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1AC Deadzones Coral Module

Deadzones kill coral reefs


Mee 2006 [Laurence Mee-Ph.D. in oceanography and the director of the Marine Institute at the University of Plymouth, “ Reviving Dead Zones”, November 2006, http://sbc.lternet.edu/~leydecke/Al's_stuff/Articles%20of%20General%20Interest/Reviving%20Dead%20Zones.pdf]

oc e a n r e se a rc h e r s today link the creation of most dead zones to a phenomenon called eutrophication, the overenrichment of the sea by nutrients (principally compounds containing nitrogen and phosphorus) that promote plant growth. A certain amount of these “fertilizers” is essential to the health of phytoplankton—floating algae and other microscopic photosynthesizers that form the base for most marine food chains—as well as for the well-being of the sea grasses and algae that live on the floors of shallow, well-lit seas. But too much of these nutrients in illuminated waters greatly accelerates plant growth, leading to disruptive algal blooms and other unwanted effects. Plants enter the food chain when tiny seaborne animals (zooplankton), herbivorous fish and filter-feeding bottom dwellers such as mussels and oysters graze them or when they die, decay, fall to the seabed, undergo bacterial decomposition and are incorporated into the underlying sediments. This organic bottom matter feeds the animals living there, including worms, shrimp and some fish. Normally the numbers of phytoplankton are limited by the availability of light and nutrients and by grazing. But large increases in nitrogen and phosphorus concentrations enable these minute photosynthetic organisms to multiply in great profusion. The water eventually turns green or even brown as phytoplankton populations burgeon, and the shade they cast deprives plants living below them of essential sunlight. Sea grasses in shallow bays also become covered with small attached algae (epiphytes) and can ultimately be smothered and die. Algae can in addition envelop coral reefs, especially where heavy fishing pressure has thinned the ranks of resident grazers. A major upsurge in the numbers of phytoplankton and epiphytes immediately causes difficulties for nearby sea life, but an even worse situation arises when oxygen levels in bottom waters decline. Lower oxygen concentrations appear when bacteria consume oxygen to break down the masses of organic matter that result from animal wastes and the dead bodies of organisms that multiply during eutrophication. Much of this material accumulates on the seafloor, where oxygen is relatively scarce to begin with. Oxygen finds its way into the water from either photosynthesis or physical diffusion from the air at the sea surface. Should an area whose bottom is covered with dead plants also feature a strong density gradient that prevents mixing with the overlying water column, the oxygen at the bottom can soon become exhausted, leading to the die-off of entire animal communities. (Such gradients can stem from temperature or salinity differences in the water at various depths.) This basic sequence—eutrophication leading to phytoplankton blooms, excess bacterial activity at the bottom, oxygen depletion, and the death of existing plants and animals—has occurred in almost every dead zone examined by researchers. The details do vary, however, according to the local biological and physical conditions as well as the rate of supply of plant nutrients from the land. Poorly flushed estuaries, for example, are particularly vulnerable to the effects of eutrophication, because low water flows lead to slow replenishment of oxygen in bottom waters. This reduction in oxygen has been a persistent problem along the eastern seaboard of the U.S., where large estuaries, such as the Chesapeake Bay, have been affected. The excess of nitrogen and phosphorus arriving in coastal seas results in large measure from the changing habits of people living in the areas draining into the sea. Rising fossil-fuel use (which releases nitrogen into the atmosphere), effluent from the mass breeding of food animals and intensive farming, and the construction of sewage systems that empty into bodies of water all lead to greater nutrient emissions into watersheds. The Millennium Ecosystem Assessment released by the United Nations in 2005 reported that the supply of nitrogen-containing compounds to the sea grew by 80 percent from 1860 to 1990. It predicted that the overall outflow to the oceans from human activities will increase by an additional 65 percent by midcentury. Dead zones are thus likely to become even more widespread unless society takes prompt action to reduce plant nutrient runoff. Watery Graveyard alt hough emergence of a dead zone is the final stage of the eutrophication process, marine systems, especially the animal populations, undergo changes long before then. A healthy coastal marine food chain often starts with silica-shelled phytoplankton called diatoms, which are consumed by copepods, minuscule zooplanktonic crustaceans. These animals, in turn, serve as food for fish. Increased nutrient concentrations affect the mix of phytoplankton species such that diatoms often become outnumbered by smaller or less digestible types. When eutrophication produces massive phytoplankton blooms, copepods often are unable to graze on the new, abundant phytoplankton species as well as the large quantities of organic detritus that result from the disruption of the natural ecosystem. This change favors the growth of highly tolerant gelatinous organisms such as Noctiluca (responsible for nighttime phosphorescence that occurs when the water surface is disturbed). Biologists sometimes call these jellyfishlike fauna “dead-end species” because higher-level predators have difficulty living off them. Their presence reduces the efficiency of the food chain, leading fish stocks to wane. Such an imbalance in the food chain can be worsened by intense commercial fishing, particularly where these efforts target high-value “top predator” species such as cod, hake, dorado or horse mackerel. Loss of apex fish species leads to rises in the numbers of small prey fish, which results in fewer zooplankton (the food of the small fish) and, consequently, even more phytoplankton. Scientists call this sequential process “trophic cascading.” An inefficient food chain engenders more organic matter on the seafloor, which enhances the risk that a dead zone will follow. Ecosystems altered by eutrophication also become more vulnerable to invasion by foreign species, which can arrive, for example, in the ballast discharge from transoceanic ships. In the 1980s the comb jellyfish Mnemiopsis leidyi, which probably originated off the eastern coast of the U.S., took up residence in the Black Sea. By 1990 this voracious dead-end predator dominated the ecosystem completely, at its maximum attaining an astounding density of up to five kilograms per square meter. Sometimes shellfish reefs can help stave off degradation of an ecosystem. In many estuaries on the eastern seaboard of the U.S., oysters act as ecosystem engineers by accumulating into huge reefs rising several meters from the seabed; these reefs support a diverse assemblage of organisms, including flounder, snapper, silver perch and blue crabs. Hunter Lenihan of the University of California, Santa Barbara, and Charles H. Peterson of the University of North Carolina at Chapel Hill have shown, for example, that the tops of oyster reefs in North Carolina’s Neuse River became refuges for displaced bottom-water species at the onset of dead zone formation because they projected above the deoxygenated water layer. Mechanical oyster harvesting frequently shortens the height of these reefs, however, which helps to destroy the natural resilience of these ecosystems.

Reef extinction ripples through the food chain making larger extinctions inevitable


Levitt 3/27/2013 [Tom Levitt, “Overfished and under-protected: Oceans on the brink of catastrophic collapse”, March 27, 2013, http://www.cnn.com/2013/03/22/world/oceans-overfishing-climate-change/]
At the same time fisheries and vital marine ecosystems like coral are being decimated, the oceans continue to provide vital services, absorbing up to one third of human carbon dioxide emissions while producing 50% of all the oxygen we breathe. But absorbing increasing quantities of carbon dioxide (CO2) has come at a cost, increasing the acidity of the water. "The two worst things in my mind happening to oceans are global warming and ocean acidification," says O'Dor, "They're going to have terrible effects on coral reefs. Because of acidification essentially, the coral can't grow and it's going to dissolve away." The ocean has become 30% more acidic since the start of The Industrial Revolution in the 18th century and is predicted to be 150% more acidic by the end of this century, according to aUNESCO report published last year. "There's a coral reef off Norway that was discovered in 2007 and it's likely to be dead by 2020," says O'Dor. "The problem is that the acidification is worse near the Polesbecause low temperature water dissolves more acid. Starting from the Pole and working south these reefs are going to suffer extensively." Current estimates suggest 30% of coral reefs will be endangered by 2050, says O'Dor, because of the effects of ocean acidification and global warming. Higher acidity also disrupts marine organisms' ability to grow, reproduce and respire. The Census of Marine Life reported thatphytoplankton, the microscopic plants producing most of the oxygen from the oceans, have been declining by around 1% a year since 1900. The falling numbers of smaller, but lesser known species and plant life has significant impact further up the marine food chain. For example, seabirds which used to visit and breed on Spitsbergen -- a Norwegian island near the Arctic -- are being wiped out because of changes in their previously abundant food sources.

Coral is the backbone of countries economic and social structures-extinction of coral would lead to global instability


Skoloff 3/26/2010 [Brian Skoloff-Associated Press, Death of world's coral reefs could wreak global chaos”, March 26, 2010, http://usatoday30.usatoday.com/news/world/environment/2010-03-26-coral-reefs_N.htm]

WEST PALM BEACH, Florida — Coral reefs are dying, and scientists and governments around the world are contemplating what will happen if they disappear altogether. The idea positively scares them. Coral reefs are part of the foundation of the ocean food chain. Nearly half the fish the world eats make their homes around them. Hundreds of millions of people worldwide — by some estimates, 1 billion across Asia alone — depend on them for their food and their livelihoods. If the reefs vanished, experts say, hunger, poverty and political instability could ensue. "Whole nations will be threatened in terms of their existence," said Carl Gustaf Lundin of the International Union for the Conservation of Nature. Numerous studies predict coral reefs are headed for extinction worldwide, largely because of global warming, pollution and coastal development, but also because of damage from bottom-dragging fishing boats and the international trade in jewelry and souvenirs made of coral. At least 19% of the world's coral reefs are already gone, including some 50% of those in the Caribbean. An additional 15% could be dead within 20 years, according to the National Oceanic and Atmospheric Administration. Old Dominion University professor Kent Carpenter, director of a worldwide census of marine species, warned that if global warming continues unchecked, all corals could be extinct within 100 years. "You could argue that a complete collapse of the marine ecosystem would be one of the consequences of losing corals," Carpenter said. "You're going to have a tremendous cascade effect for all life in the oceans." Exotic and colorful, coral reefs aren't lifeless rocks; they are made up of living creatures that excrete a hard calcium carbonate exoskeleton. Once the animals die, the rocky structures erode, depriving fish of vital spawning and feeding grounds. Experts say cutting back on carbon emissions to arrest rising sea temperatures and acidification of the water, declaring some reefs off limits to fishing and diving, and controlling coastal development and pollution could help reverse, or at least stall, the tide. Florida, for instance, has the largest unbroken "no-take" zone in the continental U.S. — about 140 square miles off limits to fishing in and around Dry Tortugas National Park, a cluster of islands and reefs teeming with marine life about 70 miles off Key West. Many fishermen oppose such restrictions. And other environmental measures have run into resistance at the state, local, national and international level. On Sunday, during a gathering of the Convention on the International Trade in Endangered Species of Wild Fauna and Flora, restrictions proposed by the U.S. and Sweden on the trade of some coral species were rejected. If reefs were to disappear, commonly consumed species of grouper and snapper could become just memories. Oysters, clams and other creatures that are vital to many people's diets would also suffer. And experts say commercial fisheries would fail miserably at meeting demand for seafood. "Fish will become a luxury good," said Cassandra deYoung of the United Nations Food and Agriculture Organization. "You already have a billion people who are facing hunger, and this is just going to aggravate the situation," she added. "We will not be able to maintain food security around the world." The economic damage could be enormous. Ocean fisheries provide direct employment to at least 38 million people worldwide, with an additional 162 million people indirectly involved in the industry, according to the U.N. Coral reefs draw scuba divers, snorkelers and other tourists to seaside resorts in Florida, Hawaii, Southeast Asia and the Caribbean and help maintain some of the world's finest sandy beaches by absorbing energy from waves. Without the reefs, hotels, restaurants and other businesses that cater to tourists could suffer financially. Many Caribbean countries get nearly half their gross national product from visitors seeking tropical underwater experiences. People all over the world could pay the price if reefs were to disappear, since some types of coral and marine species that rely on reefs are being used by the pharmaceutical industry to develop possible cures for cancer, arthritis and viruses. "A world without coral reefs is unimaginable," said Jane Lubchenco, a marine biologist who heads NOAA. "Reefs are precious sources of food, medicine and livelihoods for hundreds of thousands around the world. They are also special places of renewal and recreation for thousands more. Their exotic beauty and diverse bounty are global treasures."

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