College papers academic writing service


The issue of the mortality of coral systems and its impact on ecosystems

Overfishing and Environmental effects of fishing Overfishingparticularly selective overfishing, can unbalance coral ecosystems by encouraging the excessive growth of coral predators. Predators that eat living coral, such as the crown-of-thorns starfishare called corallivores. Coral reefs are built from stony coralwhich evolved with large amounts of the wax cetyl palmitate in their tissues. Most predators find this wax indigestible.

Its enzyme system dissolves the wax in stony corals, and allows the starfish to feed on the living animal. Starfish face predators of their own, such as the giant triton sea snail. However, the giant triton is valued for its shell and has been over fished. As a result, crown-of-thorns starfish populations can periodically grow unchecked, devastating reefs. The crown-of-thorns starfish eats coral.

This is aggravated by destructive fishing practicessuch as cyanide and blast fishing. This toxic chemical is dissolved in sea water and released into areas where fish shelter.

It narcotizes the fish, which are then easily captured. However, most fish collected with cyanide die a few months later from liver damage. In countries like the Philippines that regularly employ cyanide, more than thirty percent of the population lives below the poverty line. Sticks of dynamite, grenadesor home-made explosives are detonated in the water. This method of fishing kills the fish within the main blast area, along with many unwanted reef animals.

The blast also kills the corals in the area, eliminating the reef's structure, destroying habitat for the remaining fish and other animals important for reef health. The stones break and kill the coral. Muroami was generally outlawed in the 1980s. Gill nets, fish traps, and anchors break branching coral and cause coral death through entanglement. When fishermen drop lines by coral reefs, the lines entangle the coral.

The fisher cuts the line and abandons it, leaving it attached to the reef. The discarded lines abrade coral polyps and upper tissue layers. Corals are able to recover from small lesions, but larger and recurrent damage complicates recovery.

Bottom dragging gear such as beach seines can damage corals by abrasion and fracturing.

Environmental issues with coral reefs

Historically, industrial fishers avoided coral because their nets would get caught on the reefs. In the 1980s, "rock—hopper" trawls attached large tires and rollers to allow the nets to roll over rough surfaces. Fifty-five percent of Alaskan cold—water coral that was damaged by one pass from a bottom trawl had not recovered a year later. Northeast Atlantic reefs bear scars up to 4 kilometers 2. In Southern Australia, 90 percent of the surfaces on coral seamounts are now bare rock.

Even in the Great Barrier Reef World Heritage Area, seafloor trawling for prawns and scallops is causing localized extinction of some coral species.

Navigation menu

For example, markets for fish and other natural resources have become global, supplying demand for reef resources. Marine pollution This image of an algae bloom off the southern coast of England, though not in a coral region, shows what a bloom can look like from a satellite remote sensing system. Reefs in close proximity to human populations are subject to poor water quality from land- and marine-based sources.

In 2006 studies suggested that approximately 80 percent of ocean pollution originates from activities on land. Runoff brings with it sediment from erosion and land-clearing, nutrients and pesticides from agriculture, wastewaterindustrial effluent and miscellaneous material such as petroleum residue and trash that storms wash away. Some pollutants consume oxygen and lead to eutrophicationkilling coral and other reef inhabitants.

Without appropriate precautions, development e. For example, Aspergillus sydowii has been associated with a disease in sea fansand Serratia marcescenshas been linked to the coral disease white pox. In addition to runoff, wind blows material into the ocean.

This material may be local or from other regions. For example, dust from the Sahara moves to the Caribbean and Florida. Dust transport to the Caribbean and Florida varies from year to year [19] with greater flux during positive phases of the North Atlantic Oscillation. Pesticides can interfere with coral reproduction and growth. Nutrient pollution Nutrient pollutionparticularly nitrogen and phosphorus can cause eutrophicationupsetting the balance of the reef by enhancing algal growth and crowding out corals.

This nutrient—rich water can enable blooms of fleshy algae and phytoplankton to thrive off coasts. These blooms can create hypoxic conditions by using all available oxygen.

Biologically available nitrogen nitrate plus ammonia needs to be below 1. In addition concentrations of chlorophyll in the microscopic plants called phytoplankton needs to be below 0. High nitrate levels are specifically toxic to corals, while phosphates slow down skeletal growth. Excess nutrients can intensify existing disease, including potentially doubling the spread of Aspergillosisa fungal infection that kills soft corals such as sea fans, and increasing yellow band disease, a bacterial infection that kills reef-building hard corals by fifty percent.

Air pollution A study released in April 2013 has shown that air pollution can also stunt the growth of coral reefs ; researchers from Australia, Panama and the UK used coral records between 1880 and 2000 from the western Caribbean to show the threat of factors such as coal-burning coal and volcanic eruptions.

The researchers state that the study signifies the first time that the relationship between air pollution and coral reefs has been elucidated, while former chair of the Great Barrier Reef Marine Park Authority Ian McPhail referred to the report as "fascinating" upon the public release of its findings.

Debris may arrive directly from a ship or indirectly when washed out to sea via rivers, streams, and storm drains. Human-made items tend to be the most harmful such as plastics from bags to balloons, hard hats to fishing lineglass, metal, rubber millions of waste tiresand even entire vessels. Derelict abandoned fishing nets and other gear—often called "ghost nets" because they still catch fish and other marine life despite being abandoned—can entangle and kill reef organisms and break or damage reefs.

Even remote reef systems suffer the effects of marine debris. Reefs in the Northwestern Hawaiian Islands are particularly prone to the accumulation of marine debris because of their central location in the North Pacific Gyre. From 2000 to 2006, NOAA and partners removed over 500 tons of marine debris there.

  1. The consequences of losing coral reefs are catastrophic for the oceans. In several other tourist destinations, authorities recommend the use of sunscreens prepared with the naturally occurring chemicals titanium dioxide or zinc oxide , or suggest the use of clothing rather than chemicals to screen the skin from the sun.
  2. Muroami was generally outlawed in the 1980s. Dredging also releases plumes of suspended sediment, which can settle on coral reefs, damaging them by starving them of food and sunlight.
  3. Predators that eat living coral, such as the crown-of-thorns starfish , are called corallivores. Many of these species could be lost permanently, but with temperatures only expected to rise in the coming decades chances are slim that reefs will be able to rebuild from scratch.
  4. The fisher cuts the line and abandons it, leaving it attached to the reef.

Dredging Dredging operations are sometimes completed by cutting a path through a coral reef, directly destroying the reef structure and killing any organisms that live on it. Dredging also releases plumes of suspended sediment, which can settle on coral reefs, damaging them by starving them of food and sunlight.

Continued exposure to dredging spoil has been shown to increase rates of diseases such as white syndromebleaching and sediment necrosis among others. Some 14,000 tons of sunscreen ends up in the ocean each year. Certain formulations of sunscreen are a serious danger to coral health. The common sunscreen ingredient oxybenzone causes coral bleaching and has an impact on other marine fauna.

In several other tourist destinations, authorities recommend the use of sunscreens prepared with the naturally occurring chemicals titanium dioxide or zinc oxideor suggest the use of clothing rather than chemicals to screen the skin from the sun.

Dying Coral Reefs Impact Environment and Economy