Bahamas Travel

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Introduction to tropical environments in the Ocean

The structure of corals and their symbiotic association with zooxanthellae.

Corals belong to the phylum Cnidaria and class Anthozoa. The main points to include in a discussion on the structure of the corals are:
i) Corals are polypoid ie have the structure of a polyp with a cavity and tentacles.ii gastrovascular) corals have external skeletons of calcium carbonate secreted by the coral polyp.iii) coral polyps have a basal plate and a sheet of calcium.iv) Some species have itching nematocysts.v) corals can be divided into two groups main scleractinian (stone) and octocorals (soft corals) briefly take each group in turn to discuss the structural details of the corals. hard corals are generally higher in the reef and may be of low growth in the colonies and others are higher or branches, such as staghorn coral. Corals may be in the following ways: Plate, massive, columnar foliate, encrusting or branching. Soft corals are more common and include deep sea pen, sea fans and whip the sea. They can grow over 2 meters high. Most reef-building corals have a symbiotic relationship with dinoflagellates called zooxanthellae live inside polyps. Zooxanthellae trade in products of photosynthesis products of metabolism. Basically, a reef can get 50% of its food from the zooxanthellae but in return the zooxanthellae receive nitrogenous waste and protection.

When corals are found in the world and what are the factors constraints on growth? Discuss the threats facing corals.

Corals require a narrow range of temperature to thrive so that most corals grow between 20 degrees Celsius isotherm. In the broadest sense, the corals are in a strip along the tropics with extensions where water flows eg hot, west and east coasts of Australia. Again, in a broad sense, coral reefs are in three main areas, such as the Caribbean, including the Bahamas and Florida Keys, Red Sea and Indian Ocean islands and the Indo West Pacific. However, there are many variants of this model … for example on the coast West Africa, the cold Benguela current prevents both the formation of coral.
There are six main limiting growth factors 1) the temperature as mentioned above. Most corals prefer temperatures of 23 -25 degrees Celsius. cold currents prevent the growth of coral. 2) deep. Corals actually not grow below 50 to 100 meters below the surface and this is mainly linked to the next point 3) Light is necessary for the production zooxanthellae. These are the limiting factor in the distribution of corals in shallow warm waters. 4) The salinity is another factor limiting the growth of coral. Where freshwater runoff for example, can not succeed. For example, the mouth of the Amazon sediment 5) also influences the growth of coral on a sediment can clog the structures the food and limit sunlight.

Last appearance in the air several times to kill the coral, where changes in sea levels and coral set out will be limited.
The above are some of the threats facing coral, but also if we consider for a moment that there are other threats such as global warming perform global sea level, pollution from human activities, increased toxic runoff or run-offs, development Marine (dredging mining) haunting choral and excess nutrients from wastewater. In some cases, a species destroys the major reef areas such as crown usual thorns starfish, fish box and file fish. Corals can also be aggressive with other species of corals such as staghorn, corals in the Atlantic. Extreme weather is also a threat, such as El Niño, but the storms also open up new areas for corals. Bleaching events where zooxanthellae leave the coral because to high UV radiation levels can be caused by the degradation of the ozone layer. These are the main threats to corals and can often work together.

How are coral atolls and discuss the zoning on the reef.

The best explanation for the formation of coral atolls came from Darwin in 1842 and is still widely accepted today. Here the coral grows on the sides of a volcano emerging or when lower sea levels around an existing land mass. Corals are growing around the land is sinking or rising sea levels, growing up to stay in the light for photosynthesis zooxanthellae. Eventually, a central lagoon surrounded by atolls can form.
Regarding the zoning on the reef is concerned generally the main areas are:
Back Reef. This is near the shore in the protected side of the reefs and contains perhaps a few rocky reefs, possibly at the edges of mangroves, seagrass and a narrow lagoon. This area is shallow and protected from waves, but the circulation of water can be limited so coral growth may be limited as accordingly.

Reef crest. This is located on the outer side of the reef, with its base marked by the line of breaking waves. Dominated coral inlay here, where there is some wave action and some exposure to air. Also the formation of coral can be restricted by back reef sediments.

Wave Break Area. Here, as the name implies. no wave action so the corals have to be robust to withstand this example, Acropora palmata. This area next to the sea from the reef crest.

The slope towards the sea. extends from the low tide line to deep water. The upper 25 meters are dominated by large corals. 30 to 40 meters for example the soft gorgonians, sea fans dominate.
All areas are modified by the depth of the sea, waves and exposure.

Several species associated with coral reefs.

There are literally thousands of species associated with coral coral. The figures alone illustrate the importance of coral reefs. From the corals themselves are over 1,000 species of hermatypic or reef forming corals with a center of diversity in the Indo-West Pacific. There are over 500 species of reef fish in the Bahamas, 1500 in the Great Barrier Reef and 4,000 in vegetation Philippines.Even is influenced by the presence of reefs with over 35 species of mangroves only in the Indo-West Pacific. The number of species vary location ranging from perhaps the greatest center of diversity focused on the Indo West Pacific to the Atlantic with the least number of species.
Several species associated with coral reefs include representatives of all phyla and classes. This is only a small cross section: Among the invertebrates have been
spongesEchinoderms Eg Porifera, for example, starfish and urchinsMolluscs for example, limpets, snails, clamsArthropods eg crabs, lobsters and shrimp

Vertebrates are represented by many species of fish (some estimates claim up to 25% of fish species) and reef fish dedicated as bream, barracuda, snapper, fish parrot, groupers, reef sharks and white tip reef sharks in the Caribbean. Reptiles as hawksbill turtles also visit the reefs. The enormous diversity of habitat lead and the power of this proliferation of species associated with coral reefs coral species from peak to bottom feeders feeders day feed at night, from simple life forms to very complex and specialized. As mentioned earlier there is enormous variation in the species associated with coral reefs, both reef areas themselves and reefs in various locations around the world.

Dr. Simon Harding

www.chronosconsulting.com

www.coberongreen.com

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