Human impact on coral reefs -Daphne Zakarian


  • Coral Reefs are one of the most diverse ecosystems in the world, but their survival has been compromised because of human actions. The reefs are home and protection for up to 9 million species around the world. The coral makes an ideal habitat for many animals, and, as we sacrifice these ecosystems, we sacrifice all of the species that rely on the reefs with it.
  • The reefs are found in tropical coasts near the equator; on a map, you can see a distinct region where the reefs are present.
  • The coral cannot survive in deep water, because the algae that gives them energy relies on photosynthesis. The algae, zooxanthellae, is a vital species for the survival of the coral. Without the algae, coral would not be able to sustain itself.
  • It is important to remember that coral (the organism), is different from coral reefs (the ecosystem).

Causes of Coral Reef Destruction

-Destructive Fishing:

  • Bottom Trawling: Fishing method where trawls are used to go across the bottom of the ocean floor. Rollers drag across the reefs, tearing up the surface and destroying anything in its path. In the area where the reefs once lived, a scar of bare rock is left, and most doesn't recover for years
  • Cyanide Fishing: Sodium cyanide is put in the water to stun the fish and allows the fish to be caught more easily. According to the World Wildlife Fund, for every fish caught by cyanide, a square meter of coral reef is killed
  • Dynamite Fishing: Explosives are set off in the water, which kills the organisms in the area and ruins the habitat. The dead fish float to the surface of the water, and the environment below is left destroyed
How Bottom Trawling Effects Coral Reefs


  • Tourism leads to trash deposits and water pollution.
  • Some animals start to rely on humans to feed them.
  • When people scuba dive and snorkel, the coral reefs are trampled by the tourists and their gear.
  • When boats anchor, they break or disrupt the reefs.
  • Invasive species can be spread by boats or fishing gear, and unbalances the ecosystem.
Divers on a coral reef


  • During construction, run-off deposits on coral reefs, block the reef from the sun, and smother it. The reefs become smashed and lack of light stops photosynthesis.


  • When too many of one population are taken out of their habitat, the species becomes over-exhausted and cannot replenish the number of the fish. Not only does this effect the one species being caught, it also upsets the food web, and the balance of the ecosystem.

Coral Mining

  • Coral is sold for tourists, and is collected to be used as bricks or cement. The amount of coral that is mined in a short period of time takes decades to grow back.

Climate Change

  • Coral has algae on the surfaces, which provides it with energy, but when the water gets too hot, the coral rejects the algae and bleaching occurs. The coral turns white, and doesn't have the energy it needs to survive.

Bleaching in coral reefs

Impact on species

The reefs are a home for many marine species, and many rely on the reefs for their survival.

Hawksbill sea turtle

  • The hawksbill sea turtles live in the reefs, so when the reefs are destroyed, their home and source of food are destroyed with it.
  • The hawksbill sea turtle eats sponges, urchins, barnacles, algae, sea grasses, and other marine wildlife. These organisms also live in the reefs, so, as they don't have anywhere to live, the hawksbill sea turtle loses its source of food.

Butterfly Fish

  • They use the reefs for a shelter as they sleep, protecting them from predators.
  • One of the primary foods for the butterfly fish is coral, so as coral becomes harder for them to access, not only do they lose shelter, but they also lose a source of food.
  • Butterfly fish use crevices in coral to hide from predators.

Staghorn Coral

  • Staghorn coral is considered a threatened species of coral, and it's easy to guess that coral reef destruction will have a large impact on coral.
  • According to NOAA, some of the most prominent threats to this species are sedimentation and bleaching. It is inevitable for the coral to have some threats, but it is impractical for the population to be effected so greatly by human actions.
  • Not only does coral bleaching harm the coral by stopping the algae from providing energy, it also makes it harder for the coral to fight of diseases, which is considered the biggest threat to the species at the moment.
  • IUCN states that the staghorn coral population has reduced by at least 80%, or as much as 98%, in the past 30 years, and that it is very important to monitor the specie's growth.

Pillar Coral

  • Similar to staghorn coral, pillar coral have a high risk of disease, and the bleaching weakens their immune systems.
  • Over-fishing is another threat to pillar coral, because, when the fish don't eat the abundance of the algae on the coral, the algae suffocates it.

Elegance Coral

  • Elegance coral are also at risk because of human actions. The main reason why this species is at risk is because they are taken for tourists to buy, and, according to EDGE, they are taken because of a "nature trend.
  • In the South China Sea, elegance coral has been reduced by 80% in the past 30 years, and humans are part of the reason why.

What We can do

  • Although the damages done to coral cannot be reversed, there are steps that we can take to aid in the recovery of the ecosystems, and to avoid harming them more.


  • Although it doesn't seem like much, the more people who know that this problem exists, the more people who will work on solving the problem, and the more people work to reduce contributing to the problem. If tourists were informed about the effect that their purchase of a piece of coral has on the environment, they are much more likely to avoid the purchase. It's hard to try to save an ecosystem when people don't know that the problem exists.

Simple steps that Everyone can take

These steps are small scale, and most aren't able to actually help recover the damaged reefs, but they help avoid contributing more to the destruction of the reefs.
  • If you go diving, don't touch the coral
  • Make sure that any coral you buy is harvested legally
  • If you are boating, don't anchor in the reefs
  • Reduce pollution
  • Educate yourself on the seafood you get to see if it was caught in a way that is harmful to the environment
  • Conserve water to reduce runoff
  • Contact government officials
  • And this link has a list from NOAA of more steps you can take to prevent reef destruction

Larger scale solutions

  • Pollution is factor that has a huge effect on the health of the whole ecosystem. Australia has millions of dollars invested in improving the water that flows into the Great Barrier Reefs. Other countries can, and have been taking similar steps to stop the destruction of the reefs.
  • According to the Australian government, the steps that they have taken have already gotten results, and have "halted and reversed the decline in water quality."
  • There are now areas of the coral reefs that are government protected in the American coasts and around the world.
  • There are systems set to closely monitor the reefs, and the health of the reefs is documented and give a warning before the reef condition gets worse.

Works Cited

Primary Sources

Jackson, Jeremy, and Ayana Elizabeth Johnson. "We Can Save the Caribbean's Coral Reefs." New York Times, 19 Sept. 2014, p. A29(L). Science in Context, Accessed 20 Apr. 2017.

"A Move to Save Coral Reefs." New York Times, 5 June 2006, p. A18(L). Science inContext, Accessed 20 Apr. 2017.

Pala, Christopher. "The reel downfall of reefs: controlling fishing to save the coral reefs." Our Planet, 14 July 2008. Science in Context, Accessed 20 Apr. 2017.

"University of Derby - University lecturer calls for scientists to save coral reefs." ENP Newswire, 17 Nov. 2015. Science in Context, Accessed 20 Apr. 2017.

"UNIVERSITY OF EXETER - Climate engineering may save coral reefs, study shows." ENP Newswire, 1 June 2015. Science in Context, Accessed 20 Apr. 2017.

Secondary Sources

860_Main_Corals. Creative Ways to Help Coral Reefs Recover, Society for Science and the Public, Accessed 17 Apr. 2017.

Aronson, R., Bruckner, A., Moore, J., Precht, B. & E. Weil. 2008. Acropora cervicornis. The IUCN Red List of Threatened Species 2008: e.T133381A3716457. Downloaded on 21 April 2017.

"Australian Endangered Species: Sea Snakes." The Conversation, Accessed 19 Apr. 2017.

"Butterfly Fish." A-Z Animals, Accessed 18 Apr. 2017.

Butterfly Fish. Nature World News,

"Circulation and Sediment, Nutrient, Contaminant, and Larval Dynamics on Reefs." USGS, 17 Nov. 2016, Accessed 17 Apr. 2017.

Coral-Bleaching. All You Need Is Biology, Accessed 17 Apr. 2017.

"Coral Mining- the New Danger for Reefs." EcoChic Magazine, 2017, Accessed 17 Apr. 2017.

"Coral Reefs: Threats." WWF Global, 2017, Accessed 12 Apr. 2017.

Damage to Coral Caused By Bottom Trawling. Earth Rangers, Accessed 17 Apr. 2017.

Divers Standing on the Reef. Green Fins, Reef-World Foundation, Accessed 17 Apr. 2017.

"Elegance Coral (Catalaphyllia Jardinei)." EDGE, Accessed 20 Apr. 2017.

"Fishing Problems: Destructive Fishing Practices." WWF, 2017, Accessed 12 Apr. 2017.

Hawksbill Sea Turtle. MySilverSands,

"Hawksbill Sea Turtle." National Wildlife Federation, 2017, Accessed 18 Apr. 2017.

"Overfishing." National Geographic, National Geographic Partners, 2017, Accessed 17 Apr. 2017.


"Pillar Coral (Dendrogyra Cylindrus)." EDGE, ZSL, Accessed 20 Apr. 2017.

Reef-fish. CBS Nova Next, WGBH Educational Foundation, Accessed 17 Apr. 2017.

Reef map. CoralGeography, Accessed 20 Apr. 2017.

"Species on Coral Reefs." Microdocs, Accessed 19 Apr. 2017.

"Staghorn Coral (Acropora Cervicornis)." NOAA, 5 Mar. 2015, Accessed 20 Apr. 2017.

"10 Things You Can Do to Save the Coral Reefs." Public Affairs, Accessed 20 Apr. 2017.

"Tourism and Recreational Impacts." Reef Resiliance, Nature Conservacy, 2016, Accessed 17 Apr. 2017.

"Where Are Coral Reefs Found?" CoralGeography, 2017, Accessed 20 Apr. 2017.

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