upwelling has diverse ecological effects, with two significant impacts. Firstly, it brings cold, nutrient-rich waters to the surface, encouraging seaweed growth and supporting phytoplankton blooms. These blooms provide energy for large animal populations, including fish, marine mammals, and seabirds. Coastal upwelling ecosystems, like the U. S. west coast, are highly productive and support significant fisheries. Despite accounting for only one percent of the ocean surface, they contribute around 50% of the world’s fisheries landings.

Secondly, upwelling affects animal movement. Most marine fish and invertebrates produce microscopic larvae that drift in the water as they develop. Upwelling that moves surface water offshore can potentially move drifting larvae long distances away from their natural habitat, reducing their chances of survival. Upwelling can infuse coastal waters with critical nutrients, but it can also rob coastal ecosystems of offspring needed to replenish populations.

What causes upwelling and what is a benefit of upwelling?

Upwelling is an oceanographic phenomenon that involves the movement of dense, cooler, and nutrient-rich water from deep water towards the ocean surface, replacing warmer, nutrient-depleted surface water. This water stimulates the growth and reproduction of primary producers like phytoplankton, which can be identified by cool sea surface temperatures (SST) and high concentrations of chlorophyll a. The increased availability of nutrients in upwelling regions results in high levels of primary production and fishery production, with approximately 25 of the total global marine fish catches coming from five upwellings, which occupy only 5 of the total ocean area.

The three main drivers that cause upwelling are wind, Coriolis effect, and Ekman transport. Wind blows across the sea surface at a specific direction, causing a wind-water interaction. The water moves a net of 90 degrees from the wind’s direction due to Coriolis forces and Ekman transport. This results in a spiral of water moving down the water column, with Coriolis forces dictating the water’s movement. If the net movement of water is divergent, upwelling of deep water occurs to replace lost water.

What is coastal upwelling and explain the significance of the coast?

Coastal upwelling is a process where strong winds push surface waters offshore, causing water from ocean depths to rise to the surface. This process is closely linked to the climate and economy of California, contributing to its foggy weather, robust fisheries, and delicious wine. Upwelling intensity along the west coast of North America varies due to environmental and oceanographic conditions, with northern California experiencing the most intense upwelling. The California Current, encapsulating Bodega Bay, is one of four major upwelling-driven ecosystems globally, offering unique research opportunities.

Coastal upwelling is important because bottom water, which is colder due to lack of sunlight, more nutrient-rich due to decomposition of settling organic matter, and more acidic and less oxygenated, is pushed offshore and replaced by surface water. This nutrient-rich water fuels an ecosystem driven by high primary production when exposed to sunlight.

How can upwelling affect the nutrient and oxygen?

Downwelling is a process where surface waters move back towards the shore, driving bottom waters away from the coast. This process occurs when upwelling periods alternate with periods of strong downwelling, preventing low-oxygen waters from accumulating near the seafloor. Strong upwelling without downwelling can accumulate low-oxygen waters, causing a dead zone. Repeated upwelling brings low-oxygen waters closer to shore and more nutrients to the lighted zone, leading to phytoplankton blooms sinking and decaying, further depleting oxygen near the sea floor.

Repetitions of these events cause the mass of low-oxygen water near the sea floor to become thicker and lower in oxygen. Changes in the strength and pattern of upwelling winds and the oxygen and nutrient content of deep offshore waters impact the likelihood and severity of hypoxia events. The normal upwelling period runs from April to September, with October to March dominated by downwelling-favorable coastal winds. Low-oxygen conditions are normal in deep, offshore waters, but the occurrence of low-oxygen water close to shore is highly unusual and had not been reported prior to 2002.

What would explain the poor condition for biological productivity in the open tropical ocean?

The low biological productivity observed in the open ocean can be attributed to the scarcity of nutrients, which are essential for the growth and reproduction of producers. The higher levels of biological productivity observed in coastal areas, which receive surface runoff from land, can be attributed to the enhanced nutrient levels that result from this process.

What are the effects of coastal upwelling?

Upwelling has diverse ecological effects, with two significant impacts. Firstly, it brings cold, nutrient-rich waters to the surface, encouraging seaweed growth and supporting phytoplankton blooms. These blooms provide energy for large animal populations, including fish, marine mammals, and seabirds. Coastal upwelling ecosystems, like the U. S. west coast, are highly productive and support significant fisheries. Despite accounting for only one percent of the ocean surface, they contribute around 50% of the world’s fisheries landings.

Secondly, upwelling affects animal movement. Most marine fish and invertebrates produce microscopic larvae that drift in the water as they develop. Upwelling that moves surface water offshore can potentially move drifting larvae long distances away from their natural habitat, reducing their chances of survival. Upwelling can infuse coastal waters with critical nutrients, but it can also rob coastal ecosystems of offspring needed to replenish populations.

Why does upwelling encourage productivity?

Upwelling, a process where deeper water rises to the surface, is rich in nutrients that fertilize surface waters, encouraging the growth of plant life, including phytoplankton. These phytoplankton serve as the energy base for large animal populations, providing food for fish, marine mammals, seabirds, and other creatures. Coastal upwelling ecosystems, such as along the US west coast, are highly productive and support significant fisheries.

Although only accounting for 1% of the ocean surface, they contribute around 50% of the world’s fisheries landings. Upwelling also plays a crucial role in the movement of marine animals, as most fish and invertebrates produce microscopic larvae that can drift in the water for weeks or months.

What is the biological importance of upwelling in coastal regions?

Upwelling plays a crucial role in biodiversity and productivity, as it supports the growth of seaweed and plankton, which provide food for fish, marine mammals, and birds. Coastal upwelling regions, which cover only 1% of the world’s oceans, contribute to about 50% of the fish harvest brought back to shore by the world’s fisheries. However, El Niño, a weather phenomenon that occurs every three to seven years, significantly changes the Pacific Ocean’s climate, leading to a deeper transition zone between warm surface water and cold deep water.

This reduces nutrient-rich water, leading to a lower fish population and smaller fish crop. Additionally, upwelling affects the movement of animal life in the area, as tiny larvae can drift in ocean currents for extended periods, and a strong upwelling event can wash them far offshore, endangering their survival.