Overexploitation of groundwater from an aquifer can result in a peak water curve. Overexploitation occurs if a water resource, such as the Ogallala Aquiferis mined or extracted at a rate that exceeds the recharge rate, that is, at a rate that exceeds the practical sustained yield. Recharge usually comes from area streams, rivers and lakes. An aquifer which has been overexploited is said to be overdrafted or depleted.
Today we tell about threats to coral reefs and some new discoveries about these ancient, biological structures. Corals are groups of small organisms called polyps. Millions of polyps grow together to form coral reefs. The ancestors of these reefs were formed at least two hundred forty million years ago.
NOAA scientists say the main threats are pollution, overfishing and climate change. As a result, coral reef populations are decreasing worldwide. NOAA says an estimated twenty percent of the reefs have been damaged beyond recovery. About fifty percent of the remaining coral are under risk of collapse.
Now there is a new threat facing coral reefs in the Caribbean Sea. The threat comes from another sea creature. A recent study found that damselfish are killing head corals in the Caribbean. Damselfish live in ocean waters throughout the world.
They kill parts of coral colonies or communities, so that simple organisms like algae can grow. Damselfish use the resulting gardens of algae for feeding and producing young. In earlier times, damselfish often used staghorn corals to grow in these areas. During this period, staghorns were the most common coral in the Caribbean.
Even after damselfish killed off parts of the staghorn colonies, the areas that remained were able to survive. In recent years, coral diseases, storms and other activity in the environment have reduced staghorn coral populations. He says the damselfish had to find new grounds for algae after the staghorn coral disappeared.
He says the damselfish are now killing off parts of slow-growing coral. This coral is not able to recover from the destruction as well as its staghorn relative.
Professor Kaufman says it could take the slow-growing coral as long as one hundred years to recover. Earlier research suggested that overfishing was responsible for an increase in damselfish populations in the Caribbean.
The research found that many of the bigger fish known to eat damselfish had disappeared from the area. Scientists said the increased damselfish populations led to the killing of more coral.
The new study found that the number of damselfish is not the issue. Instead, researchers are blaming the increased killing of coral on the lack of staghorn coral in the Caribbean waters.
A report in the journal Marine Policy draws attention to another threat to corals and other sea creatures. The report says international law has failed to protect coral reefs and the tropical fish that live among them from collectors.
The researchers say the coral trade is removing about one million five hundred thousand live stony corals from the oceans each year.
They say thirty million tropical fish are disappearing every year because of a growing interest in tropical fish. Many of the fish die while being transported. Brian Tissot is a marine ecologist with Washington State University.GIANT OTTER AN ENDANGERED SPECIES.
The giant otter is the South American cousin to the sea and river otters of North America, as well as those of Europe and Africa. The giant otter can grow to more than 6 feet (2 meters) long and 70 pounds (32 kg), nearly twice as large as its American counterparts..
Giant otters once were found throughout the Tropical rainforests of the Amazon, down . Decline and recovery of coral reefs linked to years of human and environmental activities Date: October 3, reefs in this region began to recover from historical impacts due to human.
WHY IT MATTERS. Should it matter to humans that other life forms are disappearing? Many people think so.
Human populations depend on plants and animals . losing favorite recreational activities; Coral Reefs Under Stress. Learn about how scientists are monitoring coral reef health in this article. Read/download the report, or view a slideshow that evaluate human pressure on coral reefs worldwide.
Click on the interactive map . Humans Have Caused Profound Changes In Caribbean Coral Reefs Humans Have Caused Profound Changes In Caribbean Coral Reefs. of former bustling coral reefs dying due to the impact of human. Part B: Human Activities That Threaten Coral Reefs The Reefs at Risk map layers in ReefGIS allow you to separate the effects different human activities have .