Page 135 - Central America

R eef-building or hermatypic corals live etons into fragments that settle into spaces rooted, while the mangroves and sea grass
only in the photic zone (above 50 me- in the reef structure or form sandy bottoms protect the coral from large influxes of silt,
ters), the depth to which sufficient sunlight in associated reef lagoons. Many other or- fresh water and pollutants. This level of vari-

penetrates the water, allowing photosynthe- ganisms living in the reef community con- ety in the environment benefits many coral

sis to occur. Coral polyps do not photosyn- tribute skeletal calcium carbonate in the reef animals, which, for example, may feed

thesize, but have a symbiotic relationship same manner. Coralline algae are important in the sea grass and use the reefs for protec-

with zooxanthellae; these organisms live contributors to reef structure in those parts tion or breeding.

within the tissues of polyps and provide or- of the reef subjected to the greatest forces
ganic nutrients that nourish the polyp. Be- Rby waves (such as the reef front facing the
cause of this relationship, coral reefs grow eefs are home to a large variety of ani-
open ocean). These algae strengthen the mals, including fish, seabirds, sponges,

much faster in clear water, which admits reef structure by depositing limestone in cnidarians (which includes some types of

more sunlight. Without their symbionts, cor- sheets over the reef surface. corals and jellyfish), worms, crustaceans (in-

al growth would be too slow to form signifi- C oral reefs form some of the world’s cluding shrimp, cleaner shrimp, spiny lob-
cant reef structures. Corals get up to 90% of most productive ecosystems, provid- sters and crabs), mollusks (including cepha-
their nutrients from their symbionts. lopods), echinoderms (including starfish,

R eefs grow as polyps and other organ- ing complex and varied marine habitats that sea urchins and sea cucumbers), sea squirts,
isms deposit calcium carbonate, the ba- support a wide range of other organisms. sea turtles and sea snakes. Aside from hu-
Fringing reefs just below low tide level have mans, mammals are rare on coral reefs, with

sis of coral, as a skeletal structure beneath a mutually beneficial relationship with man- visiting cetaceans such as dolphins being

and around themselves, pushing the coral grove forests at high tide level and sea grass the main exception. A few of these varied

head’s top upwards and outwards. Waves, meadows in between: the reefs protect the species feed directly on corals, while others

grazing fish (such as parrotfish), sea urchins, mangroves and seagrass from strong cur- graze on algae on the reef.

sponges, and other forces and organisms rents and waves that would damage them

act as bioeroders, breaking down coral skel- or erode the sediments in which they are