The Impact of Climate Change on the Oceans Coral Bleaching Rates - Research Paper Example

The Impact of Climate Change on the Ocean’s Coral Bleaching Rates Corals are members of the cnidarian group of animals, which also include sea anemones and jellyfish, however the former do not grow and develop into larger and individual animals, but instead remain in a juvenile form called polyps, and form colonies which are collectively known as corals or coral reefs (Anthony, et al., 2008). These animals do not live alone, but have living symbiotic algae in their bodies, which are called zooxanthellae. Zooxanthellae are relatives of phytoplanktons, which are also photosynthetic in nature, however the former live inside the bodies of coral polyps, giving these animals their pigmentation (Kleypas, et al., 2001). The presence of zooxanthellae within coral polyps is able to provide protection from ultraviolet rays from the sun, as well as a stable carbohydrate supply to the corals during the day (Brown, 1997). At the same time, the corals provide CO2 for the photosynthetic activities, as well as providing a shelter from other predators (Graham, et al., 2006). Most corals can be found in sunny seas in tropical waters, which foster photosynthetic activity of the symbiotic algae during the day. Coral reefs are found throughout tropical areas across the globe, and are mostly thriving near coastal areas (Figure 1). Often called “flowers of the sea”, these creatures are not only aesthetically pleasing for many tourists such as divers and underwater photographers, these are also ecologically-important members of ocean ecosystems by being a habitat for fish and other aquatic animals, as well as protecting the shoreline’s structure by serving as breakwater for the ocean’s waves (Cesar, 2000). Such a feat is possible due to the hard exoskeletons of corals, which are durable to the kinetic effects of ocean waves. The process in which coral skeletons grow and develop takes a very long time due to the gradual calcification process in building up the coral skeleton by very small animals. However, recent climate changes causes a degeneration of this coral exoskeleton, which not only poses a threat to the corals themselves but also to the creatures that dwell within them, which in turn could affect livelihoods such as tourism and fishing industries of people living alongside coral reefs. Figure 1. The distribution of coral reef systems are limited to the tropics, seen here as dark brown markings around coastlines and islands (ReefBase, n.d.). Figure 2. Various species of common coral after undergoing bleaching lose their color. Scale bars=5cm (Anthony, et al., 2008). The steady rise in global temperatures have been causing various abnormalities in nature such as drastic weather changes, the growth and proliferation of invasive pests, and the destruction of marine ecological systems such as coral reefs. Several disasters within coral reefs have been recorded in the past decades, and most are attributed to the effects of rising atmospheric and ocean temperatures (Brown, 1997; Cao & Caldeira, 2008; Doney, et al., 2009; Glynn, 1993; Hoegh-Guldberg, et al., 2007; McNeil, et al., 2004). However, these are not the only factors that could contribute to the declining populations of corals and reefs, since other man-made factors also come into play. The acidification of sea water due to increasing dissolved CO2, saturation of nutrients due to leaching of fertilizer runoffs, and the increase of disease-causing pathogens and other agents due to the warmer waters causes the disruption of the symbiotic relationship of the zooxanthellae and the coral polyps (Bruno, et al., 2003; De’ath et al., 2009; Grandcourt & Cesar, 2003; Obura, 2004; Silverman, et al., 2009). Corals become bleached when the number of symbionts decreases in the polyps’ bodies, leaving them colorless and much more exposed to the ultraviolet rays of the sun (Figure 2). The lack of zooxanthellae decreases carbohydrate production which translates to a lesser food supply for the corals. This causes the death of the coral polyps, leaving only the exoskeletal remains, which would eventually be unable to sustain life since most aquatic creatures rely on the small ecological systems thriving within coral polyp colonies. It is thus important that coral reefs must be sustained and rebuilt in order to maintain the natural balance of ecosystems having coral reefs as habitats, not just for the marine environment but also for the livelihood of people relying on fishing or eco-tourism ventures. This paper mostly focuses the growing problem of coral bleaching, mostly around the tropical areas and island nations. Also, the paper aims to find out some ways by which nations could help in preventing further damages to coral reefs through bleaching. Identified reasons for bleaching are the increases in pollutants such as dissolved CO2 levels, nutrient runoff, destructive fishing methods, and the entry of other chemicals in the ocean, aside from the steadily increasing temperatures both in the atmosphere and the sea (Bruno, et al., 2007). Since some aspects such as the effects of global warming on the temperature of oceans may be harder to solve through human efforts in a short amount of time, it is much more feasible to simply focus on things that could be remedied simply through reducing the entry of water pollutants due to the fact that these effects are mostly man-made and are also found to contribute significantly in the increased rates of coral reef bleaching in tropical seas. Causes of Coral Bleaching Around the 1980’s the phenomenon of corals dying out rapidly and causing the “bleaching” has been reported to occur around the Pacific, the Caribbean, and the Indian Oceans (Brown, 1997). Some of the culprits and environmental triggers to the incidences were increased sea temperatures, high amounts of solar irradiation, urban pollution and waste, mining and dredging activities, poison fishing, over-fishing, acidification of seawater due to increase in dissolved CO2 levels that lead to the dissolution of coral exoskeletons, reduction of calcification processes due to bioerosions, (Anthony, et al., 2008; Cesar, 2000; De’ath, et al., 2009; Glynn, 1993; Kleypas, et al., 2001). Other factors such as coral harvesting, invasive species that prey on coral polyps, toxin build-up in polyp colonies, and disease outbreaks are also seen as causes for coral bleaching (Lafferty, et al., 2004; Ward & Lafferty, 2004). Most of the causes of bleaching are beyond the control of human efforts such as the increasing temperatures of ocean currents and the resulting acidification of water due to dissolution of the CO2 causing the formation of carbonic acid. However, the leaching of excess fertilizer nutrient runoffs and mining by-products into the seas, and the destruction of coral reefs due to overfishing and destructive fishing practices are some methods which can be controlled or limited through the creation of effective policies and constantly monitoring the progress or decline of coral bleaching in coastal areas (Cesar, 2000). The lack of proper policies and monitoring methods would not only prevent the restoration of coral reefs that became damaged, but could also have various effects on both the ecological systems as well as the livelihood of people that rely directly or indirectly on the health of corals and reefs. Effects of Coral Bleaching Coral bleaching happens when environmental triggers such as the entry of pollutants such as farm runoffs, large amounts of sediments, increase in water temperatures or a drastic change in pH (Anthony, et al., 2008; Bruno, et al., 2007; Cao & Caldeira, 2008; Grandcourt & Cesar, 2003; Silverman, et al., 2009). Corals are naturally-protected by the zooxanthellae from direct sunlight and ultraviolet rays by absorbing and using sunlight for photosynthetic activity (Doney, et al., 2009). The protective effects can be compared to the protection that melanin provides for the skin against the sun. However, once the zooxanthellae leave the coral polyps’ bodies due to various reasons such as environmental triggers, the protective barrier against the sun also goes along with the disappearance of the symbionts. The corals become colorless and transparent, revealing the white coral exoskeleton. This accounts to the “bleached” appearance of corals after losing the symbionts (Hoegh-Guldberg, et al., 2007; McNeil, et al., 2004). Due to being exposed directly to harmful rays from the sun, the coral polyps eventually become damaged and die. Other factors such as the lack of additional nutrients coming from the zooxanthellae are also seen as causes for coral polyp death. Without living polyps within the coral reefs, the creatures that previously relied on them for protection become easy targets for higher-level predators, and eventually the numbers of lower-level prey in the food chain would decrease. Consequentially, lesser predators could translate to lesser food supply for other higher predators, and that would include people belonging to the fishing industry (Cesar, 2000). Also, aside from possible problems such as decreasing fish supply, other livelihoods that rely on the aesthetic value of coral reefs such as eco-tourism and beach resorts could suffer economic losses as well, especially when the main reason that tourists flock these places, mostly the ecological systems surrounding coral reefs have already disappeared or died out. The repercussions of man-made problems such as the unmanaged entry of pollutants into the seas may not directly affect the same places where runoffs or pollutants come from, say from mainland countries such as the US or Canada. Instead, the effects of pollutants could appear in other places such as small island nations that rely on tourism and fishing industries for their livelihoods. The chain reaction starting from the uncontrolled leaching of pollutants from estuaries or river systems straight into the ocean and moving to other parts of the seas through the ocean currents could easily spread the problem of coral bleaching to other areas, which is one reason why there is a reported 90% decrease in the death of masses of coral just from coral bleaching alone (Obura, 2004). Also, while there is a reported resilience of some major coral species even though there is an increase in ocean temperatures, there might come a time when the rate of temperature increases could overtake the adaptive measure of coral species, eventually leading to bleaching and death. It is thus important to address various controllable issues while still early so as to create sustainable measures that could help in preventing further damages to coral reefs. Possible Adaptive Measures to Decrease Further Coral Damages The economic importance of coral reefs were found to be more theoretical than practical, however there is still a strong need to preserve and rebuild the destroyed reef systems because the losses still outweigh the costs (Cesar, 2000). Potential income from sustainable tourism and fishery methods become losses due to the rapid decline of resources such as corals and fish, which are resources considered hard to be replaced. Unfortunately, due to conflicting ideas of policy-makers, researchers and the people living in the coastal areas aside from the lack of measurable valuation methods that would encourage the protection of coral reef systems, there are no concrete guidelines in how to make fishing methods sustainable and non-destructive for corals. Fishermen would then tend to use destructive fishing methods such as blast or poison fishing, which increases the catch initially but eventually kills even the smaller fish, which prevents the continuity of the reproductive cycle of economically-important species (Anthony, et al., 2008; De’ath, et al., 2009; Kleypas, et al., 2001; Obura, 2004). Policy-makers do not have enough information to create effective policies that prevent overfishing or destruction of coral reefs, thus they tend to become blind-sighted with regards to the creation of sustainable fishing and tourism policies that could help the people in the long run. Instead, regulations created are mostly for short-term goals only, and enough to last till the next campaign period. Conservation experts have lesser powers over government leaders in terms of effective policy-implementation, but they have the ability to carefully monitor changes within reef systems. Their observations could help in assisting for the creation of clear policies as well as educating the people that directly rely on the health of corals reefs. While sustainable methods of fishing would mostly rely on the local leaders among island nations, the additional risks for coral bleaching that can be traced from industrial nations such as greenhouse gases and excessive nutrients and chemical pollutants flowing into the seas are issues that must also be addressed (Cesar, 2000). The effects of silt sedimentation, high rates of dissolved CO2, excessive nutrient runoffs, and the increase in water temperatures are not limited to the tropics alone, but could also affect marine life in temperate and colder regions. However because CO2 and other pollutants dissolve much more easily in warmer waters, tropical regions would eventually shoulder the burden stemming from excess pollutants from first-world countries. Thus aside from the reduction of greenhouse gases through the use of cleaner energy sources, there must also be policies concerning the disposal of mining by-products, the controlled disposal and management of agricultural inputs such as fertilizers and chemical additives, proper waste-water treatment before releasing to larger bodies of water, and testing of research-based methods in preventing further pollutant-leaching into bodies of water must be thoroughly done in order to find the best way of keeping excess chemicals out of the seas. Decreasing the carbon footprint through the use of alternative energy sources could tremendously help in preventing greenhouse effects that cause the increases in atmospheric and ocean temperatures. While this might take time before the intended results would be obtained, it would make better sense if controllable problems would be given additional focus in being resolved. If man-made factors such as careless fishing or harvesting of marine resources or the lack of control over sedimentation or leaching of agro-industrial byproducts into the oceans can be prevented altogether, there would be greater chances for controlling the excessive coral bleaching observed in many tropical areas. This may not be much but it is expected that by reducing the entry of pollutants into bodies of water, there would be lesser risks for marine life across the globe, and is not limited to the coral reefs themselves, and this in turn prevents potential economic losses in smaller nations relying from marine resources. Large and industrialized nations could help in the legacy of creating cleaner and cooler seas by making efforts in preventing the generation of large carbon footprints as well as preventing excessive pollutant runoff which could affect other areas elsewhere, such as tropical parts of the sea. Conclusions Coral reefs are rapidly declining due to various factors such as the steady increase in oceanic and atmospheric temperatures. The increase in water temperature also increases the solubility of chemicals, nutrients and CO2 which could lead to the eventual degeneration of corals and their exoskeletons through bleaching, as well as the destruction of ecological systems that reside among coral reefs. The onset of coral bleaching not only destroys the marine ecosystem but also the livelihoods of people that rely on the healthy existence of coral reefs, especially to fishing and tourism sectors. Also, when reef systems become destroyed, it makes it easier for the ocean to destroy the shoreline of islands due to the lack of naturally-occurring barriers. Aside from the potential destruction of natural habitats of marine life, there is also a possibility of an economic collapse for neighborhoods or smaller countries that solely rely on the sea, both for their food and income. However, the degeneration of marine habitats such as coral reef systems cannot be blamed for these people alone. Industrialized countries also have their share in the continuing problems that the world’s oceans and atmospheres face, such as increasing greenhouse effects that result to higher temperatures, and the release of various water pollutants coming from agro-industrial by-products. These are factors that gain cumulative effects which may not immediately affect the places where these gases or chemicals are released, but could greatly affect other parts of the world, such as the tropical regions where pollutants dissolve faster in waters with considerably higher temperatures. Thus it is important for industrialized nations to reduce the amount of pollutants being released into the atmospheres through the use of green technologies, as well as to create policies that regulate the use of fertilizers or chemicals that could easily leach into bodies of water. 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