26 Aug 2014
Introducing Antarctica, the Southern Ocean and their Ocean Health Index
The 2014 Ocean Health Index, scheduled for release in September, will
include evaluation of two new regions: the High Seas and Antarctica. Who would have thought that these places, so
distant from most of our lives, would be so important to us? Especially to the 90 percent of our
population who live in the northern hemisphere, Antarctica really seems like ‘the
end of the world." This article presents a little of its history, importance
and magic as well as background to the scores that will be presented next
month. We hope it whets your appetite to
Imagining -- and finding -- a Continent
Nearly two thousand years ago, Aristotle, Ptolemy and other early Greek
philosophers believed there must be a huge continent far to the south to
‘balance’ Europe, Asia and the other lands in the north. In the 1500s that imaginary continent began
to appear on maps, usually as ‘Terra Australis Incognito’, but once, in a map
by Marinus of Tyre, named ‘Antarctica’.
For the next three hundred years explorers ventured further and further south, but the face of the mystery continent remained hidden by a veil of ferocious seas, extravagant winds, and terrifying fields of impenetrable ice. Finally in 1820, three separate expeditions glimpsed islands and land at the continent’s closest reach, the Antarctic Peninsula.
During the next two centuries, many countries sent expeditions to describe the continent’s geography geology, biology and ecology---or to hunt its stunning populations of seals and whales. Those voyages produced epic tales of human endeavor in the world’s worst weather as well as steadily growing knowledge of this distant, forbidding, magnificent place.
Antarctica and its Ocean
Like Australia, Antarctica is an island continent, completely
surrounded by the Southern Ocean, the world’s fourth largest ocean,
encompassing more than 13 million square miles. With no land to block it, the
west wind endlessly circles the continent, spawning sudden gales with
hurricane-force winds and piling water into huge waves up to 100 feet high.
Knowledge of the Southern Ocean accumulated slowly owing to the difficulty,
danger and expense of working in those raging, frigid, ice-crusted seas. Directed studies began in the early 1900s
when Britain launched expeditions aimed at conserving whale populations that
were experiencing increased hunting pressure. Voyages of the Discovery and Discovery II from 1925-1951 produced the
Reports, 37 volumes published from
1929 to 1980, the most comprehensive historical study of the area ever completed
and the foundation for all modern studies.
More than 40 countries now maintain year-round or summer-only land bases
on Antarctica or islands in the Southern Ocean, but much of the continent and
ocean have still not been explored.
Why is the Antarctic region important?
You might wonder why so much effort is expended in this remote portion
of the world. Nobody lives there, except
for several thousand scientists and staff in the land bases maintained by 30
countries on the continent and some surrounding islands. So how does the Antarctic affect our lives;
and how do we affect it?
Antarctica and its ocean play important roles in regulating the earth’s
climate. The vast continental ice sheet, nearly 12 million sq.km in extent, extensive
ice shelves, more than 1.5 million sq.km) and seasonally-forming sea ice provide
ice-cooled air to atmospheric circulation and reduce temperature rise by
reflecting sunlight back to space.
Seawater cooled by contact with Antarctica’s ice shelves flows north. Seawater freshened by melt water stays forms the Antarctic Surface Current, moving north with its load of drifting plankton until it collides with currents flowing south to form the Antarctic Convergence. Concentration of the plankton at the Convergence drives a short, but productive food web creating a rich pasture for seabirds, and seals that depend on these populations in order to feed and rear their offspring during the Antarctic summer.
It is not yet clear how the climate of the Antarctic region itself is changing, as some locations show warming, others cooling, and changes in the extent of shelf and sea ice also appear to vary between regions. What’s more, the Antarctic climate is affected not only by increasing concentrations of atmospheric CO2, but also by reduction in stratospheric ozone—the ‘ozone hole’---caused by emissions of gases (e.g. chlorofluorocarbons) as refrigerants and propellants.
Understanding climate change in Antarctica is also crucially important, because its continental ice sheet contains 26.5 million cubic kilometers of ice that would raise sea level by 60 meters if it melted. Melting would take thousands of years, but once started would be difficult to stop---and sea level rise of only a foot or two would seriously challenge coastal cities worldwide.
For most people, the Antarctic region’s unique animals, including penguins, albatross, whales and seals, are its most alluring feature. Its mainland, islands and ocean don’t have nearly as many species as occur in more temperate and tropical climes, but the size and abundance of Antarctic species is spectacular.
Ice is central to all their lives. The ice shelters overwintering marine life from brutally low air temperatures of -100F (-37C) or colder in the continental interior and -40F (-40C) offshore. Krill shelter in small hollows or crevices on the underside of the ice, scraping food from crevices. In the spring, when the ice melts, huge populations form, releasing ice-trapped plankton to jump start the food web. Krill in turn become the major prey for nearly everything else. Without it, none of Antarctica’s signature animals would exist
The region hosts other less visible animals, too. Planktonic salps, beautiful strings of colonial jelly organisms filter food from the water, propelled by pulsing bells. Huge populations of Pteropods, tiny mollusks that swim with wing-like folds of their body tissue are eaten by krill and whales. Along the continental shelf, the bottom also teems with life, often completely covered with sea anemones, sponges, sea stars, sea lilies, worms, stalked tunicates and isopod crustaceans. Many of the species are considerably larger than their more temperate relatives.
In addition to climate change, other
pressures also threaten Antarctica’s marine life. Ocean acidification, caused by absorption of
increasing amounts of atmospheric CO2 into seawater, may already be reducing
the ability of animals like mollusks, echinoderms, corals and others to form
calcium carbonate shells. By affecting
pteropods acidification could harm pelagic food webs; by affecting sea stars,
sea lilies, corals and others, it could also affect bottom communities.
Climate warming could cause considerable harm to Antarctic bottom communities by allowing ‘new’ predators to invade. Animals with claws or jaws that can crush shells, such as crabs, sharks and most fish, have been excluded from Antarctic bottom waters by cooling that began 65 million years ago or so, since they are unable to live in waters that are permanently at 0°C. Warming would allow some of those animals to return to areas such as the Weddell and Ross Seas, where their predation would likely change the character of bottom communities.
Food from the Southern Ocean
Despite its great distance from most population centers, some of the
Southern Ocean’s profusion of life has attracted fishing fleets from many
nations. First came the sealers and whalers, beginning in about 1909, but
reaching their peak after factory ships arrived in the 1960s. The animals were mainly rendered into oil,
bone meal and pet food, though some meat was sold for human consumption. Commercial whaling ceased in 1986, but
fisheries had their eye on other species in these productive waters.
Fisheries don’t have many as many species to choose from, because few fish have colonized Antarctica’s cold waters. They include a group called Nototheniids---which includes Toothfish, Snailfish (Liparidae), eel pouts (Zoarcidae) and Icefish (Channichyidae).
is the main species that has been harvested commercially, beginning in 1996. Antarctic Toothfish (Dissostichus mawsoni), which
grow to more than 2 meters long and 135 kg, are usually sold as Chilean Sea
Bass, as is the related Patagonian Toothfish (D. eleginoides). Most Antarctic Toothfish are caught in the
Ross Sea. It is not yet clear whether
its harvest is sustainable or not though some fisheries have been certified as
sustainable. People aren’t the only ones
interested in large toothfish: Sperm Whales, Killer Whales, Weddell Seals and
others also eat them.
Antarctic fishes are interesting in other ways than as things to eat, because some have evolved unique adaptations to their very cold environment. Many Nototheniids, including the Antarctic Toothfish, produce their own antifreeze--a glycoprotein that lowers the freezing point of their blood—so that they don’t freeze in very cold water close to the ice. The Antarctic Toothfish also evolved a relatively light skeleton and large fat deposits, both of which help the fish save energy by remaining neutrally buoyant. Icefish are unique in a different way, because they are the only vertebrates that don’t have the red blood pigment, hemoglobin. Their metabolism is low enough at such cold temperatures that the abundant oxygen in the cold water can simply diffuse into their blood fluid, thereby saving the energy that other fish use to make hemoglobin.
In addition to Toothfish, another animal, Antarctic Krill (Euphausia superba), put a twinkle in
fishermen’s eyes, because these shrimp-like crustaceans are present in huge quantities.
So far they have not been used for human consumption, but instead mainly for
animal food and fish bait. About 100,000
tons are harvested annually, mostly by South Korea, Norway, Japan and
Poland. The catch is still small
compared to the size of the krill population, which may exceed 500 million
tons, with some schools said to cover hundreds of square kilometers, large
enough to be visible from space. One
factor thought to boost their populations is that krill might stimulate
productivity of the plant plankton they eat by mixing nutrients up to the
surface as they swim. Since Krill is the
foundation of the entire Southern Ocean food web, its management deserves great
Tourism in Antarctica
Tourism brings people face to face with Antarctica’s magnificent
landscape, seascape and wildlife, but with it come many pressures to what has
been until recently a nearly pristine region.
These include pollution from ship’s exhaust or overboard discharge of
waste or ballast water, and the threat of oil pollution from groundings or
other accidents. Disturbance of habitat
and wildlife and unintentional transmission of invasive species and diseases to
wildlife must also be controlled. Guidelines for tourists
emphasize these and other important considerations.
Few tourists considered the possibility of visiting Antarctic before 1969 when Lars-Eric Lindblad launched MS Lindblad Explorer, a ship specially designed to operate in ice conditions. The number of people visiting has grown from just a few hundred people in the early years, when tourism was mainly done by overflights from New Zealand or Australia, to tens of thousands. A total of 37,552 people visited in the 2006-07 season when ships and boats (including 17 yachts) were registered with the International Association of Antarctica Tour Operators (IAATO). IATTO data list the total number of people landed at all Antarctic destinations by the 20 ships reporting as exceeded 400,000 (each visitor landed at a number of locations during his/her trip).
How do you govern an enormous continent and ocean that has no permanent
residents? Individual States cannot do
it, therefore it must be done internationally, by treaties entered into
voluntarily by interested nations.
In 1959, the Antarctic Treaty was enacted to ensure that
Antarctica would forever be used exclusively for peaceful purposes and science in
the interest of all mankind. Other
treaties have since been constructed for specific purposes so that all together
they form an interconnected Antarctic Treaty System. The U.S. State Department prepared a Handbook that includes the
text of all relevant treaties current as of 2002. The Web sites of the Secretariat of the Antarctic Treaty and the Commission for the Conservation of
Antarctic Marine Living Resources (CCAMLR) provide
CCAMLR oversees (CAMLR), the Convention on Antarctic Marine Living Resources, which applies to all fish, mollusks, crustaceans and sea birds found south of the Antarctic Convergence, but not whales and seals, which are managed under other treaties, particularly the International Convention for the Regulation of Whaling and the Convention for the Conservation of Antarctic Seals.
The Scientific Committee for Antarctic Research (SCAR) coordinates high quality science in the Antarctic region and gives information on many ongoing projects.
We don’t know what the future will bring to Antarctica. There is speculation that very large deposits
of oil and gas might exist on its continental shelves. Poly-metallic nodules containing
manganese and many other elements may exist on its seafloor. Schemes to tow icebergs to
water-starved countries have been mentioned.
It remains to be seen whether such distant ventures are economically
feasible, but more important is whether they are ecologically feasible. The Antarctic region’s massive scale, ferocious
winds and waves of legendary height belie its essential fragility. Its low temperature and short food web ensure
that recovery from disturbances or accidents would have substantial impacts and
require long periods for recovery.
CCAMLR specifies that the Antarctic region is the heritage of all
mankind, so it is our common obligation to ensure that nothing damages this
extraordinary place, wondrous even beyond the imaginations of those who
imagined it to exist. We are excited to announce that this year’s assessment by
the Ocean Health Index will include an evaluation of all ten goals for
Antarctica, allowing us to better understand and better track the changes
undergoing this pivotal area.