User:Cherrycoke5/Coral bleaching

Hello, as one of your fellow students, one aspect you could look at is specfically your references, this is still a newer concept that is being undertaken and updating some of your sources ( some from 2001 and 2009) could be going out of date, and would be beneficial to stay no more than 10 years. or if including these sources can also work with addtional resources to keep up to date.

your current additions would be the bolded aspects, another component to add would be hyperlinking facts that you have mentioned to further ones research on a topic to conclude beyond coral bleaching. these can include hyperlinking:


 * 1) ocean acidification: for background
 * 2) Anthropocene: for revelvence on athropgenic activies anthropogenic

your conclusion shows "potential conservation and mitigation stragieis", change from potential to current methods and adaptions as there should be more definite information that is reliable and crediable to associate with a wikiepdia entry

I will be restructuring and adding information to the existing articles Coral bleaching. Proposed outline:


 * What is coral bleaching? What impact will it have on the ecosystem?
 * Role of ocean acidification in coral bleaching as well as negative effect on other marine organisms.
 * Economic implications of coral bleaching.
 * Conclude with potential conservation and mitigation strategies so as to reduce impact of ocean acidification on corals.

Here are some sources which I will be using to contribute to this article;

Lough, J. M.; van Oppen, M. J. H. (2018), "Introduction: Coral Bleaching–Patterns, Processes, Causes and Consequences", Ecological Studies, Cham: Springer International Publishing, pp. 1–8, ISBN 978-3-319-75392-8, retrieved 2024-02-18

Goreau, T.J.F., Hayes, R.L. Global warming triggers coral reef bleaching tipping point. Ambio 50, 1137–1140 (2021). https://doi-org.proxy.library.carleton.ca/10.1007/s13280-021-01512-2

Baker, A. C. (2001). Ecosystems: Reef corals bleach to survive change. Nature, 411(6839), 765+. https://link-gale-com.proxy.library.carleton.ca/apps/doc/A187996495/AONE?u=ocul_carleton&sid=bookmark-AONE&xid=5231eb8a

Blackstone, N. W., & Golladay, J. M. (2018). Why Do Corals Bleach? Conflict and Conflict Mediation in a Host/Symbiont Community. BioEssays, 40(8), n/a-n/a. https://doi.org/10.1002/bies.201800021

Obura, D. O. (2009). Reef corals bleach to resist stress. Marine Pollution Bulletin, 58(2), 206–212. https://doi.org/10.1016/j.marpolbul.2008.10.002

Anthony, K. R. N., Kline, D. I., Diaz-Pulido, G., Dove, S., & Hoegh-Guldberg, O. (2008). Ocean Acidification Causes Bleaching and Productivity Loss in Coral Reef Builders. Proceedings of the National Academy of Sciences of the United States of America, 105(45), 17442–17446. http://www.jstor.org/stable/25465297

Lead
Coral bleaching is the process when corals become white due to loss of symbiotic algae and photosynthetic pigments. This loss of pigment can be caused by various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as algae) that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae. Since the zooxanthellae produce the majority of coral colouration, the coral tissue becomes transparent, revealing the coral skeleton made of calcium carbonate. Most bleached corals appear bright white, but some are blue, yellow, or pink due to pigment proteins in the coral.

Causes
The leading cause of coral bleaching is rising ocean temperatures due to climate change caused by anthropogenic activities. A temperature about 1 °C (or 2 °F) above average can cause bleaching. The ocean takes in a large portion of the carbon dioxide (CO2) emissions produced by human activity. Although this uptake helps regulate global warming, it is also changing the chemistry of the ocean in ways never seen before. Ocean acidification (OA) is the decline in seawater pH caused by absorption of anthropogenic carbon dioxide from the atmosphere. This decrease in seawater pH has a significant effect on marine ecosystems. The pH of the ocean has decreased from 8.2 to 8.1 which is 0.1 unit decrease since the beginning of the industrial revolution. In the symbiotic relationship between the coral and the algae zooxanthellae, the algae plays a role in the calcification process. Calcifying organisms like corals synthesize calcium carbonate (CaCO3) which makes their exoskeletons, are directly affected by OA due to decrease in carbonate ion (C032-) concentration.

According to the United Nations Environment Programme, between 2014 and 2016, the longest recorded global bleaching events killed coral on an unprecedented scale. In 2016, bleaching of coral on the Great Barrier Reef killed between 29 to 50 percent of the reef's coral. In 2017, the bleaching extended into the central region of the reef. The average interval between bleaching events has halved between 1980 and 2016. The world's most bleaching-tolerant corals can be found in the southern Persian/Arabian Gulf. Some of these corals bleach only when water temperatures exceed ~35 °C.

Bleached corals continue to live, but they are more vulnerable to disease and starvation. Zooxanthellae provide up to 90 percent of the coral's energy, so corals are deprived of nutrients when zooxanthellae are expelled. Some corals recover if conditions return to normal, and some corals can feed themselves. However, the majority of coral without zooxanthellae starve.

Normally, coral polyps live in an endosymbiotic relationship with zooxanthellae. This relationship is crucial for the health of the coral and the reef, which provide shelter for approximately 25% of all marine life. In this relationship, the coral provides the zooxanthellae with shelter. In return, the zooxanthellae provide compounds that give energy to the coral through photosynthesis. This relationship has allowed coral to survive for at least 210 million years in nutrient-poor environments. Coral bleaching is caused by the breakdown of this relationship.

Triggers

Marine heatwaves caused by the El Nino Southern Oscillation have been found to be one of the main causes of widespread coral bleaching and consequent coral mortality.

Infectious disease

Following bleaching events, there has been a rise in the global disease outbreak among coral populations. This is due to the weakened state of the corals that makes them susceptible to infection caused by disease-carrying pathogens.

Trends due to climate change
Extreme bleaching events are directly linked with climate-induced phenomena that increase ocean temperature, such as El Nino-Southern Oscillation (ENSO). The warming ocean surface waters can lead to bleaching of corals which can cause serious damage and coral death. The IPCC Sixth Assessment Report in 2022 found that: "Since the early 1980s, the frequency and severity of mass coral bleaching events have increased sharply worldwide". Coral reefs, as well as other shelf-sea ecosystems, such as rocky shores, kelp forests, seagrasses, and mangroves, have recently undergone mass mortalities from marine heatwaves. It is expected that many coral reefs will "undergo irreversible phase shifts due to marine heatwaves with global warming levels >1.5°C".

This problem was already identified in 2007 by the Intergovernmental Panel on Climate Change (IPCC) as the greatest threat to the world's reef systems.

The Great Barrier Reef experienced its first major bleaching event in 1998. Since then, bleaching events have increased in frequency, with three events occurring in the years 2016–2020. Bleaching is predicted to occur three times a decade on the Great Barrier Reef if warming is kept to 1.5 °C, increasing every other year to 2 °C.

With the increase of coral bleaching events worldwide, National Geographic noted in 2017, "In the past three years, 25 reefs—which comprise three-fourths of the world's reef systems—experienced severe bleaching events in what scientists concluded was the worst-ever sequence of bleachings to date."

In a study conducted on the Hawaiian mushroom coral Lobactis scutaria, researchers discovered that higher temperatures and elevated levels of photosynthetically active radiation (PAR) had a detrimental impact on its reproductive physiology. The purpose of this study was to investigate the survival of reef-building corals in their natural habitat, as coral reproduction is being hindered by the effects of climate change.

Process
The corals that form the great reef ecosystems of tropical seas depend upon a symbiotic relationship with algae-like single-celled flagellate protozoa called zooxanthellae that live within their tissues and give the coral its coloration. The zooxanthellae provide the coral with nutrients through photosynthesis, a crucial factor in the clear and nutrient-poor tropical waters. In exchange, the coral provides the zooxanthellae with the carbon dioxide and ammonium needed for photosynthesis. Negative environmental conditions, such as abnormally warm or cool temperatures, high light, and even some microbial diseases, can lead to the breakdown of the coral/zooxanthellae symbiosis. To ensure short-term survival, the coral-polyp then consumes or expels the zooxanthellae. This leads to a lighter or completely white appearance, hence the term "bleached". Under mild stress conditions, some corals may appear bright blue, pink, purple, or yellow instead of white, due to the continued or increased presence of the coral cells' intrinsic pigment molecules, a phenomenon known as "colourful bleaching". As the zooxanthellae provide up to 90 percent of the coral's energy needs through products of photosynthesis, after expelling, the coral may begin to starve.

Coral can survive short-term disturbances, but if the conditions that lead to the expulsion of the zooxanthellae persist, the coral's chances of survival diminish. In order to recover from bleaching, the zooxanthellae have to re-enter the tissues of the coral polyps and restart photosynthesis to sustain the coral as a whole and the ecosystem that depends on it. If the coral polyps die of starvation after bleaching, they will decay. The hard coral species will then leave behind their calcium carbonate skeletons, which will be taken over by algae, effectively blocking coral regrowth. Eventually, the coral skeletons will erode, causing the reef structure to collapse.

Impacts
Coral bleaching events and the subsequent loss of coral coverage often result in the decline of fish diversity. The loss of diversity and abundance in herbivorous fish particularly affect coral reef ecosystems. As mass bleaching events occur more frequently, fish populations will continue to homogenize. Smaller and more specialized fish species that fill particular ecological niches that are crucial for coral health are replaced by more generalized species. The loss of specialization likely contributes to the loss of resilience in coral reef ecosystems after bleaching events.

Economic and political impact
According to Brian Skoloff of The Christian Science Monitor, "If the reefs vanished, experts say, hunger, poverty and political instability could ensue." Since countless sea life depend on the reefs for shelter and protection from predators, the extinction of the reefs would ultimately create a domino effect that would trickle down to the many human societies that depend on those fish for food and livelihood. There has been a 44% decline over the last 20 years in the Florida Keys and up to 80% in the Caribbean alone.

Coral reefs provide various ecosystem services, one of which is being a natural fishery, as many frequently consumed commercial fish spawn or live out their juvenile lives in coral reefs around the tropics. Thus, reefs are a popular fishing site and are an important source of income for fishers, especially small, local fisheries. As coral reef habitat decreases due to bleaching, reef associated fish populations also decrease, which affects fishing opportunities. A model from one study by Speers et al. calculated direct losses to fisheries from decreased coral cover to be around $49–69 billion, if human societies continue to emit high levels of greenhouse gases. But, these losses could be reduced for a consumer surplus benefit of about $14–20 billion, if societies chose to emit a lower level of greenhouse gases instead. These economic losses also have important political implications, as they fall disproportionately on developing countries where the reefs are located, namely in Southeast Asia and around the Indian Ocean. It would cost more for countries in these areas to respond to coral reef loss as they would need to turn to different sources of income and food, in addition to losing other ecosystem services such as ecotourism. A study completed by Chen et al. suggested that the commercial value of reefs decreases by almost 4% every time coral cover decreases by 1% because of losses in ecotourism and other potential outdoor recreational activities.

Coral reefs also act as a protective barrier for coastlines by reducing wave impact, which lowers the damage from storms, erosions, and flooding. Countries that lose this natural protection will lose more money because of the increased susceptibility of storms. This indirect cost, combined with the lost revenue from tourism, will result in enormous economic effects.

United states

During the 2005 mass bleaching event in Florida, the bleaching patterns varied among species. Colpophyllia natans and Diploria strigosa were particularly susceptible to thermal stress, whereas Stephanocoenia intersepta exhibited greater tolerance. Moreover, it was noted that larger coral colonies experienced more bleaching compared to smaller ones. The prediction suggests that mass bleaching events are likely to affect larger coral colonies even within the same community.

In South Florida, a 2016 survey of large corals from Key Biscayne to Fort Lauderdale found that about 66% of the corals were dead or reduced to less than half of their live tissue.

Indonesia

Acropora corals were dominant coral species of Indonesian reef system however they are extremely vulnerable to external stressors. A study was conducted to study effect of mass bleaching event in 2010 on Acropora. Post bleaching recovery is influenced by severity and frequency of the bleaching event. Research indicates that frequent moderate disturbances tend to affect Porites, while less frequent but stronger disturbances primarily impact Acropora. Consequently, Acropora demonstrates rapid regrowth in such instances.

Japan

About 94% of the corals on Japan's Iriomote Island in the Ryukyu Islands bleached during a significant coral bleaching event that occurred in 2016. Prior to this event, the region typically experienced multiple typhoons during July and August. However, during this particular event, no typhoon was detected until September, suggesting a prolonged period of high seawater temperatures.

Maldives

Moreover, the Maldivian coral reef faces risks from the growing tourism industry and coastal construction, as well as land reclamation projects , alongside natural challenges such as diseases.

Thailand

Coral reef ecosystems are a notable feature of the western shoreline of the Gulf of Thailand. In 1998 and 2010, there were bleaching events in Thailand; the effects of both occurrences varied among coral species, with some exhibiting more resilience to the 2010 bleaching. In contrast to 1998, there was a more severe bleaching event in 2010.

= Coral adaptation = In recent times, climate change has been linked to a notable increase in coral mortality Moreover, mounting evidence suggests that bacteria associated with corals contribute to their ability to withstand thermal stress. Attempts have been undertaken to enhance coral resilience in the face of bleaching incidents. Since corals serve as the fundamental components of coral reefs, their decline significantly affects the endurance and composition of reefs directly affecting the reef-dwelling organisms.

The Paris Agreement has offered reasons for hope by pledging nations worldwide to maintain the rise in global average temperatures significantly below 2°C compared to pre-industrial levels, with concerted endeavors aimed at capping the increase at 1.5°C.

Cost benefit analysis of reducing loss of coral reefs
Coral restoration is a common strategy used to combat the problems brought on by global warming; however, while ecological factors are primarily taken into account, efforts need also be made to address social, economic, and governance factors. The rapid growth in advocacy and implementation of intervention measures, such coral restoration, are a result of the intensifying effects of climate change and human pressure on coral reefs. The goal is to preserve the remaining reefs and the functions that they provide to the reef ecosystem.

The Paris Agreement has offered reasons for hope by pledging nations worldwide to maintain the rise in global average temperatures significantly below 2°C compared to pre-industrial levels, with concerted endeavors aimed at capping the increase at 1.5°C. In 2010, the Convention on Biological Diversity's (CBD) Strategic Plan for Biodiversity 2011–2020 created twenty distinct targets for sustainable development for post-2015. Target 10 indicates the goal of minimizing "anthropogenic pressures on coral reefs". Two programs were looked at, one that reduces coral reef loss by 50% that has a capital cost of $684 million and a recurrent cost of $81 million. The other program reduces coral reef loss by 80 percent and has a capital cost of $1.036 billion with recurring costs of $130 million. CBD acknowledges that they may be underestimating the costs and resources needed to achieve this target due to lack of relevant data but nonetheless, the cost–benefit analysis shows that the benefits outweigh the costs by a great enough amount for both programs (benefit cost ratio of 95.3 and 98.5) that "there is ample scope to increase outlays on coral protection and still achieve a benefit to cost ratio that is well over one".