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Saving the Reefs
Coral reefs are among the most diverse ecosystems on the planet, providing habitat to almost 25% of marine species and offering benefits to the human population. Coral reefs further provide economic benefit through tourism, fisheries, discoveries of new biochemical and drugs, contributing to approximately $30 billion annual net economic benefits. However, over the last decades, human activities have contributed to the global loss of over 10% of a valuable ecosystem. Researchers attributed the changes experienced in coral reefs to anthropogenic effects like water pollution, loading of nutrients, overfishing, physical destruction, and sedimentation in recent years. However, over 15% of adverse changes on coral reefs and oceans are caused by climate change. Climate change is the defining environmental, economic and social issue of the 21st century, and there are minimal doubts that rapid increase in carbon dioxide and other greenhouse gas and rise in temperature and sea levels following the beginning of the industrial revolution is driving significant changes in the physical and chemical environment. Coral reefs have played a vital role in understanding the impact of climate change on various ecosystems. The rising global temperature, rising sea level, increase in oceanic carbon dioxide, and other climate change effects negatively affect coral reefs.
The environment of Coral Reef
Future changes in the condition and survival of coral can be established upon understanding the environmental conditions that define coral reefs’ existence. Coral reefs are distributed on shallow, sunlit waters of the tropics and subtropical, where they can capture abundant sunlight and convert it into organic energy that flows directly through ecosystems. Coral reefs occupy mainly coastal regions ranging from 300 North and south of the equator. In higher altitudes where calcification is low, the amount of coral reefs declines significantly. Research conducted by Cortés et al. (230) shows that coral reefs mainly occupy regions characterized by an average global temperature of around 140 Celsius. Drastic changes in temperature and the release of carbon dioxide are threatening the existence of coral reefs. With time, harsh climatic conditions like intense rainfall and storm intensity are likely to affect coral reefs’ survival.
Scientist globally contends with the rising environmental impact of climate change. The growing impact of climate change on coral reefs and their associated biodiversity remains a question of scientists, policymakers, and reef managers. The three groups need to understand the effective coping strategies for coral reefs ecosystem or acclimate to environmental changes. Over the next decade, the effect of climate change is expected to change coral reefs across the world. The coral reef ecosystem has evolved through massive climate change in the past decades and is expected to survive further climate change, although some changes will negatively affect human beings (Hoegh-Guldberg et al., 2014). Cyclones are becoming stronger every day, oceans get acidic, and the sea level is rising gradually. The changes are harming coral reefs and adjacent ecosystems, which coral reefs depend on. Intergovernmental Panel on Climate Change (IPCC) argues that a combination of past and current climate change will increase stress on the growing population and economic and economic development. Coral reefs are likely to be affected by climate change since they are sensitive to thermal stress and have a low ability to cope with changing climate conditions.
Climatic Factors Affecting Coral Reef
High temperature and Coral Bleaching
Coral reefs are highly affected by climate change, like rising ocean temperature, since they are sensitive to thermal stress and have a low ability to adapt to changing conditions. Sea surface temperature plays a vital role in the growth of coral reefs by influencing their skeletal density. Scientists argue that anthropogenic-induced ocean warming has a huge impact on coral reefs through thermal coral bleaching. Widespread bleaching caused by temperature-related changes have need recorded globally and in Pacific Oceans (Waller et al. 227). High ocean temperature is resulting from global climate change is expected to increase episodes of coral bleaching. Bleaching involves the loss of symbiotic algae by either coral or other hosts. The three types of bleaching common in coral reefs include “animal stress bleaching,” “algal-stress bleaching,” and “physiological bleaching” (Fitt et al., 2001). The three bleaching mechanisms are essential to understand the interaction between climate and coral reefs. Algal-stress bleaching is an acute response that impairs photosynthesis through its high temperature and high level of light. Physiological bleaching impairs corals by reducing tissue biomass and reducing house algae’s capacity due to added demand of energy sustained above normal temperature. Bleaching in 1987 in the Caribbean and 2001 at the Great Barrier Reef was caused by physiological bleaching (Buddumeir et al. 2004). High chronic temperatures harm coral reefs by causing their decline and low reproduction. Coral reefs characterized by branching growth forms, thin tissue layers, and rapid growth rate are more sensitive to bleaching and likely to die.
Coral reefs depend on symbiotic algae for survival, growth, and reproduction. However, high oceanic temperatures have bleached the expulsion of colorful symbiotic algae. Although coral reefs can recover from the effect of bleaching, their ability has been diminishing over the years due to the high impact of climate change (Dove et al. 55). Coral bleaching affects coral species differently depending on the affected coral host and zooxanthellae symbiont (Hoadley et al. 8). As ocean temperature rises, coral species adapt to changes differently were some changes in size, color, flavor and reduce the number of viable recruits. Since the 1980s, the bleaching events of coral reef bleaching have increased significantly due to reduced cloud cover, the high air temperature above average, and an increase in SST. The El Nina event of 1998-200o caused a dramatic change in mass coral bleaching in the South-western Pacific island. Some areas that have experience coral bleaching in the last two decades include Milne Bay Province, Lihir Island, e northern and southern parts of Papua New Guinea (PNG), and the Fijian archipelago. The recent thermal core bleaching from 2015 to 2016 has led to extensive habitat and biodiversity loss globally and in the Pacific (Cortés et al., 207).
In 2016, thermal stress increased dramatically, leading to a significant reduction in oxygen concentration, especially in the Coral Coast of Fiji. The concentration led to fish and other aquatic life’s mass death due to a high temperature above 36 degrees Celcius (Singh et al. 5). A similar event occurred in Vanuatu, where seawater rose above 30 °C, leading to fish’s widespread death. A study conducted by Bashmakov et al. (90) shows an increase of between 1 to 3degrees Celsius in sea temperature has been experienced as water temperature rises. Many coral reefs around Guam have declined within the past four decades. By 1990, the live coverage of coral reefs has declined from 50% in the 1960s to less than 25% in the 1990s (Sinniger et al. 52). As the global temperature keeps rising every year, coral reefs’ bleaching pattern is expected to persist. While SST nutrients and nutrients synergize coral reefs’ bleaching effects, most of the affected coral reefs are unlikely to recover due to elevated temperature and ocean acidification.
Ocean Acidification/Rising Atmospheric Carbon Dioxide
Ocean acidification caused by an increase in carbon dioxide pressure is linked with a reduction in seawater pH. Solar radiation drives the temperature of terrestrial, atmospheric, and oceanic components of the earth. Heat balance reaching the earth is affected by ice, cloud, and vegetation cover (Hoegh-Guldberg 392). Coral reefs require shallow, clear water with a hard seafloor. A study conducted by Houghton et al. (396) shows that the ocean absorbs approximately one-third of anthropogenic carbon dioxide input into the atmosphere, which results in significant changes in the chemistry of seawater, affecting the ability of organisms present in reefs to calcify. Expansion of coral reefs is limited in areas like the southeastern United States and near the Amazon River due to muddy coasts shelves. The only areas where the acidification is low, leading to the high expansion of reefs, are in Southern China, Australia, Joan, and Southern Africa. An increase in the atmospheric concentration of carbon dioxide from fossil fuel combustion changes the ocean surface (Buddumeir et al. 28). Where there is high dissolved carbon dioxide in the ocean, the acidity level lowers carbon concentration, vital for coral reefs’ survival. The Ocean acidification reduces the concentration of carbonate ions (CO3 –2), which are vital for coral reefs’ survival. The skeleton of coral is made from calcium carbonate minerals called arrogate (Hoegh-Guldberg 392). Today, the level of aragonite saturation is highly postulated and is slowly weakening the coral skeleton and slowing its growth. Continuous release of carbon dioxide by human activities limits the growth and recovery of coral from bleaching events.
Intergovernmental Panel on Climate Change shows that ocean acidification is expected to rise in the future. There will be substantial variability in response as a result of local environmental conditions. In the next few years, CO2 concentration under RCP2.6 is expected to rise to around 450 ppm by 2100, and pH will likely range between 7.9 and 8.1 (Kayanne 88). Coral reefs in medium- to high-emission scenarios (RCP4.5, 6.0, and 8.5) are expected to be at higher risks due to a rise in acidification. Rose in acidification threatens the survival of corals and other calcifying organisms. The impact of acidification is felt even by the human species who depend on fishing for food and livelihood. As climate change continues, scientists argue that the rate of calcium carbonate dissolution will equal the calcification rate of carbon dioxide in the atmosphere. The concentration will double the preindustrial level, which is likely to lead to the loss of coral reefs in the future. A study conducted by Andersson et al. (324) shows that 55 species of Pacific Corals were identified as threatened or endangered species affected by ocean acidification and ocean warming in the past few years. The study shows that corals are becoming a major issue of concern on a local and global scale as climate change persists. Unless adequate measures are taken to deal with acidification and climate change, coral reefs will be threatened and might become extinct over the years.
The rise in Sea Level
The rise in sea level caused by climate change is another factor threatening the existence of coral reefs. Over the last decade, the sea level has risen significantly due to the combined effect of thermal expansion of ocean water and additional water from melting icecaps glaciers. Combine effect of thermal expansion of ocean water and additional water from melting glaciers and ice caps ranges from 0.1 to 0.9, which is 4.36 inches approximately (Buddumeir et al. 21). For the last many centuries, sea level has been fairly stable, leading to the high growth of coral reefs to a point where they are sea level-limited with no or limited water circulation and upward growth. Continuous growth and expansion of coral reefs require a modest rise in sea level. Although a rise in sea level benefits coral reefs’ growth, the major challenge is increased shoreline erosion that brings sedimentation. Coral reefs require specific salinity and low turbidity for survival. The influx of freshwater leads to an increase in sedimentation and changes the salinity of oceanic water. Continuous weather patterns continue to affect corals since they are unable to handle the stressful environment easily.
Ocean Circulation Changes
Changes in ocean circulation are another factor caused by climate change that affects coral reefs’ continuous growth. As global climate changes, circulation from wind-driven upwelling t global thermohaline that impact coral reefs is likely to change. Coral reefs usually grow in regions where high latitude occurs where boundary current supplies warm water from tropical regions. Changes in the strength of the current impose different temperatures on coral reefs. A study conducted by Buddumeir et al. (22) shows that ocean temperature and freshwater runoff changes will eventually shut down ocean thermohaline circulation. Slow ocean thermohaline circulation (THC) would change oceanic circulation and upwelling patterns, which affect the growth and survival of coral reefs.
Precipitation and Storms Patterns
Climate change is slowly changing the nature of precipitation and storm patterns, which later impact the growth and survival of coral reefs. Within the last century, tropical precipitation has increased, and the frequency of experiencing intense rainfall has also risen over the years due to changes in climate patterns. The rise in precipitation reduces salinity and increases sediment discharge and deposition near the river mouth, leading to mortalities of surrounding coral reefs (Wolanski et al. 133). Also, with time. Drought is expected to occur in such regions leading to a decline in vegetation cover and land use. Bare land increases soil erosion and high sediments that block the growth of coral reefs.
Solutions to Stabilize Climate Change Factors
Of all the solutions suggested, reducing the emission of carbon dioxide is most significant. Carbon dioxide is the root cause of most problems faced by coral reefs globally. There is a need to develop solutions to solve the unprecedented rise of carbon dioxide in the atmosphere. All world nations need to collaborate in preserving the invaluable ecosystem of coral reefs. Stabilizing planetary carbon dioxide concentration is an immediate solution to save coral reefs. Governments globally need to develop policies and strategies to reduce carbon dioxide emissions from human activities (Buddumeir et al. 26). Most of the carbon dioxide and methane that damage the ozone layer leading to climate change, is caused by human activities like the burning of fossil fuels, changing land use, and deforestation. If effective measures are not taken, carbon dioxide levels will exceed critical thresholds linked with thermal tolerance and carbon ions requirements. Other factors affecting reefs like sea-level rise, storm intensity, and rainfall intensity are associated with the high carbon dioxide release.
In summary, coral reefs are a vital ecosystem that benefits human beings and other species. Losing coral reefs due to climate change and human activities will be detrimental on many levels. While many signs discussed above point to climate change being the major threat to coral reefs’ survival, more data will be collected for accuracy. More data need to be collected to determine the specific factors that cause bleaching and affect the making of calcium carbonate shells. When scientists discover these facts, it will be easy to establish the most suitable solution to save coral reefs and prevent their extinction in the future. Coral reefs are beneficial to human beings; hence widespread effort and global collaboration will be required to save reefs. Climate change is a widespread issue that cannot be solved by a single solution. With the high rate at which coral reefs are dying, there is a need to implement immediate changes. Based on research findings, little evidence is established that coral reefs will adapt to climatic changes in the future, making scientists conclude that reef ecosystems will become rare worldwide.
Works Cited
Andersson, Andreas J., and Dwight Gledhill. “Ocean acidification and coral reefs: effects on breakdown, dissolution, and net ecosystem calcification.” Annual review of marine science 5 (2013): 321-348.
Bashmakov, Igor, et al. “Technical summary.” Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (2007): 70.
Buddumeir, R. W., Kleypas, J. A., & Aronson, R. B. (2004). Coral reef’s potential contributions of climate change to stresses on coral reef ecosystems & global climate change. Pew Center on Global Climate Change, Arlington. https://www.reefresilience.org/pdf/Coral_Reefs_and_Global_Climate_Change.pdf
Cortés, Jorge, et al. “Marine biodiversity of Eastern Tropical Pacific coral reefs.” Coral reefs of the eastern tropical Pacific. Springer, Dordrecht, 2017. 203-250.
Dove, Sophie G., and Ove Hoegh-Guldberg. “The cell physiology of coral bleaching.” Coral Reefs and Climate Change: Science and Management, Coastal and Estuarine Studies (Eds J. Phinney, O. Hoegh-Guldberg, J. Kleypas, W. Skirving, A. Strong) 61 (2006): 55.
Fitt, William K., et al. “Coral bleaching: interpretation of thermal tolerance limits and thermal thresholds in tropical corals.” Coral reefs 20.1 (2001): 51-65.
Hoadley, Kenneth D., et al. “Host–symbiont combinations dictate the photo-physiological response of reef-building corals to thermal stress.” Scientific Reports 9.1 (2019): 1-15.
Hoegh-Guldberg, Ove. “The impact of climate change on coral reef ecosystems.” Coral reefs: an ecosystem in transition. Springer, Dordrecht, 2011. 391-403.
Kayanne, Hajime. “Response of Coral Reefs to Global Warming.” Coral Reef Science. Springer, Tokyo, 2016. 81-94.
Singh, Ambrish, and Mumtaz A. Quraishi. “Acidizing corrosion inhibitors: a review.” J Mater Environ Sci 6.1 (2015): 224-235.
Sinniger, Frederic, et al. “Biodiversity of mesophotic coral ecosystems.” Mesophotic coral ecosystems—a lifeboat for coral reefs (2016): 50-62.
Waller, Catherine L., et al. “Microplastics in the Antarctic marine system: an emerging area of research.” Science of the Total Environment 598 (2017): 220-227.
Wolanski, Eric, Robert H. Richmond, and Laurence McCook. “A model of the effects of land-based, human activities on the health of coral reefs in the Great Barrier Reef and Fouha Bay, Guam, Micronesia.” Journal of Marine Systems 46.1-4 (2004): 133-144.