Tuesday, March 20, 2018

Photo: Microphotograph of a radiolarian (Lamprocyclas maritalis) Courtesy of D. Boltovskoy (CONICET-UBA)

This region is the breeding ground and foraging area of 75% of the black-browed albatross global population (around 400,000 pairs).  More than one million pairs of Magellanic penguins breed annually in several colonies on the coast of both the continent and the islands.  The only southern elephant seal population that breeds on the continent is to be found on the Patagonian coast of Argentina.  The southern right whale, a species that is recovering from the threat of extinction, breeds off the same shores.  The blue whale (the largest animal in the world) has a major breeding ground in Chilean waters, in the Corcovado Gulf area where over 200 of these marine giants have been counted in one season.   Nearby, Guafo island is home of the largest seabird colony in the world with around four million sooty shearwaters.


Natural spectacles
The Patagonian Sea is extremely rich in living species some of which are exclusive to this part of the world.   The great abundance and biomass of intermediate organisms in food chains which provide food for predators, is outstanding.  Some 1,400 species of organisms which belong to the zooplankton group have been described in the Brazil and Falklands (Malvinas) currents, almost all of them microscopic. Only a fraction of the invertebrates which inhabit these waters are known.  Among these we know that there are more than 900 species of molluscs and it is estimated that other groups such as crustaceans and polychaetes (sea worms) make up at least hundreds of species.   Just under 700 species of vertebrates have been registered of which approximately 400 are bony fish; 120 are cartilaginous fish (sharks and skates); 80 are sea birds; 50 are marine mammals and 5 are marine turtles.

Rock and imperial shags – © V. Zavattieri (WCS)

Biodiversity crosses political boundaries

The edge of the continental shelf is an environment in which there are remarkable aggregations of marine life, both in the water column and on the seabed, that in turn attract a variety of species on the surface.   This area is globally significant as a source of food for migratory species of seabirds, fish, turtles and marine mammals which come from afar.   More tan 35 species of albatrosses and petrels use the Patagonian Sea as their foraging area.   Some albatrosses and petrels migrate from distant places such as the South Georgia Islands, Tristán da Cunha, Diego Ramírez and New Zealand.  Elephant seals that breed on the Patagonian coast have been recorded foraging in the ocean along the edge of the continental shelf.  They have also been found translocating as far as the South Georgia Islands, the Falkland Islands (Islas Malvinas) and southern Chile.  Magellanic penguins migrate by sea, after breeding on the Patagonian coast, as far north as the waters off the southern shores of Brazil during the austral winter.

Migration of fauna and political jurisdictions – © Sea and Sky Project (WCS)
Elefante marino del Sur: Southern elephant seal
Lobo peletero antártico:  Antarctic fur seal
Pingüino de Magallanes:  Magellanic penguin
Tortuga laud:  leatherback turtle


Threatened species

Some 65 species inhabiting the Patagonian Sea were categorized as threatened in 2007 following global criteria established by the International Union for Conservation of Nature (IUCN). Some human-caused factors in this region contribute to the decline of the populations of these living organisms, adding to the threats they suffer in other parts of the world. If the threats that affect them do not decline, all marine turtle species and a growing number of sharks and skates face the high probability of extinction.

About 20 seabird species are threatened either to a lesser or greater degree. This number amounts to 30 % of the species of the region in this group. The majority are albatrosses and petrels, among them the Wandering, Southern Royal and Northern Royal Albatrosses, whose breeding colonies suffered rapid declines during the last decades.

Among the marine mammals that visit and live in the Patagonian Sea, some are considered “vulnerable” or “endangered” on a global level, being the Franciscana dolphin, the blue whale and the sperm whale part of this group.


Black-browed albatross – © L. Tamini (AA-BLI)


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