What are coral reefs?
Coral reefs are the most diverse ecosystems in the world. These marine ecosystems occupy less than one percent of the ocean floor, but are occupied by not less than twenty percent of all ocean going species. Studies estimate that more than 25,000 known species from thirty-two of the world’s thirty-three animal species inhabit coral reefs, this is four times the number of animal species found in tropical rain forests in Brazil and Indonesia. Coral reefs are one of the oldest environments in the world. Most coral reefs we know of have been growing for over 5,000 years. Coral reefs are found within the authority of more than 100 countries and cover around 600,000 square kilometers of tropical oceans. They normally need clear, warm water and high light intensity in order to survive. This restricts them to shallow water, with large diversity occurring within 10 to 30 meters below the surface. Reefs are found in nutrient-poor environments and it is because of this that small fluctuations in the nutrient content of the water can negatively affect their survival.
Coral reefs are very productive marine ecosystems. They play an important role as habitat and nursery grounds for 10% to 20% of the world’s fisheries. They are closely connected to other marine ecosystems such as mangrove forests, sea grass beds, and the open seas as water currents carry larvae, plants, animals, nutrients, and organic materials. Coral reefs play a critical role in the progress of other ecosystems such as mangroves and wetlands and protect coastlines from wave, storm damage and erosion. Medicines like anticoagulants, and anticancer agents, such as prostaglandins, originate from coral reefs. The structure of coral reefs are formed from the calcium carbonate deposited mostly by calcareous algae and the stony corals, most of which are colonial animals looking like tiny, interconnected sea anemones. Reef building corals hold symbiotic algae in their tissues, allowing them to develop the large, massive, branching, or encrusting carbonate skeletons that provide homes and food resources for support of other reef species, such as fish, lobsters, giant clams, and sea urchins. Coral reefs support a network of important ecological relationships and fragile food webs. Disturbance of coral reef communities destroy these ecological bonds. Under a natural environmental state, a functional coral reef can recover from natural disturbance such as hurricanes, within 10 to 20 years. However when exposed to persistent human stressors, recovery from even natural disturbance may be irreversible.
Human activities, both direct and indirect, are increasing the loss of coral reefs around the world.
- Over-fishing, especially of long lived, low density fish like the grouper, and obstructive fishing practices such as the pervasive use of cyanide and dynamite in order to catch fish.
- Pollution, particularly from increased sedimentation (from poor land practices) that engulfs the coral tissue and nutrients (from runoff) that encourage algae growth which ultimately, suffocates the corals.
- Physical degradation from holiday makers damaging the reefs, anchors dropped in coral beds, and ships crashing into reefs.
- Alteration of other coastline ecosystems, such as cutting of mangrove forests and other coastal habitats.
- Harvesting live aquarium fish and coral for food, traditional medicine, and aquaria. These bring high prices and have resulted in destructive fishing techniques that destroy the reefs, as well as the species that live in them. The United States is one of the largest importers of live coral for aquaria.
Escalating global temperatures caused by climate change have negatively affected coral reefs, caused by an increase in the regularity of large-scale bleaching events. Corals live in specific habitats, requiring limited boundaries of salinity, nutrients, and temperature. Even small fluctuations (for a couple of weeks) above this range can stress corals, which then displace their intracellular symbiotic zooxanthellae causing coral bleaching. The United States National Oceanic and Atmospheric Administration (NOAA) announced 2015 and 2016 to be a global coral bleaching event, this is the third event in the past 20 years. It has been documented as the longest and most widespread global coral bleaching event with some reefs in Hawaii and the Great Barrier Reef succumbing to severe bleaching on two occasions. A number of areas that do not often experience high rates of bleaching during El Nino years were heavily affected, including areas in subtropical Hong Kong, reefs in Western Australia, and the central and southern Red Sea. Coral bleaching has now become the main cause of coral reef degradation globally.
Some research have shown that some corals are capable of wide acclimatization to microclimates and developed enhanced resistance to bleaching without changing the relationship of the two organisms that make up coral. Scientists do not yet know the amount of coral species which can acclimatize or evolve. It is also likely that many stressors such as acidification and heat can decrease the ability of corals to react. This means that we cannot rely solely on acclimatization to overcome the threat of coral reefs from the bleaching events around the world, particularly if the high-temperature stress is sudden and sustained. In this manner the speed and severity of heat and variations will be important for effective coral acclimatization. For the fast-growing, shallow-water species that was researched, adaptive responses allowed them to establish reef areas with water temperatures high above their expected tolerances. How well other corals can similarly react , and what the boundaries of these responses are, will show how well current frameworks accurately predict the future decline of coral reefs.
It’s not only warm temperatures that affect the corals. In January 2010, cold water temperatures in the Florida Keys caused a coral bleaching event that resulted in coral death. Water temperatures decreased by12.06 degrees Fahrenheit (-11°Celcius) lower than the normal temperatures seen at this time of year. Researchers will study if this cold-stress event could make corals more prone to disease in the same way that warmer waters impact corals.
Oxybenzone is mainly used as an active ingredient in sunscreen creams and other products, such as body fragrances, hair-styling products, shampoos and conditioners, anti-aging creams, lip balms, mascaras, insect repellents, as well as dishwasher soaps, dish soaps, hand soaps, and bath oils/salts. Benzophenone and other forms of it can be found as pollutants in boating, residential, and municipal wastewater effluents and are considered ‘‘emerging environmental contaminants of concern’’ by the U.S. Environmental Protection Agency. Around 6000 and 14,000 tons of sunscreen lotion, are estimated to be released into coral reef areas each year, putting at least 10 % of the global reefs at risk of vulnerability, and it is estimated that 40% of coral reefs located adjacent to coastal zones are at risk of contamination. In Okinawa, Oxybenzone levels on coral reefs that were 300–600 m away from public swimming beaches ranged from 0.4 to 3.8 parts per trillion in South America, sediments near coral communities/reefs contained Oxybenzone concentrations between 54 and 578 parts per trillion. Scientists discovered through a Toxicity Identification Evaluation that Oxybenzone was strongly identified as the source of estrogenic activity in marine sediments around wastewater outfalls. Although the half-life in seawater is a number of months, Oxybenzone can act as a pseudo (false) persistent pollutant; its pollution of an area may be repetitively renewed. Concerns regarding the adverse impacts of exposure to Oxybenzone on coral reefs and other marine and aquatic habitats have resulted in either banning oxybenzone-containing products in marine managed areas or public relations campaigns by stakeholders to promote reduction of environmental contamination of sunscreen creams by swimmers. You can read more about pollution and its effects on nature here http://exploringconservation.com/2018/05/25/contaminating-the-earth/
Significance of Ecology
- Ecological research has helped pinpoint some of the causes of reef degradation. Recent studies show that the loss of large predatory fish and other key elements of the ecosystem, such as snappers and lobsters, have caused large disruptions of reef food webs. These disruptions have shown a decrease of coral and increases in algae.
Ecologists have found diseases such as black-band disease and white plague that can kill coral in less than 1/100th of the time it takes for coral to grow. The cause of these diseases are still not fully known. Consistent disease descriptions and structured diagnostic procedures are important for the effective management of disease in animal and plant populations. However, despite increasing impacts of coral diseases on reef habitats globally, varied and counter-statement descriptions and diagnostic criteria continue to impede research and management of coral diseases.
- Remedies to destructive fishing techniques can be gathered through information collected on the life and breeding cycles of threatened reef species, such as groupers. This can lead to less stress through commercial breeding.
- Ecological knowledge is important to reef management and restoration, and long term monitoring and evaluation of the status of reefs are necessary components of these contributions.
Ecologically-based management can provide important ways in which to restore reef ecosystems by addressing some of these threats. For example, improved water quality and fisheries management are necessary to restore reef ecosystems. Marine Protected Areas such as sanctuaries, reserves, and no-fishing zones can allow degraded ecosystems to recover.
Coral reef managers are changing their focus from a strictly stress relieving point of view to incorporating a broader framework of ecosystem resilience. In other words, supporting ecosystem processes that decrease sensitivity, encourage recovery and grow adaptive capacity. This change has been strengthened by an increase in adaptive management efforts and putting into place system approaches for management and conservation. Resilience enables an important model for these more integrated and varied approaches and aids managers deal with the combined and often more harmonious impacts of worldwide and local stressors.
Without coral reefs a large amount of diversity will be lost, not only in the ocean but on a global aspect as well. Local tourism will be (if not already) the hardest hit as holiday makers do not want to look at a bunch of dead coral with the odd fish here and there. I had first hand experience with this when going on a glass bottom boat in Mauritius and all we saw was dead coral. Coastal zones will become heavily damaged when a big storm approaches because there’s no buffer zone ( coral reefs) to protect them. The root cause of bleaching is climate change which is an entire separate blog post all together. However we need to be more conscious of the carbon footprint we as individuals leave on this earth, in regard to having a more sustainable lifestyle. There is still hope for coral reefs but we need to start altering our mindsets in what we buy and do in order to save not only the corals but many other animal species we share the world with.
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[NATL] Reefs in Ruin: Coral Bleaching Around the World
kcet earth focus
Mission blue- restoring coral gardens in Fiji