Why do subtropical gyres have low biological productivity? The Ekman pumping process takes some of the water out of the gyre system and puts it into the ocean. The low nutrient levels often seen in subtropical gyres can be attributed to the vertical flow carrying the needed resources.
What is a subtropical gyre?
subtropical gyre, an area of anticyclonic ocean circulation that sits beneath a region of subtropical high pressure. The movement of ocean water within the Ekman layer of these gyres forces surface water to sink, giving rise to the subtropical convergence near 20°–30° latitude. The centres of subtropical gyres are shifted to the west.
What is the name of the high productivity gyre?
In the north Atlantic, the gyre is called the Sargasso Sea. Pacific: Relatively high productivity, but still low in gyres. What causes these high productivity areas?
Why is the tropics warmer than the subtropics?
Moreover, across most of the ocean's area, including the tropics, subtropics, and the temperate zone, the absorption of sunlight causes surface water to be much warmer than the underlying deep ocean, the latter being filled with water that sank from the surface in the high latitudes.
What are the Rings of low productivity water?
There are rings (or lenses) of low productivity water north of the Gulf Stream. This is water from the Sargasso Sea (tropical, gyre water) trapped in a meander (looping curve) of the Gulf Stream. They form when a meander breaks off, trapping water from the OPPOSITE side of the Gulf Stream.
What is subtropical gyre?
How do subtropical gyres move?
Which direction do subtropical gyres shift?
Which current is most similar to the Gulf Stream?
Where are warm eddies found?
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Why do gyres have low productivity?
According to the textbooks, winds push surface waters into the center of the gyres and then downward, taking nutrients away from the sunlit zone and therefore preventing phytoplankton from thriving.
Do subtropical gyres have high productivity?
Earth's five subtropical gyres—large current systems north and south of the tropics—encircle much of the surface water of the open ocean. Known for their low biological activity, these “desert” waters nonetheless contribute significantly to marine productivity because of their vast size.
Which ocean zone has the lowest productivity?
the marine zone with the lowest rate of photosynthesis would likely be the B) abyssal zone as this zone is furthest from the surface and therefore receives the least sunlight. Since sunlight is required for photosynthesis the abyssal zone has the least potential for primary productivity.
Why is productivity low in tropical regions?
Biological productivity is low in tropical regions because the strong thermocline prevents the mixing of waters and movement of nutrients. Polar regions have low biological production because of the lack of sunlight.
What are subtropical ocean gyres?
Subtropical gyres circle areas beneath regions of high atmospheric pressure. These are placid ocean areas thousands of kilometers in diameter. Unlike coastal zones, these central regions are relatively stable. The ocean water generally stays in one place while the currents of the gyre circulate around it.
When compared to the sub tropical gyres in the Northern Hemisphere what is the direction of the sub tropical gyres in the Southern Hemisphere?
Five permanent subtropical gyres can be found in the major ocean basins—two each in the Atlantic and Pacific Oceans and one in the Indian Ocean—turning clockwise in the Northern Hemisphere and counterclockwise in the Southern.
What limits productivity in tropical oceans?
Answer and Explanation: Primary productivity in tropical oceans is limited by the amount of nutrients available. Tropical oceans have plenty of sunlight in the upper regions, but the areas that have a lot of sunlight are surprisingly poor in nutrients.
What factors limit productivity in the ocean?
These factors include the availability of essential inorganic nutrients, particularly nitrogen and phosphorus; water temperature; and the turbidity of the water. Open oceans have relatively low primary productivity because of low levels of the essential nutrients nitrogen and phosphorus.
Why is primary productivity high in some ocean areas and low in others?
The proximity to land and its nutrient sources, the interception of sinking organic matter by the shallow seafloor, and the propensity for coastal upwelling all result in highly productive ecosystems.
Why tropical water is unproductive?
Why are tropical waters highly unproductive? Algae and other plants are able to photosynthesize to produce organic material from inorganic nutrients. And the organic material forms the building block for all animals higher up in the food chain.
Why do polar waters have a lower productivity than temperate waters?
In polar oceans, the productivity is high all year round, especially during summer. This is because of the absence of thermocline, as the water is uniformly cold throughout the ocean. However, productivity is low because of the lack of sunlight during winters.
Which ecosystem has the lowest average primary productivity?
The highest net primary productivity in terrestrial environments occurs in swamps and marshes and tropical rainforests; the lowest occurs in deserts.
What 3 ecosystems have the lowest productivity?
Deserts, tundra, and the deep ocean are the least productive ecosystems, typically having an energy fixation of less than 0.5 × 103 kilocalories per square meter per year (thousands of kcal/m2/yr; it takes one calorie to raise the temperature of one gram of water by 34°F [1°C] under standard conditions, and there are ...
What 3 ecosystems have the highest productivity?
The highest net primary productivity in terrestrial environments occurs in swamps and marshes and tropical rainforests; the lowest occurs in deserts.
Which aquatic region has the highest productivity?
coral reefsThe most productive aquatic ecosystem is the benthic area of a body of water. The benthic area is the lowest ecological level of a body of water. The productive parts of these regions are coral reefs.
What zone of the ocean has the lowest temperatures?
The temperature never fluctuates far from a chilling 39°F (4°C). The pressure in the bathypelagic zone is extreme and at depths of 13,100 feet (4,000 meters), reaches over 5850 pounds per square inch! Yet, sperm whales can dive down to this level in search of food.
South Atlantic Gyre - Wikipedia
The South Atlantic Gyre is the subtropical gyre in the south Atlantic Ocean.In the southern portion of the gyre, northwesterly (or southeastward-flowing) winds drive eastward-flowing currents that are difficult to distinguish from the northern boundary of the Antarctic Circumpolar Current. Like other oceanic gyres, it collects vast amounts of floating debris as a garbage patch.
Meridional changes in the South Atlantic Subtropical Gyre during ...
Subtropical ocean gyres play a key role in modulating the global climate system redistributing energy between low and high latitudes. A poleward displacement of the subtropical gyres has been ...
On the recirculation of the subtropical gyre
1518 J. MARSHALL and G. NURSER 60*N 40" 20" ,O' Figure 1. Warm water (>17"C) circulation diagram of Worthington (1976, Fig. 42).The solid segments of section lines indicate the location of a strong continuous potential vorticity minimum layer near a = 26.5 mg cm-3, and therefore the main recirculation of eighteen-degree water. In this study the mechanism responsible for the gyre ...
How do winds affect phytoplankton?
According to the textbooks, winds push surface waters into the center of the gyres and then downward, taking nutrients away from the sunlit zone and therefore preventing phytoplankton from thriving.
What would Doddridge like to do in the future?
In the future, Doddridge would like to carry out further experiments using more complex models, to gain further insights into the way in which nutrients are fed into and recycled within subtropical gyres.
What is the role of the nutrient poor upper ocean waters in the ocean?
The nutrient-poor upper ocean waters of the subtropical gyre play globally important roles in ocean carbon uptake, with biological processes mediating a large fraction of this carbon uptake, but the processes supplying nutrients required to support net biological production in these ecosystems remains unclear, according to Matthew Church at the University of Montana, who was not involved in the research.
What is the name of the layer of water that is not included in the ocean model?
Beneath this layer of mode water is the abyss, which was not included in the model.
Does thicker mode water increase phytoplankton growth?
When the researchers tested the results of the model using data from satellites, autonomous robots, and ships, they found that it supported their findings, suggesting that thicker mode water does indeed enhance phytoplankton growth within subtropical gyres.
Does eddy pumping cause plateaus?
However, the effect of this eddy pumping began to plateau at higher levels. The more the researchers increased the eddy pumping mechanism, the smaller the increase in nutrient concentration became.
Do nutrients go back to the surface?
While the nutrients remain in the homogenous layer, it does not take much energy for them to be mixed back up to the surface, Doddridge says. But if they quickly drop below it into the abyss — because the homogenous layer is thin, for example — the nutrients are essentially cut off from the surface water above, he says.
How does the existence of a thin buoyant surface layer affect ocean productivity?
At the same time, the existence of a thin buoyant surface layer conspires with other processes to impose nutrient limitation on ocean productivity. The export of organic matter to depth depletes the surface ocean of nutrients, causing the nutrients to accumulate in deep waters where there is no light available for photosynthesis (Figure 2). Because of the density difference between surface water and the deep sea across most of the ocean, ocean circulation can only very slowly reintroduce dissolved nutrients to the euphotic zone. By driving nutrients out of the sunlit, buoyant surface waters, ocean productivity effectively limits itself.
How is coastal ecosystem productive?
Furthermore, sinking organic matter isintercepted by the seabed, where it supports thriving benthic faunal communities, in the process being recycled back to dissolved nutrients that are then immediately available for primary production. The proximity to land and its nutrient sources, the interception of sinking organic matter by the shallow seafloor, and the propensity for coastal upwelling all result in highly productive ecosystems. Here, we mainly address the productivity of the vast open ocean; nevertheless, many of the same concepts, albeit in modified form, apply to coastal systems.
What is the relationship between GPP and respiration?
"Gross primary production" ( 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; it is thus the rate at which the full metabolism of phytoplankton produces biomass. " Secondary production " ( SP) typically refers to the growth rate of heterotrophic biomass. Only a small fraction of the organic matter ingested by heterotrophic organisms is used to grow, the majority being respired back to dissolved inorganic carbon and nutrients that can be reused by autotrophs. Therefore, SP in the ocean is small in comparison to NPP. Fisheries rely on SP; thus they depend on both NPP and the efficiency with which organic matter is transferred up the foodweb (i.e., the SP / NPP ratio). "Net ecosystem production" ( NEP) is GPP minus the respiration by all organisms in the ecosystem. The value of NEP depends on the boundaries defined for the ecosystem. If one considers the sunlit surface ocean down to the 1% light level (the " euphotic zone ") over the course of an entire year, then NEP is equivalent to the particulate organic carbon sinking into the dark ocean interior plus the dissolved organic carbon being circulated out of the euphotic zone. In this case, NEP is also often referred to as " export production " (or "new production" (Dugdale & Goering 1967), as discussed below). In contrast, the NEP for the entire ocean, including its shallow sediments, is roughly equivalent to the slow burial of organic matter in the sediments minus the rate of organic matter entering from the continents.
What is Ocean Productivity?
Ocean productivity largely refers to the production of organic matter by " phytoplankton ," plants suspended in the ocean, most of which are single-celled. Phytoplankton are " photoautotrophs ," harvesting light to convert inorganic to organic carbon, and they supply this organic carbon to diverse " heterotrophs ," organisms that obtain their energy solely from the respiration of organic matter. Open ocean heterotrophs include bacteria as well as more complex single- and multi-celled " zooplankton " (floating animals), " nekton " (swimming organisms, including fish and marine mammals), and the " benthos " (the seafloor community of organisms).
Which end of the spectrum has the highest productivity?
Red end of spectrum is highest productivity, blue/violet end is lowest. The overall pattern with latitude is clearly visible: low productivity in the tropics and subtropics, probably due to nutrient limitation brought about by strong, year-round thermocline and pycnocline.
Why are tropical waters productive?
Inshore tropical waters have a productivity as much as 10 times higher than offshore because of high nutrients and light. 2. Upwellingzones bring nutrient-rich deep water to the surface, fueling primary productivity. Three major mechanisms: Coastal upwelling, equatorial upwelling, island mass effects.
What happens to anchovies during El Nino?
During El Nino episodes, winds switch to W, N-ward current slows, warm counter current brings warm water from the equator, and upwelling ceases. Anchovy seek cooler, water deeper, and predators can't get them. During the 1972 El Nino, anchovy fish catch went from 20 to 2 million metric tons.
How does island mass affect coral reefs?
Island Mass effects: As currents encounter islands, deeper nutrient rich water is forced toward the surface. This helps increase productivity to coral reefs. The shows the coast of Australia, and the Great Barrier Reef shows up as high productivity specks to the east.
What percentage of oceanic productivity is in the shelf?
Shelf areas cover 15% of ocean area, but 50% of oceanic primary productivity. --Nutrients recycle from bottom in shallow, well-mixed shelf waters. --Nutrients run off from land, a major reservoirs of P. --Light levels are highest just off coastline. Inshore tropical waters have a productivity as much as 10 times higher than offshore because ...
What are the factors that affect ocean productivity?
Abiotic factors like solar radiation and nutrients, and biotic factors like zooplankton predation may affect ocean primary productivity. Productivity varies with the season, and also locally and globally.
Where are the rings of low productivity water?
There are rings (or lenses) of low productivity water north of the Gulf Stream. This is water from the Sargasso Sea (tropical, gyre water) trapped in a meander (looping curve) of the Gulf Stream. They form when a meander breaks off, trapping water from the OPPOSITE side of the Gulf Stream.
What is subtropical gyre?
Subtropical gyre, an area of anticyclonic ocean circulation that sits beneath a region of subtropical high pressure. The movement of ocean water within the Ekman layer of these gyres forces surface water to sink, giving rise to the subtropical convergence near 20°–30° latitude. Read More on This Topic. ocean current: The subtropical gyres.
How do subtropical gyres move?
Stommel(1948) as resulting from the fact that the horizontal Coriolis forceincreases with latitude. This causes the poleward-flowing western boundary current to be a jetlike current that attains speeds of 2 to 4 metres (about 7 to 13 feet) per second. This current transports the excess heatof the low latitudes to higher latitudes. The flow within the equatorward-flowing interior and eastern boundary of the subtropical gyres is quite different. It is more of a slow drift of cooler water that rarely exceeds 10 centimetres (about 4 inches) per second. Associated with these currents is coastal upwelling that results from offshore Ekman transport.
Which direction do subtropical gyres shift?
The centres of subtropical gyres are shifted to the west. This westward intensification of ocean currents was explained by the American meteorologist and oceanographer Henry M. Stommel (1948) as resulting from the fact that the horizontal Coriolis force increases with latitude.
Which current is most similar to the Gulf Stream?
The path that they follow defines a clockwise-flowing recirculation gyre seaward of the Gulf Stream. Among the other western boundary currents, the Kuroshio current of the North Pacific is perhaps the most like the Gulf Stream, having a similar transport and array of eddies.
Where are warm eddies found?
The warm eddies, composed of thermocline water normally found south of the Gulf Stream, are injected into the waters of the continental slope off the coast of the northeastern United States.
