HARBORING AQUATIC LIFE

HARBORING AQUATIC LIFE:

Why do we need artificial reefs to harbor aquatic life? To fully appreciate what artificial coral reefs have to offer coral reef ecosystems, a discussion on the background of coral reef ecosystems is needed, including the reasons coral reefs are dying. Once the problem is fully addressed, several restoration techniques, including artificial reefs can be discussed.

Background: Natural Coral Reefs

Coral reefs are calcium carbonate (limestone) structures primarily found near coastal areas between the Tropic of Cancer and Tropic of Capricorn [Naval Research, 11/20/03]. As coral die on the reef, their calcium carbonate shells are left behind. Now a vacant spot on the reef, another coral finds refuge in the shell; it eventually dies and deposits its shell on top of the shell it inhabited. This continuing cycle of life and death on the reef is what gives the reef its structure.

Conditions Necessary for Coral Reefs

In order for coral reefs to survive, they must be present in shallow waters with near constant temperatures (between 73 and 80 degrees Fahrenheit), and long hours of sunlight, which the area between the Tropics of Cancer and Capricorn provide [Naval Research, 11/20/03]. A graphical representation of this area is shown in the figure below:

Most coral reefs are located between the Tropic

of Cancer and the Tropic of Capricorn.

Scarcity of Coral Reefs

To put coral reefs in perspective, consider a comparison to the tropical rain forest ecosystem. Tropical rain forests cover slightly more than 6% of the world’s landmass [San Diego Zoo, 11/20/03]. Even though these forests cover such a small amount of area, they contain a staggering “50% of the world’s plant and animal species” [San Diego Zoo, 11/20/03].

Coral reefs are the tropical rain forests of the ocean. These reefs contain nearly a quarter of all marine species, yet they only cover 0.17% of the ocean’s area [Ives, 4/5/02]. If the exact same type of ecosystem were to exist on land, it would be equivalent to taking a quarter of the land species, and constricting them to an area the size of Colorado. These very diverse, yet small ecosystems are under attack.

Coral reefs are threatened. Ten percent of the world’s reefs are dead, and another thirty percent are damaged [Ives, 4/5/02]. In response to these facts, the question of degradation mitigation has been on the forefront of oceanic studies.

Threats to Coral Reefs

There are several reasons for the declination in health of coral reefs. The reef’s exposure to sedimentation, pollution, a change in climate, tourism, and over-fishing affect the reef community’s ability to maintain the conditions necessary to keep the reef healthy [McGinn, 2000].

Examples of Harboring-Aquatic-Life Artificial Reefs (click on each to find out more):

1) FLORIDA

2) TRUK LAGOON

HARBORING AQUATIC LIFE

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