Small organisms that carry a lot of weight.
The Look of a Curious MindThe warmer months provide me with a great opportunity to take students down to the local bay and explore the coastal ecology. I usually show them the diversity of life on the beach (that is, if the tide co-operates with us) as we explore crabs, clams, fish, and shoreline birds. Sometimes we use nets and attempt to catch some sea life, other times we explore factors affecting water quality. Almost every time, the students come back with bags full of clams, mussels, oysters, sea glass, and whatever else they found that is deemed interesting. They usually ask me to define things or talk about a particular animal’s behavior. As with many kids, the questions at times can be quite interesting or even unusual. Many are simply questions of curiosity and occasionally they stick with you. This was the case recently, when a child asked me if there would be any coral at the beach.
Reef building coral are usually found in warmer waters living at depths from 500 to 8000 feet and optimally grow in temperatures between 74⁰ F and 84⁰ F (as I explained to the student). They cannot survive in temperatures below 64⁰F. Corals are invertebrates in the phylum Cnidaria, with their closest relatives being anemones and jelly fish. They typically form colonies made up of many individual organisms called polyps. These polyps begin life as a larva swimming around. Eventually it attaches to a hard surface and begins to form an exoskeleton. With the help of brown algae, corals extract calcium and bicarbonate from the sea water to form calcium carbonate (limestone). Corals feed on microscopic plankton primarily but also eat floating dead material called detritus and even small fish. They use their tentacles to sting and immobilize their prey in order to bring the food into their stomach. Once the meal is digested, they open their stomach and allow the waste to float away. Corals can reproduce sexually and asexually and many organisms within a colony can be genetically identical. Once the animal dies, it leaves behind its exoskeleton and a new organism takes up residence in it and adds to the structure. They grow slowly; up to 4 inches per year and large coral reefs can take decades or centuries to form.
Coral reefs only make up 1% of the earth’s surface but support an estimated 25% of marine life. Fish, lobster, crabs, and sea turtles make up a few of the thousands of species that reside in them. Reefs provide protection for many animals and a food source for others. Humans also benefit from coral as well as a source of food and jobs. They generate billions of dollars in revenue each year; Southeast Asia’s coral reef alone is estimated to generate $2.4 billion per year. Reefs are natural barriers which protect coastlines from storms and can reduce wave activity up to 97% by some estimates. Many of the plants and animals that reside in them are sources of new medicine that treat a variety of diseases including cancer, heart disease, and Alzheimer’s.
It is no secret that coral reefs are in danger and are being destroyed. Estimates state that up to 25% of the worlds coral reefs are gone. The most destruction has been in the Philippines where up to 70% of them are gone. Climate change is the leading culprit in the loss of reefs and is affecting them in two ways: warming waters and ocean acidification. When waters warm up, the algae that coral rely on die and cause the coral to weaken. Increasing carbon dioxide in the water leads to increasingly acidic water, a condition that many scientists believe will be the biggest threat to ocean ecosystems. Other threats to coral reefs include overfishing, pollution, and coastal development.
Restoration of coral reefs is of the utmost importance and the question on the minds of many is: Can we rebuild them before it is too late? Scientists are studying reefs around the world and in many places are seeing new polyps forming. Projects are widespread and include, creating structures that polyps could build new colonies on, harvesting coral in a lab, and engineering new organisms that can withstand the changing environment that is killing them off. It will take years to grow new colonies and we can only hope that they offset the damage that has been done.
By Daniel J. Steiger
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