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Marine Impacts

Marine Impacts. Ocean Issues Fisheries Dead Zones Coral Reefs. COASTAL FACTS.

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Marine Impacts

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  1. Marine Impacts • Ocean Issues • Fisheries • Dead Zones • Coral Reefs

  2. COASTAL FACTS • The oceans cover 70 per cent of the planet’s surface area and marine and coastal environments contain diverse habitats that support an abundance of marine life; coastal zones account for 20 per cent of the world’s land area • Coral reef ecosystems are increasingly being degraded and destroyed worldwide by a variety of human activities and by global warming • Global harvests for marine fisheries have been above 80 million tonnes per year since the latter half of the 1980s, with peak of 87 million tonnes in 1997 and 2000 • Mangroves extend over 18 million hectares (44 million acres) worldwide, covering a quarter of the world’s tropical coastlines UNEP-CBD 2005; GEO Year Book 2006; UNEP 2005

  3. Fisheries The world's great marine predators are being wiped out. Populations of marlin, swordfish, tuna, cod, and rays have crashed by more than 90% since the advent of industrial-scale fishing (around 1950). 80% depletion occurred in just the first 15 years of industrial fishing. Moreover, fish are on average roughly 50% of the size they once were. Nature, May 15, 2003 Longline factory processor fishing is main culprit; simple overconsumption.

  4. Fisheries Harpooned swordfish in 1930s averaged 300 lbs. By the mid 1990s they averaged barely 90 lbs. - NYT July 29, 2003 Longline factory processor fishing is main culprit; It’s a case of simple overconsumption aided by technology.

  5. Fisheries “Rebuilding North Atlantic Swordfish, a Report for the U.S. Congress and the Administration” 1998, Recreation Fishing Alliance

  6. Overfishing occurs when the amount of fish caught exceeds the amount of fish needed to sustain fish stocks in a given region. Put simply, there are too many boats, especially large-scale, industrial vessels such as factory trawlers, with too much capacity for devastating fish stocks. To picture how many fish can be caught at one time by a factory trawler, imagine a net as large as four football fields, with a circumference at the mouth of the net big enough to encompass three Statues of Liberty standing head-to-toe. Overfishing Globally, fisheries are the largest source of protein on earth, exceeding even all animal husbandry sources. Global Fisheries 52% are exploited at maximum sustainable level 16% over-exploited 7% are completely depleted 23% can sustain expansion(Source: FAO, 2005)

  7. North Atlantic Cod Catch, 1850-2004 Atlantic Cod Annual Catch, 1850-2004

  8. Even with the newest technologies we are not catching any more wild fish. Source: UNEP/GRID-Arendal Maps and Graphics Library. Retrieved 04:59, April 26, 2011

  9. Overfishing Thursday, 2 November 2006, 19:01 GMT 'Only 50 years left' for sea fish By Richard Black Environment correspondent, BBC News website There will be virtually nothing left to fish from the seas by the middle of the century if current trends continue, according to a major scientific study.

  10. Is Aquaculture the Answer? • On rise all over the world. 1/4 of all finfish and shellfish consumed worldwide! • Much of the fish and shrimp you buy today is farmed in shallow bays or in holding tanks. • There are many environmental and health impacts with this type of agriculture. Arizona Catfish Farming Norwegian Salmon Farming

  11. Is Aquaculture the Answer? • Coastal marine ecosystems are among the most productive in the world.¼ of the tropical coastline worldwide is mangroves- storm protection- fish nurseries- bird habitat • Mangroves are rapidly being replaced by shrimp and fish farms. Mangroves Replaced by Shrimp Farms

  12. Shrimp farms replacing mangroves in Gulf of Fonseca, Honduras 1987-1999: shrimp farms and ponds have mushroomed, carpeting the landscape around the Gulf of Fonseca, in blocks of blue and black shapes

  13. Studies of Overfishing and Marine Protected Zones 1. Experiments show that reducing the diversity of an ecosystem lowers the abundance of fish 2. Historical records show extensive loss of biodiversity along coasts since 1800, with the collapse of about 40% of species. About one-third of once viable coastal fisheries are now useless 3. Catch records from the open ocean show widespread decline of fisheries since 1950 with the rate of decline increasing. In 2003, 29% of fisheries were collapsed. Biodiverse regions' stocks fare better 4. Marine reserves and no-catch zones bring an average 23% improvement in biodiversity and an increase in fish stocks around the protected area

  14. Marine environments recover very quickly, if left unmolested. • Reviews of global data show that marine reserves produce major benefits in just the first two years: • 91% increase in density of organisms • 192% increase in biomass of organisms • 31% increase in average size of organisms • 23% increase in species diversity Sources: Halpern, Benjamin S. 2003. The Impact Of Marine Reserves: Do Reserves Work And Does Reserve Size Matter? Ecological Applications 13; Withgott and Brennan. 2009. The Essential Environment. Pearson.

  15. Source: UNEP Geo Year Book 2003 Ocean Dead Zones • Morning Edition story on dead zones (click)

  16. Eutrophication • Eutrophication is a natural process taking place in water-characterized by a development towards an environment rich in nutrients and increased primary productivity. • Human activities have greatly increased the rate of the process of eutrophication via excessive discharge of nutrients like phosphorus (P) and nitrogen (N). • Eutrophication results in an increase in primary productivity ( in form of algal blooming ) algal blooming may shade out plants in lower water and cause a loss of biodiversity and development of zero oxygen (hypoxia) conditions.

  17. Oceanic Dead Zones • The term for low oxygen is hypoxia.Hypoxia=<2 mg/l dissolved oxygen (DO) • • Little or no oxygen is present • • Little or no marine life can survive • The decay of algae blooms via bacteria takes oxygen and is what depletes the ocean of vital dissolved oxygen.

  18. Louisiana BayouSeptember, 2010 BP Oil Spill? Eutrophication? The answer is probably some of both!

  19. Mississippi River Basin • Largest river basin in North America • Third largest basin in the world • Including 70 million people, 30 states • One of the most productive farming regions in the world • 58% of the basin is cropland ( corn, soybeans, wheat) • 18% woodland, • 21% barren land, • 2.4% wetland, and • 0.6% urban land (Goolsby and Battaglin, 2000 ) (Goolsby & Battaglin , 2000)

  20. (Source: Goolsby, 1998) (Source: Goolsby, 1998)

  21. (Source: Goolsby, 1998)

  22. Effects of Oceanic Dead Zones • Food base is reduced and/or lost • Habitat is reduced and/or lost • Migratory patterns are disrupted • Species diversity is reduced • Commercial fisheries damaged • Tourism affected

  23. Reversal of Oceanic Dead Zones Dead zones are not irreversible. The Black Sea dead zone, previously the largest dead zone in the world, largely disappeared between 1991 and 2001 after fertilizers became too costly to use following the collapse of the Soviet Union.

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