Many theories have been proposed as to what causes coral bleaching and how serious the threat is to coral ecosystems. While literature holds many theories on coral bleaching, the continuing theme for this review is to what extent is coral bleaching a threat to coral reefs around the world and what is the main cause of coral bleaching. This review will explore the coral and algae symbiont relationship, its role in coral bleaching as well as reviewing past bleaching events and exploring potential adaptation solutions. The literature around these topics will be critically reviewed and analysed. Coral is home to many marine tropical and subtropical species, which rely heavily on the resources provided by the reefs - over 4000 species of molluscs …show more content…
The genus Symbiodinium has 8 divergent lineages from clades A to H, with C as most predominant in corals (Stat, Morris, & Gates, 2008). A close endosymbiotic mutualistic association is formed between the zooxanthellae and the host as the zooxanthellae cells of Symbiodinium live within the vacuoles of the coral host cells (Johnson & Marshall, 2007). Approximately 95% of the photosynthetic products that zooxanthellae produce are given to the host coral (Littman, Willis, & Bourne, 2011). Some sources vary on this percentage however reliable sources such as (Bhagooli & Hidaka, 2004), (Littman, Willis, & Bourne, 2011) and (Hoegh-Guldberg, 1999) state that it is a 95% transfer of photosynthetic products to the coral. Coral provide inorganic waste metabolites such as inorganic nitrogen and phosphorus as well as shelter to the zooxanthellae in exchange for organic nutrients such as amino acids and sugars, and this is well supported by all literature reviewed in this section (Stat, Morris, & Gates,
Leading scientists advise climate change will cause increases to the frequency and intensity of extreme weather events. Rising sea levels pose a significant risk to coastal communities, while the world’s oceans could become too acidic to support coral reefs and other calcifying marine organisms. Coral reefs contain only six per cent of the area of the Great Barrier Reef, yet they provide critical habitat and food for numerous species in the ecosystem. However, climate change has already impacted coral reefs in the Great Barrier Reef as corals are very helpless against its potential impacts. Eight mass coral bleaching events has occurred since 1979, triggered by unusually high water temperatures. And because of this, zooxanthellae (photosynthetic algae) leave their tissues and corals will have no more colours hence ‘bleaching’. Without the zooxanthellae, the corals that remain gradually starve to death. Once the coral dies, fish and a multitude of other marine species are soon affected. Rising sea levels and more frequent and intense storm surges will see more erosion of Australia’s coastline, causing community and residential
Bleaching is when the ocean water become too warm, “corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This is called coral bleaching. When a coral bleaches, it is not dead. Corals can survive a bleaching event, but they are under more stress and are subject to mortality.” (Cave and Gillis). When a coral bleaches, it is more of like a self defense mode, which makes it turn white. The coral loses its food source as well. The downfall of this is that without the cooler waters, the corals could die of starvation or disease. Cooler waters from below can help a bleached coral bounce back to its natural state. However, if the water stays too warm for an extended period of time, “the corals don't just bleach, they cook and they die very quickly,.” (Westcott). Throughout time, much of the corals near Cairns and northward have lost the most corals. Hughes states that, “near Cairns, the Great Barrier Reef has lost 47 percent to 83 percent of their coral and as you go northward, the Great Barrier Reef has lost 11percent to 35 percent of its corals.” (Cave and Gillis). In another report, “a study last year found the largest die off of corals ever recorded with about 67 per cent of shallow water coral found dead in a survey of a 700km stretch.” (Johnston). In 2016 and 2017, there were back to back bleaching events. According to CNN reports, “back to back bleaching events in 2016 and 2017 have devastated a 1,500 km (900 miles) stretch of the UNESCO World Heritage Site.” (Westcott). Before the 2016 bleaching event of the Great Barrier Reef, there have only been two bleaching events, 1998 and 2002. According the Hughes, “only 9 percent of the reef has avoided bleaching since 1998.” (Cave and Gillis). That means that over 90 percent of the Great Barrier Reef has been affected by coral bleaching at least once in the past 19 years.
...of coral. Zooxanthellae provides corals with their pigmentation as well as glucose and amino acids. Loss of zooxanthellae leads to "bleaching", a loss of coloration and stamina within the coral that lends the organism prone to disease.
In absence of calcium carbonate, coral and shellfish can’t survive. The ecosystem of ocean depends on these organisms because they offer a large source of food at the bottom of the food chain. They need to be abundant in order t...
Soft corals such as sea fingers and sea whips, are soft and bendable and often resemble plants or trees. These corals do not have stony skeletons, but instead grow wood-like cores for suppor...
Over the last century, [it is evident that] the current levels are beginning to impact organisms that make their shells out of the minerals aragonite and calcite…” (Bralower) “Coral reef[s] are highly vulnerable to ocean acidific...
Coral bleaching is when the tiny algae that lives in the coral which causes it to be bright and colourful, gets so stressed out when the water temperature exceeds the limit that it can handle, which then makes the algae
The outer layer of a reef consists of living animals, or polyps, of coral. Single-celled algae called zooxanthellae live within the coral polyps, and a skeleton containing filamentous green algae surrounds them. The photosynthetic zooxanthellae and green algae transfer food energy directly to the coral polyps, while acquiring scarce nutrients from the coral. The numerous micro habitats of coral reefs and the high biological productivity support a great diversity of other life.
Coral Reefs are said to be the “tropical rainforest” of the sea. They are home to over 25% of all marine life (http://coralreefalliance.org.stories/storyReader$77). Over the past few decades they have been subjected to destructive anthropogenic practices. Some of the major threats to coral reefs include sedimentation, water pollution, harmful recreational activities, and global warming. All of these things cause stress on corals and can potentially cause mortality. Corals are made up of two parts, a polyp and zooxanthellae. A polyp is a calcerous body that grows from a hard part of the ocean floor. Zooxanthellae is a photosynthetic algae which lives in the polyp and provide energy for themselves and the coral. In many cases, corals undergo “bleaching,” which is a process where corals lose the zooxantheallae or chlorophyll pigment, and turn white (Wilkinson et all). After bleaching corals can survive for several months. It is possible for corals to recover by hosting more zooxantheallae, but it can take between 5 and 50 years for them to recover completely (Wilkinson et all, 1999).
Imagine a lush underwater place. Beautiful structures colorful animals and places that would never have been thought of before. In reality that's not what it really looks like, really the ocean is a desolate place that is barren like a desert. Many marine species have been lost by as much as 49%.(seeker) A big part of that reason is because of coral bleaching which causes as stated above a decline in species that depend on the coral as there home. Coral bleaching is a serious problem that could cause problems for everyone if we don’t fix it.
Soft corals are grouped in the phylum Cnidaria, class Anthozoa, and order Alcyonacea. Their distinguishing characteristic is that their polyps always bear eight tentacles which are on both edges fringed by rows of pinnules (Fabricius and De’ath, 2002). The common name “soft coral” comes from the fact that they have no massive external skeleton as compared to the more commonly studied hard corals.
Rates of coral calcification on the Great Barrier Reef and many other reef systems around the world have declined by 15-20% since 1990 due to increasing thermal stress (De’ath 2012). It has already been mentioned that the oceans absorb almost all of the excess heat from climate change. This affects coral reef systems in what is known as coral bleaching. The term bleaching refers to the loss of corals’ colors. A coral’s color is the result of the zooxanthellae present.
This article discusses how important the organisms symbiotic with coral reefs are, as well as how important coral reefs are to our environment. Also explained is how natural and non natural things things like hurricanes and overfishing affects them. A study is quoted about how water acidity also plays a role in the bleaching of corals. Lastly, restoration and conservation efforts are discussed and how we could possibly help our oceans.
The Great Barrier Reef is an exemplary model of the famous exotic coral reef seen in a copy of the National Geographic or the popular animated film Finding Nemo. Located on the coast of Australia, it is known as the “largest biological organism in the world” (“Human Impact on the Great Barrier Reef” par. 1). The idea bears that coral reefs are again not an assortment of organisms functioning separately but rather working together to thrive. The groups of coral that are seen in t...
Coral reefs need to be preserved for many reasons. In this paper, I will discuss a few of them. First of all, they house a collection of diverse organisms, and contribute to fisheries which provide food items such as fish, crustaceans, and mollusks. Furthermore, coral skeletons are being used as bone substitutes in reconstructive bone surgery and may be able to provide important medicine, including anti-cancer drugs and a compound that blocks ultra-violet rays, they even help reduce global warming by taking carbon dioxide out of the air. These reefs provide a habitat for many species.