Natural Versus Artificial Coral Reefs - Coursework Example

Natural vs. Artificial Coral Reefs Introduction Coral reefs, whether natural or artificial are as much an attractive tourist destination as are they fascinating to the environmentalists. The turquoise waters of the coral reefs are home to many unique marine species such as sponges and sea fans; fishes as well as plants. Besides this are the beautifully and variously colored coral colonies. The flora and fauna of the coral reefs add to its beauty and form an ecosystem that is unique, complex, extremely diverse and fragile. As a consequence of the high biodiversity of the coral reefs, they are frequently termed as “rainforests of the sea” (Palm Beach County History Online). Simply defined coral reef is “a kind of living undersea mountain that grew up to reach the sea surface”. Though not scientific this gives a clear mental picture of a reef (Stanley, 2001). Coral reefs are structures made by a group of Cnidarians known as corals that deposit their skeleton of calcium carbonates (CaCO3). Besides biological significance they are also remarkable formations from a geological point of view. Plants and animals that get calcified on the reef are source of vast amounts of CaCO3. Estimates reveal that 400-2000 tons of CaCO3 are produced per hectare of the part of reef that remains exposed on the sea floor. Natural Coral Reef Distribution Corals reefs are exclusively a feature of the tropical and subtropical oceans located usually on the eastern coasts of the continents within 20 to 30◦ north and south of equator. They are found in the tropical waters of Indo pacific areas including South East Asian seas along Polynesia and Australia; and in the East they are found in Indian Ocean along Africa. The Great Barrier Reef of Australia runs almost 1200 km into the shore of Australian continent (Stanley, 2001). Figure 1: Major coral reef sites of the world Tropical coral reefs have the scenic beauty of a tropical rainforest. They are characterized by clear waters, with vast numbers of living organisms clearly visible under the water. Like the rain forest this ecosystem also provides a set of conditions that enables the formulation of a three dimensional framework in which many diverse habitats with unique set of characters are formed where a variety of species are able to thrive. Like the rainforests they too have a biological origin. Further because of their massive size they are not only considered biological but are also considered to be of geological significance (Coral Reefs). Organisms that form Coral reefs Corals reef are formed by corals that are anthozoans, belonging to phylum Cnidaria. The framework builders are primarily scleractinians or stone corals. However, fire corals, blue and organ pipe corals also contribute to the reef framework, though they are not stony corals. Corals are colonial organisms, each colony comprising of up to thousands of polyps or individuals. The scleractinians, exhibit a symbiotic association with zooxanthellae. These are algae that are of immense significance for the reef forming corals (Barnes & Hughes, 1999). Besides corals, polychaete worms, and red algae are also capable of forming reefs (Coral Reefs). The deep water coral Laphelia pertusa forms a 100ft high reef on the Northeast Atlantic floor. But the uniqueness of tropical coral reefs in terms of both size and diversity of life forms is unparalleled (Coral Reefs). Formation The CaCO3 skeletons of corals are secreted by the lower part of the living polyp. A cup like structure ‘calice’ is formed from this deposition raising the coral and into which the coral conceals itself when under stress. Polyps are also connected to adjacent colonies through coenosarcs or lateral tissue which forms the living component of the reef along with the coral. The depositions occur at the rate of 0.5 to 2cm, though may be much faster under favorable conditions (Barnes & Hughes, 1999). Coral Reef Ecology Like every other ecosystem coral reef ecosystem is also formed by a variety of biotic and abiotic factors (Figure 2). Figure 2: Coral reef trophic Pyramind (Rose, 2009) Importance (Ecokids) Provide a protective shelter to many marine organisms Protect shores form the strong waves Are a source of food for human use Help in C cycle Despite the high biodiversity and usefulness, the natural coral reefs are at risk due to many factors, both natural and man-made: Excessive seepage of fertilizers leads to increased growth of algae which covers corals causing its death High CO2 emissions which when absorbed in to oceans render the water acidic making reef formation difficult Global warming leading to raised temperatures of waters Chemical pollution and increased interference by human activites Artificial Coral Reefs The continuous disturbance and degradation of coral reef ecosystems due to natural and anthropogenic causes has lead to increasing interest in development of artificial coral reefs (Perkol-Finkel et al., 2006). Wherever restoration is not possible artificial reefs are installed (Zimmer, 2006). A man made structure placed under sea specifically for the purposes of providing shelter to marine organisms in areas where no such natural shelters are available is known as artificial reef. The prime goal of an artificial reef is to promote marine life, but it also alters wave force and current, provides for tourist attractions and reduces rubble. They can be fabricated either by deploying a pre existing structure such as oil rigs or ships; or they can be constructed using PVC, wood, fiberglass, boulders or concrete. Electrolytic precipitations of certain minerals such Mg(OH)2 and CaCO3 are being explored in recent researches; which thereafter are transplanted with corals (Zimmer, 2006). The two major goals of development of artificial reefs is to restore the biodiversity and population of natural reef community and to be able to harvest the same for human use. During recent years overexploitation has lead to considerable loss of marine ecology and hence loss of stocks of useful species. Conservation programs have therefore gained momentum leading to considerable research, policy formation and implementation of restoration and rehabilitation programs (Carr & Hixon, 1997). Natural vs. Artificial Artificial reefs have been promoted as tools for restoration of natural reefs and rehabilitation of the species inhabiting these ecosystems. Even though the ecological succession in these ecosystems is well understood, a comparative analysis of these two ecosystems in terms of biodiversity, population, interactions among and within species is difficult. Most artificial coral reef ecosystems are either too small or young to comparable to natural coral reefs. Thus many fundamental questions still remain unanswered. It is possible that an artificial coral reef in vicinity of a natural coral reef may gradually acquire the same biodiversity as the former; or they can be similar only if they possess structural similarities; or finally they can never achieve similarity irrespective of age and structure. The second of these options has been supported by research but nothing can be claimed with certainty (Perkol-Finkel et al., 2006). In artificial coral reefs coral survival has been reported to be higher since here corals are placed above the sandy sea floor. On the other hand in natural reefs the corals begin deposition in submerged, low lying areas where they are submerged by sedimentation of sand, thus reducing survival chances. However; the coral diversity has been reported to be much higher for natural reefs. This could be due to much lesser age of artificial reef that have been found to have lower hard coral diversity (Burt et al., 2009). In terms of production of organisms, it has been established that if natural coral reef is present in vicinity of an artificial coral reef and is not isolated from it, the population as well as variety of obligate reef organisms will be more on natural than on artificial coral reef. It is only when the two are isolated; the population on artificial reef may become comparable to that of natural reef and sometimes even higher (Carr & Hixon, 1997). Further compared to artificial reef, fish communities in natural reefs have been reported to be more stable (Burt et al., 2009). In terms of biodiversity, artificial reefs score above natural reefs. A research by Rooker and colleagues (1996), for the artificial and natural reefs located in the Flower Garden Banks National and Marine Sanctuary (FGBNMS) has shown that while in natural reefs fishes predominantly belong to one family (in this case to Pomacentridae) and formed approximately 50% of the population. Artificial reefs on the other hand showed higher diversity with approximately 43 species occupying the upper 24m of the reef. The number reduced during the night; and rose as a consequence of increasing habitat variability as well as fouling levels. Further the species inhabiting artificial reefs have been found to differ from those on natural ones. One major disadvantage of artificial reefs in comparison to natural is that the former reduces the survival chances of fishes. Juvenile settlers get a protected environment inside the artificial reefs and thus they never develop the ability to struggle in open seas. These settlers could have better survival ability in natural reefs if present in vicinity (Burt et al., 2009). Conclusion It can be concluded that compared to natural, artificial coral reefs are rapidly colonized with a comparable population of fishes and benthic communities. In certain cases a higher species richness as well as abundance has also been reported for artificial coral reefs; thereby greatly enhancing the biomass and promoting fisheries stock in regions where it was formerly absent. But the evidences remain inconclusive. Usually it’s the local fish population that aggregate at the artificially provided shelter during certain parts of day and certain seasons such as during breeding seasons. Harvesting of these fishes under the assumption of increased abundance leads to depletion of local population and is harmful for the ecosystem. References 1. Artificial and natural reef evaluation. (2014, March). Retrieved from Coastal and ocean resource economics: http://coastalsocioeconomics.noaa.gov/core/reefs/welcome.html 2. Barnes, R. S., & Hughes, R. N. (1999). An Introduction to Marine Ecology. Oxford: Blackwell Science Ltd. 3. Burt, J., Bartholomew, A., Usseglio, P., Bauman, A., & Sale, P. F. (2009). Are artificial reef surrogates of natural habitats for corals and fish in Dubai, United Arab Emirates? Coral reefs. 4. Carr, M. H. (1997). Artificial reefs: the importance of comparisons with natural reefs. Artificial reef management, 28-34. 5. Chapter 14 Coral Reefs. (n.d.). Retrieved from McGraw-Hill Higher Eduaction: highered.mcgraw-hill.com/sites/dl/free/.../123865/cas09341_CH14.pdf‎ 6. Ecokids. (2014, March). Coral reefs. Retrieved from Ecokids: http://www.ecokids.ca/pub/eco_info/topics/oceans/coral_reefs.cfm 7. Natural and artifical reefs. (2014, March). Retrieved from Palm beach county history online: http://www.pbchistoryonline.org/page/natural-and-artificial-reefs 8. Perkol-Finkel, S., Shashar, N., & Benayahu, Y. (2006). Can artificial reefs mimic natural reef communities? the roles of structural features and age. Marine environmental research, 121-35. 9. Rooker, J. R., Dokken, Q. R., Pattengill, C. V., & Holt, G. J. (1997). Fish assemblages on artificial and natural reefs in the flower garden banks marine sanctuary, USA. Coral reefs, 83-92. 10. Rose, A. (2009). Coralscience.org. Retrieved from Coral reef Ecology. 11. Stanley, G. D. (2001). Introduction to reef ecosystems and their evolution. In G. D. Stanley, The History and Sedimentology of Ancient Reef Systems (pp. 1-38). Springer. 12. Zimmer, B. (2006). Coral reef restoration: an overview. In W. F. Precht, Coral reef restoration handbook (pp. 39-60). CRC press. Read More