23 Jan

The reciprocal relationships between the various life forms and their environment

The coral reef is a most complex and diverse ecosystem. This is actually one of the largest natural structures on Earth, and has been created by living creatures.
Stony corals are the main component of the coral reef, forming the complex and complicated limestone structure and coral reef with their skeletons. Apart from the corals, many species of plants and animals live in close proximity to the reef, with all kinds of reciprocal relationships between them.

Marine creatures and plant life share the area of the coral reef and must compete for its limited resources, such as food and space. As a result, a diverse complexity of life strategies and reciprocal relationships has developed.
During development, the coral reefs come under pressure and disorder, both predictable and unforeseen, that are associated with its biotic (an environmental factor associated with living creatures: for example, competition or predation); and abiotic environment (a factor not related to living things: for example, physical or chemical causes).

In a biotic environment, the coral reef is exposed to the pressures of competition, disease and predation between the living creatures that inhabit it over any extended period, or to any degree of density. In contrast, the abiotic environment presents the reef with ecological disturbances and physical stress such as an explosion or wave activity (caused by the state of ocean tides), many powerful storms, “algal bloom” (also caused during periods of low tide), the accumulation of alluvial residue (sedimentation – sand, dust) extreme temperatures, tides (unusually low tides cause a condition of “whitening”, the death of polyps). On top of all these are the additional activities and involvement of humans, who cause distress such as oil pollution, industrial pollutants (a phosphate plant located inside a port, vast amounts of phosphates which are lifted into the air while the boats are being loaded and then settle down onto the sea – consequently creating algae in large amounts); also, lots of sea urchins that multiply there; the flow of waste water, construction of power plants, tourism, aquaculture (fish that do not belong in the Gulf of Eilat) and more.

Ocean life very much resembles a chain, with one link supporting the other. One missing link in the chain may disrupt the entire system. The damage will be in direct proportion to the size of the disruption, and nature will balance or make up for only a limited amount of such loss or damage.
For example, let’s take the case of the ‘crown of thorns’ starfish – acanthaster planci – a creature that feeds on coral. This starfish has developed forms of predation that are unparalleled in the animal world; it extrudes its own stomach outwards through its mouth, spreads the stomach over the coral tissue, and then begins to secrete digestive enzymes. After a few hours the starfish sucks the partially digested coral tissue back into its stomach, leaving the surface of the coral skeleton bare.

Shells provide a lot of pleasure to people who look at them, and therefore they are taken as souvenirs. The natural enemy of the ‘crown of thorns’ starfish, it is a gastropod that grows inside a large shell which is similar to a trumpet. The shell itself is a collectors’ item, or is taken by ordinary people just for its beauty. Consequently, we have impacted the chain of life system and the crown of thorns starfish multiplies. Presently, it is so rare to find them in the sea that its enemies are able to reproduce freely, and cause destruction to the reef which is of major concern.

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