Coastal and Marine Habitats

Coastal and Marine Habitats

The Earth is often referred to as the 'Blue Planet'. This is because, when you look at it from outer space, the oceans and seas that cover more than 70 percent of its surface give it a blue appearance. Our coastal and marine environments harbour some of the richest biodiversity on the planet, but these fragile environments are under threat from a broad variety of manmade sources.

In Australia, for example, the world's greatest diversity of seagrass and mangrove species provide a home to a multitude of plants and animals that are found nowhere else on Earth. But Australia's marine life is under increasing pressure from global warming, destructive land uses, and industrial pollution. Without a greater understanding of the threats to these fragile habitats - and the tools to protect them - a host of species of vital importance to our future could be lost forever.

Coral Reefs

Various species of coral are found in the world's seas and oceans, from the tropics to the polar regions. The majority of coral reefs are found within tropical and sub-tropical waters, between the latitudes of 30? North and 30? South. The red dots on the map show the location of our major stony coral reefs.

Mangroves

There are approximately 40 species of mangroves, which dominate about 75% of the world's tropical coastlines between 25? North and 25? South. In certain areas, this range extends beyond these limits due to the movement of unusually warm waters from the Equator. These areas include the East Coast of Africa, Australia and New Zealand, where mangroves occur 10-15? further south. In Japan, Florida, Bermuda and the Red Sea, the range of mangroves extends 5-7? further north. The mangroves of the Indo-West Pacific are more diverse than those in Florida, with at least 30 different tree species identified. Image courtesy Florida Museum of Natural History

Seagrasses

Seagrasses comprise a functional group of about 60 species of underwater flowering plants. Thousands more associated marine plant and animal species utilise seagrass habitats. Seagrasses range from the strap-like blades of eelgrass (Zostera caulescens) in the Sea of Japan, which can measure over 4 metres long, to the tiny, 2-3 cm rounded leaves of sea vine (halophila deceptions) in the deep tropical waters of Brazil. Vast underwater meadows of seagrass skirt the coasts of Australia, Alaska, Southern Europe, India, East Africa, the islands of the Caribbean, and several other coastal areas. They provide habitats for fish and shellfish and nursery areas to the larger ocean, and perform vital functions in filtering coastal waters, dissipating wave energy, and anchoring sediments. Seagrasses often occur in proximity to, and are ecologically linked with, coral reefs, mangroves, salt marshes, bivalve reefs and other marine habitats. They are the primary food of manatees, dugongs and green sea turtles - all threatened species of great public interest. For more information click here (UNEP_WCMC).

Rocky Shores

Rocky shores form the transition between terrestrial and marine environments, and are thus exposed to very different physical conditions. In the course of a day, rocky shores are covered with seawater at high tide and exposed directly to the air at low tide. These habitats are often found in close vicinity to coral reefs, and are usually set against steep slopes on the landward side. They are usually characterised by large sedimentary boulders and low-tide rock pools. Examples can be found at St. John's Island in Singapore, Swansea in Britain, Diani Beach in Kenya, and Luk Keng and Kei Ling Ha Lo Wai in Hong Kong. Rocky shores provide vital habitats and shelter to a wide variety of reef-dwelling plants and animals, which can tolerate these two very different physical conditions. Click on Free Rocky Shores Pictures for a larger picture (200 kb) of a rocky shore in Puerto Rico and browse to Rocky Shores to also see other coastal photos.

Sandy Shores

Sandy shores can be divided into two major habitats - exposed sandy shores and protected sandy shores - depending upon the strength of the wave action they receive. Exposed sandy shores receive strong wave action, which gives the sand substratum large particles and makes it highly mobile. An example is the immense sandy shore under the towering cliffs at Paracas State Preserve, near Pisco, Peru. Click on Free Beaches Pictures for a larger photo of this and other sandy beaches

Protected sandy shores are found in more sheltered locations, where the weaker wave action results in a more stable substratum with a smaller particle size. The more stable substratum generally means that protected sandy shores have a greater variety of resident species. Examples of sandy shores include Starfish Bay in Hong Kong, the East Coast Parkway in Singapore, and Diani Beach in Kenya.

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