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Coral reefs are not only extremely diverse marine ecosystems, hosting many species, they are also eye candy for divers and snorkelers. Some major facts about corals, resuming a recent article by Nicole Helgason, PADI Dive Instructor at ScubaDiverLife. Coral reefs are not only extremely diverse marine ecosystems, hosting many species, they are also eye candy for divers and snorkelers.
Some major facts about corals, resuming a recent article by Nicole Helgason, PADI Dive Instructor at ScubaDiverLife. 1. Corals are colonial animals formed by many identical polyps. The individual polyps look like sea anemones, with similar body structure: mouth, stomach and tentacles. During the nights these tentacles are exposed and waiting for the meals to pass by. Some have longer tentacles too, to catch food, or sting other corals that encroach on their territory. 2. There are two general categories, hard corals, where polyps form hard skeletons and soft corals, where jelly-like or rigid, spiny structures hold together soft coral polyps. Another difference is that hard corals are built on a six-fold symmetry, while soft corals are built on an eight-fold symmetry. 3. Hard corals live in tropical, sunny waters, where light penetrates the ocean water to a depth of approximately 230 feet (70 m). Optimal water temperatures for corals are between 73 and 84 F (23 and 29 C), although some can tolerate higher temperatures for short periods. Coral polyps live in symbiotic relationship with photosynthetic marine algae. The coral provides home and protection for the algae and, in exchange, the algae absorb sunlight and produce energy for the polyp. They also give the coral its color. Polyps can also get energy from ingesting plankton and food particles, but being fixed in place, their energy from food consumption is limited. When too much light or high water temperatures stress the polyps, the stressed polyp expels the zooxanthellae algae. If the water temperatures don’t fall quickly enough, the polyp will die without its important symbiont. This is the reason behind the coral bleaching. 4. Corals are regional, and the Australian Institute of Marine Science's website is a great tool in regional coral identification. Please choose "CORAL REEF-FRIENDLY" products, when purchasing the sun cream for your next holiday!  For many years we are aware of it, that most chemicals are harmful for underwater life, but the study, that even one drop of sunscreen is enough to damage fragile coral reef systems is only known since the past years.
Above we are talking about one drop, but in reality some 14,000 tons of sunscreen lotions wind up in coral reefs around the world each year. The ingredient oxybenzone is causing coral bleaching, and it can also disrupt the development of fish and other wildlife. Scientists conducted the study in the U.S. Virgin Islands, Hawaii and Israel, but the results are worldwide. Reefs are in general at risk, due to destructive fishing, pollution, global warming and development all pose threats to the coral reef. "The use of oxybenzone-containing products needs to be seriously deliberated in islands and areas where coral reef conservation is a critical issue," co-author Craig Downs said according to the Washington Post. "Any small effort to reduce oxybenzone pollution could mean that a coral reef survives a long, hot summer, or that a degraded area recovers." Local economies, as ours in Seychelles depend on the tourism that coral reefs attract. As a result, we shall completely ban the use of harmful sunscreen in their waters. There are good examples, in Akumal, Mexico, an area known for its reefs and sea turtles, visitors are warned against wearing sunscreen and are restricted to certain areas to prevent too much disruption of reef life. Damaging sunscreen from beachgoers is just part of the concern. When people wear sunscreen, it is anyway going to end up in the waterways, after cleaning it off, just like other chemicals used by in household cleaning products. These are all washed down into the sewage systems. "People come inside and step into the shower. People forget it goes somewhere," co-author John Fauth told the Post. To avoid harming coral reefs, use "reef friendly" sunscreen (those made with titanium oxide or zinc oxide, which are natural mineral ingredients) and wear clothing and hats to protect the skin from the sun. |
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