The Impact of Global Climate Change on Acropora Cervicornis
The scientific classification of Staghorn Corals is described as follows: Kingdom Animalia, Phylum Cniadaria, Class Anthozoa, Order Scleractinia, Family Acroporidae, Genus Acropora, Species Acropora cervicornis (NMFS, 2015). The A. Cervicornis has algae that lives inside its tissues and gives the animal its Golden tan or pale brown color, and the Staghorn coral colonies usually appear in these colors but they also contain white tips (NMFS, 2015). These corals usually have tentacles in multiples of three, and at night their tentacles are visible from the surface of the water and they look like stars in water (Alter, 2000; McGregor, 1974). Staghorn corals have antler-like branches and typically branch out from the center and angle upward (McGregor, 1974; NMFS, 2015). Branches are typically 1 to 3 inches thick. They form relatively large colonies, which are mad up by individual polyps that grow together and they are copies of each other. Individual colonies can grow to four feet high and six feet wide (NMFS, 2015). Staghorn corals need specific stinging cells to be able to feed. They are located on their tentacles, and these cells are called nematocysts (Sisson 1973; Alter, 2000).
A. cervicornis corals prefer warm waters and they are usually found close to the surface in marine waters, more specifically, they are found around 15-16 feet where the temperature is warmer and it is higher than twenty degrees. The most coral diversity appears around the tropical western regions of the oceans. These corals are commonly found in clear, oxygenated, and shallow water because they need supplies of small planktonic animals, they need to reduce light, and they need protection against heavy rain of sediment that could suffocate them (Alter, 2000; McGregor 1974; NMFS, 2015). The specific locations where A. cervicornis are found include: Bahamas, Florida, and the Caribbean. A. cervicornis lives in many coral reef habitats including spur and groove, bank reef, patch reef, and transitional reef habitats, as well as on limestone ridges, terraces, and hardbottom habitats for the polyps to settle (NMFS, 2015).
A. cervicornis like many other corals have a unique symbiotic relationship with algae and a strong dependency on them. Without the algae these corals’ growth decreases, and they are not able to produce as large colonies as they usually do with the presence of algae (Alter, 2000; McGregor 1974). The reason for this dependency is that carbon is passed to the coral by the alga. Based on the fact that algae need sun for photosynthesis, and corals need algae, algae determine and limits the coral habitat and environment (Alter, 2000). Staghorn corals provide complex habitat for fish and many other coral reef organisms because of their bush-like growth form. When there are a lot of staghorn coral colonies, they tend to provide shoreline protections from large waves and storms (ABRT, 2005). Their diet is not known to be broad and complex. They usually eat planktonic animals floating in the water (Alter, 2000). They also get food from the photosynthetic algae, which lives inside their cells (ABRT, 2005).
They have an interesting way of reproducing as it contains both sexual and asexual reproduction, which is common among corals. A. cervicornis reaches reproductive maturity when it is seven inches tall. It is a simultaneous hermaphrodite, in other words, each colony produces both eggs and sperm but does not self-fertilize. Staghorn corals sexually produce once per year, and this sexual reproduction occurs after the full moon in late summer by releasing eggs and sperm into the water column (NMFS, 2015). The first step of reproduction is a sexual reproduction stage called reef-building. Reef-building happens because the polyps produce millions of spermatoza into the water, later, these gametes find their way into other polyps that are nearby. If the situations are suitable the fertilization begins and the fertilized eggs develop the larva, which then floats to produce new polyps.
The larva produced is called planula. It is very small and has a bulb shape. The planula larva will float in water to get to an appropriate hard surface to continue its development and produce more polyps and colonies. It is a food source for many aquatic animals, but some of them manage to survive and when they do, they attach themselves to the hard surfaces and spread. According to scientific research, some specific species of crustose coralline algae (CCAs) have been observed to facilitate larval settlement of the coral species Acropora cervicornis (Williams, 2010; Sharp & and Ritchie, 2012). After the attachment, they begin to secrete a white star-like outer skeleton, which eventually will develop tentacles and grow into mature polyps. Once the first skeletons are built, the sexually produced polyps, multiply by asexual reproduction, such as, budding. Acropora grow branches, also known as buds (McGregor 1974; Alter, 2000).
A. Cervicornis is one of the most important corals in the Caribbean because along other corals they have built the Caribbean reef for thousands of years (NMFS, 2015). The existence of these corals provides important habitats for other animals. However, throughout many years there have been many factors that have affected the population of Staghorn corals. Even though their lifep reaches thousands of years, there have been occurrences, such as severe diseases, that caused the death of more than half of the Staghorn corals. Other than diseases, Land-based sources of pollution, Unsustainable fishing, Small population size, Habitat degradation have had a great impact in decreasing the population of this coral. Moreover, the most important factor that causes the death of this coral is the Global Climate Change.
The global warming causes the ocean warming. This situation forces the Staghorn corals to release the algae they have inside their tentacles, which provides them with carbon and food, and leads to the corals’ death. One of the reasons to global warming is the increased amount of 〖CO〗_2 (Carbon Dioxide) in the atmosphere, and this ends up creating more hydrogen protons in the water making it more acidic. Ocean acidification caused by global climate change, threatens the A. cervicornis since the more acidic water dissolves the carbon that the algae provides to the coral to build its skeleton. More acidic water makes the formation of coral skeleton harder. Climate change is the greatest global threat to corals. Although there are some people who doubt the accuracy of the global warming, scientific evidence now clearly indicates that the earth’s atmosphere and oceans are warming.
Scientists state that these changes are caused by the greenhouse gases produced by human activities. As temperatures rise, more corals release their algae and lose their food resources, also, more infectious disease outbreaks are happening frequently. Additionally, Ocean acidification, carbon dioxide altering the water chemistry by decreasing the PH of water, has already begun to reduce calcification rates in reef-building and reef-associated organisms (NMFS, 2015).
As mentioned before, A. Cervicornis corals have a very important role in providing habitat for many animals including fish. Acropora cervicornis provides shelter and houses many creatures. Some of these creatures might be useful in scientific researches including the medical research field. Some of the species which are found in the corals have yielded compounds against inflammations, asthma, leukemia, tumors, heart disease, fungal and bacterial infections, and some viruses such as HIV (Chadwick 1999). Based on the fact that Staghorn corals have an important positive impact on human and other animals’ lives, there are many researches and studying being done on their genetic and biological structures. According to the reaserch “Ecology and Evolution” by Crawford Drury, Stephanie Schopmeyer, Elizabeth Goergen, Erich Bartels, Ken Nedimyer, Meaghan Johnson, Kerry Maxwell, Victor Galvan, Carrie Manfrino, and Diego Lirman, threatened Caribbean coral communities can benefit from high‐resolution genetic data used to inform management and conservation action (Drury et al, 2017).
Acropora cervicornis corals are very beneficial and they provide habitat for many creatures including fish. They are, however, very effected and vulnerable against the Global Climate Change. They prefer to be close to the surface of water (15-16 feet), although they prefer warm, clean, and oxygenated water, the global warming has increased the temperature of ocean water too high and it is not suitable for the Staghorn corals. The warmer water causes them to release their algae, which are the providers of their food and carbon, and this leads to the corals’ death. Another way that the global warming is affecting the Staghorn corals is by ocean acidification, which means the PH of water decreases due to the addition of too many hydrogen protons caused by the extra Carbon Dioxide in the atmosphere. The more acidic the ocean water get, the harder it is for the corals to make and form their skeleton.