Parrotfish in a reef near Roatan, Honduras
Click on image for full size
Courtesy of Anne Pharamond
Reef Health Depends on Algae Chomping Fish
News story originally written on October 31, 2007
Can unhealthy coral reefs recover once they become unhealthy? According to a recent study, they may not be able to unless people take steps to make reefs healthier.
A healthy coral reef is full of life. Corals are the little animals that build much of the rocky parts of a reef. Large eels and rays, tiny snails and shrimp, and numerous fish all live there. Algae are a part of the reef ecosystem too. But when a reef is unhealthy, algae overgrow the reef, taking over areas where corals once lived. More and more reefs, especially in the Caribbean Sea, are becoming unhealthy and overgrown with algae.
Creatures that eat algae are very important in reefs. They keep algae from overgrowing. And the biggest algae eaters on Caribbean reefs today are parrotfish. Parrotfish have a hard plate in their mouth that allows them to bite at algae-covered rocks. They eat the algae along with a bit of rock too. All that munching makes a crunching sound underwater. However, fishing has reduced the number of parrotfish and this may make reefs less healthy.
A team of scientists wanted to know whether Caribbean reefs that are overgrown with algae could become healthy again. They made a computer model of a reef and tested what happened to it when factors, like the number of parrotfish, were changed. They discovered that without enough parrotfish munching algae from the reef, more of the reef becomes covered with algae and corals become less healthy. The scientists suggest that protecting parrotfish can help coral reefs to survive.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science
You might also be interested in:
Scientists say that some coral reefs started to become healthier during 2002, even after they have been damaged for many years. The reefs that are getting healthier are in places that are protected from...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. Adam Kent, a geologist at Oregon State University, says this...more
The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core. The mantle is made up of many different reservoirs that have different chemical compositions. Scientists...more
Some faults look strong and like they wouldn’t cause an earthquake. But it turns out that they can slip and slide like weak faults causing earthquakes. Scientists have been looking at one of these faults...more
The sun goes through cycles that last approximately 11 years. These solar cycle include phases with more magnetic activity, sunspots, and solar flares. They also include phases with less activity. The...more
Studying tree rings doesn't only tell us the age of that tree. Tree rings also show what climate was like while the tree was alive. This means that tree rings can tell us about climates of the past. Two...more
Earth's first life form may have developed between the layers of a chunk of mica sitting like a multilayered sandwich in primordial waters, according to a new hypothesis. The mica hypothesis, which was...more