Sea grasses form an important part of the vegetation to be found on coral reefs. They tend to grow in sheltered places on the reef flats or in shallow water in between land and fringing reefs. Sea grasses are not algae but proper plants with roots and tiny flowers that bloom under water. Pollen is carried from the female flowers to the male ones by currents. They provide ideal shelter for a number of marine animals, and as such they are very important, but few animals feed on sea grasses.
Coral reefs are also very productive ecosystems.
These two figures are ample evidence of the importance coral reefs have for humanity as a whole. Reefs are also of great value to tourism, especially in Mauritius where this industry depends entirely on clear lagoons and sandy beaches. Tourism with excessive hotel and beach developments, the dredging of bathing and ski areas and anchor damage by pleasure crafts and fishing vessels are now also becoming major threats to coral reefs. Coral bleaching occurred massively during the 80's, including in Mauritius, and it caused depressed coral growth, coral mortality and loss of aquatic life. It is thought that a variety of causes were responsible, including siltation and changes in salinity or, most likely, abnormally high sea water temperatures, approximately 30 o C. Further threats can be termed as global.