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Dominican ecosystems:
The Dominican Republic occupies the eastern two thirds of the Caribbean island of Hispaniola. The Dominican Republic is a tropical country with a land area of 48,442 square km and a population close to 8 million. Hispaniola (76,192 sq km) is the second largest island of the Greater Antilles, after Cuba 6. Jamaica (14,000 sq km) and Puerto Rico (8,800 sq km) also form part of the Greater Antilles. The Dominican Republic contains many different ecosystems, from mountain rain forests to arid depressions, which contain hundreds of endemic species of plants and animals. It is a very important island to study speciation, ecology and Caribbean geology, especially island formation.
The Caribbean was formed by the break-up of Pangea and the separation of North and South America approximately 140 million years ago. As the two continents moved apart, volcanic activity produced a volcanic isthmus archipelago, similar to the formation of Central America a few million years later 17. Due to the pressure of the movement of the pacific plate, those first volcanic fragments were pushed eastwards in the direction of the present Caribbean sea and then where subducted to form parts of the Greater Antilles via volcanism. The fragments where being pulled along by marine plate subduction on the northern margin of the oceanic crust that lies between the Florida-Bahama platform and North American Plate 17. The subduction of these crustal block (fragment islands) triggered active volcanism, which formed the volcanic arc of the Caribbean. However, with the arrival of the thick carbonate platform (which was behind the crustal block) at the trench or the subduction zone, the subduction along northern Cuba, Hispaniola and Puerto Rico ceased and volcanic activity along the western arc stopped 18. This was later describes as the closing-zipper effect as the subduction zone ceases to create volcanism in a northwest to southeast fashion. This explains why there is currently no volcanism in the Greater Antilles, but still present in the Lesser Antilles, because the subduction in the southeastern region of the Caribbean is still active today 18. This collision of the plates formed the 180 km long Cordillera Septentronal on the northern edge of Hispaniola consisting of uplifted limestone, blue schist of oceanic crust, and tectonic mélange 24. This collision is still active today and occasionally will cause a small tremor on the northern coast of the Dominican Republic
The Dominican Republic mountain ranges, which are the highest of the Antilles, are an important factor in determining ecosystem formation and location on Hispaniola. These mountain ranges extend from northwest to southeast and continue to the submarine mountain ranges of the continental bridge of Central America 25. The Cordillera Central is the island’s oldest range at approximately 130 million years old. Its magmatic center dates back to the Cretaceous Era and it contains the islands tallest peaks 17. There is no evidence that Tertiary rocks were deposited on the mountain range and there is Cretaceous sediment in the Cibao and San Juan de la Maguna valleys, which indicates that the Cordillera Central was structurally-Topographically much higher in the past 18. The highest peak of the Cordillera Central, is the Pico Duarte at 3,175 meter above sea level and Pico Alto de la Bandera at 2,620 meters above sea level. The Cordillera Oriental, which has smaller peaks is an extension of the Cordillera Central, and is located on the Eastern peninsula from Hato Mayor to Higuey 33. This region, which is mostly composed of Karstic deposits, was recently (during the Pleistocene) uplifted to form Los Llanos del Este 24. The Sierra de Samana, which is also composed of Karstic deposits, was also formed around this time period, but it is of different geological origin from the Cordillera Central and was not made out of volcanic activity, but rather uplifted oceanic crust. The next mountain range that forms the typical northwest to southeast pattern is the Sierra de Neiba and Sierra de Ocoa 17. The Sierra de Neiba runs parallel to the Cordillera Central with a fertile valley in between (Valle de San Juan) made of alluvial soil from the Cordillera Central and Sierra de Neiba 18. The formation of these mountains was caused by volcanism that occurred in the early Cenozoic Era, approximately 50 million years ago. The Sierra de Neiba is not as high as the Cordillera Central, but is does reach about 1,500 meters above sea level. The peninsula of Barahona is located on the southwestern region of the Dominican Republic 21. Its formation was separate from the formation of the rest of the island via the Caribbean arc. This range of mountains is bounded by the fault bounded Enriqullo depression and by the Caribbean Sea. There is strong indication that this portion of the island was a section of the Caribbean seafloor that was uplifted during the Oligocene 23. This separate island was not joined to the main island until recent, about 30 thousand years ago. This also explains why there is so much endemism on the peninsula of Barahona (Park National Jaragua).
The Dominican Republic has many different ecosystems, from lush rain forest to arid deserts. It is important to study these ecosystems in the context of a tropical island environment, but also as separate entities. Most of these ecosystems have their own flora and fauna, which gives them a certain appearance and uniqueness. The geographic regions of the island appear different, like separate islands, but they still must be looked at as a singular approach of island development. The destruction of one ecosystem affects countless others and changes the composition of the remaining ecosystems. It is therefore important to look at single ecosystems in more detail to understand the biodiversity of Hispaniola. In this manner a bigger picture of the flora, fauna, and geological and biological (evolutionary) development of the island can be achieved.
Dominican pine forests are found in a wide range of locations scattered over the Dominican Republic. They are mostly found in high mountain regions containing elevations of 2,500 meters above sea level and moderate amounts of rainfall 34. Hispaniola contains three large pine forests the main one located on the Sierra de Baoruco and the other two in the Cordillera Central and the Sierra de Neiba 19. These are the last remaining true Boreal-like forest in the Caribbean Antilles and definitely worth conservation. These forests are monoculture forest predominantly containing only one native species of pine (Pinus occidentalis) and many other species of underbrush; Europeans introduced all other species of conifers 19. It is presumed that Pinus occidentalis was the only species able to colonize the Hispaniola archipelago during the Cretaceous, since Puerto Rico, Jamaica and the Lesser Antilles do not contain any native species of pine 20. It is also presumed that during this period the island was mostly covered by pine forest before they were overtaken by flowering plants (Angiosperms) in the lowlands. More studies of fossilized pollen from this period must be performed to determine a clear answer. Today, these once vast conifer forests are only found on the highest mountain ranges and elevated valleys of Hispaniola 19. This is due to that fact that tropical and sub-tropical flora are highly competitive in the lowlands and thus have isolated these conifer forest to higher elevations, which are more inhospitable to broad leave plants because of the low temperatures and poor soil quality 19. The Sierra de Baoruco and the Cordillera Central contain the last dense pine forests of the island with many endemic underbrush species of plants and a rich epiphytic flora of mosses and lichens, which give the forest an undisturbed feel. The fauna is very sparse in these remote and extreme regions of the countryside with very few species of amphibians, reptiles and mammals. Birds are more common, but in reduced numbers. These last remaining pine forests are a true treasure of Hispaniola and should be protected for future generations 6.
Cloud forests are found on mountain regions 2,000 meter above sea level that have a high level of humidity all year round. This effect is cause by the trade winds moisture not being able to climb the high picks of the Cordillera Central and Sierra de Baoruco. The moisture condenses and covers the region around the peaks of the high mountains (mostly north facing slopes) with a permanent fog mist. These forests have a mossy appearance with abundant mixed flora of dwarf conifer and broadleaf species and many fern species 16. Because of the wind, most of the plant species do not grow very tall and remain dwarf. The Sierra de Baoruco has the most undisturbed cloud forest of Hispaniola with many endemic species of trees 9. Ferns form the lower underbrush of these forests and there is an abundance of mosses, liverworts and lichens 16.
Mountain broadleaf forests are common in Hispaniola and are found on all the major mountain ranges of the island. These forests are mainly found in the valleys in-between mountain ranges at about 900 to 2,000 m above sea level, such as Jarabacoa, Constanza (Cordillera Central) and el Polo (Sierra de Baoruco) 19. These forests provide one of the most important mountain ecosystems of Hispaniola. Unfortunately most of these forests have been clear-cut for agricultural purposes and are very rare in an undisturbed state 14. These forests contain a tall tree layer like canopy where species of Lauraceae, Myrtaceae and Melastomataceas families are abundant. They also contain many animal species. There are also isolated Manaclal forests islands in the broadleaf forests. Manaclal are palm trees that seem to form a number of micro ecosystems in the middle of these forests 8. There are abundant numbers of bird species and amphibians. The only two native terrestrial mammals are also present in the higher elevations of this environment because it is relatively undisturbed. The Solenodon (Solenodon paradoxus) is an endemic insectivore of Hispaniola, which is endanger of extinction. The Solenodon has a close “cousin” in Cuba and a distant relative in Madagascar. It is the size of a rabbit with whiskers and a naked tail and is nocturnal. The other endemic mammal is the Jutia (Plagiodonte aedium), which is part of the rodent family and about 45 cm long 6. Both mammals are extremely rare and are under the protection of the law. These mammals can also be found in rainforest and mangroves in undisturbed regions of Hispaniola 3.
The Hispaniola rainforests are found on the northeastern part of the island. This region of the island near San Francisco de Macoris and Nagua receive 3,000 to 4,000 mm of rainfall a year 34. This region of the island is in direct contact with the west blowing trade winds, which deliver most of their moister to this part of the island 35. This region was one of the first regions that Columbus saw when he reached Hispaniola, and he was amazed at the density of the impenetrable forest. This is a unique ecosystem in Hispaniola and one of the only regions where true rainforest can arise on the island. The dominant tree in this forest is Mora abbotti, which is not only endemic to Hispaniola, but also endemic to the Cordillera Septentrional 20. Another common species is Cyrilla racemiflora, which is a giant tree of 25 meters tall and with Mora abbotti 20 meters tall form the canopy. This kind of tall canopy forests are rarely present in the Greater Antilles. Because of the canopy very little light reaches the ground and there is a lack of underbrush, except for some ferns (Asplenium cuneatum) and mosses and decomposing material covers most of the ground 16. This ecosystem is rich in fauna as well. There are abundant species of birds, amphibians, reptiles and mammals. Common birds include the Guinea, Paloma Ceniza, Perico, Cotorra, and Codorniz. Common amphibians include many endemic frogs like Osteopilus dominicensis and salamanders. There are also many distinct species of reptiles such as iguanas, snakes, Boas, river turtles “Jicotea”. Also present is the endemic mammal Solenodon (Solenodon paradoxus) and many species of tree bats 8. There are many species that were introduced by Europeans such as the mongoose, rats, and wild pigs. This area is important for conservation purposes because it is the birthplace of two major rivers and countless tributaries of the northwestern Dominican Republic; because of this the mountains in the region where legally protected by the formation of the Parque National Loma Quita Espuela 13. The region contains very important river ecosystems that are vital to the fisheries of the north Atlantic Dominican coastline 13.
Desert like conditions exist in many small-scattered areas of the Dominican Republic. The most common regions are the southwest (lago Enriquillo) and extreme northwest Cibao (Monte Cristi) 2. These regions where the trade winds do not reach are rain shadowed by the high mountain ranges of the center of the island. This ecosystem can be considered as an introduced ecosystem on Hispaniola by intensive human destruction of natural semi-arid forest. The present regions where there are deserts were once semi-arid forest of Caoba (Swietenia mahagoni), Baitoa, and Bayahonda, which have been clear-cut and sold to the world market. The barren land is then slowly eroded and loses its ability to sustain medium size trees like Caoba 6. The land is then useless and a process of desertification begins, with clear-cutting resulting in more deserts. Most of these regions have been reclaimed by semi-arid thorn brush called Matorrales 1. These regions contain many endemic cacti species, but they don’t provide shade or moister retention like the semi-arid forest, and thus cannot maintain the same type of biodiversity.
Semi-arid forests are a common ecosystem in the southwestern and northwestern part of the Dominican Republic. These forests are formed from low amounts of precipitation and good soil conditions. These regions are usually sheltered from the Trade Winds by mountain ranges and thus not much moister reaches these regions. These regions are also dominated by dry and raining seasons each year 1. The northern and southern slopes of the Sierra de Baoruco contain this type of vegetation 9. It is distinguished by low elevations of less than 700 meters above sea level and low rainfall below 500mm per year. The flora in this vegetation zone does not grow very tall, less than 5 meters, but they provide the necessary shade and moister retention to maintain a vibrant ecosystem 34. In this dry habitat you can find many endemic animals like the Solenodon, Jutia and Iguana de Ricord (Cyclura ricordii) 15.
Semi-arid thorn brushes called Matorrales in the Dominican Republic are very common in arid regions of the country. They are very common in the southern region (Barahona, Lago Enriquillo, Parque National Jaragua) of the country and in the extreme northwestern provinces (Monte Criste) 2, 9. These areas are characterized by low rainfall amounts and poor soil nutrients. Monoculture populations of cactaceae and Fabaceae characterize these thorn brushes. There are a few species of endemic woody cactus tress that grow a few meters in height and are used by the native population for building material 6. There is no canopy present, because of the abundance of cacti; this also limits the amount of underbrush since there is no shade. The fauna of this ecosystem is restricted to small mammals of the rodent family and in the southern regions large Iguanas (Cyclura ricordii) 15. This type of ecosystem is more prevalent in the southwestern region of the Dominican Republic because of the Cordillera Central barrier to the north. The matorrales in the northwestern region are much smaller in their range and receive more rainfall than the southern region. The northwestern region also has more rivers such as the Yaque del Norte, which tends to make the region less arid.
The Island of Hispaniola has many salt-water lagoons on its coastline 14. This habitat provides an important ecosystem for many native and foreign organisms. Most of the salt-water lagoons are found in the vicinity of the Bahia de Samana (Laguna Redonda, Jina and Bavaro), but the largest salt-water lagoon is found in the south (Laguna de Oviedo). These lagoon systems are usually small and associated with mangrove forest. These lagoons are very ecologically productive, because they serve the purpose of fisheries and sanctuaries to migratory birds. Juvenile fishes find protection in the murky waters that lack strong ocean currents. Many types of fishes inhabit these ecosystems, but the most prevalent is the Tilapia, which was introduced from Africa in the 1960’s. This alien species has competed with many native species and is now very prevalent in Dominican lagoons 28. This is another example of introduced species harming the native Dominican populations of fauna and flora. The Laguna de Oviedo is the largest salt-water lagoon in the Dominican Republic at 30 sq km. It is very shallow and probably formed by the influx of the Caribbean Sea 28. This lagoon also has a large population of Tilapia, which is locally fished. This lagoon has become popular to ecotourism, because of its large population of migratory birds, mostly the flamingo. This lagoon serves as a winter-feeding ground for 43 species of North American birds. In addition the lagoon also contains a large percentage (60%) of native bird species. There are also populations of endemic iguanas and endangered sea turtles (Carey, Tinglar, Caguamo).
The most important Brackish Lake in the Dominican Republic is the Lago Enriquillo. It is 260 sq km wide and is the largest lake in the Caribbean. The lake is located in a geological depression, which is 42 meters below sea level, making it the lowest point in the Caribbean as well 34. The lake was a sea channel in the recent past. This channel divided the island of Hispaniola into a northern and southern island less than 50,000 thousand years ago 22. This is one of the major reasons why the southern region (Barahona, Pedernales) has such a high level of endemic species. The whole island elevated 35 meters during the Miocene, which trapped the water in the basin and formed the lake 22. The lake is a very important region ecosystem for the southern part of the country offering a large resting ground for migratory birds, like Flamingos and Herons. The lake has a negative water flow so it requires hurricanes to replenish its water level every few years. The lake has a few fresh water rivers that feed it water, but it has a limited effect on its water level and salinity. The lake is considered hyper saline with an average salinity higher than the Caribbean Sea 35. The lake is well known for its population of endangered crocodiles (Crocodylus acutus), which probably originated in Central America. They number in the hundreds and have probably been isolated for thousands of years in the lake basin. There are also populations of endangered endemic iguanas. In addition the lake also has a small population of Tilapia and other Herbivorous fishes. These fish populations have a constant problem with the lakes low oxygen content, which fluctuates depending on the amount of water present. As the lake dries up the water becomes more anaerobic. The surrounding flora is semi-arid thorn brush, caused by the low amounts of rainfall and because of the high salinity of the soil in the vicinity of the lake.
The Dominican Republic has many fresh water lakes caused by the high level of rainfall that reach the island. The largest fresh water lake is the Laguna del Rincon, which is located in the Southern region in the province of Neiba 9. The lake is very important for natural and human populations, as it is the largest source of fresh water in the region. The lake receives most of its waters from the river Yaque del Sur, which is then passed to the Lago Enriquillo 6. The Laguna del Rincon has a rich fauna of birds, amphibians and reptiles. The lake has many species of small fresh water turtle and lizards; it also has many species of native frogs and salamanders 15. The lake is surrounded by semi-arid forest, which are due to the high salinity and poor nutritional content of the soil. Another important fresh water lake is the Laguna de Limon, located in the eastern part of Hispaniola (Bahia de Samana). This lagoon is smaller but equally as diverse and is surrounded by mangrove forest 3. These lakes are vital to the survival of fresh water ecosystems on Hispaniola, since most of the major rivers systems have been destroyed ecologically by human activities 31.
Hispaniola has many river systems that crisscross the island. The river system of the Yaque del Norte, which flows through the Cibao valley, is one of the longest in the Antilles. River systems provide a vital ecosystem for many organisms in Hispaniola. In semi-arid areas like the south, river systems provide much needed fresh water to sustain many plants, animals and human populations. Dominican rivers have been greatly affected by human activities in the recent past. Deforestation of mountains where rivers are born and the deforestation of riverbanks have caused the slow erosion of the riverbanks 19. This leads to a reduction in size and water flow. The island once had numerous rivers that had strong currents and wide banks. Today very few rivers maintain their historical levels, and only a trickle of water remains in most rivers. This has caused many species of river fish, reptiles, amphibians and invertebrates to become rare or endangered 14. The rivers of Hispaniola traverse every known habitat of flora on the island from mountain top springs to semi-arid valleys. Dominican river systems have a great variety of fauna, which include many species of mammals, amphibians, reptiles and invertebrates. There are many species of frogs and salamanders and river turtle, which were very common in the past 15. There are also abundant species of fresh water fish species and Crustaceans, like river shrimp and lobster. These habitats must be protected because once they dry up they become almost impossible to replenish.
The whole island of Hispaniola is surrounded by natural occurring coral reefs as is typical of other Caribbean islands. Fringing reefs and small barrier reefs are scattered along some 170 kilometers of its coastline, and there are also many important reef communities on the offshore banks of Navidad and La Plata 5, 11, 12.The Dominican Republic’s coastline has both fringing reefs and bank reefs. These are identified by the location (distance) of the reef from the coastline. Bank reefs are usually attached to the coastline, while fringing reefs are following the outline of the coastline, but are a few meters offshore. The Dominican Republic also has a small population of coral reefs located in salt water lagoons, and what is considered to be a growing barrier reef system in Monte Cristi 12.Coral reefs have very high biodiversity and can be compared to the marine equivalent to terrestrial rainforest. In the Del Este National Park the diversity of the main reef groups is high, with 22 octocorals, 26 scleractinians and 36 sponges on the shallow spur and groove formation 29, 30. Coral reefs exist a few meters from the coastline, where they are protected from land soil sediment and are shallow enough to get sufficient sunlight. Coral reefs form an important ecosystem in the Caribbean and are necessary to maintain healthy fisheries and aquaculture production 31. They form a macro ecosystem with mangroves and sea grass communities. If the costal mangroves are destroyed the coral reefs will soon follow 31. One of the most important coral reef communities in the Dominican Republic is located in the northwestern region from Monte Cristi to Punta Rucia 12. This coral reef community forms a real miniature barrier reef system following the coastline. The southern part of the Dominican Republic contains less coral reef ecosystems; this is probably due to river sedimentation and low nutrient content in this region of the Caribbean Sea. There are scattered populations of coral reef near the western vicinity of the Parque National del Este and also in the western vicinity of the Parque National Jaragua 11. These fringe reefs are found on the western side of these peninsulas, because of strong ocean currents that disturb natural coral reef formation. There are many species of fishes, crustaceans, bivalves, mollusks, and many other invertebrates that inhabit coral reef ecosystems. The major species captured for fishing consumption are shrimp, lobsters, mussels, Lambi (Strombus gigas), which is highly endangered and many species of fish like Mero, Dorado, Sharks, Chopa, and Cherna 6. Coral reefs are very sensitive to environmental change and are highly threatened by sedimentation and pollution. Nutrients from fertilizers (as well as domestic wastewater) and pesticides (from agricultural runoff) can cause Coral disease and the Diadema die-off has undoubtedly exacerbated the effects of these direct human impacts 31.
Mangroves are an important part of the Dominican flora. They are spread all over the island usually near coastal lagoons and river deltas. There are four major regions where mangrove forests exist on the island; in the north near Monte Criste, in the Bahia de Samana, in the Parque National del Este and in the Parque National de Jaragua 31, 12. These mangrove forests are very important for the protection of island marine fauna. The northern mangrove forests are present around the river deltas cause by the rivers Yaque del Norte and Rio Yuna. The southern mangrove forests are found on the perimeter of coastal lagoons like Laguna Oviedo, and the many little lagoons in the Parque National del Este 30. The Dominican Republic has 3 species of mangroves these are the Red Mangrove (Rhizophora mangle), the Black Mangrove (Avicennia germinas), and the White Mangrove (Laguncularia racemosa) 3. These species appear in both dry and wet coastal environments. Mangrove forests reduce the speed of terrestrial water flow, which reduce soil erosion and also sedimentation of the coastline 3. Via this retention method mangrove forests can reclaim land from the ocean. Mangrove forests are extremely adapted to their tidal environment, which give then the advantage of conquering this specific habitat. If you ever see a mangrove forest the first thing you would notice would be the giant root systems that hold the trees to a stable base, but allow the tides to recede. They also have the ability to form aerial roots called Asparagus roots, which serve as respiration organs 3. Mangroves also display partially developed seedlings that germinate on the mother tree and then when sufficiently heavy they drop to the ground where they are cemented into the soil by gravity. Mangrove forests are important because they form natural fisheries for many species of fish and crustaceans. They also reduce sedimentation, which protect the sea grass communities and coral reefs from being destroyed 31.
Sea grass communities cover most of the Dominican Republic and are a very important part of the marine environment. Sea grass communities are usually found near the shoreline on sandy patches of ocean floor. They provide habitat for many different species of fishes and marine invertebrates 27. Seagrass beds have been recognized as productive fishery areas in the Caribbean. The queen conch Strombus gigas is associated with Thalassia testudinum beds and is now seriously threatened by over fishing. Seagrasses are colonized by calcareous and filamentous epiphytes. The dominant species of grass is Thalassia testudineum and Cymodea manatorum. These underwater pastures provide food for herbivore animals such as sea turtles and the manatee 4. Turtle grass, Thalassia testudinum, is the most abundant seagrass in the region, but is not known south of Venezuela. Plants are erect, leaves generally varying from 5 to 15 mm wide and from 10 to 50 cm long, but can reach up to 1 meter 32. This seagrass forms dense rhizome mats below the sediment creating extensive meadows on shallow sand or mud substrates from the lower intertidal to a maximum 10-12 meter depth 27. In classic models of Caribbean seagrass succession, rooted vegetation starts with rhizophytic algae followed by Halodule wrightii and sometimes Syringodium filiforme, which are considered to be pioneer species, with a Thalassia testudinum-dominated vegetation as climax 10. Migratory movements of various animals such as fish, spiny lobsters, prawns and sea urchins enhance the links between the seagrasses, reefs and mangroves 31. These migratory movements can occur on a daily basis, for example foraging in the seagrass beds during the day and sheltering from predation in the reefs during the night or seasonally, when juvenile stages of species migrate from mangroves or seagrasses to the reefs when they reach adulthood 32. The Dominican Republic has four species of marine turtle that inhabit its coastal seagrass communities. These are the Hawksbill turtle (Carey), Green turtle, loggerhead turtle (Caguamo) and the Leatherback turtle (Tinglar). All of these species are endangered of extinction on the Dominican coastline. Another species that is threatened on the Dominican coastline is the marine mammal the Manatee; very few individuals still remain in Dominican waters. In the late 1970 a number of individuals were counted at 50 near the coast of Samana 4. There have also been sightings in the Parque National del Este. Their sightings have become increasingly rare in the past few decades. This is probably due to human hunting and the destruction of their natural habitat for the purpose of increasing national tourism 4.
Sea grass communities are also very important in reducing sedimentation of eroded terrestrial soil into the oceans 31. This protects coral reefs from land sedimentation Pollution from land-based sources varies from country to country. The greatest threats are from eutrophication (sewage and agricultural fertilizers), hydrocarbons, pesticides and other toxic wastes. Eutrophication is characterized according to type of effluent discharge, being diffused through freshwater surface runoff (like rivers and streams), distinct point sources (like sewage treatment plants) or multiple point sources (like submarine springs connected to the aquifers that are contaminated by land-based human activities.). Hurricane activity may result in loss of seagrass vegetation because of sediment erosion or sediment deposition on the seagrass beds 26. Tens of square kilometers of highly productive seagrass meadows were destroyed by the formation of large sediment “blow-outs”, which are holes in otherwise continuous seagrass meadows 26. Reports indicate that overall, under natural conditions, Caribbean seagrass beds seem to be fairly resistant or resilient to major natural disturbances.
There are two large sea banks that are under the Dominican Republic’s Zona Exclusiva Economica (ZEE). These under water sand banks and coral reefs are about 50 nautical miles from Puerto Plata and are about 25 meter deep 7. Theses Banks form the Parque National Banco de Plata (Silver Bank). The Banco de Plata and the Banco Navidad became a national park in 1977 to protect the humpback whale population (Megaptera noaeangliae) that use the bank as a nursery 6. It became apparent that if the north Atlantic humpback whale was to avoid extinction, these banks were going to have to be protected by Dominican and international authorities. There is also an abundance of dolphin species and many Caribbean shark species. The humpback whales come to breed during the winter months (Jan-May) and then return to the North Atlantic during the summer. Almost 90 percent of Canada and New England’s whale population migrate to reproduce in the Banco de Plata 5. The bank serves as a perfect nursery because of the shallow water where the baby calves could be relatively protected from predators and strong ocean currents 5.
Hispaniola has many costal islands that provide a distinct ecosystem to their inhabitants and provides an evolutionary look at the affects of founder effect populations. An example of this is the southern island of Beata, which is part of the island shelf of Hispaniola. This island has a few endemic species of small salamander reptiles and small snakes 15. These species were presumably separated from their mainland cousins in the south. A semi-arid thorn brush covers the island, but it still has many endemic flowering plants like the Ulbrichia beatensis that are not found any were else in the world 23. The island Beata offers great insight on island evolution. In the southeastern part of Hispaniola there are small islands that were formed by ancient animal activities (coral reefs). These islands (Isla Catalina and Isla Saona) have similar ecosystems to their mainland regions, but are more affected by sea winds and marine climate 2. These islands are important because they are relatively untouched by man and they support a large marine ecosystem that includes one of the last populations of Dominican manatees.
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