OUR OCEAN PLANET OUR OCEAN PLANET SECTION 11 – CAYMAN ISLANDS AND THE SEA
11. CAYMAN ISLANDS AND THE SEA 11. CAYMAN ISLANDS AND THE SEA
11.1 OVERVIEW 11.1 OVERVIEW
11.1 OVERVIEW 11.1 OVERVIEW The Cayman Islands are three small islands that lie approximately 241 km (150 miles) south of Cuba and 290 km (180 miles) west of Jamaica almost in the center of the Caribbean Sea. The Cayman Islands are composed of Grand Cayman, Cayman Brac and Little Cayman. Christopher Columbus discovered the islands in 1503 and named them Las Tortugas after the large sea turtles he sighted in the surrounding seas. Sea turtles have subsequently become very important to the cultural heritage of the Cayman people. The islands were later renamed “Caymanas” from the Carib Indian word for a crocodile. With a tradition as shipbuilders, sailors, turtlers, fishermen, and in rope-making, the people of the Cayman Islands have a long history of being a resourceful and resilient people. Once a dependency of Jamaica, the Cayman Islands came under direct British rule after Jamaica declared independence in 1962. Granted greater autonomy under a 1972 constitution, the islands today are largely self-governing and economically self-sufficient.
11.1 OVERVIEW The Cayman Islands have many natural attractions. Coral reefs, beaches and abundant marine life make them a popular destination for tourists and other visitors for scuba diving, snorkeling, and other water sports. The Cayman Islands are also one of the world's largest financial centres with several hundred banks and financial institutions, and tens of thousands of companies that operate through the islands. Tourism, banking and property have overtaken the traditional trades of fishing, turtle hunting and shipbuilding. CLIMATE Tropical. The average temperature is a pleasant 20-23.9°C (68-75°F) between mid-December and mid-April with lowest humidity (tourist peak season). The average temperature for the rest of year is 28.3°C (83°F). Rainfall is highest from mid-May through October. The water temperature is about 24°C (75°F) in winter and 29°C (85°F) in summer with visibility ranging from 21-30 m (70-100 ft). CAPITAL George Town, Grand Cayman POPULATION 40,000 (about 37,000 live in Grand Cayman)
11.1 OVERVIEW 11.1.1 Geography All three Cayman Islands are low-lying, flat-topped landmasses which are the tips of massive submarine mountains that just barely emerge from the ocean. Encircling each island are shallow waters and a reef system harboring a rich diversity of marine life. The world-renowned Seven Mile Beach and the sheer coral reef walls surrounding all three islands have made the Cayman Islands one of the premiere tourism destinations in the Caribbean. At Bloody Bay Wall for example, on the north shore of Little Cayman, the sea floor ends abruptly at a depth of only 5.4-7.5 m (18-25 ft) before dropping off to a 1,800 m (6,000 ft) vertical cliff. Along the face of the wall grows a large variety of corals, sponges, and other coral reef life. The bedrock of all three islands is a porous limestone. Although this is thousands of meters thick, it is built from the external skeletons of millions upon millions of tiny marine organisms, mostly corals.
11.1 OVERVIEW Long before Columbus navigated the three islands on his last voyage, major tectonic unrest along the boundary of the Caribbean and North American plates created a ridge from Cuba southwestward to Nicaragua. This ridge created a series of mounds across the Caribbean Sea that were close enough to the sunlit surface for corals to begin to congregate and settle. Slowly, over 40 million years, through several major shifts in the earth’s climate and dramatic fluctuations in sea levels, the Cayman Islands were formed. Even the rock formations that rim the shores are remnants of reefs that formed only in the last few thousand years as ice melted and the sea level rose. During times of lower sea level, large caves formed in the limestone as it dissolved (imagine that underneath the islands the rocks look like Swiss cheese!)
11.1 OVERVIEW Over time, corals built the modern fringing reef up to sea level, creating a powerful barrier to large waves, protecting the islands from erosion, and allowing plants to grow. The reefs and their inhabitants produced sand for the beaches and provided a barrier for the shallow lagoons. The reefs also play a significant role in reducing coastal flooding as the sea level continues to rise. The connection between the reef, sandy beaches and mangroves that developed are evident. The three islands also have no rivers that can carry sediment and nutrients into the sea, which gives the Cayman Islands some of the clearest waters on Earth. The healthy marine environment of the Cayman Islands provides inhabitants food, shelter and the very land that they live on.
11.1 OVERVIEW 11.1.2 Historical Timeline 1503 For the first century after Columbus happened upon the Cayman Islands in 1503, the islands were uninhabited by people, the main inhabitants being turtles. The sun-bleached landscape languished in near-pristine state, undisturbed but for the occasional sailors stopping to replenish ship stores on turtles and to refill freshwater barrels. Unlike many Caribbean Islands, pre-Columbian artefacts have never been discovered on the islands. Archaeologists have suggested that the Amerindians, who had excellent maritime skills, may not have an interest in permanently settling in the Cayman Islands because the islands had swamps with mosquitoes and did not have much fresh water. 1586 Sir Francis Drake's fleet of 23 ships stops for two days at Grand Cayman. The island is not inhabited but crocodiles, alligators, iguanas and numerous turtles are recorded.
11.1 OVERVIEW 1655 England captures Jamaica from the Spanish. 1670 Under the Treaty of Madrid, Spain recognizes England's sovereignty over Jamaica and various other Caribbean islands, including the Cayman Islands. No permanent settlers set up house on Grand Cayman until after the 1670 acquisition of the islands and its turtles by the British Crown, which has held dominion over the three islands ever since. Once settlers started trickling in from Jamaica in the early 18th Century, Cayman Islanders quickly established their reputations as world-class seafarers.
11.1 OVERVIEW 1680–1718 Edward Teach (“Blackbeard”), a notorious English pirate, frequented the Cayman Islands, reputedly spending quite a bit of time around Cayman Brac. 1700 Permanent settlement had probably begun by this time with a few families, notably the Boddens, living on Grand Cayman. Land grants and records of land transactions discovered in Jamaica, England and Spain provide a fairly good early history of settlement. With formal land grants reported from the 1730s–1740s in Grand Cayman, settlement evidently began at the East End of Grand Cayman. Historical records indicate Isaac Bodden as the first recorded inhabitant of Grand Cayman who was born on Cayman around 1700. The East End district was formerly known as Old Isaacs. Stories have it that Isaac was the grandson of one of Oliver Cromwell’s soldiers who helped capture Jamaica in 1655. Other stories indicate that the first settlers were two soldiers from Oliver Cromwell’s disbanded army with the names of Walter and Bowden in 1658. 1734-1742 Five land grants in Grand Cayman are made by the Governor of Jamaica. Mahogany and logwood are being exported to Jamaica. Population perhaps 100-150.
11.1 OVERVIEW 1773 First survey or map of Cayman made by the Royal Navy. Population is about 400 (approximately half free, half slaves). 1780s From the 1780s, the Cayman shipbuilding industry produces schooners and other sea craft for inter-island trade. Cotton, turtles, sarsaparilla and wood being exported to Jamaica. 1790 Fort George probably constructed to ward off attacks by French or Spanish pirates. 1794 "Wreck of the Ten Sails" occurs. Ten ships, including HMS Convert, the navy ship leading a convoy of 58 merchantmen, wrecked off East End. 1798 First record of a magistrate in Cayman being appointed by Governor of Jamaica. 1800 By 1800, the population numbered less than 1,000 – of which half were slaves. After the Slavery Abolition Act (1834) was read at Pedro St. James in 1835, most freed slaves remained and by 1900 the Cayman population had quintupled.
11.1 OVERVIEW 1820s Local laws being passed by a self-appointed group of "principal inhabitants." 1831 Decision to form an elected assembly taken at Pedro Castle on 5th December. Elections follow on 10th and new Assembly passes first legislation on 31st December. Population is approximately 2,000. 1835 Governor Sligo of Jamaica lands in Cayman to declare all slaves free in accordance with the British Slavery Abolition Act of 1834. 1830s First missionaries from the Anglican and Wesleyan churches visit and a church is built in George Town. 1830s-1840s First schools established by the Mico Charity and Wesleyans. 1846 Presbyterian church established by the Rev. James Elmslie.
11.1 OVERVIEW 1863 Act of the Imperial Parliament in London makes Cayman a dependency of Jamaica (although Cayman had been loosely "governed" as such from 1670). 1898 Frederick Sanguinetti, an official in the Jamaican Government, appointed as the first Commissioner of the Cayman Islands. Cayman will be governed by Commissioners until 1962. 1920 A major Education Act provides for government schools in all districts. 1937 The first cruise ship (“Atlantis”) visits. This signals the beginnings of tourism with the first tourist booklet published. 1939-1945 During World War II, a "Home Guard" is formed to provide protection and surveillance of enemy shipping. 1950s Until the mid-20th Century, the economy would remain tied to the sea with fishing, sea turtle fishing and shipbuilding as the main industries.
11.1 OVERVIEW 1950s Divers put the Cayman Islands on the international tourist map as early as the 1950s. A number of hotels open as adventurous tourists begin to visit the islands. 1953 An airfield is opened in Grand Cayman, eventually replacing the seaplane service which had operated since the 1940s. 1953 The George Town Hospital is opened. Barclays Bank, the first commercial bank, opens. 1959 Cayman receives its first written constitution which grants the vote to women. Cayman ceases to be a dependency of Jamaica. 1962 Following Jamaica's independence from Great Britain, Cayman chooses to remain a Crown Colony, governed by an administrator who reports directly to Westminster.
11.1 OVERVIEW 1966 Cayman Islanders begin fashioning the tax structure that has made Grand Cayman an economic powerhouse and designing an infrastructure that has made it a capital of Caribbean tourism. Landmark legislation is introduced to encourage banking industry. 1970 Population of the Cayman Islands is 10,249 with only 403 visitors. 1972 New Constitution introduced under which Cayman is governed by a Legislative Assembly, Executive Council and a Governor. 2004 Hurricane Ivan hits Grand Cayman in September, 2004, causing widespread destruction and halting tourism. A curfew is introduced to prevent looting. Cayman Brac and Little Cayman do not receive a direct hit and damage to the two smaller islands is more limited. TODAY Population of the Cayman Islands is about 50,000, most of which live in Grand Cayman. Historically, the population is an amalgamation of Jamaican, North American, European and African roots. In the aftermath of Hurricane Ivan, a large influx of expatriate workers (from 78 countries and growing) has led Cayman Islanders to become a minority in their own country. The upside is that the Cayman Islands have a rich social fabric that celebrates diversity.
11.1 OVERVIEW • 11.1.3 National Symbols • FLAG • The Cayman Islands flag consists of the Union Flag of the United Kingdom at the top left quarter of a dark blue background with the Cayman Islands crest appearing at the bottom right quarter. • The Union flag or “Union Jack” is formed from three separate country flags: • England; St. George (red cross on white background) • Scotland; St. Andrew (white x on blue background) • Ireland; St. Patrick (red x on white background)
11.1 OVERVIEW COAT OF ARMS The Cayman Islands were granted their own coat of arms on 14 May 1958. The arms depict three green gold edged stars on blue and white wavy lines. This represents the three islands and the blue lines, the Caribbean Sea. The red chief above the stars shows the Lion of England which represents the ties to Great Britain. The turtle is the national symbol of the Cayman Islands and the rope it stands on represents the thatch rope industry that is an important part of Cayman's history. The pineapple at the top of the Cayman Island arms symbolizes the time when the Islands were a dependency of Jamaica (which was until 1962 a dependency of Great Britain). MOTTO The Cayman Island motto “He hath founded it upon the seas” is from the Bible. Psalm 24 Verses 1-2 are: 1. The earth is the Lord's, and the fullness thereof; the world, and they that dwell therein. 2. For he hath founded it upon the seas, and established it upon the floods.
11.1 OVERVIEW • 11.1.4 Natural Resources • The Cayman Islands are embedded in an azure, turquoise and indigo coloured sea. Below these warm waters lie a world of corals, stingrays, sea turtles and tropical fish. Towering underwater walls, shipwrecks and reefs have made the Cayman Islands renowned among scuba divers and snorkellers while mile after mile of pristine white sand beaches, cliffs and caves are popular with tourists. • In short, the Cayman Islands are blessed with many natural ocean resources that are highly in demand in today’s world including: • Coral reefs • Sandy coasts – white sand beaches, cliffs & caves • Mangroves • Sea Food – fish, crustaceans and molluscs • The natural ocean resources support local inhabitants in a variety of industries such as tourism, shipping and fishing. These resources, coupled with good government, political stability and strong relationships with the UK and USA has led to a healthy economy and, in turn, wealth for Cayman Islanders. These resources will be described in more detail later.
11.1 OVERVIEW REFERENCES & FURTHER READING http://www.gov.ky – Cayman Islands Government http://www.gocayman.ky – Cayman Islands http://news.bbc.co.uk/2/hi/americas/country_profiles/3709816.stm - Cayman Islands http://news.bbc.co.uk/2/hi/americas/country_profiles/3710044.stm - Cayman Islands Timeline http://www.caribbeanbusinesscommunity.com/cayman.asp - Cayman Business Community https://www.cia.gov/library/publications/the-world-factbook/geos/cj.html - Cayman Islands Gorry, Conner, Kohnstamm, Thomas and Ver Berkmoes, Ryan, Caribbean Islands (Multi Country Guide), Lonely Planet (2007) Porter, Darwin and Prince, Danforth, Frommer’s Portable Cayman Islands, Wiley Publishing Inc. (2007)
11.2 CORAL REEFS 11.2 CORAL REEFS
11.2 CORAL REEFS 11.2 CORAL REEFS 11.2.1 Corals Although coral heads resemble rocks or plants, they are actually colonies of numerous marine animals living together. Corals are invertebrates (animals without backbones) and belong to the phylum Cnidaria and class Anthozoa. Corals are members of the same phylum as sea anemones, siphonophores, hydroids, true jellyfish and box jellyfish because all these animals have nematocysts (stinging cells) and their bodies are sac-like with a single opening at one end, which functions as a mouth and an anus. Corals are different from other cnidarians because they secrete an external skeleton around themselves and form colonies that are usually attached to a hard surface. Corals are considered the most important part of a reef because of the long-lasting structures they build and the habitat that these structures provide for countless reef organisms.
11.2 CORAL REEFS HARD VS. SOFT CORAL Corals can conveniently be considered as either hard or soft depending on the consistency and nature of their skeletons. Hard Corals Hard corals are reef-building corals that secrete a hard external limestone skeleton. This skeleton remains when the corals die and forms a base upon which other corals can grow. A coral polyp has tentacles, and hard coral polyp tentacles are arranged around the mouth in multiples of six. Hard corals grow in three basic forms: branching, massive, and plate. Examples include brain coral (a massive coral), elkhorn (a branching coral), and leaf coral (a plate coral). In the Cayman Islands alone, 44 species of hard coral can be found. Soft Corals Soft corals produce a flexible skeleton made of a protein called gorgonin and do not significantly contribute to the building of a reef. Soft coral polyps have eight tentacles arranged around their mouth and are classified as octocorals. Examples of octocorals include common sea fans and sea whips. Octocorals take branching or fan-like shapes that bend and sway with the movement of the water. Typically, a sea fan blade faces into the prevailing current to help the coral trap food in the water.
11.2 CORAL REEFS ANATOMY Coral Polyp A coral polyp or body consists of a sac with a digestive cavity and a single opening that functions as mouth and anus. The open end of the polyp is surrounded by tentacles that help filter food into its central digestive cavity. Nematocysts (stinging cells) on the tentacles assist the coral in catching prey. The nematocysts paralyze the prey and the sticky tentacles then deposit the food in the coral's mouth. Stinging Cells (“Nematocysts”) Corals (and all cnidarians) have specialized cells that carry stinging organelles called nematocysts. These specialized stinging structures are a characteristic of the phylum and are borne in the tentacles and other body parts. Corals employ these stinging cells to kill prey. The nematocysts function by a chemical or physical trigger that causes it to eject a coiled fiber with a barbed and poisoned hook that can stick into prey. Dead or paralyzed prey is pushed into the coral's oral opening by the tentacles and digested in the digestive (gastrovascular) cavity. All undigested food, waste & other secretions leave through the same oral opening.
11.2 CORAL REEFS Coral Skeleton In the case of the hard corals, each polyp secretes a calcium carbonate (limestone) cup around itself, which is fused with others to form boulder or rock-like colonial fortresses. The deposition process is a slow one, but the efforts of one generation are not lost when the polyps die, for subsequent generations build over the skeletal cups of their dead ancestors ever increasing the coral's hold on the reef. In contrast, the soft coral polyps often secrete a horn-like substance, called gorgonin, into which the calcium carbonate is embedded. This arrangement gives the soft corals greater flexibility than their hard coral counterparts, allowing them to form more pliable, bushy or fan-shaped colonies. Because coral reefs are the leftover skeletons of once-living organisms and are not created by geological processes, they are called biogenic (“bio” means life and “genic” means create, so reefs are "created by life"). DIET Corals are considered to be primarily carnivorous because they eat other small animals, such as fish, although some corals are omnivores and eat both plants and animals. Corals typically feed on animal and plant plankton which are microscopic in size. There are billions of plankton in the oceans. Animal plankton is called zooplankton while plant plankton is called phytoplankton.
11.2 CORAL REEFS SYMBIOSIS Coral polyps form a symbiotic (mutually beneficial) relationship with algae called zooxanthellae. Zooxanthellae are known as endosymbionts because they live inside (endo) the body of a coral polyp and are part of a symbiotic relationship (symbionts). Zooxanthellae have both animal & plant features but are usually considered to be algae since they are able to utilize energy from sunlight and use it to convert carbon dioxide and water into oxygen and sugars (photosynthesis). When many zooxanthellae live within a coral polyp, they provide the polyp with extra food and oxygen from photosynthesis, which the polyp uses to build its skeleton. In exchange, the zooxanthellae are given a protected place to live and additional carbon dioxide produced by the coral polyp during respiration. Different zooxanthellae live with different corals and come in many different forms and colours. It is the zooxanthellae that give corals their beautiful colours. When corals are stressed, however, they eject their zooxanthellae. This makes them white or bleached; this condition is known as "coral bleaching". Corals do not generally thrive without their zooxanthellae and may even die.
11.2 CORAL REEFS DISTRIBUTION Coral reefs are generally located in warm tropical and subtropical regions of the world's oceans between 35°N and 35°S of the equator. Corals live in shallow, clear, and sunlit sea water at a temperature between 18°C and 36°C. There are three primary regions coral reefs are found: the Indo-Pacific (including the Indian and Pacific Oceans), the Red Sea and the Western Atlantic (including the Caribbean Sea). About 60% of the world's coral reefs are found in the Indian Ocean and Red Sea, 25% are in the Pacific Ocean, and the remaining 15% are in the Western Atlantic and Caribbean Sea. Coral reefs have evolved over millions of years. The reefs of the Western Atlantic Ocean and Caribbean Sea evolved slightly later as the Atlantic is the youngest of the world's oceans. Today's reefs represent about 10,000 years of accumulated growth since the end of the last ice age. REFERENCES & FURTHER READING http://www.nationaltrust.org.ky/info/coral.html - Coral reefs
11.2 CORAL REEFS 11.2.2 Coral Reef Life Cayman Island coral reef life is rich and diverse. It consists of many animals including: CORALS Hard corals – brain coral, elkhorn coral, staghorn coral Soft corals – sea fans, sea whips SPONGES Tube sponges Vase sponges Basket sponges CRUSTACEANS Crabs – hermit crabs Shrimps Lobsters – Caribbean spiny lobsters (adults) MOLLUSCS Cephalopods – octopus, squid, nautilus Conch – queen conch ECHINODERMS Sea stars Sea urchins
11.2 CORAL REEFS FISHES The Cayman Islands boast about 350 species of fishes including: Bony Fish Families: Angelfish – French angelfish, grey angelfish, queen angelfish Butterflyfish – spotfin butterflyfish, four-eyed butterflyfish Damselfish – sergeant majors Goatfish Grunts – French grunts, smallmouth grunts Jacks – lookdowns, permits Moray eels – green morays Parrotfish – stoplight parrotfish, blue parrotfish Sea basses – sea basses and groupers Snappers – yellowtail snapper Surgeonfish Tarpon Triggerfish – queen triggerfish Wrasses Cartilaginous Fish Families: Eagle rays – spotted eagle rays Stingrays – southern stingrays Nurse sharks Requiem sharks – bull shark, sandbar shark, whitetip reef shark
11.2 CORAL REEFS The following highlight some of the animals that are found on Cayman Island reefs and are of particular interest. QUEEN CONCH The queen conch (Strombus gigas) grows to an average adult length of 25.4 cm (10 in). From birth, it creates a hard shell to protect its soft body. The mantle, a layer of skin surrounding the foot and lining the shell wall, discharges calcium carbonate as a liquid which hardens to form the shell. The inside of the shell is a beautiful pink colour. A conch shell grows in a clockwise spiral until a lip begins to form. The lip forms the base of the shell and helps prevent a conch from being overturned. Once the lip forms, the shell ceases most of its growth in length but it continues to thicken with age. Queen conch is a popular sea food. Indeed, demand for it is so great that, even with protection, conch is widely over-exploited and threatened in much of the Caribbean. SOUTHERN STINGRAY The Southern stingray (Dasyatis americana) is a cartilaginous fish with a body that is almost a perfect rhombus shape. It can reach a length of 1.5 m (5 ft) across disk and is usually a bottom-dweller that lies buried in sand except for the eyes. It has a whip-like tail with a venomous spine at the base of its tail. Like all stingrays, it bears live young. The southern stingray eats clams, mussels, and oysters and has flattened teeth which are suitable for crushing shellfish.
11.2 CORAL REEFS BLUE PARROTFISH The blue parrotfish (Scarus coeruleus) has a sky to royal blue body, a blunt snout and a parrot-like beak from fused teeth. It eats corals and algae and swims using its pectoral fins. The blue parrotfish can reach a length of almost 122 cm (4 ft) but it is usually much smaller with a length of 61 cm (2ft) TARPON Tarpon (Megalops atlanticus) are large, powerful, predatory silvery bony fish. They have large mouths with protruding lower jaws and they have large scales on their body. They are considered important game fish and can reach a length of 2.4 m (96 in) and weigh 136 kg (300 lb) REFERENCES & FURTHER READING http://www.nationaltrust.org.ky/info/queenconch.html - Queen Conch
11.3 SANDY COASTS 11.3 SANDY COASTS
11.3 SANDY COASTS 11.3 SANDY COASTS 11.3.1 Beaches, Cliffs, Caves & Blowholes BEACHES The Cayman Islands are blessed with miles and miles of white-sand beaches. Coral reefs are a major source of white sand beaches. The white sand consists of crushed shells and limestone from coral skeletons, which are ground down and excreted by parrotfish. Some of the most beautiful white sand beaches in the Cayman Islands include Seven Mile Beach on Grand Cayman, the southwest coast on Cayman Brac and Point of Sand on Little Cayman. CLIFFS Probably the most famous cliff in the Cayman Islands is the “Bluff”, a dramatic, wedge-shaped limestone formation that rises from the flatlands of the west end of Cayman Brac to a height of 42.6m (140 ft) traveling the length of the island before plunging into the sea. The word “Brac” comes from a Gaelic word for bluff. The Bluff is made of marine limestone and is estimated to be 25 million years old.
11.3 SANDY COASTS CAVES The Cayman Islands are riddled with caves – which in previous years were sometimes used as hurricane shelters. The islands themselves are limestone which is very soft. With time and the incessant waves, the limestone has become eroded in many places forming caves and caverns. The islands have been likened to holey “cheese”. Underwater, there are many dive sites to see these caves, caverns, tunnels, and grottoes such as Eden Rocks and Devil’s Grotto off Grand Cayman. Above land, caves can be seen in Cayman Brac. BLOW HOLES “Blow holes” are holes in the rock formation formed by wave erosion that produce huge spouts of water when waves hit and force water through the hole. They can be seen on the East End of Grand Cayman.
11.3 SANDY COASTS 11.3.2 Sandy Coast Life Cayman Island sandy coast life is also rich and diverse. It consists of many animals including: CRUSTACEANS Crabs – hermit crabs Shrimps Lobsters – Caribbean spiny lobsters (adults) ECHINODERMS Sea stars Sea urchins REPTILES Sea turtles – green, loggerhead, hawksbill
11.3 SANDY COASTS The following highlight some of the animals that may be seen on Cayman Islands beaches and are of particular interest. SEA URCHIN Sea urchins are echinoderms. They are round, spiny and herbivorous invertebrates that graze on algae and detritus from grass beds and rocky areas. Many sea urchins have long, sharp spines on their backs, which protect them from predators such as fish, crabs, moray eels and sea otters. However, their underside is often spineless and they are vulnerable to attack from that side if the predator can turn the sea urchin over. SEA TURTLE Sea turtles are large air-breathing reptiles with paddle-shaped fore-flippers and a number of other adaptations that make them perfectly at home in the ocean. Today, only seven species remain worldwide – green, loggerhead, hawksbill, flatback, Kemp’s ridley, olive ridley, and leatherback turtle. Although they may live their entire life at sea, sea turtles must return to the land to nest. Under cover of darkness, a female will drag her body across a sandy beach where she will dig a nest and deposit about 100 eggs in the warm sand. After about 60 days of incubation, the eggs will hatch and the hatchlings will make their way back to the sea.
11.4 MANGROVES 11.4 MANGROVES
11.4 MANGROVES 11.4 MANGROVES 11.4.1 Mangroves Mangrove trees are found in many sub-tropical and tropical areas of the world growing along sheltered coastlines. Mangrove wetlands form an important link between the land and the sea. In the Cayman Islands, three types of mangroves are found in wetlands – red, white and black – each of which has adaptations for tolerating the high level of salt and lack of oxygen that would ordinarily kill other plants. These woody, seed-bearing plants range in size from small shrubs to tall trees. Mangroves have many important functions including providing the basis of the food web upon which the marine creatures feed, acting as a nursery for small fish and juveniles, protecting land from the effects of storms and surges, and filtering the water of sediment resulting in the clear waters surrounding Cayman.
11.4 MANGROVES Mangroves provide an ideal habitat for birds, fishes and many invertebrate species. For example, Cayman’s parrots nest in black mangrove trees. Fish live amongst the roots of red mangroves, hiding from larger fish and feeding on smaller fish and creatures that also live in the tree roots. Juvenile turtles and lobsters live in the sanctuary offered by the root systems and shallow water areas. Invertebrates, such as the mangrove oyster, crabs, snails and shrimps, also live on the submerged mangrove trees and roots. Mangrove wetlands also have other essential functions. The dense and strong root systems protect against the large waves and storm surges that Cayman can experience during hurricanes and other storms. The roots also help stabilize muddy and soft sediments that would be stirred up by wave activity which would cause shoreline erosion and murky waters devoid of marine life. They dampen wave energy and protect the Cayman coastlines. Mangrove wetlands also absorb vast quantities of fresh water from heavy rains, and release it slowly and harmlessly into the marine environment. This means that by the time rain water reaches the reef, it has been filtered by the mangroves and the sediment stirred up by the storm has settled. Mangrove ecosystems are also very important providers of nutrients that feed into surrounding ecosystems, making them healthier and more productive.
11.4 MANGROVES REFERENCES & FURTHER READING http://www.nationaltrust.org.ky/info/mangroves.html - Mangroves
11.4 MANGROVES 11.4.2 Central Mangrove Wetland Grand Cayman's Central Mangrove Wetland is critical to the ecological health of Grand Cayman. The Wetland is part of a large-scale water flow system that filters and conditions the surface and shallow ground water which flows into North Sound. The Wetland also provides a flow of nutrients into North Sound by constant tidal flushing of the mangrove fringes and by occasional overflows of accumulated rainwater from the whole Central Mangrove basin. These nutrients form the base of a complex food chain from the Turtle Grass and shrimp mounds in Little Sound, through to the snappers and lobsters which move from the mangroves to the reef. North Sound’s entire ecosystem is bound to the Central Mangroves and it would collapse if the Wetland was ever destroyed. West Indian whistling duck, Grand Cayman parrots, snowy egrets and many other native birds depend on the Central Mangrove Wetland for food, shelter and a breeding area. Crustaceans, insects and other invertebrates inhabit the Wetland, along with fish, hickatees, agouti and many other animals. Red, black, white and buttonwood mangroves are found along with dry land trees such as mahogany and wild fig.
11.4 MANGROVES The Wetland covers an area of about 8,500 acres and is almost entirely in its natural state. It is largely covered by a canopy of trees, which absorb sunlight and radiate part of that energy as heat, warming the air near the leaves. This air becomes saturated with water vapour, evaporating from the leaves pores and from the ponds below. Warm saturated air rises above the Central Mangrove Wetland and can form clouds, which are carried west by the prevailing winds to rain on the central and western districts of Grand Cayman. This process is believed to contribute greatly to western Grand Cayman's rainfall, which is 40% higher than the eastern districts. Without the Wetland, George Town and West Bay could be as dry as East End. REFERENCES & FURTHER READING http://www.nationaltrust.org.ky/info/centralmangrove.html - Central Mangrove Wetland
11.4 MANGROVES 11.4.3 Mangrove Life Cayman Island mangrove life consists of many plants and animals including: PLANTS Red Mangrove Black mangrove White mangrove Buttonwood mangrove Mahogany Wild fig CRUSTACEANS Crabs – hermit crabs Shrimps Lobsters – Caribbean spiny lobsters (juveniles) MOLLUSCS Mangrove oyster FISH Juvenile reef fishes Bonefish
11.4 MANGROVES REPTILES Central American river turtle (Dermatemys mawii) – “hickatee” Sea turtles BIRDS Cayman parrots West Indian whistling duck Frigate birds MAMMALS Agouti
11.4 MANGROVES The following highlight some of the particularly interesting animals that are found in Cayman Islands mangroves: CARIBBEAN SPINY LOBSTER The Caribbean Spiny Lobster (Panulirus argus) gets its name from the sharp spines that adorn its hard outer shell and antennae. Their bodies have 19 segments. The first 13 segments are fused together forming a rounded outer shell or carapace. The head region of the carapace contains the eyes, long whip-like antennae, flexible antennules and jaws. The thorax contains five pairs of spindly legs with the last 6 segments forming the abdomen and tail fan. Caribbean Spiny Lobsters are brown with four cream coloured spots on the dorsal surface of the abdomen and much smaller cream spots scattered over the rest of its body. To avoid capture, lobsters always face their potential predators. In this position they are best able to use their large abdominal muscles and tail fan to rapidly propel them backwards and away from an advancing predator. An additional defence mechanism is their ability to break off an appendage when caught. Once free from a predator's grasp the lobster can flee to safety and, in time, re-grow its missing appendages.