Coral+Reefs

** Background: ** Coral reefs are one of the most diverse communities per unit area on Earth. They made up only 0.1% of the Earth’s surface and about 0.2% of the oceans, but, with 95,000 described species, they represent about 5% of the world’s known species and about 35% of known marine species. Marine environments have more high-level taxonomic diversity and are hard to study. Coral reefs are underwater structures composed mainly of calcium carbonate that is secreted by the corals themselves. The calcium carbonate forming coral reefs are present in significantly thin layers. There is a specific type of coral that is responsible for the formation of coral reefs; the stony corals. These corals lay the foundations of reef structures. Coral reefs are complex ecosystems that a have an incredibly large biodiversity. Although they occupy less than one percent of the surface area of the world’s oceans, they are home for approximately twenty-five percent of all marine fish species. These species tend to stand out from the others, as they are particularly colorful. In Curacao, we visited two coral reefs. One was in the coral reef ecosystem in Caracas Bay. The other one was a coral reef located on the coastline behind the Curacao Sea Aquarium. The coral reef in Caracas Bay was extremely rich in terms of biodiversity. In this reef there were many parrotfishes, grunts, angelfishes, damselfishes and much more species. It was clear that this coral reef was much older than the coral reef next to the aquarium due to its high biodiversity, but it could also be seen that it was a growing coral because a lot of juvenile fishes could be seen even though, their sizes and color varied from one species to another. This coral reef was tremendously large. It was not possible for us to explore the entire structure. The coral reef in the Curacao Sea Aquarium was substantially large too. Too large for us to explore it completely, but as it was much richer in corals it fish biodiversity was not as rich as the coral reef at Caracas Bay. The current in this coral reef was intense, and the waves were large and frequent, which could be the reason that biodiversity there was, although very rich, not as rich as it was in Caracas Bay. 

** History: **  Curacao happens to be very rich in terms of shipwrecks and coral reefs. Caracas Bay is the site of the wreck of a tugboat that sank about 30 years ago and is now located in just 5.5m (18ft) of water. The boat is almost intact, though it may seem otherwise due to the fact that it is now covered mostly by brain corals, orange cup corals and gorgonians on the outer hull. This wreck is known as Curacao’s ‘unofficial diving emblem’. The boat is just over 8m (25ft) long and it is accessible to both scuba divers and snorkelers. This wreck is the home to many reef species such as parrotfish, moray eels and French angelfish.  

** Factors that influence Coral Reefs: **

 There is great concern over human impact on corals. Approximately 20% of the world’s coral reefs have been destroyed. Reports predict that 24% of the world’s reefs are under imminent risk of collapsing and another 26% is threatened to collapse over a longer period of time. So far, none show any prospects of recovery. Coral reefs around the world are affected by over-fishing, nutrients and chemical pollution, sediments from deforestation and poor land use, coral bleaching and, and the development of coastal areas for urban, industrial, and touristic purposes.

 Coral reefs are often considered the marine equivalent to rainforests because of their great biodiversity. Marine biologists estimate a range of 600,000 to 9 million different reef species. In Curacao, we noticed how biodiversity was significantly higher in the coral reef ecosystems when compared to some of the other ecosystems that we visited, including mangroves and sea grass.

 Recently, scientists have noticed how coral reef ecosystems have been harmed by ocean acidification and coral bleaching. It has have observed that over the last decade, the excess of CO2 in the atmosphere, caused by polluting human activity, has led to significant changes in ocean water properties providing harmful conditions for many marine organisms. Ocean acidification can lead to the extinction of reef species, disrupting food webs, and tourism business worldwide.

 Like many ecosystems, coral reefs require a certain level of temperature, irradiance, calcium carbonate, sedimentation, salinity, pH, turbidity, and nutrients (the Encyclopedia of Earth) to sustain its population. Recently, the last years there has been many factors that have affected the corals reefs around the world, such as ‘El Niño’ incidents, which have caused a variation in oceans’ surface temperature and air surface pressure. (National Oceanic And Atmospheric Administration).

 Unlike terrestrial environments, oxygen is typically a limiting factor in aquatic ecosystems. The amount of oxygen does affect the amount and type of aquatic species since many species of fish and macro invertebrates are sensitive to low DO levels. DO affect the nutrients and many physical and biological factors.

 Changes in temperature do have a great impact on fish’s abundance and distribution, since temperature determines which organisms will thrive and which will diminish in numbers and size. For each organism there is a range of temperature that produces optimal abundance. The last 100 years seawaters in many tropical regions have increased by almost 1°C, and are currently increasing at ~1–2°C per century. This puts corals reef at risk so if water temperature keep changing at the long run it will cause coral reefs’ biodiversity to decrees.



<span style="color: #000000; display: block; font-family: 'Times New Roman'; font-size: 120%; text-align: justify;">**Bibliography:**
 * http://www.casaoceanview.com/diving/tugboat-curacao
 * http://www.atlantisdiving.com/Tugboat.2680
 * http://curacao-guide.info/activities/diving.and.snorkeling/
 * http://diveglobal.com/explore_destinations/destinations/caribbean/curacao.asp
 * http://www.publish.csiro.au/?paper=MF9907