The Extinction Of Coral Reefs Research Papers Example

ABSTRACT

Coral reefs according to multiple scientific pieces of information are one of the most precious and valuable living structures on our planet. They provide food and home to marine organisms that would otherwise not survive. Take, for instance, the delicate oysters, shrimps, sponges, the numerous fish species, and hydras. From an environmental perspective, coral reefs further help barricade our coasts and prevent coastal erosion. They protect us from the destructive tsunamis and storm waves. Coral reefs further play significant roles in the fishing industry as they house many species of fish and seafood, which are commercially viable. Coral reefs serve as an economic source as they attract tourists and provide recreation in the form of lagoons. Today, however, coral reefs are undergoing significant physical and ecological changes and are threatened by both nature and humankind at both local and global levels. Unlike other planetary ecosystems, coral reefs are a fragile community of organisms that in the recent years have experienced a decline in population. Scientific studies have however isolated and attributed this coral populace decline to changes in planetary climate design and unsustainable human activities on the surface of the earth. The studies further project that the coral community will eventually become extinct unless measures are taken to protect them. The extinction of these reefs will undoubtedly have a disastrous effect on the global biological population as well as the physical dry land mass structure. This is expected to be pronounced along continental coastline margins and at the periphery of the world’s islands. This is because in the ecological web all organisms are interdependent, and the demise of such an enormous ecosystem will impact all organisms together with their physical world aspects in both mighty and lesser ways. Mostly the extinction of corals will result in the loss of the many ecological services and goods derived from them by humanity and other living organisms. It is, therefore, paramount in order to safeguard the interests and survival of global organisms first to protect, manage, and conserve our coral reefs.

Introduction

Corals or for this case coral reefs are arguably the world’s most beautiful and greatest natural sensations. Dubbed the rainforests of planetary oceans, coral reefs come in an ostensibly infinite array of structural shapes, pennants, and lifeform diversity (Allen p. 13). However, this exquisiteness and vibrancy is equally matched by their fragility. And in light of this consciousness, multiple scientific studies report that a lot of the word’s corals is facing a threatened existence especially from human-instigated factors. In a broader perspective, these coral-threatening elements span across marine pollution (especially water-based pollution), unguided human activities such as destructive fishing, and the rising global marine temperatures. Correspondingly, this article further describes the potential and other contributory factors to coral extinction. However, the central arguments in this article is an explanatory expose’ that addresses coral formation and composition, their importance, and perceived threats to their survival.

What are coral reefs?

Granted that coral reefs occupy less than one percent of the overall world’s ocean floor, the consensus among scientists tell that coral reefs rival the tropical rainforests as one of the most biologically diverse ecosystems on earth (ReefBase.org). Consequently, with a majority of these biologically significant organisms under threat, planetary efforts to isolate and mitigate these stressors and in the process preserve these vital ecosystems are now more imperative than ever. In the collection of thoughts below, this section explains what corals are and describes their formation and composition while briefly articulating their various types.
According to United States, Environmental Protection Agency (EPA), the coral reef is an integral component of a uniquely larger biological ecosystem structurally made of marine organisms referred to as corals. In this take, this collectivity of living organisms forms a coral community. Corals themselves are miniscule aquatic organisms that taxonomically belong to the class group Anthozoa. In reference to their biological grouping, studies assert that anthozoans are the largest single assemblage of organisms within the phylum Cnidaria. With thousands of other organisms clustered in class, scleractinians (otherwise referred to as stony or hard corals) is the single organism in charge of the structural underpinnings in the formation of reef structure. This it does partly because with allusion to the other group members such as sea anemones, hydras, and jellyfish, hard corals is the most dominant both in number and ecological virility. According to Allen, corals are “sessile organisms that feed by reaching out their tentacles to catch prey” (p. 13). Therefore, as their inherent survival instinct, scleractinians live in colonies composed of numerous “genetically identical” corals each of which is called a polyp ( Lalli and Parsons, 1995 as cited in Coral Reef Information System (CoRIS); International Coral Reef Initiative (ICRI)).
Still, according to ICRI, these coral colonies are formed by a process called “budding," in which in an unadorned language the “original polyp continuously grow copies of itself" (sec. 1; Anderson). Though Classified into two main categories - "hard coral" and "soft coral", the hard coral is the fundamental underpinning for the materialization of coral reefs. In this reef formation process, the coral (hard) polyps extract calcium carbonate (CaCO3) from the seawater during the budding process. However, most of the CaCO3 material is secreted and with the help of other organisms such as the coralline algae, used to form the substrate foundation for the development of the coral colony. Coral reefs are, therefore, underwater carbonated rock outcrops covered by a stratum of living coral polyps (Allen, p.13).

Formation and composition of coral

As noted earlier the reef-building corals are tiny colonial aquatic organisms that live in protective shells of CaCO3 that which upon secretion form the basis for reef development (Anderson). However, scientific studies shows that a combinational interplay of other entities particularly an alga known as zooxanthellae aid the growth of coral reefs. However, the cementation process of the polyps by the secreted CaCO3 contributes significantly to the growth of the coral reef. Further information from Allen divulges that the dominant organisms in the reef-building process such as the coralline algae are collectively designated as framework builders as they provide the blueprint and matrix for the growth of the reef (p. 13). In this biological process, the corals powered by their synergetic relationship with the coralline algae precipitate CaCO3 from the surrounding seawater. According to Anderson, this symbiotic relationship between the corals and zooxanthellae makes the reef-building corals hermatypic – an ecological adaptation for survival in low productive ocean waters. In general, the formation of coral reefs is a slow process but the result is a topographically and structurally complex living community of organisms.
However, in the course of this building process, every CaCO3 secreted by the coral polyps (through their lower quotas) is mechanically incorporated into the structural makeup of the reef. This carbonate secretion forms a structural component called a calyx (the seat of the polyp) whose wall and floor are known as theca and basal plate respectively. In addition to the above structural makeup, sclerosepta (a calcareous erection) is also formed and incorporated into the coral design. The sclerosepta functions to increase the polyp’s surface area to volume ratio for the deposition and creation of the reef’s new materials. Additionally, it provides structural integrity to the growing polyp and its carbonate skeleton. This carbonate deposition is a continuous process as long as the polyp is alive and is thus the premise upon which coral reef formation is attributed.
Furthermore, according to Barnes, R.S.K & Hughes (1999), the formation of coral reefs is further facilitated by the lateral interconnections between adjacent polyps (as cited in CoRIS). The structural presence of coenosarc between adjacent calyxes enables this connection. Consequently, the entire reef colony lies above the limestone skeleton and are interconnected by the fabric of coenosarc traversing between them.
Concerning coral composition, multiple studies reveal that these tiny microbes exhibit a narrow gradation of body organ development – a three tissue layered body (Allen p.13). Structurally these layers are the outer epidermis separated from the inner gastrovascular cavity by the mesoglea (Barnes, R.D., 1987 as cited in CoRIS). In this structural makeup, the gastrovascular cavity opens at only one end (the mouth) as the other end is affixed to the base of the calyx. The mouth is additionally surrounded by a circle of tentacles – the central feature of food capture and defense. Moreover, as part of their biological structural composition, corals as pointed out earlier on contain zooxanthellae (a symbiotic alga) within their gastro-dermal cells. In mutual coexistence, the algae for photosynthesis use the coral metabolites whereas the coral uses the photosynthetic products for growth and establishment. This mutual exchange of products (metabolites and photosynthates) is the fundamental footing to the natural productivity and carbonate-secreting capacity of reef-building corals. (Sumich, 1996 as cited in CoRIS).

Nematocysts

According to Beckmann and Özbek, nematocysts (otherwise referred to as cnidocytes (cnidocysts)), are tiny often elongated bodily features exclusive to organisms of the phylum cnidarian such as corals and compatriots jellyfish, sea anemones among others (p. 577). Morphologically, these capsules occur on the surface of the organism as secretory products of the Golgi apparatus from specialized organism cells known as nematocytes or cnidocyte. In corals and other cnidarians, nematocysts are biologically designed for prey capture, defense, and for mobile cnidarians, for locomotion. However, according to ICRI, a cnidocyte is an organism-specific secretory cell that in most cases contain a sub-cellular organelle in the form of nematocyst. Therefore, biologically speaking a nematocyst is, in essence, a part of a cnidocyte.
Structurally, however, these hollow body organs contain a barbed thread (cnidocil) that when stimulated is expelled out of the capsule matrix and releases neurotoxins. Predominantly these structures are found in the ectodermal layer of the organism i.e. in the tips of the tentacles of the corals, nematocysts contain venomous cells (nematocyst) that releases neurotoxins to bodies of prey or adversaries as soon as their presence is felt. The toxins cause prey or enemy paralysis. Studies show that this mechanism enable the immotile corals to obtain their food and defend themselves against predators. Conclusively, cnidocytes are a defense as well as offensive mechanisms in members of the phylum cnidarian.

Types of coral reefs

In most scientific pieces of literature, the most employed basis for differentiating the various reef types is based on a number of assessment criteria. However, the existing relation between the coral reef and adjacent dry land (coastline configuration) and the structural size and shape of the reef is used. However, the spatial scale of the reef morphology is another deterministic element. Nonetheless, in a given biogeographic region, there is always remarkable overlap among the various reef types. The level of ecological interactions and species dominance in most cases defines this coral overlap. Therefore based on the above and other criteria, scientists divide coral reefs into four main classes. These groupings include the rare patch reefs and the most frequent atolls, fringing, and barrier reefs. Differentiating between these types of reefs, Global Coral Reef Monitoring Network (GCRMN), assert that fringing reefs are common near the continental coastlines or seaboards around tropical islands. There are also according to multiple sources the most common type of coral reefs.
Exemplified by the Great Barrier Reef in Continental Australia, Barrier reefs, on the other hand, are separated from mainlands by deeper and wider lagoons. In addition, at their shallowest points, barrier reefs are known to reach the ocean’s water surface and are thus normally a navigation barrier. Contrary to barrier and fringing reefs, atolls are rings of coral rocks usually located in the middle of the sea. They thus form around submerged islands whose initial fringing reefs continue to grow to form a protected lagoon in the middle of the reef circle. Compared to the other three types of reefs, patch reefs are the smallest and usually isolated reefs. Common between fringing and barrier reefs, these reefs grow up in the open bottom of submerged continental shelves or island platforms. And even though patch reefs vary in size, these reef types are often too small to reach the surface of the ocean water.

Extinction of coral reefs

Recent scientific findings show that coral reefs are facing many threats from multiple sources both at the global as well as at the smaller, isolated, regional, and local scales. Most of these threats, however, are caused by human unsustainable and destructive activities on the surface of the earth. According to GCRMN, even though corals are resilient to change, if continually subjected to anthropogenic and unfavorable natural stressors, they in the long-term lose their resiliency and be less able to survive or thrive. In a nutshell, scientific research divulges that planetary coral reefs are continually being threatened by an increasing array of impacts. However, the impact of global climate change, planetary pollution, and unsustainable sea resource extraction has been isolated as the most contributory of the other factors to coral extinction. However, for explanatory reasons, the contributing factors to coral destruction can be categorized into two main groups – natural causative factors and anthropogenic factors.

Contributing factors for extinction

Even though the effects of climate change have been recognized as one of the supreme global threats to the coral reef ecosystems, human factors play significant roles in this coral extinction saga. For instance, dissolved anthropogenic carbon dioxide (CO2) emissions in the seawaters have been documented to reduce the rate of the calcification process in coral polyps. The alteration of this process stems from the fact that dissolved CO2 alters the optimum seawater chemistry required for the calcification process to take place. The resultant ocean acidification phenomenon decreases the required pH required by the polyps. Other anthropogenic factors include unsustained coral harvesting, submarine cable and pipeline deployment, and an introduction of invasive species in marine aquaculture practices. Of late, however, mineral exploration and extraction such as petroleum mining has taken center stage as one of the leading causes of marine coral destruction.

Natural threats

Among the factors causing global degradation of coral reefs, natural factors such as localized damage from storms were initially thought to pose little threat to coral existence (Wilkinson, p. 867). However, these factors augmented by global climate change have been shown to inflict greater damage to corals and increase their mortality turnover. These factors include natural seawater acidification, underwater volcanic eruptions, earthquakes, diseases, species invasion, and even predation. For instance, in mid-2009 reports document that an earthquake in the western Caribbean destroyed almost “half of the Belizean Barrier Reef lagoon's corals reefs” (Martin). Further analysis into the destruction of the Belizean reefs, scientific research shows that preceding the earthquake, the reef structure had been severely altered by White band bacterial infection. The diseases, which was caused by natural means, killed the dominant staghorn corals thus rendering the coral integrity susceptible to external disturbance.
While stating the impacts of natural factors on corals, Martin documents that the high temperatures that accompanied the high rainfall in the region induced mass coral bleaching. Bleaching of corals occurs when El Nino brought high temperatures, the subsequent dominant species, lettuce coral, died off due to mass bleaching. Coral bleaching is a phenomenon where the corals, stressed by temperature changes, expel their algal symbionts and turn bright white. Extremely low tides, salinity, increased Ultra-Violet radiation (UV), and changes in ocean water nutrient levels have also been identified as possible causes of coral bleaching. Natural elements such as hurricanes, earthquakes, tsunamis, natural absence grazing organisms (due to overfishing causes algal overgrowth) are known to destabilize coral communities.
However, multiple studies show that these natural coral stressors are magnified by human disturbances. For instance, the presence of coral disease such as the black band disease is higher in corals stressed by human impacts such as pollution and mechanical damage.

Anthropogenic threats

Even though, human activities have been identified as the prime shapers and modifiers of the planetary ecosystems, the generalized disturbance of such activities on coral reefs make a remarkably short list. To begin with, is the influence of human activities on global climate change with particular emphasis on increased Green House Gases (GHGs). GHGs has been acknowledged in multiple studies as the principal driver in the realm of global warming impacting significantly on both the atmospheric and sea level temperatures as well as fluctuations in global sea levels (Rosenzweig, Casassa, Karoly, Imeson, Liu, Menzel, Rawlins, Root, Seguin, and Tryjanowski).
Secondly, concerning the influence of human activities on coral extinction is the impacts of marine resource extraction on coral reef survival. Although the effect of these extractive activities is multifaceted, particular emphasis has been given to their consequential impacts on the reef stability and the resultant damage to coral resiliency gears. Finally, however, the causative effects of coral survival within the realm of human-induced causes lies deeply in the role of humans in exacerbating marine pollution. Of significance though, are the land-based sources of seawater pollution such as maritime sewage disposal, toxic chemical pollution, human-aided pathogenic infestation, and seawater sedimentation from continental land destabilization processes.
However, scientific studies such as Anderson shows that changes in climate (climate change) is the only human-induced global influence and the parasol under which all other stresses to reefs operate. Therefore, marine sources of pollution and the impacts of marine resource extraction are localized and regional influencers of coral survival. However, other sources of pollution such as aerosols and run-off are geographically expansive players as far as seawater pollution is concerned. Marine resource extraction, on the other hand, are largely local problems to coral survival. Concerning such comprehensions, multiple studies however highlights that climate change is the single most detrimental effect on corals survival. Still according to Martin, even though, Coral bleaching is the most understood effect of global warming on coral reefs, it is not the only effect. For that reason, other factors such as protracted warm temperature seasons catalyze the growth rate and widen the geographical expanse of pathogenic microbes responsible for the coral disease. Besides, high temperatures both at the sea and at the immediate atmosphere above the ocean waters are renowned to stress corals significantly.
In addition, increased GHGs in particular CO2 in the atmosphere causes augmented maritime temperatures besides lessening calcium carbonate concentration in seawaters. Studies show that decreased levels of calcium carbonate decreases the coral calcification process. Calcification is an integral process in coral reef formation as it permits the development of the carbonate base for coral establishment. Similarly, studies show that uncontrolled and unsustainable fishing in ocean waters is ecologically detrimental to the survival of coral reefs. According to Intergovernmental Panel on Climate Change (IPCC) and others such as GCRMN ecologically unsustainable fishing activities lead to the depletion of the coral keystone groups of organisms. The lessening of such functional cluster of entities in an already fragile ecosystem, result to the cascading of the resultant adverse shock to the entire coral habitat and associated species. Identified fishing practices with disastrous effects on coral survival include among others bottom trawling and other sea bottom-contact fishing gears such as traps. Studies have specifically identified such deep sea fishing practices to be significant threats to corals mainly the deep- sea coral communities such the patch coral reefs.
With reference to pollution, United States Department of Commerce and NOAA assert that the type, magnitude, and intensity of such pollution depends to a greater extent on the source of the marine pollutants in question. Granted that land-based fonts of marine pollution are numerous, the primary sources, however, include chemical spills, waste and sewerage disposal, coastal developments, agricultural practices, and infrastructural developments. These pollutants and correlated synergistic effects disrupt the coral ecological balance by first and foremost causing the death of the sensitive corals species. Other effects are the disruption of the favorable conditions necessary for coral growth and reproduction such as increased disease and pathogenic attacks and eutrophic conditions. . Additionally, the impacts of marine pollution on corals span across increased ocean sedimentation, nutrient enrichment (eutrophication), and pathogenic and toxins introduction into seawater.

Importance of coral reefs

Even though, little is currently known about corals and the global oceanic dimensional sphere; the numerous benefits of corals to humankind is exceptional. Considered one of the richest sources of biodiversity on the planet, corals offer a manifold of valuable goods and services that over the years has been vital to human survival. Do Not only coral reefs benefit the thousands of species of marine organisms that inhabit them, but also the humankind in general and as well as the physical environment. According to NOAA Coral Reef Conservation Program (CRCP) Public Service Announcement Project (PSAP) report, healthy corals are economically valuable earth ecosystems as depicted in the summary graph below.

A chart summarizing significant economic benefits of corals to the human economy

Information as derived from (NOAA Coral Reef Conservation Program (CRCP))
The graphic representation above gives a picture of the breakdown of component values of coral reefs contribution to the annual planetary value of corals. Similarly, according to multiple sources such as ICRI and The Ocean Portal Team and Knowlton corals are important in several other ways besides providing tangible monetary income and housing diverse planetary marine organisms. These coral significances include the sequestration of excess atmospheric and oceanic carbon and nitrogen elements, assisting in the planetary biogeochemical cycles (nutrient cycling), and the provision of food to both humankind and other marine organisms. However, the economic aspect of corals has prompted global consciousness on their value significance. For instance, the global fishing industry depends on the healthy state of corals as natural fisheries. This is because several species of fish spawn and shelter their young ones amidst these corals.
Consequently, studies on corals show that reducing coral biodiversity by disrupting the ecology of reefs results to tremendous financial losses to the fishing sector as the health and function of the reefs is are compromised. In addition, the biological diversity of corals renders vital services in the marine biomes such as air and water recycling and purification. The reefs also play crucial roles in the detoxification of pollutants. Therefore, it is within the prerogative of humanity to conserve this communal diversity of species, as it is within it that exists the global grander genetic pool. In scientific terms, diverse gene pools found in corals gives organisms’ natural survival options. Diversity in survival options is essential now than ever given the current status of the changing global climatic and physical conditions. Accordingly, the conservation of reefs is thus vital because coral extinction poses a greater threat to species for which there is limited diversity.

It is hypothesized that coral reefs will become extinct if they are not protected

Concerning, the future state of global coral reefs multiple scientific studies across the world show that reefs are declining at an alarming rate. These downward trends as pointed out in various texts is due to an “increasing range of threats - predominantly from anthropogenic land-based pollution, and global climate change. Consequently, according to the Status of Coral Reefs of the World: 2008 report, about 19% of the total global reefs have already been lost. 15% are also seriously threatened with extinction in the next two decades. Moreover, an additional 20% is under threat and are presumed to go extinct in the next 20-40 years (NOAA Coral Reef Conservation Program (CRCP)).
Projecting on the status of global coral reefs, Wilkinson (2004) also concur with the above findings. His study results are shown in Table (I) below.

Information as retrieved from (Intergovernmental Panel on Climate Change (IPCC))

Synthesized information from the data shows that approximately 90% of reefs in this area is lost or show concrete signs of non-recovery. Additional 50% to 90% of the original reefs are at a critical stage of extinction and are thus likely to be lost in the next ten to twenty years if neglected. Additionally, reef totals in the range of 20 % to 5% are also likely to be destroyed in the coming twenty to forty years. The decline and loss of coral reefs as partly articulated in the above cases clearly demonstrates that the global reefs are in a state of despair and immediate action to conserve them should be undertaken. This is because coral reefs have significant and far-reaching impacts spanning across the socio-cultural, economic, as well as ecological realms of human existences.

Conclusions

As documented in the article, coral reefs is the foundation of numerous marine organisms and since time past have been crucial in supporting human life. Ecologically identified as one of the most biologically diverse ecosystems on the planet, coral reefs bestow countless number of goods and services to humankind as well as to other living organisms. For instance, as itemized in the paper, corals provide a stable habitat for the establishment of numerous marine organisms such as fish, shrimps, and oysters. Moreover, coral reefs provide valuable goods in the form of food and resources and services such as coastline stability and shelter from oceanic waves and currents to humanity. However, as hitherto pointed out coral reefs across the world have been dying at an alarming rate with studies suggesting that unless the trend is curbed, the survival of corals is in jeopardy. The paper in detail highlighted the contributing factors to coral decline with a particular emphasis however on the role of humans in exacerbating this trend. While underpinned with the reason pleas for why humanity should conserve corals, the role of climate change in coral extinction is explicitly discussed

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