More Roatan Information

Roatan's Reef System

It all starts with a single coral polyp. Measuring only a few millimeters across, these miniscule animals build exoskeletons out of calcium carbonate obtained through the photosynthetic efforts of their mutualistic zooxanthellae algae. The nutrient-poor but crystal-clear tropical waters of the Caribbean allow the algaes to receive light at depths that far exceed other parts of the world, thereby making it possible for coral growth to occur at significant depths. Corals reproduce both sexually and asexually. A sexually-reproduced coral polyp, called a planula, will drift until it can affix itself to an unoccupied surface. The single polyp then reproduces asexually to form a colony, often referred to as a coral head.

Millions of years ago, a single polyp growing at a mere 1.5-2cm per year began the long, tedious process of forming the entire Caribbean Barrier Reef, the second largest reef system in the world. As the Caribbean Tectonic Plate slowly grinds its way into the North American Tectonic Plate, several extensive underwater mountain chains have gradually been pushed to the surface. The Bonacca Ridge, which sits on the northwest corner of the Caribbean Plate and connects all the Bay Islands, is the combined result of plate movements along the Cayman Trench and millennia of coral growth. Roatan itself is simply an ancient coral reef that has been pushed over 270m/900ft above sea level!

Roatan has a fringing reef system: the coral reef extends directly from the shoreline. As a diver or snorkeler, this means that all the best sites are mere minutes from the shore. The gnarled black ironshore formations that define our shoreline are the most recent by-products of the fringing reef being thrust above the waterline. Parrotfish use their powerful beaks to crack open the polyp exoskeletons in order to dine on the juicy zooxanthellae algae, digesting and excreting over a ton of calcium carbonate per fish each year. Believe it or not, the white sand beaches that draw tourists year after year are nothing more than a huge pile of parrotfish excrement!

Roatan’s reef is divided into four distinct zones: lagoon, reef crest, fore reef, and drop-off. The lagoon (alternatively called the inner reef or reef flat) starts from where your toes hit the water and extends to the breakers over the reef crest. Like a green carpet spread across the lagoon, fields of eel grass and other algae act as the lungs for the reef system, constantly photosynthesizing light and oxygenating the water. This shallow, sun-soaked sanctuary is home to juveniles of many aquatic species; tiny lobsters, barracudas, butterflyfish, and reef squids reach maturity in this zone, safe from the competition of bigger fish on the reef. Graceful eagle rays fly over the lagoon in search of a crustacean treat, while sharptailed eels slither through the eel grass, hoping to ambush an innocent juvenile.

From the surface, the reef crest appears as a rolling line of breakers. Underwater, this complex coral structure rises straight to the surface, where shifting tides and fierce waves make survival a constant battle. Nonetheless, tenacious stony corals such as the staghorn and elkhorn corals have adapted branching structures to dissipate the perpetually pounding waves. Other corals have a different strategy: soft gorgonians such as the sea fan have very flexible structures, allowing them to “roll with the punches” as the sea ebbs and flows. Heading seaward, the reef crest quickly drops 6m/20ft to a series of a sand and rubble patches formed by the remains of tidal action against the shallow corals. This interior wall (or mini-wall) is home to many intermediate-phase fish transitioning from the lagoon, schooling surface-feeders such as sergeant majors and Bermuda chubbs, and various nimble crustacean life forms.

As the sand patches extend from the interior wall towards the drop-off, large boulder corals, including star and brain corals, form the coral heads of the fore reef (or outer reef). These coral heads merge into prominent ridges of coral fingers following the “spur and groove” formation, meaning that they run perpendicular to the wall and parallel to each other. Colonies of staghorn and lettuce corals build forests of intertwined limestone, creating tiny oases of shelter for nocturnal and territorial aquatic life. Colorful soft corals such as sea fans, sea whips, and sea plumes undulate in the surge. The relatively shallow depths of the fore reef provide ample sunlight for supporting a host of marine life; most of your diving will be in this densely populated, brilliantly illuminated stretch of reef.

The fore reef reaches its buttress in the 12-18m/40-60ft depth range, dramatically plunging into the blue abyss. Plate coral, a deeper version of large star coral, follows the wall in cascading overlapping shelves, gradually settling out on a sandy slope in the 24-50m/80-165ft depth range. Plate coral uses its large flat structure to maximize its surface area exposed to sunlight, thereby increasing the photosynthetic production of its zooxanthellae algae in these darker waters. Deep-water soft corals such as black gorgonians and wire coral stretch their wiry frames away from the wall, capturing drifting nutrients from the prevailing currents. Marine life, while less dense than the fore reef, consists chiefly of larger reef fish and free-swimming pelagics such as groupers, barracudas, oceanic triggerfish, and eagle rays.

Despite its incredible size and longevity, the world’s coral reefs remain very delicate ecosystems. Our current reef required about 20,000 years to evolve, but it only takes a few seconds for a single errant fin kick to destroy millennia of progress. Coral reefs worldwide are suffering from a devastation rate tenfold that of the rain forests. Uncontrolled land development has ravaged the mangrove forests that once protected the reef from pollutants and runoff. Global warming, coupled with the effects of recent El Niño years, has elevated ocean temperatures to unmanageable levels, killing off much of the zooxanthellae algae responsible for reef health; coral bleaching results when these color-giving algae perish, exposing the bleach-white exoskeleton of near-dead coral polyps. Surviving fish are relentlessly hunted by unsustainable overfishing practices, decimating their populations to dangerously low levels.

Fortunately, through the efforts of the Roatan Marine Park with the Sandy Bay - West End Marine Park, our reefs are showing signs of improvement. Poaching has been reduced by nearly 95%, while the lobster and conch populations within the park have significantly rebounded. Still, much remains to be done. As a diver, you can help us keep Roatan beautiful for future generations by:

• Purchasing a marine park tag for just $10 per year. All proceeds go to save our reef, restore our fish population, and encourage educated reef management.
• Maintaining neutral buoyancy while you dive. Watch your fin kicks around the reef, especially during swimthrus. If you are struggling with your buoyancy, remain at least 1m/3ft away from the reef and take your Peak Performance Buoyancy specialty.
• Being extra careful when taking underwater photographs. It is far too easy to get distracted by lining up the perfect shot while unwittingly trampling on the reef. No picture is worth being a careless shutterbug!
• Respecting reef life by not touching anything. Not only does this damage the organisms, it is also incredibly rude. Would you like it if a turtle decided to ride you? What if an eel decided to give you a little “pet?” Leave the creatures alone, they will leave you be, and everyone can dive together in peace.
• Knowing what you are buying. Conch shells, dried seahorses, and black coral jewelry may seem like nice tourist trinkets, but they represent the uncontrolled destruction of endangered reef life. Buying these items only propagates the problem.

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