Bros Deiv Blog: ANIMAL LIFE IN THE ARCTIC REGION

“Arctic” comes from the Greek word arktos, meaning bear. The Arctic is often described as a region of snow and ice surrounding the North Pole. A large part of the Arctic is composed of forested tundra where a large number of plants and animals live. Technically, scientists define the Arctic as the region above 66 degrees, 30 minutes of North Latitude, and an area known as the Arctic Circle. Within this region, the sun does not set in the summer. The Arctic is the northernmost part of the earth. The Arctic Circle rings the globe at 66° 33" north latitude, Arctic lands and oceans lie within this circle. North of this imaginary line lie the frozen lands of the Arctic. Seven countries share the Arctic—Canada, Finland, Greenland, Norway, Sweden, Russia, and the United States (Serreze et al., 2007).

The Arctic is large, almost equal in size to the entire continent of North America. Ironically, though most of the Arctic is made up of water it is technically a desert. Since the water is frozen most of the year, it is not accessible to plants or animals. Because of the extreme cold, the atmosphere is unable to hold enough moisture for it to snow or rain very much. In the summer, when the ice melts, water does become available in the lower Arctic regions. Since there is no drainage, it collects and pools to form huge wetlands. The layer of permafrost beneath the surface stays permanently frozen and does not allow water to percolate through the soil (Serreze et al., 2007).

Climate of the Arctic

It’s cold in the Arctic. Ocean water temperatures often stay below the freezing point of fresh water (0°C or 32°F). Dissolved salts and constant movement of the water keep it from freezing solid. On land, air temperatures average only 15.5°C (60°F) during the warmest months. During the winter, weather can be severe, with the temperatures falling to -70°C (-94°F). Strong winds can drop temperatures more. The annual snowfall compares to the snowfall of Chicago; about 30 to 60 cm (12–24 in.). Trees are rare, and plants grow low to the ground. Because the Arctic is at the “top” of the world, the sun may never rise above the horizon on some winter days and may never set below the horizon on some summer days. For example, in December, some days may be 24 hours dark, but in June some days may be 24 hours light. Portage Glacier in the Kenai Peninsula slowly moves down the mountainside, releasing ice and snow decades old to the sea (Addison, 2002).

Biota of the Arctic

There are many different species of plants and animals that live in the Arctic. South of the Arctic tree line lies the Boreal forest which is comprised primarily of coniferous trees such as spruce, fir and larch. To the north of the tree line, there are many low growing herbs, forbs and shrubs such as heath, lingonberries, bilberries, blueberries, arctic poppies, tundra grasses, lichens, mosses, birch and willow shrubs. There are also several different species of animals, including lemmings, Arctic hares, Arctic fox, polar bears, caribou, musk ox, ptarmigan, snowy owl, Arctic tern and many others (Grinberg, 2008).

Animals in the arctic region includes; Land Animals: Polar bear, wolf, musk ox, Arctic fox, snowshoe hare, wolverine, weasel, lemming, moose, elk, reindeer. Marine animals; walrus, seals, whales, sea otters. Birds; Raven, ptarmigan, geese, ducks, swans, phalarope, gulls, horned lark, snow bunting, Arctic tern, skua (Toledo Zoo, 2000).

Shrimps, fishes, seals, walruses, and whales thrive in the cold, nutrient-rich waters of the Arctic Ocean. Caribou, moose, and musk oxen roam the tundra. Polar bears prowl the ice. Birds such as ptarmigans and snowy owls live year-round in the cold weather. Many other animals visit arctic lands to feast on summer plants and insects. Some birds, seals, and whales migrate south during the coldest arctic months. Others stay year-round, protected by thick layers of blubber or dense coats of fur. The arctic fox and grouse change colors; they are brown in summer, white in winter (Toledo Zoo, 2000).

Climate change in the Arctic

In the Arctic, climate changes are particularly intense. These changes will affect the rest of the world by increasing global warming further and raising sea levels. Evidence of the recent warming of the Arctic is provided by: records of increasing temperatures; melting glaciers, sea ice, and permafrost; and rising sea levels. Global temperatures are expected to increase further during the 21st century. In the Arctic, this warming is expected to be substantially greater than the global average, and the following changes are expected over the current century*: The average annual temperatures are projected to rise by 3 to 7 °C (5 to 13°F), with the greatest warming occurring in the winter months Precipitation is projected to increase by roughly 20%. Sea ice is expected to continue to decline significantly, reflecting less solar radiation and thereby increasing regional and global warming. The area of Arctic land covered by snow is expected to decrease by 10 to 20%. These projections assume a gradual warming. However, abrupt and unexpected changes cannot be ruled out (Arctic Climate Impact Assessment (ACIA) 2004).

Many Arctic animals, such as polar bears, seals, walruses, and seabirds, rely on the sea’s biological productivity and on the presence of sea ice, both of which are highly dependent on climatic conditions. Changes in sea surface temperatures or currents could have a strong effect on Arctic marine fish stocks, which are an important food source for the world and play a vital role in the region’s economy. Rising temperatures could have both positive and negative impacts on the aquaculture of salmon and trout, which is a major industry in the Arctic.

A decline in certain types of vegetation would affect the animals that feed on them (such as lemmings or reindeers). In turn, predators (such as foxes or birds of prey) and human communities that depend on these animals would be affected. Freshwater ecosystems, such as rivers, lakes, and wetlands are home to a variety of animals. They would be affected by increases in water temperature, thawing of permanently frozen ground, and ice cover breaking up earlier in spring. Arctic Climate Impact Assessment (ACIA) 2004

Animal’s survival in the Arctic region

The polar bear (Ursus maritimus) is the world’s largest bear. The polar bear is often regarded as a marine mammal because it spends many months of the year at sea Polar bears live on the ice-covered waters of the Arctic, relying almost entirely on the sea ice for their survival. Polar bears do not exist as one large population throughout the Arctic, but are distributed as 19 more-or-less isolated groups of bears called stocks or populations (NOAA 2011, Durner et al., 2009). They are found in Arctic areas of Canada, Greenland, mainland Norway, Russian Federation, Alaska, Svalbard and Jan-Mayen and on the ice surrounding the North Pole (Schliebe et al., 2008). Polar bears do not occur in large numbers – a scientific paper published in 2006 estimated that the total number of polar bears in the Arctic was between 20,000 and 25,000 (Wigg 2008).

A boar (adult male) weighs around 350–700 kg (770–1,500 lb), while a sow (adult female) is about half that size. With many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet. Although most polar bears are born on land, they spend most of their time at sea. Their scientific name means "maritime bear", and derives from this fact. Polar bears can hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present (Brach, 2008).

Polar Bear Adaptation and Survival in the Arctic

The polar bear is the most carnivorous member of the bear family, and most of its diet consists of ringed and bearded seals (PBS, 2008). The Arctic is home to millions of seals, which become prey when they surface in holes in the ice in order to breathe, or when they haul out on the ice to rest. Polar bears hunt primarily at the interface between ice, water, and air; they only rarely catch seals on land or in open water. The polar bear's most common hunting method is called still-hunting. The bear uses its excellent sense of smell to locate a seal breathing hole, and crouches nearby in silence for a seal to appear. When the seal exhales, the bear smells its breath, reaches into the hole with a forepaw, and drags it out onto the ice. The polar bear kills the seal by biting its head to crush its skull. The polar bear also hunts by stalking seals resting on the ice: Upon spotting a seal, it walks to within 90 m (100 yd), and then crouches. If the seal does not notice, the bear creeps to within 9 to 12 m (30 to 40 ft) of the seal and then suddenly rushes forth to attack. A third hunting method is to raid the birth lairs that female seals create in the snow (Kendall, 2013).

With the exception of pregnant females, polar bears are active year-round, although they have a vestigial hibernation induction trigger in their blood. Unlike brown and black bears, polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen. When sea ice is unavailable during summer and early autumn, some populations live off fat reserves for months at a time. Polar bears have also been observed to eat a wide variety of other wild foods, including musk ox, reindeer, birds, eggs, rodents, shellfish, crabs, and other polar bears. They may also eat plants, including berries, roots, and kelp, however none of these are a significant part of their diet. The polar bear's biology is specialized to require large amounts of fat from marine mammals, and it cannot derive sufficient caloric intake from terrestrial food (Eliasson, 2004).

Being both curious animals and scavengers, polar bears investigate and consume garbage where they come into contact with humans. Polar bears may attempt to consume almost anything they can find, including hazardous substances such as Styrofoam, plastic, car batteries, ethylene glycol, hydraulic fluid, and motor oil (Eliasson, 2004).

This bear is “built” just right for life in the frigid Arctic. Its coat has two layers of fur and a layer of thick fat (called blubber) underneath. These keep a bear’s body heat in and the cold out—even better than a heavy winter jacket could. Polar bears have adapted well to their northern climate. Their hair follicles are hollow so that they have a natural insulation to the cold. They have fur on the soles of their paws so that they are able to grip the ice when walking or running. They swim well in the arctic waters with this insulation and their paws are webbed to make swimming easier. In the winter they have their young in snow dens. This time of the year is safe for the young cubs. Polar bears have inhabited the Arctic for a long time. 130,000 years of evolution have created an animal uniquely suited to the harsh, unforgiving arctic climate. Large claws, fur and papillae (small bumps on the pads of their feet) give the bears traction on the ice, while their characteristic white fur provides camouflage and insulation.

Polar bear and climate change

The key danger posed by climate change is malnutrition or starvation due to habitat loss. Polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt earlier in the year, driving the bears to shore before they have built sufficient fat reserves to survive the period of scarce food in the late summer and early fall (Regehr et al., 2006). Reduction in sea-ice cover also forces bears to swim longer distances, which further depletes their energy stores and occasionally leads to drowning (Monnett et al., 2006). Thinner sea ice tends to deform more easily, which appears to make it more difficult for polar bears to access seals. Insufficient nourishment leads to lower reproductive rates in adult females and lower survival rates in cubs and juvenile bears, in addition to poorer body condition in bears of all ages (Amstrup et al., 2007).

In addition to creating nutritional stress, a warming climate is expected to affect various other aspects of polar bear life: Changes in sea ice affect the ability of pregnant females to build suitable maternity dens. As the distance increases between the pack ice and the coast, females must swim longer distances to reach favored denning areas on land (Derocher et al., 2004).

Polar bears accumulate high levels of persistent organic pollutants such as polychlorinated biphenyl (PCBs) and chlorinated pesticides. Due to their position at the top of the food pyramid, with a diet heavy in blubber in which halocarbons concentrate, their bodies are among the most contaminated of Arctic mammals. Oil and gas development in polar bear habitat can affect the bears in a variety of ways. An oil spill in the Arctic would most likely concentrate in the areas where polar bears and their prey are also concentrated, such as sea ice leads. Because polar bears rely partly on their fur for insulation and soiling of the fur by oil reduces its insulative value, oil spills put bears at risk of dying from hypothermia. Polar bears exposed to oil spill conditions have been observed to lick the oil from their fur, leading to fatal kidney failure. Maternity dens, used by pregnant females and by females with infants, can also be disturbed by nearby oil exploration and development. Disturbance of these sensitive sites may trigger the mother to abandon her den prematurely, or abandon her litter altogether (Monnett et al., 2006).

Polar bears are uniquely adapted to the harsh Arctic environment. It may be one of the toughest places on Earth to survive but to a polar bear, its home. And since the sun never sets during summer in the Arctic, bedtime is anytime.

Source: Stirling et al., (2011)

Stirling, I., Richardson, E., Thiemann, G. W. & Derocher, A. E. (2008). Unusual predation attempts of polar bears on ringed seals in the southern Beaufort Sea. Possible significance of changing spring ice conditions. Arctic, 61 (1), 14-22.

In Arctic regions, the walrus (Odobenus rosmarus) inhabits the Bering and Chukchi Seas of Russia and Alaska, the Laptev Sea in the west and the western Beaufort Sea in the east (Chadwick & Fischbach 2008, Lowry et al., 2008). Male walruses reach about 3.6m in length and weigh 880- 1,557kg; adult females are about 3m and 580-1,039kg. Walruses feed on the sea bed on clams, worms, snails and crabs and other bottom-dwelling creatures. Although walruses can dive to depths of 250m, they generally feed in shallow waters less than 80m deep over the continental shelf (Chadwick & Fischbach 2008).

Adaptation and survival of Walruses in the Arctic

Walruses spend most of their lives associated with sea ice and migrate with the ice as it expands and moves south in the winter and breaks up and retreats in the spring and summer. In winter, the ice is a platform for resting, feeding and breeding. During the spring and summer the male walruses remain mainly on land, whereas large numbers of the females with their calves stay on the ice, using it as a rafting platform for resting, feeding and nursing their young. For those walruses floating on sea ice, they use the ice as a platform to dive for food and the prevailing ocean currents continually carry them over new areas where new food sources are abundant (Robards et al., 2009).

Over the past several decades the extent of Arctic summer sea ice has decreased. In the past few years, the areas over the Chuckchi Sea shelf was ice free from one week to as much as two-and-a-half months, whereas previously there was always some ice cover over this region. When the sea ice retreats to just the deep ocean basin, walruses must either continue to use the ice in deeper waters where there is little access to food, or move to the land. In 2007, there was no ice for about 80 days and several thousand walruses moved to shores in northwest Alaska that had never been used by walruses before. This retreat of the sea ice has caused problems for the walruses. During the autumn of 2007, herds of walruses had to move to land along the northern coast of Chukota because of retreating sea ice. Here, a few thousand deaths among the population were reported because of overcrowding and panic stampedes into the water (Chadwick & Fischbach 2008). Such mass congregations that can lead to violent stampedes are particularly dangerous for the young walruses.

Pinnipeds (Phoca vitulina) also known as fin-footed mammals, often generalized as seals, are a widely distributed and diverse group of fin-footed marine mammals which are semi aquatic comprising the families Odobenidae (the walrus), Otariidae (eared seals, sea lions, and fur seals), and Phocidae (earless seals). Seals are typically sleek-bodied and barrel-shaped. Their bodies are well adapted to the aquatic habitat where they spend most of their lives. Their limbs consist of short, wide, flat flippers. The smallest pinniped, the Baikal seal, weighs about 70 kg on average when full-grown and is 1.3 m (4 ft 3 in) long; the largest, the male southern elephant seal, is over 4 metres (13 ft) long and weighs up to 4,000 kilograms (Jeff et al., 2007).

Adaptation and Survival of Pinnipeds in the Arctic

Pinnipeds are carnivorous, eating fish, shellfish, squid, penguins, and other marine creatures. Most are generalist feeders, but some specialize. For example, Ross seals and southern elephant seals mainly feed on squid. Crabeater seals eat mostly krill, and ringed seals almost exclusively consume crustaceans. The walrus consumes its molluscan prey by sucking the soft parts from the shell. Some seals eat warm-blooded prey, including other seals. The leopard seal, which is probably the most carnivorous and predatory pinniped, eats penguins as well as crabeater and Ross seals. The South American sea lion also eats penguins, flying seabirds and young South American fur seals. Steller sea lions eat northern fur seal pups, common seal pups, and birds. Almost all pinnipeds are potential prey for orcas and larger sharks. Arctic species are an important component of polar bear diets (Rybczynski et al., 2009).

As the Arctic ice pack diminishes, more species of pinnipeds are hauling out on the shores. Walrus and spotted seals on the coasts of the United States, Canada, and Russia, show increasing signs of an often-fatal, mystery disease of unknown etiology. Harp seals in Greenland may be similarly affected (Rybczynski et al., 2009).

Fur seals have both blubber and a specially adapted fur coat, including outer guard hairs that repel water and a layer of insulating under fur. This coat is adapted for the terrestrial, preweaning period, either a thick pelage to keep them warm in arctic environments, or a thin layer of fur to keep them cool on summer sands. Pinnipeds have unique lungs with airways highly reinforced with cartilage and smooth muscle, and alveoli that completely collapse during deeper dives (Ulfur et al., 2006).

Some pinnipeds can hold their breath for nearly two hours underwater by conserving oxygen. During long duration dives, the heart rate can be reduced to about one-tenth of its normal rate. The arteries vasoconstrict and the sense organs and nervous system are the only organs to receive normal blood flow. They are able to resist more pain and fatigue caused by lactic acid accumulation than other mammals. However, once they return to the surface, they need time to recover and normalize their body chemistry (Jeff et al., 2007).

Pinniped eyes are well adapted for seeing both above and below the water surface. The animal has a clear membrane that covers and protects its eyes underwater. In addition, its nostrils close and blood circulation to most of its organs is reduced while diving. Testicles and mammary glands are located in slits under the skin to maintain the pinniped’s streamlined shape. They also have whiskers to help navigate, and sensors in their skull to absorb sounds underwater and transmit them to the cochlea (Rybczynski et al., 2009).

Other Land mammals in the Arctic

Moose, unlike most Arctic animals, have long legs. These are helping for stepping in the snow, but could cause it to lose a lot of body heat.

Caribou often migrate long distances to avoid the cold and search for food and shelter. They have broad hooves that splay out and help them walk across the snow. The hooves also help them swim and to dig in the snow to find plants buried below.

Many small mammals, particularly rodents like the ground squirrel, hibernate during the winter. Hibernation means they rest- almost like sleeping- for many weeks or months without eating, drinking or even waking up! Their body temperature drops and they live off of stored fat. Many people think of bears when they think about hibernation, but most bears don’t really hibernate. They get up several times throughout the winter to forage for food, and some females give birth during this time.

Caribou herds migrate to the North Slope of Alaska at the end of every winter, participating in one of the largest migrations on Earth. For ten thousand years, caribou have traveled here to give birth to their calves.

Arctic hares have very short ears and legs to prevent heat loss. They also have large padded feet that act like snowshoes to help them hop across the snow. In spring, hares are brown with black flecks, but in winter, they change to all white. The color change serves as camouflage to protect it from predators.

Ptarmigans remain in the Arctic year round. They change color from brown in the spring to solid white during the winter. The color change helps to protect them from hungry predators. To keep warm, they have water-repellent outer feathers in addition to inner feathers. They even grow feathers on the soles of their feet to keep their feet warm and serve as snowshoes to prevent them from sinking in the snow! Another solution to staying warm is to take flight and dive into drifts of snow. The snow acts like a blanket and traps heat from the ground (Ulfur et al., 2006).

Other birds deal with the cold winters by avoiding the situation all together. As winter approaches, birds like the Red throated Loon and Arctic Tern migrate south to warmer regions.

The Arctic Tern is an amazing bird in that every year it migrates all the way from the Arctic to the Antarctic. That’s over 22,000 miles (Jeff et al., 2007).

Unlike seals and other mammals, fish do not keep their body temperature much higher than the water around them. The important thing is for the fish to keep ice crystals from forming inside their body, because ice builds quickly once it starts. Therefore, some fish have a protein in their blood that acts like antifreeze in a car. It binds to ice crystals, isolating them from each other so they can’t grow (Ulfur et al., 2006).