Natural Succesion in Ecosystems: Coral Reefs

Coral Reefs:
How they are affected

Coral reefs are some of the world’s most old and complex organisms, around since more than 200 million years ago, taking 50 million years to achieve the biological diversity they have now. The coral reefs we see today have built themselves throughout the last 8,000 t o 10,000 years.
Coral is a living organism, created through a cooperative alliance of coral polyps, a tiny animal that filters rock fragments from the surrounding water and single-celled plants that dwell within the polyps. The plants generate many of the nutrients the corals need to live and capture calcium from the seawater, which the polyps use to build their limestone shells.

Reefs are most commonly found between the Tropic of Capricorn and the tropic of Cancer. Here the waters are stable and warm (64-86 degrees Fahrenheit) year-round and the days are longer, providing more sunlight to the reef.
Reefs serve as home not only to live polyps but also, to many species of algae, seaweed, sponge, and mollusks. Coral reefs cover merely .2% of the ocean bottom, but account for over 25% of the world’s marine species.

There are many threats, both natural and anthropological to coral reefs. Due to erosion, the coral reefs are clouded with silt and mud and sediment from the earth drags into the ocean, clouding the reefs. This also means that fertilizers and untreated sewage drag into the reefs and impact negatively on the reefs as well. Because of sedimentation, garbage is also dragged and also ends up into the reefs, and also clouds the reefs as well. The untreated sewage also promotes the growth of excess algae, which in turn attracts predators and thus creates a cycle of destruction in which the coral reefs are the main victim.
This impacts the reef negatively because coral reefs flourish in clear waters because they need sunshine. Due to an excess of nutrients because of the erosion and sedimentation, there is algae overgrowth. The excess of algae attracts predators and this decreases the biodiversity of the coral reefs.
As ocean temperatures rise, the coral reefs start to turn white, causing what is known as “Coral bleaching”. The carbon dioxide that is expelled by cars, factories and the like is also being absorbed by the ocean. This in turn, acidifies the sea water and organisms with a calcified shell such as lobsters and coral reefs, are more prone to simply dissolving, much like a pearl dropped in acid.
Natural disasters, such as storms and tsunamis, also cause damage on the population of the coral reefs and destroy them as well.

Tourism impacts the reefs negatively because tourists take pieces of coral, damaging and breaking coral branches for souvenirs ignoring the fact that a single branch of coral reef can take hundreds of years to grow to it’s proportions. Also, careless boat operators drop anchors directly on the reefs and navigate directly over the reefs, damaging them with the propeller blades of their boats, and even scraping them in very shallow waters.
By fishing with cyanide, fishermen stun and confuse fish and then scoop them out of the ocean. By doing this, the fish are still alive and are then sold for aquariums, or for live fish restaurants. However, this kills the delicate organisms that live within the coral reefs, and also kills the coral polyps themselves.

Fishermen also create bombs with substances that will kill the fish in the surrounding area of the explosion; however, this also explodes the coral reefs into bits and pieces, and kills the inhabitant organisms as well.

Because of all the damages that coral reefs are suffering, scientists predict that there might be a severe threat to them by the year 2050. Reefs are very fragile and susceptible to damage. A single branch or a coral reef can take hundreds of years before it grown fully into a large portion of the reef. Because of this, we can say that reefs are not very resilient. Although some reefs adapt quicker to changes than others, they are still affected and impacted in a large manner, and they are quickly declining worldwide. In order to preserve the existing coral reefs from future damage, people must intervene in a large collected effort, because overall, mankind is the biggest causer of the damage to coral reefs. The reasons why men must intervene in order to propitiate the recovery of coral reefs are the following:

• Fishing practices must be changed in order to stop killing the coral polyps and in order to stop exploding the reefs
• Sewage systems must be improved in order to avoid excessive algae growth
• Carbon Dioxide emission must be reduced in order to delay and reduce the acidification of the oceans, which causes for a more sensible, fragile skeleton on the polyps and also causes the coral reefs to be more vulnerable to damages
• Tourism and fishing must be allowed in designated areas of coral reefs in order to allow for other areas to flourish and grow.
• There must be designated protected areas of coral reefs where they are able to grow with no threats and where reefs can recover from damages already caused.
  

References

http://www.reefrelief.org/coralreef/threats.shtml

http://www.usatoday.com/weather/climate/2006-10-25-coral-reefs_x.htm

http://www.essortment.com/all/coralreefinda_mzx.htm

http://www.jpl.nasa.gov/news/features.cfm?feature=9

http://oceanacidification.wordpress.com/2008/07/20/acidifying-oceans-pose-danger-to-coral-reefs/

http://www.riverdeep.net/current/2001/11/111201_reefs.jhtml

http://www.usforacle.com/2.5741/coral-reefs-in-danger-1.625527

http://www.msnbc.msn.com/id/9815322/