Ecology And Environment

Nature Controlling Population

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"Nature Controlling Population"
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How the Red Sea got its name?
Really I don't know.
But the colour of the coral reef blooming, on the early morning sun, over the mirror calm sea. The reflection of the reddish colour of the mountains, surrounding its shores, may be the cause for the name.
The Red Sea is very beautiful sea . Its beauty is due to two factors:
1- The geological structure. This Sea is formed as a result of a fissure occurred due to the continental drift. Which gave this Sea special characteristics: it is narrow, rocky shore, and a wall that run vertically down and deep.
We can notice this fissure that formed the Red Sea, from the Gulf of Aqaba North, to Babe El Mandab South, with one exception. The Gulf of Suez, from the Suez Canal north, to the islands near Hurghda South.
The Gulf of Suez does not belong to the Red Sea geologicaly, it is part of the Mediterranean Sea .
It is a fact that this Sea is well preserved through time, from its birth till the 80s because:
a-It is surrounded by mountains which gave protection to its shores against the action of winds (north to south & vice-versa on the longitudinal axis of the Red Sea) and waves.
b- Its shape as a narrow deep and rocky shores hindered its use for fishing at a large scale.
c- Most of its shores are not populated, that until the 80s where the Red Sea became a major attraction to divers and leisure water sports.
As a result of this protection the coral reef had the chance to grow over along periods of time undisturbed.
2-The coral reef is the second major factor contributing to the beauty of the Red Sea.
What is the coral reef?
Coral reef is a massive structures therefor we consider it the largest geological Structure built by organisms.
We usually classify coral reef to three categories:

- Fringing reefs: are the simplest and most common reefs they
Develop near shores they flourish best on rocky areas in fact
The longest reef in the world is the Red Sea 4000 km long.
- Barrier reefs: are very similar to the fringing reefs but it
Occurs considerably farther from shore some times as far as
100 km the most famous is the Great Barrier Reef of
- Atolls: They are ring of reef often islands or sand cays that
Surrounds central lagoon the majority are found in the Indo-
West pacific region.

How the Coral Reef is built?
Small creatures known as the reef builders, build this wonderful coral reef we enjoy diving on, they belong to the phylum cnidaria (sometimes called Coelenterates ) most of them are in the class Anthozoa they are about 6100 species. Unlike many cnidarians, they lack a medusa stage ( free swimming stage) and live only as polyps, this polyps lie in a cup-like skeleton of Calcium Carbonate that they make themselves. Over the years a series of polyps, each laying down a new layer of calcium carbonate, builds up the skeleton, which form the colony that can take many different shapes. The actual living tissue is only a thin layer on the surface.
It is the calcium carbonate coral skeletons, growing upward and outward with the Coral, that create the framework of the reef.

The deposition calcium carbonate as their skeleton is very important to our plant. It keeps carbon dioxide low in the atmosphere.

Coral reef from the point of view of divers and geologists are nice and impressive structures, but for the marine biologist they are the richest and the most complex of all marine ecosystems, literally thousands of species live on a reef. How do all these different species live? How do they effect each other? What is their role in the ecosystem?
With so many species on the coral reefs, the interactions among them are exceedingly complex. What is known about these interactions is fascinating; what remains to be learned will be even more so.

Conditions effecting Reef Growth
Coral reef do not develop without Corals, in order to grow they need particular requirements that determine where reef develop
1-Hard surface for the coral larvae to settle in.
2- light and Temperature.
Coral grow only in relatively shallow water where light can penetrate. Particular types of coral have different depth limits some grow in deeper water than others , but coral rarely develop deeper than 50 meters they prefer clear waters and temperature between 20 to 35 C.

3- Sediments, Pollution and Predators.
One) Sediments: The coral reef doses not flourish in the presence of sediments this sediment will decrease the light and will cover the coral smothering it. Although the coral have a defence against that, by shedding the mucus secretion away with the sediment, but this need the waves action to drive it away from the coral, that is hindered in the Red Sea. Human activities like mining, construction, and dredging increase the amount of sediment. Fresh water runoff from the near by construction is very harmful on the local reef.
The tourist villages and hotels on the Red Sea cost in order to have sandy beaches they destroy coral by covering it with sand from the near by desert !.
Two) Pollution: Corals are very sensitive to pollution of any kinds. Even low concentrations of chemicals like pesticides industrial wastes. High concentration of nutrients (Human release tremendous amounts of nutrients in sewage) and fertilisers can harms the coral directly by interfering with the formation of their skeleton and indirectly by tilting the balance toward the growth of seaweed, which will grow fast, this will prevent light, and choke the slow growing coral.

This beautiful coral is under attack by a predator. The Crown-of-Thorns (Acanthaster planci) first noticed in 1994, then reappeared again in July 1998 in large numbers. The Crown-of-Thorns has a devastating effect on reef. Some times this star numbering in thousands (normally they are between 20 to 40 in 10000 square meter) move in a mass across the reef, consuming almost every coral in their pass.
The recreation industry in the Red Sea depends completely on the coral reef. Divers travels from deferent parts of the world to the Red Sea to enjoy the richness of this coral reef.
Due to the importance of the coral reef as economic resources the Ministry of Tourism and the Ministry of Environment studied this problem and put a strategy to deal with it based on the experience of other out-breaks occurred in the Great Barrier Reef.
Different strategies have been used on the Great Barrier Reef ranging from injecting this stars by toxic martial to picking it by hand all was time efforts and money consuming.
There is a conflict among the Marine Biologists regarding how to deal with this problem.
Some of them consider this as a natural phenomenon that occurs in cycles every few years they base their argument on
1- The discovery of this plague lately does not excludes that it did not occur before and its discovery is due to the increased scuba diving, which gave us the chance to see it.
2- Geologists discovered fossil evidence 8000 year old that outbreaks of Crown of Thorns had occurred.
They concluded that it might be natural parts of the reef ecosystem human have nothing to do with it. The causes may be associated with natural phenomena as unusually wet years or other conditions related to the climatic changes.
Others strongly believe that the life in any ecosystem is well balanced i.e. No life form will grow destroying other communities unless there is some thing that tilt the balance toward the flourishing community helping it to grow and hindering the others.
They contradict the cyclic phenomena theory as follows:-
The 8000 year old fossil evidence is good and it shows that this out break occurred before but it did not show successive fossils indicating a cyclic phenomena. The reasons for that, is may be the unusually wet years or a phenomena as El NIO or the climatic changes. There is evidence that this lead to the distraction of the Coral Reef as it occurred in the Galapagos Islands in82-83
Regarding the recent outbreaks in Australia at the end of 50s and beginning of 60s there is increase and decrease in the numbers of star fish but whether is due to cyclic phenomena or due to faulty measures on how to deal with the problem is another arguing point.
In the Red Sea the outbreaks were noted in 94 then in 98 and to my knowledge divers were diving in the Red Sea well before that and did not report out breaks.
It is a fact that we need a lot of studies and information about the reef ecosystem because if this outbreak is due to environmental imbalance resulted from the development of the Red Sea Coast. Then it is very important to find a solution for this problem. On the other hand if it is a natural phenomenon and a part of the reef ecosystem then fighting it is very wrong.
What is the Crown-of-thorns?
It is a sea star member of the Echinoderms, which include also the sea urchins and sea cucumbers they total about 6000 species all are marine.
The Crown-of-thorns is the only venomous star. Its size is about 60 cm in diameter. The spine length about 6 cm. the venom is present in the tissues covering the spines.
They lay eggs once a year at the end of spring and beginning of summer. They reach their full size after four years.
They destroy coral by pushing their stomach out through the mouth, covering all or part of the colony, and digesting away the living coral tissues.
What divers should do?
1- Do not touch coral as you dive your touch is harmful to it
2- Try always to adjust your buoyancy so you do not stair the sand, which can cover the coral and hinder its growth.
3- Do not kill the Crown of thorns by cutting it with your knife, the star can grow back and each part will form a new star i.e. you are helping its spread.
4- This star is venomous you should not put your hand on it. If you did that accidentally you should remove the spines bleed the site of puncture wash the site with fresh water and seek medical help.
5- Do not leave plastic bags on seashore. the wind will take it to the sea and marine animals will eat it and die of intestinal obstruction
6- Always be aware of the environmental issues, read, listen, and ask questions, the interaction of life in any ecosystem can be effected by any changes even if it seemed to you that there is no harm was done.

More about this author: Raghid El-Maarry

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