By: Stephenie M.
Over the last 30 years, the number of coral reefs has dramatically declined as a result of stress from water pollution, a rise in sea levels, changes in storm patterns, and global warming. Believe it or not, 50 percent of the world’s coral reefs have been destroyed, and scientists predict that they will be extinct by the end of the century. This keystone species sustains approximately one-quarter of marine life and takes up less than 1 percent of the ocean floor. It is crucial to protect these valuable ecosystems that play a significant role in the environment. They provide food, medicine, protection from storms, and they play a huge role in the economy through tourism, fishers, and jobs. Without coral reefs, billions of people worldwide could experience a disastrous hit to the economy, famines, widespread poverty, as well as the marine ecosystem collapsing.
Coral reefs benefit different aspects of many people's lives, not just to the economy. Without them, many species would suffer, and so would millions of people who depend on them for food and a source of income. Photo by Christina Gloor, NOAA
Coral reefs are vivid and complex organisms that hold an incredible amount of biodiversity. Many people think they are plants, due to their physical qualities, but they are actually animals. They are made up of Polyps, which are tiny organisms related to jellyfish, that have tentacles and a protective base skeleton made of limestone, which forms the structure of reefs and creates coral colonies (Coral Reef Alliance). Polyps get their nourishment from sugar, which is produced by symbiotic algae located in a corals tissue, which uses sunlight to make sugar for energy. In return, the coral provides the algae with a protected environment and certain substances they need to undergo photosynthesis, such as carbon dioxide, nitrogen, and other compounds they need to survive. When a coral becomes damaged by pollution or a change in temperature, it stresses the coral and expels algae from its tissues, which eventually results in a bleached white coral. Bleaching inflicts additional stress and increases mortality likelihoods, making it quite difficult for coral to survive. If this phenomenon continues, it could lead to the extinction of coral reefs.
Polyps use their tentacles to grab food from the water. Photo by: NOAA
Plastic pollution is posing a threat to reefs, as its dangerous chemical compounds carry microbes into aquatic environments. According to the International Union for Conservation of Nature, “at least eight million tons of plastic end up in our oceans each year,” making corals extremely vulnerable to disease and contamination. Corals mistakenly identify plastic debris as food, causing them to contract diseases such as white syndrome, black band, or skeletal erosion. According to a research report from Journal Magazine, corals reefs have “a likelihood of 4 percent to 96 percent of disease” when in contact with plastic, especially branching corals, where plastic can easily entangle on its branches. Plastic waste also blocks sunlight from reaching the surface of the ocean. As a result, algae are unable to undergo photosynthesis, since corals are without their primary food source, algae are expelled from corals. Without algae, coral reefs become bleached, meaning it will lose their vibrant colors and not have an energy source. If the annual rate of plastic thrown into the ocean continues, there could be billions of tons of plastic produced by 2050. Mass bleaching will become more common if we do not find a way to decrease the amount of plastic ending up in them.
When a coral gets bleached, it loses its vibrant colors, and is more susceptible to disease and death. Photo by: The Ocean Agency, Richard Vevers
Due to climate change, coral reefs are struggling even more to survive. Global warming is altering various ocean components. Sea level rises have led to an increase in sedimentation, a natural process where running water erodes the land and causes sediment runoff. This adds harmful chemicals to sediment loads that are ruining the biological process of sedimentation, causing permanent damage to the carbon skeleton layers of corals. Changes in storm patterns are also destroying coral reefs, as they are more frequent and intense. Human activities are causing warming, which is contributing to an increase in the amount of vapor present in the atmosphere. The storm system has additional moisture, which increases the likelihood of precipitation events according to the Proceeding of the National Academy of Sciences. Large storms can cause extreme damage to a coral reef structure because winds generate aggressive waves that shift sand and smother colonies.
Climate change has been influencing extreme weather, increasing the intensity of natural disasters. Image from Shutterstock/Lavizzara
Other physical disturbances include storms breaking corals into pieces and causing damage to small and delicate coral reefs, which is leading massive corals that aren't fragile to dominate a community. The outcome of changes in storms is ultimately overturning coral colonies and is causing damage to some parts of the reef, which are propelling into other parts of the reef.
Overfishing is another threat to coral reefs, as it is creating an imbalance in a coral reefs ecosystem. There are many benefits of fishing as it improves livelihoods, strengthens family relationships, teaches patience, encourages appreciation of nature, and promotes economic growth. As the human population rises, there has been a growing demand for fish due to its status as an important source of protein. According to the Food and Agriculture Organization of the United Nations, “the number of overfished stocks globally has tripled in a half-century”, and it is pushing fisheries past their biological boundaries. Herbivorous fish such as parrotfish and surgeonfish are algae-eating fish, which keep the low levels of algae on reefs. When these fish disappear as a result of overfishing, it disrupts the coral reef ecosystem, and macro algae (seaweed algae) can grow and eventually smother a reef. To combat this, we must protect fish species because the loss of one species could create an ecological imbalance that could damage many coral reef ecosystems.
Scientists are trying to save coral reefs in numerous ways. The main goal is to help coral reefs recover quicker from bleaching and to create marine refuges to help coral reefs be more resilient and healthier. Marine biologists are attempting to recover coral reefs using micro-fragmentation and fusion. Most scientists believe that they will revitalize the coral reefs quicker, rather than leaving them alone to recover. Some corals can adapt to varying temperature levels, depending on their DNA. By modifying a corals DNA, it could create super corals whose genes are more robust. These efforts to save corals are made by Mote Marine Laboratory’s Coral Reef Restoration Program, which focuses on restoring corals by cultivating strategies. Another solution to protect corals is to make marine refuges, where activities such as fishing, mining, and recreating are off-limits to help coral reefs stay healthy. They hope they can achieve their goals so that these beautiful creatures do not keep rapidly declining as they have been for the last thirty years.
Coral reefs are threatened by many factors caused by pollution, changes in frequency and intensity of storms, global climate change, and overfishing. Many people and aquatic organisms who are dependent on these valuable, ancient, and complex ecosystems will face struggles if they are not protected. These consequences include poverty, the suffering of marine life, a loss of food source for millions of people, and political instability. Scientists are coming up with many ways to save corals, as their populations are dramatically declining. If we don't take care of corals, we could lose them by the end of the century.
Discussion Questions:
Researchers believe most coral reefs may be wiped out by 2050. Do you think efforts by scientists to protect coral reefs are promising?
What impact has global warming had on coral reefs?