Islands 101: Ocean Zones & Important Species


Welcome back to Seacology's "Islands 101" blog series! Knowing that not everyone eats, sleeps, and breathes islands, we've put together some basic information to help bring you up to speed on the ins and outs of island conservation. If you haven't already, check out our first "Islands 101" post, which covered island geography and ecosystems. 

Thumbnail image for 800px-Ocean_surface_wave.jpgIdentifying Ocean Zones             

Scientists have identified several zones within the ocean,    representing differing marine biomes. The most important for island ecology are the littoral and pelagic. More about ocean zones can be found here.


Littoral Zone: The littoral zone refers to the area of the ocean near the coast. This zone is important because it acts as a bridge between terrestrial and marine ecosystems, much like wetlands. Wildlife species found in the littoral zone include mollusks, crustaceans, seabirds, small fish, and some plants. Additionally, many pelagic animals (see below) use the littoral zone for feeding or nesting. One such animal is the sea turtle, many species of which are endangered due to loss of nesting habitat. Seacology works in the Caribbean and on other island locations around the world to protect littoral zones that are critical for sea turtle survival.


Pelagic Zone: The pelagic zone refers to open-water ocean areas but does not include the deep ocean zones. A wide variety of fish and marine mammals live in the pelagic zone, including tuna, dolphins, and sharks. Although most Seacology projects focus on littoral areas closer to islands, all marine ecosystems are highly interdependent and many pelagic species, like the sea turtles described above, depend on the littoral zone for feeding and nesting.



Important Types of Species

While all living species are important for the health of the earth, some are particularly significant for robust ecosystems.


Keystone Species: Keystone species serve critical roles in their ecosystems, with many other species depending on them for survival. Coral is an example of a keystone species; without coral, the invertebrates, fish, and other wildlife in coral reefs lose their home and cannot survive.


Endemic Species: An endemic species is one that is exclusive to a certain location. For example, the Madagascar Flying Fox is endemic to Madagascar. Surrounded by water, islands evolve independently of other regions, and are therefore often home to many endemic species. Seacology works to protect endemic species like the Madagascar Flying Fox, since these cannot be found anywhere else on the planet.


Indigenous Species: An indigenous species is one native to a certain ecosystem. Unlike endemic species, indigenous species may be found in multiple locations. Nonetheless, it is important to preserve the native habitat of indigenous species, since they may have trouble surviving in other areas.


Invasive Species: Also referred to as introduced, alien, or exotic species, an invasive species is one that is not native to a specific region. Often, these species can upset the ecosystem's natural balance, causing harm to many native plants and animals. Seacology has funded projects that seek to eradicate invasive species from sensitive island habitats, restoring the ecosystem to its natural state. 

Images from Wikimedia Commons


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About this Entry

This page contains a single entry by Carynne McIver published on March 11, 2010 10:30 AM.

The Exotic Lakshadweep Islands was the previous entry in this blog.

State of the Birds is the next entry in this blog.

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