Humboldt Current

The Humboldt Current, also called the Peru Current, is a cold, low-salinity ocean current that flows north along the western coast of South America.[1] It is an eastern boundary current flowing in the direction of the equator, and extends 500–1,000 km (310–620 mi) offshore. The Humboldt Current is named after the Prussian naturalist Alexander von Humboldt. In 1846, von Humboldt reported measurements of the cold-water current in his book Cosmos.[1]

The current extends from southern Chile (~45th parallel south) to northern Peru (~4th parallel south) where cold, upwelled, waters intersect warm tropical waters to form the Equatorial Front.[1] Sea surface temperatures off the coast of Peru, around 5th parallel south, reach temperatures as low as 16 °C (61 °F).[2] This is highly uncharacteristic of tropical waters, as most other regions have temperatures measuring above 25 °C (77 °F). Upwelling brings nutrients to the surface, which support phytoplankton and ultimately increase biological productivity.[1]

The Humboldt Current is a highly productive ecosystem. It is the most productive eastern boundary current system.[3] It accounts for roughly 18-20% of the total worldwide marine fish catch. The species are mostly pelagic: sardines, anchovies and jack mackerel. The system's high productivity supports other important fishery resources as well as marine mammals (eared seals and cetaceans) and seabirds. Periodically, the upwelling that drives the system's productivity is disrupted by the El Niño-Southern Oscillation (ENSO) event, often with large social and economical impacts.

The Humboldt has a considerable cooling influence on the climate of Chile, Peru and Ecuador. It is also largely responsible for the aridity of Atacama Desert in northern Chile and coastal areas of Peru and also of the aridity of southern Ecuador. Marine air is cooled by the current and thus is not conducive to generating precipitation (although clouds and fog are produced).

Humboldt current
Humboldt Current

Physical oceanography

Tropical cyclones 1945 2006
The presence of the Humboldt Current and its associated wind shear[4] prevents the formation of tropical cyclones in the area.(The same effect occurs in the South Atlantic with the Benguela Current.)
(Worldwide tropical cyclone tracks, 1945–2006.)

The trade winds are the primary drivers of the Humboldt Current circulation.[1] Variability in this system is driven by latitudinal shifts between the Intertropical Convergent Zone and the trade winds in the north. Shifts within the South Pacific High at mid-latitudes, as well as cyclonic storms and movement of the Southern Westerlies southward also contribute to system changes. Atmospheric variability off central Chile is enhanced by the aggravation of coastal low pressure systems trapped between the marine boundary layer and the coastal mountains. This is prominent poleward from 27th parallel south to 42nd parallel south.[1]

The Humboldt current, occupying the upper ocean, flows equatorward carrying fresh, cold Sub-Antarctic surface water northward, along the outskirts of the subtropical gyre.[1] The main flow of the current veers offshore in southern Peru, as a weaker limb continues to flow equatorward. Around 18th parallel south the fresh, cold waters begin to mix with the warm, high salinity Subtropical Surface waters. This collision causes partial subductions. Within this region, the equatorial undercurrent (EUC) flows eastward along the equator, feeding the Peru-Chile undercurrent (PCU) that moves poleward.[1]

Off the coast of central Chile, there is a coastal transition zone (CTZ), which is characterized by high eddy kinetic energy.[1] This energy forms mesoscale eddies which extend 600–800 km (370–500 mi) offshore. The CTZ has three distinct regions within its boundaries:

  1. high chlorophyll-a concentrations in wide regions off the coast of Peru (10–15°S),
  2. high chlorophyll-a concentrations in wide regions off the coast of Chile (30°S), and
  3. high chlorophyll-a concentrations in narrow regions off the coast of northern Chile (Montecino and Lange 2008). High chlorophyll-a concentrations are generally found within 50 km of the coast.[1]

The limb of the HCS that veers off the coast of Peru creates a decrease in ventilation within the system.[1] This lack of ventilation is the primary driver of an intense oxygen minimum zone (OMZ) which is formed in the sub-surface to intermediate depths. In the north, the EUC ventilates the OMZ, and in the south the PCU advects low oxygen waters southward towards northern Chile.[1] This OMZ is the fourth largest permeant hypoxic zone in the world's oceans. It occupies an area about 2.18 ± 0.66 × 106 km3. The core of this zone is centered off Peru, creating a shallow upper boundary that reaches from about 100 m (330 ft) down to 600 m (2,000 ft).[1] Another factor contributing to the OMZ is sinking and decay of primary productive resources.[2]

Consequently, the OMZ forces many organisms to stay near the surface where nutrients and oxygen are obtainable.[2] The presence of a shallow OMZ restricts the migration of zooplankton within the water column. Between 0 and 600 m (0–1,969 ft), many species of zooplankton occupy this space within the OMZ. This allows for a substantial exchange of carbon between the euphotic layer and the OMZ. 75% of the total zooplankton biomass move in and out of the OMZ. The OMZ also serves as a refuge for organisms that can live in hypoxic conditions.[2]

Coastal upwelling is the main factor contributing to the high biological productivity of the Humboldt current.[1] Upwelling within the current is not uniform across the entire system. Three notable upwelling subsystems are produced by this current:

  1. seasonal upwelling in Chile only during the spring and summer, because of the displacement of the subtropical center of high pressure during the period January–March,
  2. upwelling "shadow" that is less productive, but still large in northern Chile and Southern Peru, and
  3. highly productive year-round upwelling in Peru.[1] The upwelling shadow identified between 35°S and 15°S is caused by the oligotrophic subtropical gyre impinging on the coast. This creates a narrow, but highly productive, upwelling zone.[1]

Biological productivity

Due to the upwelling zones within the Humboldt current, biological diversity is extremely high. The Humboldt Current is considered a Class I, highly productive (>300 gC/m2/yr) ecosystem. The current hosts a wide range of organisms including multiple species of plankton, mollusks, sea urchins, crustaceans, fish, and marine mammals.[1] The food web starts with the phytoplankton. The conditions of the Humboldt current are prime for these organisms to thrive. This causes a cascade effect in which larger and larger organisms are drawn to the area.

Fisheries

The Humboldt current produces some of the most successful commercial fisheries in the world.[1] The major catches include: sardines, anchovies, mackerel, hake, and squid. Three major stocks of anchoveta are distributed between 4°S and 42°S within the HCS. North-central Peru's fishery is primarily composed of one stock of anchoveta. Sardines, chub mackerel, and bonito are also common catches, but not as prominent, in Peru.[1] Southern Peru and Northern Chile host a major sardine fishery. Other common stocks include: a second anchoveta stock, jack mackerel, tuna, and swordfish. Anchoveta, jack mackerel, and sardines are the primary commercial stocks in central Chile.

Anchoveta are found in more recently upwelled waters, close to the coast. Sardines, on the other hand, are typically found farther offshore.[1] Seasonal upwelling plays a major role in the spawning behaviors of both sardines and anchoveta. By spawning at the end of winter, egg and larval survival is greatly enhanced. This is due to the moderate upwelling, which causes lower turbulence, as well as a weakened Ekman drift offshore. These two species experience population shifts related to climate changes and environmental events such as El Niño. This is due to changes in the availability of each species habitat. Anchoveta are an important component in the diets of marine mammals, seabirds, and larger fish. Shifts in these populations ultimately cause a shift in the energy processing within the HCS.[1]

Jack mackerel (jurel) is the second largest fishery in the HCS.[1] As with the anchoveta in Peru, this species is believed to be composed of a single stock. Jurel are a straddling species. This means the species is found both within and outside of the 200-mile economic exclusive zone. Jurel became an important fishery in the 1970s to alleviate the pressure put on the anchoveta stock. During the 1980s, however, the jurel decreased in population size due to poor recruitment and overfishing. Restrictions of jurel fishing were imposed in 1998 which led to regrowth of the population. Since 2002, the jurel population is now under full exploitation.[1]

Between 1993-2008, the hake fishery in Peru declined significantly.[1] This was due to overfishing, environmental stress, and decreased reproductive capacity. The Chilean hake population in central-south Chile catch exceeded 100,000 tons, and dropped to 40,000 tons in 2007.[1]

Influence of El Niño

Sitting at the Top of a Cloud
La Silla is in the Southern outskirts of the Atacama Desert, one of the driest places on Earth, it may come as a surprise to see cloud formations result of the Humboldt Current.[5]

The productivity of the HCS is strongly affected by El Niño and La Niña events.[1] During an El Niño event, the thermocline and upper region of the OMZ deepen to greater than 600 m. This causes a loss of nitrogen and decrease in export of carbon. El Niño also causes poleward currents to increase in velocity. During non-El Niño years, productivity is very high due to the high nutrient contents, nitrogen recycling through processes such as denitrification, increased carbon export, and remineralization [1]

During El Nino events, fish abundance and distribution are significantly affected, often leading to stock crashes and cascading social and economic impacts. These events have led to sequential changes, where sardines and anchovies have replaced each other periodically as the dominant species in the ecosystem. These species changes can have negative consequences for the fishing industry and the economies of the countries that fish the system. The anchoveta fishery in Peru was booming during the 1960s.[2] In 1970, catches were reported to exceed 12 million tons per year. This accounted for 20% of the world's catches. An El Niño event occurred during 1972 and caused the anchoveta population to collapse. However, sardine populations saw a dramatic increase in the next 15–20 years. Consequently, sardine fisheries grew in this "regime shift".[2]

See also

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa Montecino, Vivian, and Carina B. Lange. "The Humboldt Current System: Ecosystem components and processes, fisheries, and sediment studies." Progress in Oceanography 83.1 (2009): 65-79.
  2. ^ a b c d e f Chavez, Francisco P., et al. "The northern Humboldt Current System: Brief history, present status and a view towards the future." (2008): 95-105.
  3. ^ Penven, P., V. Echevin, J. Pasapera, F. Colas, and J. Tam (2005), Average circulation, seasonal cycle, and mesoscale dynamics of the Peru Current System: A modeling approach, J. Geophys. Res., 110, C10021, doi:10.1029/2005JC002945.
  4. ^ Ruminski, Mark (Jan 1991). "Two Unusual Tropical Cyclones in the Southeast Pacific". Monthly Weather Review. 119 (1): 218–222. doi:10.1175/1520-0493(1991)119<0218:TUTCIT>2.0.CO;2. Retrieved 1 Jun 2016.
  5. ^ "Sitting at the Top of a Cloud". www.eso.org. European Southern Observatory. Retrieved 8 December 2014.

 This article incorporates public domain material from the United States Government document "NOAA article on Humboldt current".

External links

Agricultural history of Peru

Much of the pre-history of Peru has been wrapped up in where the farmable land was located. The most populated coastal regions of Peru are the two parallel mountain ranges and the series of 20 to 30 rivers running through the coastal desert. In dry periods only the mountains are wet enough for agriculture and the desert coast is empty, while in wet periods many cultures have thrived along the rivers of the coast. The well known Inca were a mountain-based culture that expanded when the climate became more wet, often sending conquered peoples down from the mountains into unfarmed but farmable lowlands. In contrast, the Moche were a lowland culture that died out after a strong El Niño, which caused abnormally high rainfall and floods, which was followed by a long drought.A study has shown that the crops of squash, peanuts, and cotton were domesticated in Peru around 10,000, 8,500, and 6,000 years ago, respectively. They were grown by the Ñanchoc people in the Ñanchoc Valley. No earlier instances of the farming of these crops are known.Peru is both afflicted and blessed by a peculiar climate due to the Humboldt Current. Before overfishing killed its fishery, Peru had the most productive fishery in the world due to the cold Humboldt Current. The current brings nutrients from a large portion of the Pacific floor to Peru's doorstep. On land, it results in a cold mist that covers coastal Peru to the extent that the desert plants have adapted to obtain water from the air instead of from the infrequent rainfall. The soil on the wet side of the mountains is thin, and the rivers on the dry side are few. This means all the water must be brought from the Atlantic side of the mountain ranges that split Peru.

There were many obstacles to improving Peru's agricultural production. Since the conquest of the Inca, Peru has always been rich in natural resources such as tin, silver, gold, guano and rubber. These resources share the attribute that, at least in Peru, they were found, not grown. The train tracks laid in Peru did not connect its peoples, they connected the sources of these valuable resources to the sea. So there are few ways to bring agricultural products to market. The road system is still primitive in Peru, there is no connection to Brazil and only a little over a quarter of the 15th-century Inca road system has been rebuilt as modern highway. Another obstacle is the size of Peru's informal economy. This prevents Peru from practically applying an income tax, which means much of its revenue comes from a 13% tax on gross agricultural sales. This means Peruvian farmers must produce that much more product per dollar just to break even with farmers in countries that tax farmers on net profit. They have no chance at all of competing with agricultural products from countries that subsidize farmers, such as Japan, the United States and Europe.

Today Peru grows agricultural commodities such as asparagus, potatoes, maize, rice, and coffee. Peru provides half of the world supply of quinoa. Peruvian agriculture uses synthetic fertilizers rather than the still-abundant guano due to infrastructure issues. The maize is not exportable due to large subsidies in Europe and the United States to its high-cost producers, but coffee is exportable. In recent years Peru has become the world's primary source of high-quality organic coffee. Peru does not have a quality control program such as Kenya's but its government has worked to educate farmers on how to improve quality. Despite the glut of coffee producers in the market today, coffee production in Peru is still promising. It naturally has the high altitudes and partial shade desired by Coffea arabica, and it has much more of such land available than competitors such as Jamaica and Hawaii.

California Current

The California Current is a Pacific Ocean current that moves southward along the western coast of North America, beginning off southern British Columbia and ending off southern Baja California Peninsula. It is considered an Eastern boundary current due to the influence of the North American coastline on its course. It is also one of five major coastal currents affiliated with strong upwelling zones, the others being the Humboldt Current, the Canary Current, the Benguela Current, and the Somali Current. The California Current is part of the North Pacific Gyre, a large swirling current that occupies the northern basin of the Pacific.

Cerro Azul, Peru

Cerro Azul ("Blue Hill") is a fishing village and formerly a commercial port in the Cañete Province, Lima Region, Peru. Located 131 km south of Lima, it is frequently visited in the summer by its residents, and those of San Vicente de Cañete. The village has come to depend more heavily on tourism than on fishing. It was quite considerably damaged in the 2007 earthquake that shook much of the southern coast of Peru.

The beach forms an attractive bay that ends in a rocky point where the waves it is famous for break. These break from left to right, are well shaped and go for about half a mile on a good day. The renowned quality of its waves is mentioned in the Beach Boys' song "Surfin' Safari". However, the quality of the waves changes seasonally and from year to year, as the sand and stones that make up the beach are chronically withdrawn by the sea to form a bank where the waves break.

South of the pier is the area known as Puerto Viejo ("old port" ), where all the holiday homes are and where most of the surfing takes place (left breaks). To the north of the pier, the beach is much longer, less curved and much sandier. There are no holiday homes on it and in the winter is empty. During the summer, it is popular with campers and day-trippers. It is possible to surf here too, when the swell is high, particularly adjacent to the pier, where the waves are fast and the rides tend to be short. .

Cerro Azul's main feature is the pier which was built by a British company around 1900 for the export of locally grown cotton. The pier has been disused for over 60 years and is now frequented by fishermen and tourists and is one of the main tourists attractions.

The village also has an attractive main square and the remains of Pre-Inca mud buildings, half buried by sand between two hills which are made from the blue rock that gives the village its name. The other hill features a derelict lighthouse from the days when the area functioned as a port. It sits above craggy, vertical, dangerous cliffs, where birds in the area make their nests. Of note is the Inca tern, a bird endemic to the Humboldt Current, which sweeps the Peruvian coast. Other wildlife of note commonly seen in the area: porpoises, pelicans, sea lions, herons and, on rare occasions, sharks. The village prides itself in catching the largest shark in Peruvian history (in 1989), a 5m long great white. Behind the village, across the Pan-American Highway, are fields and winding valleys in the foothills of the Andes.

Chala

The Chala or "Coast" is one of the eight natural regions in Peru. It is formed by all the western lands that arise from sea level up to the height of 500 meters. The coastal desert of Peru is largely devoid of vegetation but a unique fog and mist-fed ecosystem called Lomas is scattered among hills near the Pacific coast as elevations up to 1,000 metres (3,300 ft).

In this region, the flora includes vegetation that grows near the rivers, like the carob tree, the palo verde, salty grama grass, manglar or mangrove tree, the carrizo or giant reed and the Caña brava (ditch reed); and plants that grow in the hills, such as the Amancay or Peruvian daffodil (Hymenocallis amancaes), the wild tomato, the mito or Peruvian papaya (Vasconcellea candicans), and the divi-divi (Cæsalpinia coriaria).

The coastal fauna of the Chala includes sea lions, the anchovy and several seabirds.

Common trees in the north are the faique, the zapote, the zapayal, the barrigon and other thorny tropical savanna trees of the equatorial dry forests on the northern coast of Piura and Tumbes. Páramo and the northern coast of the Piura region are not under the influence of the cold Humboldt Current. Páramo has a tree line at the border, even on the westside of the continental divide.

Climate of Chile

The climate of Chile comprises a wide range of weather conditions across a large geographic scale, extending across 38 degrees in latitude, making generalizations difficult. According to the Köppen system, Chile within its borders hosts at least seven major climatic subtypes, ranging from low desert in the north, to alpine tundra and glaciers in the east and southeast, humid subtropical in Easter Island, Oceanic in the south and Mediterranean climate in central Chile. There are four seasons in most of the country: summer (December to February), autumn (March to May), winter (June to August), and spring (September to November).

On a synoptic scale, the most important factors that control the climate in Chile are the Pacific Anticyclone, the southern circumpolar low pressure area, the cold Humboldt current, the Chilean Coast Range and the Andes Mountains. Despite Chile's narrowness, some interior regions may experience wide temperature oscillations and cities such as San Pedro de Atacama, may even experience a continental climate. In the extreme northeast and southeast the border of Chile extends beyond the Andes into the Altiplano and the Patagonian plains, giving these regions climate patterns similar to those seen in Bolivia and Argentina respectively.

Climate of Peru

The climate of Peru is very diverse, with a large variety of climates and microclimates, including 28 of the 32 world climates. Such a diversity is chiefly conditioned by the presence of the Andes mountains and the cold Humboldt Current.

The climate on the coast is arid and semi-arid with high temperatures and very little rainfall. The Andes mountains observe a cool-to-cold climate with rainy summers and very dry winter. The eastern lowlands present an Equatorial climate with hot weather and rain distributed all year long.

Elliot's storm petrel

Elliot's storm petrel (Oceanites gracilis) is a species of seabird in the storm petrel family Hydrobatidae. The species is also known as the white-vented storm petrel. There are two subspecies, O. g. gracilis, which is found in the Humboldt Current off Peru and Chile, and O. g. galapagoensis, which is found in the waters around the Galapagos Islands. It is a sooty-black storm petrel with a white rump and a white band crossing the lower belly and extending up the midline of the belly. It has long legs which extend beyond the body in flight.

In spite of the frequent sightings of this species it is very poorly known; only one nest has ever been found. The feeding behaviour of the Galapagos subspecies is unusual amongst storm-petrels as it forages close to shore; all other storm-petrels are exclusively pelagic.

Fishing in Chile

Fishing in Chile is a major industry with a total catch of 4,442,877 tons of fish in 2006. As of 2010, Chile has the seventh largest commercial catch in the world. With over 4,000 km (2,500 miles) of viable coastline, fishing has been a vital resource for small-scale business and family development for hundreds of years. Due to the Humboldt Current, the Chilean Sea is considered among the most productive marine ecosystems in the world as well as the largest upwelling system. Artisan fishing is practised all over Chile's 6,435 km long coastline and combines industrial techniques with pre-Hispanic traditions. Recreational fishing tourism in southern Chile's rivers has recently gained worldwide fame attracting actors such as Harrison Ford, Michael Douglas, and Kevin Costner.

Guanay cormorant

The Guanay cormorant or Guanay shag (Leucocarbo bougainvillii) is a member of the cormorant family found on the Pacific coast of Peru and northern Chile. (The Argentinian population on the Patagonian Atlantic coast appears to be extirpated.) After breeding it spreads south to southern parts of Chile and north to Ecuador, and has also been recorded as far north as Panama and Colombia – probably a result of mass dispersal due to food shortage in El Niño years. Its major habitats include shallow seawater and rocky shores.

The Guanay cormorant is similar in coloration to the rock cormorant, Phalacrocorax magellanicus, but larger, measuring 78 cm from the tip of the bill to the end of the tail. Its bill is grayish with some red at the base. The face is red with a green eye-ring. It has roseate feet. The head, neck and back are black as are the outer parts of the thighs. The throat patch, breast and belly are white. In breeding plumage it has a few white feathers on the sides of the head and neck.

Breeding occurs year-round with a peak in November and December. The nest is built of guano on flat surfaces on offshore islands or remote headlands. There are up to three nests per square meter in high-density colonies. The Guanay cormorant lays two or three eggs of approximately 63 x 40 mm in size.

It feeds mainly on the Peruvian anchoveta, Engraulis ringens, and the Peruvian silverside, Odontesthes regia, which thrive in the cold Humboldt Current. The Guanay cormorant is the main producer of guano.Habitat loss and degradation and over-fishing have resulted in a steady decline of the population of about 30% from an estimated figure of 3 million birds in 1984. This species is listed as Near Threatened by IUCN.

Some taxonomic authorities, including the International Ornithologists' Union, place this species in the genus Leucocarbo. Others place it in the genus Phalacrocorax.

The scientific name commemorates the French explorer Louis Antoine de Bougainville. The bird's droppings were such an important source of fertilizer to the peoples of the Andes that it was protected by Inca rulers, who supposedly made disturbing the cormorants in any way punishable by death.

Hornby's storm petrel

Hornby's storm petrel or ringed storm petrel (Oceanodroma hornbyi) is a seabird that ranges in the Humboldt Current off the coasts of South America. The species is a very distinctive member of the storm petrel family, with a dark cap, white face and underparts, forked tail and a black band across the chest. It is relatively common in the seas off Peru, Chile and Ecuador. The species is named after Admiral Sir Phipps Hornby.

Humboldt squid

The Humboldt squid (Dosidicus gigas), also known as jumbo squid, jumbo flying squid, pota, or diablo rojo (red devil), is a large, predatory squid living in the waters of the Humboldt Current in the eastern Pacific Ocean. It is the only species of the genus Dosidicus of the subfamily Ommastrephinae, family Ommastrephidae.

Humboldt squid typically reach a mantle length of 1.5 m (4 ft 11 in). They have a reputation for aggression towards humans, though this behavior may possibly only be manifested during feeding times. Like other members of the subfamily Ommastrephinae, they possess bioluminescent photophores and are capable of quickly changing body coloration (metachrosis). They notably rapidly flash red and white while hunting, earning them the name diablo rojo (Spanish for "red devil") among fishermen. These chromatophores (which belong to more than one set and are of different sizes) may rapidly cycle through colors other than red and white, flashing too quickly for the human eye to see the transitions. They have a relatively short lifespan of just 1-2 years.

They are most commonly found at depths of 200 to 700 m (660 to 2,300 ft), from Tierra del Fuego to California. This species is spreading north into the waters of Oregon, Washington, British Columbia, and Alaska. They are fished commercially, predominantly in Mexico and Peru.

The genus contains bioluminescent species.

Illescas Peninsula

Illescas is a peninsula in northwestern Peru. It forms the southern boundary of the Sechura Bay, the largest bay in Peru. Sechura Bay also includes the northernmost portion of the Pacific Ocean that is under the influence of the Peru-Chile or Humboldt Current. The Illescas Peninsula is located in the department of Piura, and is scarcely inhabited. Part of Illescas was declared a reserved zone. Illescas is also the name given to the highest point of the peninsula (500 m.), the Cerro Illescas.

Inca tern

The Inca tern (Larosterna inca) is a tern in the family Laridae. It is the only member of the genus Larosterna.

This uniquely plumaged bird breeds on the coasts of Peru and Chile, and is restricted to the Humboldt Current. It is an erratic, rare visitor to the southwest coast of Ecuador. It can be identified by its dark grey body, white moustache on both sides of its head, and red-orange beak and feet.

Leeuwin Current

The Leeuwin Current is a warm ocean current which flows southwards near the western coast of Australia. It rounds Cape Leeuwin to enter the waters south of Australia where its influence extends as far as Tasmania.

The West Australian Current and Southern Australian Countercurrent, which are produced by the West Wind Drift on the southern Indian Ocean and at Tasmania, respectively, flow in the opposite direction, producing one of the most interesting oceanic current systems in the world.

Its strength varies through the year; it is weakest during the summer months (winter in the northern hemisphere) from November to March when the winds tend to blow strongly from the south west northwards. The greatest flow is in the autumn and winter (March to November) when the opposing winds are weakest. Evaporation from the Leeuwin current during this period contributes greatly to the rainfall in the southwest region of Western Australia.

Typically the Leeuwin Current's speed and its eddies are about 1 knot (50 cm/s), although speeds of 2 knots (1 m/s) are common, and the highest speed ever recorded by a drifting satellite-tracked buoy was 3.5 knots (6.5 km/h). The Leeuwin Current is shallow for a major current system, by global standards, being about 300 m deep, and lies on top of a northwards countercurrent called the Leeuwin Undercurrent.

The Leeuwin Current is very different from the cooler, equatorward flowing currents found along coasts at equivalent latitudes such as the southwest African Coast (the Benguela Current); the long Chile-Peru Coast (the Humboldt Current), where upwelling of cool nutrient-rich waters from below the surface results in some of the most productive fisheries; the California Current, which brings foggy conditions to San Francisco; or the cool Canary current of North Africa.

Because of the Leeuwin Current, the continental shelf waters of Western Australia are warmer in winter and cooler in summer than the corresponding regions off the other continents. The Leeuwin Current is also responsible for the presence of the most southerly true corals at the Abrolhos Islands and the transport of tropical marine species down the west coast and across into the Great Australian Bight.

The ‘core’ of the Leeuwin Current can generally be detected as a peak in the surface temperature with a strong temperature decrease further offshore. The surface temperature difference across the Current is about 1 °C at North West Cape, 2° to 3° at Fremantle and can be over 4° off Albany in the Great Australian Bight. The current frequently breaks out to sea, forming both clockwise and anti-clockwise eddies.

The Leeuwin Current is influenced by El Niño conditions, characterised by slightly lower sea temperatures along the Western Australian coast and a weaker Leeuwin Current, with corresponding effects upon rainfall patterns.

The existence of the current was first suggested by William Saville-Kent in 1897. Saville-Kent noted the presence of warm tropical water offshore in the Houtman Abrolhos, making the water there in winter much warmer than inshore at the adjacent coast. The existence of the current was confirmed over the years, but not characterised and named until Cresswell and Golding did so in the 1980s.

Mollendo

Mollendo is a town bordering the Pacific Ocean in southern Peru. It is located in the Arequipa Region and is the capital of both the Islay Province and the Mollendo District. Mollendo was the main port in the Peruvian southern coast until Matarani was developed about 50 years ago; the port of Mollendo only serves fishermen for the local economy currently and all the commercial shipping is done through Matarani 12 kilometers north; the old port is in ruins. From about 1830 to 1880 it was important in the Guano trade.

The railroad used to run a passenger train daily, but a good highway connects Mollendo to the Panamerican Highway now and the train now only runs the summer express that goes down from Arequipa on Saturday and returns on Sunday; the beach is the main attraction, even though it is visited by the Humboldt Current that brings cold water from Antarctica.In the summer months, which run from January to March, the population more than doubles as people from the largest city in the region Arequipa use Mollendo and its beaches as a vacation spot, especially on weekends. Mollendo exports wool and has industries producing cement, textiles, canned fish, and cheese. It is also a popular beach resort. The Auxiliary Ship BAP Mollendo (ATC-131) of the Peruvian Navy is named after the town.

Ocean current

An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements.

An ocean current flows for great distances and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth’s regions. More specifically, ocean currents influence the temperature of the regions through which they travel. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Other example is Lima, Peru, where the climate is cooler, being sub-tropical, than the tropical latitudes in which the area is located, due to the effect of the Humboldt Current.

Phosichthyidae

Lightfishes are small stomiiform fishes in the family PhosichthyidaeThey are very small fishes found in oceans throughout the world: most species grow no longer than 10 cm, while those in the genus Vinciguerria only reach 4 cm or so.

They make up for their small size with abundant numbers: Vinciguerria is thought — with the possible exception of Cyclothone — to be the most abundant genus of vertebrates. Deep-sea trawls of the Humboldt Current in the southeast Pacific have found that lightfishes make up 85% by mass of mesopelagic fishes, with Vinciguerria lucetia by far the most numerous species.They are bioluminescent fishes, possessing rows of photophores along their sides, with which they hunt planktonic invertebrates, especially krill.

South Pacific High

The South Pacific High is a semi-permanent subtropical anticyclone located in the southeast Pacific Ocean. The area of high atmospheric pressure and the presence of the Humboldt Current in the underlying ocean make the west coast of Peru and northern Chile extremely arid. The Sechura and Atacama deserts, as the whole climate of Chile, are heavily influenced by this semi-permanent high-pressure area. This high-pressure system plays a major role in the El Niño–Southern Oscillation (ENSO), and it is also a major source of trade winds across the equatorial Pacific.

Upwelling

Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The nutrient-rich upwelled water stimulates the growth and reproduction of primary producers such as phytoplankton. Due to the biomass of phytoplankton and presence of cool water in these regions, upwelling zones 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 thus fishery production. Approximately 25% of the total global marine fish catches come from five upwellings that occupy only 5% of the total ocean area. Upwellings that are driven by coastal currents or diverging open ocean have the greatest impact on nutrient-enriched waters and global fishery yields.

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