Coral Reefs
Coral reefs seem to be the ecosystem with highest biodiversity worldwide. They can be found only in shallow tropical seas with permanently high water temperature. Coral reefs are extremely attractive for all nature lovers. Because of their unique character coral reefs were separated from other marine ecosystems.
Coral reefs are aragonite structures produced by living organisms. In most reefs the predominant organisms are colonial cnidarians that secrete an exoskeleton of calcium carbonate. The accumulation of this skeletal material, broken and piled up by wave action and bioeroders, produces massive calcareous formations that make ideal habitats for living corals and a great variety of other animal and plant life.
Coral reefs are estimated to cover 284,300 square kilometres, with the Indo-Pacific region (including the Red Sea, Indian Ocean, Southeast Asia and the Pacific) accounting for 91.9% of the total. Southeast Asia accounts for 32.3% of that figure, while the Pacific including Australia accounts for 40.8%. Atlantic and Caribbean coral reefs only account for 7.6% of the world total.
Coral reefs are either restricted or absent from the west coast of the Americas, as well as the west coast of Africa. This is due primarily to upwelling and strong cold coastal currents that reduce water temperatures in these areas. Corals are also restricted from off the coastline of South Asia from Pakistan to Bangladesh. They are also restricted along the coast around north-eastern South America and Bangladesh due to the release of vast quantities of freshwater from the Amazon and Ganges Rivers respectively.
Although corals are found in temperate and tropical waters, shallow-water reefs are formed only in a zone extending at most from 30°N to 30°S of the equator.
Coral reefs support an extraordinary biodiversity; although they are located in nutrient-poor tropical waters. The process of nutrient cycling between corals, zooxanthellae, and other reef organisms provides an explanation for why coral reefs flourish in these waters: recycling ensures that fewer nutrients are needed overall to support the community.
Coral reefs often also depend on other habitats as seagrass meadows and mangrove forests in the surrounding area for the supply of nutrients. Seagrass and mangroves supply dead plants and animals, which are rich in nitrogen and also serve to feed fish and animals from the reef by supplying wood and vegetation to eat. Reefs in turn protect mangroves and seagrass from fierce waves and produce sediment for the mangroves and seagrass to root in.
Coral reefs are home to a variety of tropical or reef fish which can be distinguished. Generally, fish that swim in coral reefs are just as colourful as the reef itself. Examples are the beautiful parrotfish, angelfish, damselfish, Pomacanthus paru, Clinidae and butterflyfish. At night however, some change colour to a more less catchy colour. Also, it should be noted that besides colourful fish swapping their colour to that of the environment, other fish (eg predatory and certain herbivorous fish as Lampanyctodes hectoris, Holocentridae, pterapogon kauderni, ...) as well as aquatic animals (Comatulida, Crinoidea, Ophiuroidea, ...) emerge and become active and certain go to rest.
Reefs are also home to a large variety of other organisms, including sponges, Cnidarians (which includes some types of corals and jellyfish), worms, crustaceans (including shrimp, cleaner shrimps, spiny lobsters and crabs), molluscs (including cephalopods), echinoderms (including starfish, sea urchins and sea cucumbers), sea squirts, turtles such as the sea turtle, green turtle and hawksbill turtle and sea snakes. Aside from humans, mammals are rare on coral reefs, with visiting cetaceans such as dolphins being the main group. A few of these varied species feed directly on corals, while others graze on algae on the reef and participate in complex food webs.
Albatros Travel and Expeditions can provide you trips directed into areas with the most remarkable coral reefs ecosystems worldwide. These trips are usually very easy. Even not trained people can take part in such journeys. There is a list of countries where coral reefs can be visited:
Tanzania - two localities on the eastern coast