|
Beneguela Current
The Benguela Current is the broad, northward flowing ocean current that forms the eastern portion of the South Atlantic Ocean gyre. The current extends from roughly Cape Point in the south, to the position of the Angola-Benguela Front in the north, at around 16°S. The current is driven by the prevailing south easterly trade winds. Inshore of the Benguela Current proper, the south easterly winds drive coastal upwelling, forming the Benguela Upwelling System. The cold, nutrient rich waters that upwell from around depth in turn fuel high rates of phytoplankton growth, and sustain the productive Benguela ecosystem. Boundaries Source waters for the Benguela include cold upwelled waters from the depths of the Atlantic Ocean close inshore, joined further off-shore by nutrient poor water that has crossed the Southern Atlantic from South America as part of South Atlantic Gyre. Eddies from the warm South Indian Ocean Agulhas current along South Africa's east coast come round the Cape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Atlantic Gyre
The South Atlantic Gyre is the Ocean gyre#Subtropical gyres, 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. Southern boundary South of this gyre is the Antarctic Circumpolar Current. This current flows from West to East around Antarctica. Another name for this current is the West Wind Drift. This current allows Antarctica to maintain its huge ice sheet by keeping warm ocean waters away. At approximately 125 Sverdrup, Sv, this current is the largest ocean current. Western boundary The Brazil Current is the western boundary current of the gyre. It flows south along the Brazilian coast to the Rio de la Plata. The current is considerably weaker than its North Atlantic co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upwelling
Upwelling is an physical oceanography, oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted surface water. The nutrient-rich upwelled water stimulates the growth and reproduction of primary producers such as phytoplankton. The biomass of phytoplankton and the presence of cool water in those regions allow upwelling zones to 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 thus fishery production. Approximately 25% of the total global marine fish catches come from five upwellings, which occupy only 5% of the total ocean area.Jennings, S., Kaiser, M.J., Reynolds, J.D. (2001) "Marine Fisheries Ecology." Oxford: Blackwell Science Ltd. Upwellings that are driven by coastal ocean curr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern African Pilchard
''Sardinops'' is a monotypic genus of sardines of the family Alosidae. The only member of the genus is ''Sardinops sagax''. It is found in the Indo-Pacific and East Pacific oceans. Its length is up to . It has numerous common or vernacular names, some of which more appropriately refer to subspecies, including blue pilchard, Australian pilchard (''S. s. neopilchardus''), blue-bait, Californian pilchard (''S. s. caeruleus''), Peruvian Pacific sardine (''S. s. sagax''), South American pilchard, Chilean sardine (''S. s. sagax''), Japanese pilchard (''S. s. melanostictus''), Pacific sardine, and Southern African pilchard (''S. s. ocellatus''). South Australian sardine fishery The South Australian sardine fishery targets ''Sardinops sagax'' and is the highest yielding single species fishery in Australia by volume. The fishery employs the technique of purse seining, which contributes to the sardines' status as sustainable. Schools of sardines are encircled by a net up to 1 kilometre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engraulis
''Engraulis'' is a genus of anchovies. It currently contains nine species. They are found in Pacific, Atlantic and Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ... sea, as well. Species ''Engraulis'' contains the following species: * ''Engraulis albidus'' Philippe Borsa, Borsa, Adeline Collet, Collet & Jean-Dominique Durand, J. D. Durand, 2004 (White anchovy) * ''Engraulis anchoita'' Carl Leavitt Hubbs, C. L. Hubbs & Tomás Leandro Marini, Marini, 1935 (Argentine anchoita) * ''Engraulis australis'' (George Shaw (biologist), Shaw, 1790) (Australian anchovy) * ''Engraulis capensis'' John Dow Fisher Gilchrist, Gilchrist, 1913 (Southern African anchovy) * ''European anchovy, Engraulis encrasicolus'' (Carl Linnaeus, Linnaeus, 10th edition of Systema Naturae, 1758) (Euro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sardinops
''Sardinops'' is a monotypic genus of sardines of the family Alosidae. The only member of the genus is ''Sardinops sagax''. It is found in the Indo-Pacific and East Pacific oceans. Its length is up to . It has numerous common or vernacular names, some of which more appropriately refer to subspecies, including blue pilchard, Australian pilchard (''S. s. neopilchardus''), blue-bait, Californian pilchard (''S. s. caeruleus''), Peruvian Pacific sardine (''S. s. sagax''), South American pilchard, Chilean sardine (''S. s. sagax''), Japanese pilchard (''S. s. melanostictus''), Pacific sardine, and Southern African pilchard (''S. s. ocellatus''). South Australian sardine fishery The South Australian sardine fishery targets ''Sardinops sagax'' and is the highest yielding single species fishery in Australia by volume. The fishery employs the technique of purse seining, which contributes to the sardines' status as sustainable. Schools of sardines are encircled by a net up to 1 kilometre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulphur-reducing Bacteria
Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product of these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and as electron donor. The first pure cultured species of sulfur-reducing bacteria, ''Desulfuromonas acetoxidans'', was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Minimum Zone
The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about , depending on local circumstances. OMZs are found worldwide, typically along the western coast of continents, in areas where an interplay of physical and biological processes concurrently lower the oxygen concentration (biological processes) and restrict the water from mixing with surrounding waters (physical processes), creating a "pool" of water where oxygen concentrations fall from the normal range of 4–6 mg/L to below 2 mg/L. Physical and biological processes Surface ocean waters generally have oxygen concentrations close to equilibrium with the Earth's atmosphere. In general, colder waters hold more oxygen than warmer waters. As water moves out of the mixed layer into the thermocline, it is exposed to a rain of organic matter from above. Aerobic bacteria feed on this o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Production
In ecology, the term productivity refers to the rate of generation of biomass in an ecosystem, usually expressed in units of mass per volume (unit surface) per unit of time, such as grams per square metre per day (g m−2 d−1). The unit of mass can relate to dry matter or to the mass of generated carbon. The productivity of autotrophs, such as plants, is called primary productivity, while the productivity of heterotrophs, such as animals, is called secondary productivity. The productivity of an ecosystem is influenced by a wide range of factors, including nutrient availability, temperature, and water availability. Understanding ecological productivity is vital because it provides insights into how ecosystems function and the extent to which they can support life. Primary production Primary production is the synthesis of organic material from inorganic molecules. Primary production in most ecosystems is dominated by the process of photosynthesis, In which organisms synt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Production
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are known as '' primary producers'' or autotrophs, and form the base of the food chain. In terrestrial ecoregions, these are mainly plants, while in aquatic ecoregions algae predominate in this role. Ecologists distinguish primary production as either ''net'' or ''gross'', the former accounting for losses to processes such as cellular respiration, the latter not. Overview Primary production is the production of chemical energy, in organic compounds by living organisms. The main source of such energy i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomass (ecology)
Biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to ''species biomass'', which is the mass of one or more species, or to ''community biomass'', which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community. How biomass is measured depends on why it is being measured. Sometimes, the biomass is regarded as the natural mass of organisms ''in situ'', just as they are. For example, in a salmon fishery, the salmon biomass might be regarded as the total wet weight the salmon would have if they were taken out of the water. In other contexts, biomass can be measured in terms of the dried organic mass, so perhaps only 30% of the actual weight might count, the rest being water. For other purposes, only biological tissues count, and teeth, bones and shells are excluded. In some application ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zooplankton
Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers. Zooplankton can be contrasted with phytoplankton (cyanobacteria and microalgae), which are the plant-like component of the plankton community (the " phyto-" prefix comes from , although taxonomically ''not'' plants). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding), often generating biological energy and macromolecules through chlorophyllic carbon fixation using sunlightin other words, zooplankton cannot manufacture their own food, while phytoplankton can. As a result, zooplankton must acquire nutrients by feeding on other organisms such as phytoplankton, which are generally smaller t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytoplankton Bloom
Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Phytoplankton obtain their energy through photosynthesis, as trees and other plants do on land. This means phytoplankton must have light from the sun, so they live in the well-lit surface layers ( euphotic zone) of oceans and lakes. In comparison with terrestrial plants, phytoplankton are distributed over a larger surface area, are exposed to less seasonal variation and have markedly faster turnover rates than trees (days versus decades). As a result, phytoplankton respond rapidly on a global scale to climate variations. Phytoplankton form the base of marine and freshwater food webs and are key players in the global carbon cycle. They account for about half of global photosynthetic activity and at least half of the oxygen production, despite a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
