Cause and effect essays look at the reasons (or causes) for something, then discuss the results (or effects). The language of cause and effect (أسباب و نتائج) is important in academic writing because it helps answer the question: Why?
In addition to the above reading, watch the following three videos. With Videos 1 and 2, there are accompanying note-taking sheets. With Video 3, there is a gap-fill worksheet. As you watch the videos below:
- Make notes about what coral reefs are, including their locations, size, importance etc. (useful for an introductory paragraph);
- Identify and list what factors (“reasons”) might be endangering (“threatening”) coral reefs (useful information to include when writing about causes);
- Identify and list what consequences might result from the destruction of coral reefs (useful information to include when writing about effects);
- Note down what you think are important facts and figures;
- Build your general knowledge on the subject.
Video 1: “Australia Revealed: Great Barrier Reef”
Video 1 Note-taking sheet
Source: Discovery Go. (n.d.) Australia Revealed: The Great Barrier Reef. Retrieved from http://www.discovery.com/tvshows/other-shows/videos/discovery-atlas-australia-revealed-great-barrier-reef/
Video 2: “Coral Reefs”
Video 2 Note-taking sheet
Source: National Geographic. (2016). Coral Reefs. Retrieved from
Video 3: “Dredging the Great Barrier Reef”
Video 3 Gap-fill worksheet
Source: Stevens, C. (2014). Dredging the Great Barrier Reef. Retrieved from https://youtu.be/Uko4hTlcLp0
Fast facts: why coral reefs are important to people
Source: WWF. (2016). Fast facts: why coral reefs are important to people. Retrieved from
Occupying less than one quarter of 1 per cent of the marine environment, coral reefs are home to more than 25 per cent of all known marine fish species.
More than 450 million people live within 60 kilometres of coral reefs, with the majority directly or indirectly deriving food and income from them.
Properly managed coral reefs can yield an average of 15 tonnes of fish and other seafood per square kilometre each year.
More than 80 per cent of the world’s shallow reefs are severely over-fished.
58 per cent of the world’s coral reefs are potentially threatened by human activity.
If present rates of destruction are allowed to continue, 60 per cent of the world’s coral reefs will be destroyed over the next 30 years.
Coral reefs: importance
Source: Harvey, Martin. (2016). Coral reefs: importance. Retrieved from
Tropical coral reefs are very productive ecosystems. Not only are do they support enormous biodiversity, they are also of immense value to humankind.
Latest estimates suggest coral reefs provide close to US$30 billion each year in goods and services, including:
Fisheries: Coral reefs are vital to the world’s fisheries. They form the nurseries for about a quarter of the ocean’s fish, and thus provide revenue for local communities as well as national and international fishing fleets. An estimated one billion people have some dependence on coral reefs for food and income from fishing. If properly managed, reefs can yield around 15 tonnes of fish and other seafood per square kilometre each year.
Tourism: Tourism revenues generated by coral reefs are also significant. For example, according to a report by the Key West chamber of commerce, tourists visiting the Florida Keys in the US generate at least US$3 billion dollars in annual income, while Australia’s Great Barrier Reef generates well over US$1 billion per year. Sustainably manged coral reef-based tourism can also provide significant alternative or additional sources of income to poorer coastal communities in developing countries.
Coastal protection: Coral reefs break the power of the waves during storms, hurricanes, typhoons, and even tsunamis. By helping to prevent coastal erosion, flooding, and loss of property on the shore, the reefs save billions of dollars each year in terms of reduced insurance and reconstruction costs and reduced need to build costly coastal defences – not to mention the reduced human cost of destruction and displacement.
Source of medical advances: We can also expect coral reef species to contribute to future medical advances. Already coral reef organisms are being used in treatments for diseases like cancer and HIV. Just as with tropical forests, we may continue to find the answers to medical problems in the coral reefs – so long as we can keep them healthy.
Intrinsic value: For many coastal societies around the world, coral reefs and their inhabitants are intricately woven into cultural traditions. For these people – as well as for those who have floated with a mask and snorkel, immersed themselves in the three dimensional wonderland of a scuba dive, or experienced these habitats through media and books – a world without coral reefs would be an infinitely poorer place.
Coral reefs: threats
Source: Freund, Jürgen. (2016). Coral reefs: threats. Retrieved from
Coral reefs have survived tens of thousands of years of natural change, but many of them may not be able to survive the havoc brought by humankind.
Roughly one-quarter of coral reefs worldwide are already considered damaged beyond repair, with another two-thirds under serious threat. Major threats to coral reefs and their habitats include:
Destructive fishing practices: These include cyanide fishing, blast or dynamite fishing, bottom trawling, and muro-ami (banging on the reef with sticks). Bottom-trawling is one of the greatest threats to cold-water coral reefs.
Overfishing: This affects the ecological balance of coral reef communities, warping the food chain and causing effects far beyond the directly overfished population.
Careless tourism: Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs. Some tourist resorts and infrastructure have been built directly on top of reefs, and some resorts empty their sewage or other wastes directly into water surrounding coral reefs.
Pollution: Urban and industrial waste, sewage, agrochemicals, and oil pollution are poisoning reefs. These toxins are dumped directly into the ocean or carried by river systems from sources upstream. Some pollutants, such as sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algae, which ‘smothers’ reefs by cutting off their sunlight.
Sedimentation: Erosion caused by construction (both along coasts and inland), mining, logging, and farming is leading to increased sediment in rivers. This ends up in the ocean, where it can ‘smother’ corals by depriving them of the light needed to survive. The destruction of mangrove forests, which normally trap large amounts of sediment, is exacerbating the problem.
Coral mining: Live coral is removed from reefs for use as bricks, road-fill, or cement for new buildings. Corals are also sold as souvenirs to tourists and to exporters who don’t know or don’t care about the longer term damage done, and harvested for the live rock trade.
Climate change: Corals cannot survive if the water temperature is too high. Global warming has already led to increased levels of coral bleaching, and this is predicted to increase in frequency and severity in the coming decades. Such bleaching events may be the final nail in the coffin for already stressed coral reefs and reef ecosystems.