Read the passage below and summarize it using one sentence. Type your answer in the box below (5-75 words). You have 10 minutes to finish this task. Your response will be judged on the quality of your writing and on how well your response presents the key points in the passage.
There are strong mutual dependencies between corals and fishes, with many fish species depending on corals for food and habitat, while corals depend on the grazing by certain fishes for reproductive success. Globally, there are some 130 species of fishes that consume live coral tissue. A recent study estimated that Butterfly fishes consume up to 6% of the tissue of corals per year, and are therefore likely to influence the distribution, abundance and composition of corals. Parrot fishes, which live in tropical marine climate, feed off algae found on live corals, which normally requires them to chew off the coral heads, causing substantial damage to the physical structure of coral reefs. Coral reefs also contribute to the survival of fishes by providing refuge. Even a little coral loss will lead to a decline in the abundance of reef fishes. In one study, both the abundance and diversity of the community declined by approximately two-thirds after the reef collapsed into a formless rubble state.
Having discussed the many benefits corals bring to fishes, they in turn facilitate the settlement and survival of corals. Some of these fishes consume algae growing on the reef. Many species of Parrot fishes perform this role by scraping clean the surface of reefs which they feed on. This action provides new sites for corals to settle. Another functional group of herbivorous fishes are the ‘grazers’. Much like a lawn mower, these fishes keep the growth of algae in check by literally grazing the reef surface. This serves to limit the growth of algae, which would otherwise outcompete corals for space and light. Although the actual mass of algae consumed by an individual may be relatively small, because many species of grazers move in large groups and are relatively abundant, their overall impact is considered significant.