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The Pacific Ocean
The Pacific Ocean is the largest and deepest ocean. Its 181 million square kilometer surface is greater than that of all the land masses combined. The Pacific Ocean holds 714 million cubic kilometers of water with an average depth of 3940 meters. The deepest place on Earth is in the Mariana Trench where the sea floor is 11034 meters below the sea surface. From its base on the seafloor to the volcanic peak, Mauno Loa in the Hawaiian Island archipelago is taller than Mount Everest in the Himalayas. Nine seas rim the Pacific Ocean basin. The Bering Sea, Sea of Okhotsk, and Sea of Japan are temperate waters in the north and northwest Pacific. The East China Sea, South China Sea, Java Sea, Arafuna Sea, and South Coral Sea are in subtropical and tropical regions along the western Pacific. The Polar Sea lies along the shore of Antarctica. Ocean currents circulate in the Pacific including the North Pacific Current, California Current, Kuroshio Current, North Equatorial Current, South Equatorial Current, Humboldt Peru Current and East Australian Current1. The Earth’s climate is dictated by the immense capacity of the Pacific Ocean. The Pacific Ocean holds the greatest biodiversity of tropical marine fauna in the world. The waters between the Philippines, Malay Peninsula, and New Guinea known as the Indo-West Pacific hold 6000 species of mollusks, 800 species of echinoderms, 500 reef forming coral species, and 4000 species of fish2. The Pacific Ocean has rich and poor feeding areas between which migrate many species of marine mammals and birds. Nine of 11 species of baleen whales migrate annually between tropical and polar regions of the Pacific3 and some shearwaters transit between southern hemisphere breeding islands and northern hemisphere winter quarters. Some species of albatross traverse thousands of kilometers in a few days to find food in temperate ocean regions that they will feed to their chicks on tropical islands4. Thus, the Pacific Ocean holds a diversity of species unique to particular regions while sharing other species across its vast expanse.
Ten Unanswered Questions about the Ocean Many people think scientists know a lot more than they do. This is especially true in ecology where the discipline is only four decades old and some of the basic theory is not well understood. The following ten questions are topics that might intrigue a curious young scientist to explore for answers.
1. Limpets and shorebirds do it. So do some fish and whales. Many animals travel but they return repeatedly to the same location the next day, month or year. Homing is a common phenomenon of many, but not all animals. How they find their homes is not well understood and even more interesting is why some, but not all animals return to a home base.
2. The commercial removal of many large predatory fish from the oceans is one of the most pressing conservation issues for the oceans. The unanswered question is how will other species respond to the sudden departure of their predators.
3. Why do some individuals of the same species migrate across the hemisphere while others do not? The sanderling is a sandpiper that breeds in the high arctic. It migrates in late summer to sandy beaches from Canada to Chile. Why some stay on the Queen Charlotte Islands in British Columbia while others migrate as far south as the beaches of Chile is a mystery.
4. Ecologists refer to sea otters, sea stars and sea ducks as ‘keystone species’ in North Pacific rocky shore ecosystems. Keystones are species whose removal results in major upheavals in the presence and abundance of other species. How do some species become keystones in ecosystems while others only get to play minor roles?
5. Why are a few species superabundant while most species are uncommon or rare in ecosystems? If you tally all the birds or invertebrates along a beach, you will soon discover that one or two species far outnumber the rest. This is a common phenomenon to all ecosystems.
6. Although there has been much attention to the plight of whales, for the majority of marine mammals scientists know very little. Even some aspects of the lives of well known species are yet to be discovered. Where do North pacific killer whales go in the winter? Where do western Pacific gray whales give birth to their calves?
7. With the exception of commercial species, the biology of most fishes is hardly known. Basic information such as age of maturity, the number of offspring produced each year, life span, diet and breeding habitat is yet to be described for most species.
8. How do seabirds find food in the open ocean, under dim light conditions and in cloudy water?
9. Plastic particles as small as grains of sand reside in the tissues of nearly every living marine animal. What affect will these plastic particles have on the survival of marine life and what can we do if it is a problem?
10. Marine ecosystems undergo large scale changes every few decades or so. These changes are referred to by scientists as regime shifts because the abundance of organisms dramatically changes in a few years. The factors that bring about the sudden change are not well understood.
References 1: Leier, M. 2000. World atlas of the oceans. Key Porter, Toronto. 2: Biggs, JC. 1999. Evolution 53:326-335. 3: Bowen, WD and DB Siniff 1999 Biology of Marine Mammals (Reynolds & Rommel, eds.), Smithsonian. 4. Whittow, GC. 1993. Birds of N. Am. No. 66, Am. Ornithol. Union. |
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