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Nutrient upwelling
| Fisheries glossary |
Nutrient upwelling is the 'welling-up' of deeper water that is usually richer in nutrients than surface water.
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Nutrient, английский
- A substance in food which is necessary to provide energy or to help the body grow, e.g. protein, fat or a vitamin
- Any element or simple compound necessary for the health and survival of an organism. this includes air and water, as well as food.
Nutrient con ten t, английский
Nutrient cycling, английский
All the processes by which nutrients are transferred from one organism to another. for instance, the carbon cycle includes uptake of carbon dioxide by plants, ingestion by animals, and respiration and decay of the animal.
Nutrient cycling monitoring, английский
Nutrient export rates pi, английский
Nutrient intensity, английский
Nutrient lack, английский
Nutrient liquid, английский
Nutrient loading, английский
Nutrient removal, английский
Nutrient-rich water, английский
Вода, обогащенная биогенными веществами о
Nutrients, английский
Биогенные вещества
Upwelling, английский
- The process by which water, usually cold and nutrient-rich, rises from a deeper to a shallower depth. this is often a result of offshore surface water flow, particularly when persistent wind blows parallel to a coastland and the resultant ekman transport
- The oceans are layered; with sunwarmed water on top, and colder water containing 343 upwelling nutrients and dissolved gases below. upwelling is a phenomenon that brings this deeper water to the surface. when nutrients rise towards the sunlight, microscopic plants (phytoplankton) combine them with carbon dioxide and solar energy by photosynthesis. the organic compounds thus produced form the basis of the oceanic food chain. oceanographers have identified many different forms of this phenomenon, the more significant of which are: • coastal upwelling: coriolis effect causes winddriven currents to move to the right of winds in the northern hemisphere. thus winds blowing south along an eastern land-ocean boundary, or north along a western one, drive surface water away from the coast, allowing cold, nutrient-rich deep water to rise and replace it. in the southern hemisphere, these directions are reversed. some of the world’s most productive fishing grounds are in regions where coastal upwelling occurs. • equatorial upwelling: a related phenomenon. the equatorial surface current flows from east to west in both the atlantic and pacific basins. coriolis force turns the flow away from the equator (north to the right, south to the left) once again clearing a path for colder water to rise from the depths. as phytoplankton feast on the rising nutrients they bloom, causing the water to become green and murky—to the extent that space travelers can visually locate the pacific equatorial region by a line of high phytoplankton concentration. • dynamic uplift: occurs in response to variations in coastal ocean currents and is independent of coastal wind conditions. • tidal pumping: strong tidal currents produce upwelling through amplification and associated topographic turbulence. during flood tide, oceanic water mixes with and transfers part of its nutrient load to the shelf water before being removed again during ebb tide. each flood tide brings another load of nutrients, and the resulting enrichment can be substantial. marine life on the great barrier reef benefits greatly from tidal pumping, as do similar geographical settings where tidal currents are amplified in channels between islands. • eddy formation:western boundary currents spawn several eddies per year, each of which maintains its identity for two years or longer. warm core eddies are characterized by a deep thermocline in the centre and shallow thermocline around the eddy fringe. as they impinge on the continental slope, the thermocline is lifted up, having the same effect as when the main current impinges on the shelf.
- The raising of benthic nutrients to the surface waters. this occurs in regions where the flow of water brings currents of differing temperatures together, and increases productivity of the ecosystem.
- A rising of nutrient-rich water toward the sea surface.
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Overfishing, английский
- Occurs when fishing activities reduce fish stocks below an acceptable level. this can occur in any body of water from a pond to the oceans.
- Harvesting a fish population (stock) at a rate greater than which will meet the management goal within a particular year or season. note that overfishing and overfished have different definitions.
Biotoxins, английский
Natural toxins produced by organisms, often for use as a defence mechanism.
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