Lagoons are calm bodies of shallow water surrounded by barriers. These barriers can be geographic features such as coral reefs, barrier islands, sand bars, and anything that can protect an area from the outside ocean. There are multiple kinds of lagoons: Coastal, Atoll, and Hapua Lagoons.
Coastal Lagoons are found surrounding portions of continents and are commonly sheltered by sandbars or barrier islands. Also commonly called estuaries, well-known coastal lagoons such as Pamlico and Albermarle Sound of North Carolina are important transition zones between freshwater rivers and the saltwater oceans.
Atoll lagoons are formed by upward growing coral reefs. These reefs grow upwards until the point where the only thing showing above water is the reefs themselves.
Hapua are a unique type of lagoon that form near river-heads and are primarily composed of fresh water. Common on New Zealand coastlines, Hapua are important to a number of migratory birds and fish.
There are numerous famous Lagoons throughout the world. One of the most well known would be the Great Barrier Reef Lagoons which are off the coast of Australia. A few other lagoons around the world are the Sounds of North Carolina, the Maldives, and even Venice. There is even one lagoon that appears on the UNESCO World Heritage list, the Reefs of New Caledonia.
Plant and Animal life in Lagoons
Plant and Animal life is incredibly diverse in lagoonal areas. New Caledonia alone houses thousands of species within 20,000 square kilometers. There are numerous endemic species of fish, birds, mammals, and even over 2000 endemic plant species. This high number of endemic species is due to a warm climate with high variation in altitudes on islands in addition to a long time period of isolated evolution, typical of areas near Australia. Despite the high level of biodiversity in the area, current conservation institutions do not have adequate funding to properly manage and protect unique species such as Galaxius neocaledonicus and Phoboscincus bocourti.
Importance to Coral Reefs
Lagoons are protected by numerous natural barriers and are therefore calm areas of water that are ideal for the spawning and raising of fish native to coral reefs.The unique environment provided by nearby land masses and fresh water makes the area ideal for other species of bird and fish to also migrate to Lagoons for mating seasons.
Being near shore, Lagoons suffer from a number of stresses that can be devastating to an aquatic ecosystem. Massive amounts of fertilizers from agricultural lands will increase the nutrient load of the waters. This leads to accelerated algal growth covering the surface of a body of water with algae. This process is called Eutrophication. Algae will grow out of control and suffocate other aquatic plant life by absorbing nutrients and blocking sunlight from reaching lower water levels, destroying the nursery area for young fish.
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