Coral Reef Threats

Discussion in 'Diving, Collecting and Environmental Discussions' started by seank, 15 Jun 2009.

  1. seank

    seank

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    Something I stumbled upon tonight. Will post Link at bottom of page if you want to read more:

    Coral Reef Threats

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    Sedimentation-Construction along coasts mining, farming and logging of Rainforests causes soil run off smothers coral reefs blocking sunlight that it needs to survive.
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    Soil runoff, Hawaii
    National Oceanic and Atmospheric Administration
    Fishing with explosives -In depleted fisheries, people resort to desperate tactics to catch the fish that remain—one of those is dynamite. The explosions send dead fish to the surface and destroy living reefs.
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    ©Jeffrey N. Jeffords
    This Coca-Cola bottle, found near one of the Capone islands,Philipines still shows a slightly burned fuse and explosive inside

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    Dynamite not only kills the fish that live in the reef, but the reef as well
    (Photo courtesy Thomas Heeger: Philippines)

    Fishing with Poisons-Poison fishing commonly referred to as “cyanide fishing,” is another popular destructive fishing method. Sodium cyanide and bleach are the two most commonly used poisons. Other fish poisons, also called icthyotoxins or piscicides, occur in several related plant species. A variety of chemicals found in these plants will stun fish when it passes through the gills or in some cases ingested. The fish then floats to the surface for easy capture. These practices also poison "non-target" species, including corals, and can cause a variety of human health problems. The impact of these poisons on the reef ranges from coral bleaching to death.

    Water Pollution-Petroleum products and chemicals are lethal to Coral Reefs.
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    Massive Oil Slicks Bahrain NASA Space Shuttle
    They are dumped directly into the ocean or carried by river systems from sources upstream.
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    Runoff from this pipe in the U.S. Virgin Islands spews directly into the ocean only a few hundred yards from reefs. Photo courtesy of the NOAA Coastal Programs Division

    Some pollutants, such as sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algae, which 'smothers' reefs by cutting off their sunlight.
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    Careless recreation and collection of coral-Careless boating, diving and fishing can cause damage to Coral Reefs. Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs.
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    Overfishing- This affects the ecological balance of coral reef communities, warping the food chain and causing effects far beyond the directly over fished population.
    Coral mining- Live coral is removed from reefs for use as bricks, road-fill, or cement for new buildings. Corals are also sold as souvenirs to tourists and to exporters
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    Climate Change/Global Warming-When ocean temperatures increase the coral polyps lose the symbiotic algae inside them, causing them to turn white and die.
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    This is referred to as "bleaching". In the past several years there has been an unprecedented number of "bleaching" events world wide.
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    The effects of bleaching can be seen already in sections of the Great Barrier Reef
    Anthropogenic Threats to Corals
     
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  3. seank

    seank Thread Starter

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    Anthropogenic Threats to Corals

    Human-caused, or anthropogenic activities are major threats to coral reefs. Pollution, overfishing, destructive fishing practices using dynamite or cyanide, collecting live corals for the aquarium market and mining coral for building materials are some of the many ways that people damage reefs all around the world every day.

    One of the most significant threats to reefs is pollution. Land-based runoff and pollutant discharges can result from dredging, coastal development, agricultural and deforestation activities, and sewage treatment plant operations. This runoff may contain sediments, nutrients, chemicals, insecticides, oil, and debris .

    When some pollutants enter the water, nutrient levels can increase, promoting the rapid growth of algae and other organisms that can smother corals .
    Coral reefs also are affected by leaking fuels, anti-fouling paints and coatings, and other chemicals that enter the water . Petroleum spills do not always appear to affect corals directly because the oil usually stays near the surface of the water, and much of it evaporates into the atmosphere within days. However, if an oil spill occurs while corals are spawning, the eggs and sperm can be damaged as they float near the surface before they fertilize and settle. So, in addition to compromising water quality, oil pollution can disrupt the reproductive success of corals, making them vulnerable to other types of disturbances. .

    In many areas, coral reefs are destroyed when coral heads and brightly-colored reef fishes are collected for the aquarium and jewelry trade. Careless or untrained divers can trample fragile corals, and many fishing techniques can be destructive. In blast fishing, dynamite or other heavy explosives are detonated to startle fish out of hiding places. This practice indiscriminately kills other species and can crack and stress corals so much so that they expel their zooxanthellae. As a result, large sections of reefs can be destroyed. Cyanide fishing, which involves spraying or dumping cyanide onto reefs to stun and capture live fish, also kills coral polyps and degrades the reef habitat . More than 40 countries are affected by blast fishing, and more than 15 countries have reported cyanide fishing activities .
    Other damaging fishing techniques include deep water trawling, which involves dragging a fishing net along the sea bottom, and muro-ami netting, in which reefs are pounded with weighted bags to startle fish out of crevices. Often, fishing nets left as debris can be problematic in areas of wave disturbance. In shallow water, live corals become entangled in these nets and are torn away from their bases . In addition anchors dropped from fishing vessels onto reefs can break and destroy coral colonies .

    Reef Check Australia: The Reef Needs You

    Natural Threats to Coral Reefs
    Coral reefs face numerous threats. Weather-related damage to reefs occurs frequently. Large and powerful waves from hurricanes and cyclones can break apart or flatten large coral heads, scattering their fragments . A single storm seldom kills off an entire colony, but slow-growing corals may be overgrown by algae before they can recover .

    Reefs also are threatened by tidal emersions. Long periods of exceptionally low tides leave shallow water coral heads exposed, damaging reefs. The amount of damage depends on the time of day and the weather conditions. Corals exposed during daylight hours are subjected to the most ultraviolet radiation, which can overheat and dry out the coral's tissues. Corals may become so physiologically stressed that they begin to expel their symbiotic zooxanthellae, which leads to bleaching, and in many cases, death.
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    Black-band disease
    Corals face serious risks from various diseases, including black-band disease. The susceptibility of corals to disease may be on the rise as a result of human activities.
    Increased sea surface temperatures, decreased sea level and increased salinity from altered rainfall can all result from weather patterns such as El Niño. Together these conditions can have devastating effects on a coral’s physiology . During the 1997-1998 El Niño season, extensive and severe coral reef bleaching occurred in the Indo-Pacific and Caribbean. Approximately 70 to 80 percent of all shallow-water corals on many Indo-Pacific reefs were killed.
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    Credit: FSPI
    In addition to weather, corals are vulnerable to predation. Fish, marine worms, barnacles, crabs, snails and sea stars all prey on the soft inner tissues of coral polyps . In extreme cases, entire reefs can be devastated by this kind of predation. In 1978 and 1979, a massive outbreak of crown-of-thorns starfish (Acanthaster planci)attacked the reef at the Fagatele Bay National Marine Sanctuary in American Samoa. Approximately 90 percent of the corals were destroyed.
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    crown-of-thorns starfish
    Coral reefs may recover from periodic traumas caused by weather or other natural occurrences. If, however, corals are subjected to numerous and sustained stresses including those imposed by people, the strain may be too much for them to endure, and they will perish.


    Link:www.solcomhouse.com/coralreefthreats.htm
     
  4. Boendoe

    Boendoe

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    Thats scary and very sad. :(
     
  5. jacquesb

    jacquesb Retired Moderator

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    HHHMMM - this is indeed terrible Sean! ONE THING you have left out - is commercial fisherman dragging their nets and anchors across coral reefs! These TOO causes EVER MORE damage to our worlds coral reefs!
     
  6. Jaak

    Jaak

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    Very sad !!!
     
  7. Lowflyer

    Lowflyer

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    This is why I will support guys who grow and frag corals themselves. This is aweful
     
  8. seank

    seank Thread Starter

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    But to an extend, I will say that the Recreational fisherman- like us, are "morely" the culprits, as we use anchors on the reefs:(
     
  9. riyadhessa

    riyadhessa

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    Very very sad...
     
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