Why is most productivity in open oceans limited to surface waters?

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.

1. Why does the open ocean have low productivity?
2. What limits the primary productivity of the ocean?
3. Which part of the ocean is most productive?
4. Where is ocean productivity the lowest?
5. Why are coastal waters more productive?
6. When in the oceans is productivity high at the surface?
7. Why are cold oceans more productive?
8. Why do open oceans produce the largest share of Earth's biomass?
9. Which of the following nutrients is most limiting to the productivity of open oceans?
10. Why is the marine environment productive?
11. Where are the most productive fisheries?
12. Why is productivity higher for coastal and estuarine waters than for the open ocean?
13. Is productivity in the tropical open ocean always high or low?
14. Why is the coral reefs the most productive ecosystem?
15. Why is the open ocean called a marine desert?

Why does the open ocean have low productivity?

In surface waters away from coastlines, generally there is plenty of sun but not enough nutrients. So most of the ocean surface is not very productive. The water is too deep for storms to stir up nutrients from the bottom and there isn't upwelling.

What limits the primary productivity of the ocean?

Reduction of sunlight by sea ice is a major limiting factor for primary productivity in the Arctic Ocean.

Which part of the ocean is most productive?

Although they occupy less than two percent of the oceans, the coastal upwelling areas in the eastern parts of the Pacific and Atlantic Ocean are among the biologically most productive marine areas worldwide.

Where is ocean productivity the lowest?

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 coastal waters more productive?

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.

When in the oceans is productivity high at the surface?

Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Therefore, good fishing grounds typically are found where upwelling is common.

Why are cold oceans more productive?

Why is cold water more productive? Cold water can hold more dissolved oxygen than warm water. The levels of dissolved oxygen in Antarctic waters are so high that many fish have few or no red blood cells (the blood cells other animals, including humans, use to carry oxygen).

Why do open oceans produce the largest share of Earth's biomass?

Open oceans produce the largest share of Earth's biomass because the net primary productivity (NPP) of the ocean is... ... Both forest have the same gross primary productivity (GPP). Forest A has a net primary productivity of 1650 kcal/m^2/year, and forrest B has a net primary productivity of 1110 kcal/m^2/year.

Which of the following nutrients is most limiting to the productivity of open oceans?

Outside high-nutrient low-chlorophyll areas, productivity in most of the ocean (∼ 75%) is limited by the availability of inorganic nitrogen (Figure 1B), despite very low concentrations of iron and, in some cases, phosphate.

Why is the marine environment productive?

The most productive waters of the world are in regions of upwelling. Upwelling in coastal waters brings nutrients toward the surface. Phytoplankton reproduce rapidly in these conditions, and grazing zooplankton also multiply and provide abundant food supplies for nekton.

Where are the most productive fisheries?

The most productive areas include the Grand Banks of Newfoundland, the shelf area off Nova Scotia, Georges Bank off Cape Cod, the Bahama Banks, the waters around Iceland, the Irish Sea, the Dogger Bank of the North Sea, and the Falkland Banks.

Why is productivity higher for coastal and estuarine waters than for the open ocean?

There is generally greater productivity near the coasts than in the open ocean. Coastal areas are hotspots for primary producers who require higher sunlight conditions, nutrient sediment, and organic inputs, and protection from large tidal events in order to be productive.

Is productivity in the tropical open ocean always high or low?

The surface water is always warm and there is always a pronounced thermocline, leading to highly stratified water that prevents the nutrient-rich bottom water from reaching the surface (section 6.2). Thus productivity in tropical water is always nutrient-limited, and productivity is low throughout the year (Figure 7.4.

Why is the coral reefs the most productive ecosystem?

Coral reefs are among the most productive ecosystems on the planet, with the primary producers at the base of the food chain (including corals) supporting their complex food webs. ... Although light provides the energy that fuels reef productivity, key nutrients such as nitrogen and phosphorus are also required.

Why is the open ocean called a marine desert?

So-called “ocean deserts” or “dead zones” are oxygen-starved (or “hypoxic”) areas of the ocean. ... Furthermore, warmer upper layers of water stifle the process that brings nutrients up from colder, deeper parts of the ocean to feed a wide range of surface-dwelling marine wildlife.