Audience: Middle School Students
Finding Nemo – a Disney classic. Though it differs significantly from the common Disney
princess, its unique story is what makes it so compelling. The various talking sea animals and human-to-animal interaction creates an unusual yet exciting perspective for people to witness the lives of animals. The movie begins as the clownfish Nemo prepares for his first day of school, as do the rest of the sea animals. Upon leaving their homes, all the animals swim through beautifully colored plant-like structures that sway with them as they glide through the water, as seen in the image below. But what are those things? Are they rocks? Shells? Plants? Animals? Are they even living? As a matter of fact, those are coral reefs, composed of both living and nonliving components.
Coral reefs are huge underwater structures made up of the skeletons of coral. Coral are colonial marine invertebrates, i.e. animals that have no backbone. Colonial organisms consist of hundreds to thousands of individual animals, called polyps. The species of coral that builds reefs are called hermatypic, or “hard” corals. This is because they create a hard exoskeleton to protect their soft bodies by extracting the compound calcium carbonate from the sea’s water. Coral polyps add their own exoskeleton to coral structures that already exist, allowing the coral reef to slowly grow over centuries until they become a prominent aspect of the marine environment.
Coral reefs are located all over the world’s oceans, but the biggest ones are found in tropical waters where it’s clear and shallow. This allows algae to have plenty of sunlight, which is crucial for coral as they rely on algae for food. Though these reefs are located in shallow waters, almost none of them are recently developed. In fact, most of them are around 5,000 to 10,000 years old. The largest coral reef resides in Australia, called the Great Barrier Reef, stretching over 1,500 miles long. Though coral reefs are one of the most diverse and productive ecosystems on Earth, with various relationships with other marine organisms, coral reefs make up less than one percent of the ocean floor.
These relationships are called symbiotic relationships, which are relationships between two organisms and consist of three types: mutualism, commensalism, and parasitism. In mutualism, both organisms benefit. This is seen between corals and zooxanthellae, where corals provide zooxanthellae with a survivable environment and zooxanthellae use photosynthesis to produce compounds that the coral use for food. Commensalism is when one species benefits while the other is neither benefited nor harmed. Within the coral reefs reside animals like clownfish and sea anemones. The sea anemones have tentacles with stinging cells in which clownfish hide, unharmed, allowing for protection from predators. Lastly, in parasitism, one organism benefits while the other is harmed. In coral reefs, small invertebrate animals called isopods live in the gills, fins, and scales of fish, sucking the blood from the fish to get their nutrients, eventually killing the fish.
Approximately 25% of marine species depend on coral reefs for survival, whether it’s for food, shelter, and/or reproduction. Since coral reefs have such high biodiversity – the variety of life in a particular habitat or ecosystem – they are known as the “rainforests of the sea.” Over 700 coral, 4,000 species of fish, and thousands of other plans and animals utilize coral reefs as their primary home.
Coral reefs provide many benefits to the environment and humans as well as to marine animals protecting coastlines from storms and erosion, providing jobs, and acting as a huge source of food and medicine. More than half a billion people depend on reefs for their food, income, and protection. Businesses also thrive, as people spend money for entertainment purposes, such as fishing, diving, and snorkeling – all to see the beautiful sea animals and coral reefs.
Unfortunately, while coral reefs benefit the natural world and humans vastly, their ecosystems are immensely threatened. Some of these threats are due to storms, diseases, and predators, while others are caused by people. One of which is ocean acidification, which occurs when large amounts of carbon dioxide — released into the atmosphere from the burning of fossil fuels — is taken in by the ocean. In consequence, corals are unable to produce calcium carbonate exoskeletons, which they depend on for shelter. An additional consequence driven by human activity is water pollution, which occurs when pesticides and fertilizers from farming, gas, oil, sediment, and garbage go into the ocean, increasing the difficulty for coral reefs to survive.
Additionally, when temperature rises, coral polyps get stressed, resulting in the loss of the zooxanthellae that reside in the polyps’ tissues, depleting the coral of its color. Transforming to simply a white exoskeleton, a process called coral bleaching, corals often die as a result. Corals are sometimes able to recover from coral bleaching, but it takes many years before the ecosystems can fully recuperate.
Different methods of fishing can demolish coral reefs that are thousands of years old in just a few minutes. This can be caused by cyanide fishing (cyanide sprayed in the water because it catches fish easier), “blast fishing” (using explosives), and overfishing.
It is heartbreaking to see the damaging threats to coral reefs, but promising efforts are being made to protect and support the coral reefs. Some coral are being rebuilt by growing them in a nursery and transplanting the new coral to damaged areas. Efforts by the Australian government are being made to protect the Great Barrier Reef by prohibiting the dumping of garbage and chemicals, decreasing the amount of fishing and poaching, and analyzing the quality of the run-off that goes to the reef.
Together, we can help save coral reefs by being mindful of our surroundings. It is crucial to dispose of trash properly and not let it get into our oceans. You could volunteer for beach and/or reef cleanups! Additionally, it is important to respect the natural marine life. If you participate in activities like diving and snorkeling, make sure not to touch the reefs and that your boat doesn’t get anchored to the reef. These seem like small actions, but they go a long way in protecting the beautiful coral reefs.
Bibliography:
Coral Reef Basics - Symbiosis. HSIE Teachers. (n.d.). http://www.hsieteachers.com/blog/coral-reef-basics-symbiosis#:~:text=There%20are%20three%20types%20of,he%20detriment%20of%20the%20other
Coral Reef Ecosystems - National Oceanic and Atmospheric Administration. (n.d.). https://www.noaa.gov/education/resource-collections/marine-life/coral-reef-ecosystems
Ross, R. (2018, September 24). What are coral reefs?. LiveScience. https://www.livescience.com/40276-coral-reefs.html
Sanctuary, F. K. N. M. (2011, April 4). Coral bleaching and ocean acidification are two climate-related impacts to coral reefs. How is climate change affecting coral reefs? https://floridakeys.noaa.gov/corals/climatethreat.html#:~:text=Rising%20(or%20even%20falling)%20water,the%20coral%20turns%20completely%20white
US Department of Commerce, N. O. and A. A. (2013, June 1). What are corals? - corals: NOAA’s National Ocean Service Education. What Are Corals? Corals Tutorial. https://oceanservice.noaa.gov/education/tutorial_corals/coral01_intro.html
US Department of Commerce, N. O. and A. A. (2013, June 1). What species live in and around coral reefs?. NOAA’s National Ocean Service. https://oceanservice.noaa.gov/facts/coral_species.html#:~:text=Coral%20reefs%20are%20home%20to,on%20reefs%20for%20their%20survival
What are coral reefs? are they considered living creatures due to the fact that they’re hard as rock or are they just dead corals? what I... Quora. (n.d.). https://www.quora.com/What-are-coral-reefs-Are-they-considered-living-creatures-due-to-the-fact-that-theyre-hard-as-rock-or-are-they-just-dead-corals-What-is-coral-reef-bleaching#:~:text=Corals%20are%20marine%20invertebrates%20that,countless%20generations%20of%20coral%20polyps
What is an example of parasitism in coral reefs? - homework.study.com. (n.d.). https://homework.study.com/explanation/what-is-an-example-of-parasitism-in-coral-reefs.html
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