There are a wide of variety of issues that affect the marine environment around the US Virgin Islands.
Sea turtles are among the longest extant reptiles on Earth mainly because of a number of evolutionary adaptations that have made them resilient to an ever-changing planet. Seven species inhabit tropical and subtropical regions globally and although a loggerhead sea turtle (Caretta caretta) recently began nesting at Buck Island on St. Croix, three species of sea turtles are common to the US Virgin Islands. Leatherback sea turtles (Dermochelys coriacea) seasonally migrate to nest in the territory. The largest, oldest, and most unique sea turtle species, leatherbacks grow to 6-8ft in length, are over 100 million years old, and are the only non hard-shelled sea turtle species. Because of its leathery carapace (shell), leatherbacks are able to dive beyond 3,000ft. They do so in search of sea jellies, which make up its main diet. Historically, leatherbacks were hunted for its oil and along with incidental captures in the commercial fishing industry have lead to dramatic population declines. Green sea turtles (Chelonia mydas) are the largest of the hard-shelled sea turtles, growing to 3-5ft in length. Many green sea turtles are year-round residents of the USVI and are common in sea grass meadows where they can be seen feeding on a variety of sea grasses. Historically, green sea turtles were harvested most in the sea turtle commercial fishing industry, as their meat is most palatable and less oily as compared to other sea turtle species. Also, their fat (calipee) would be dried and used to make green turtle soup. Contrary to popular belief, green turtles were named for the color of their fat, not because of the color of their carapace. Hawksbill sea turtles (Eretmochelys imbricata) are the smallest of the hard-shelled sea turtles found in the USVI, growing to 2-3ft in length. As their name suggests, they have the head just like that of a hawk’s and the spongivores are commonly found on coral reefs and preferentially feed on a handful of sponge species. The hawksbill sea turtle was hunted more for its shell than any other turtle. Its carapace has overlapping plates with imbricated ridges and was used to make jewelry and other ornaments. Because of the popularity of its carapace, hawksbill turtles were over-exploited in many countries, especially in the Caribbean.
The current global decline in sea turtle populations is primarily due to illegal harvesting, incidental interactions with fishing gear and vessels, loss of nesting habitat, pollution, global warming, and diseases. Currently, all species of sea turtles are federally protected by the Endangered Species Act of 1973, locally by the USVI Endangered and Indigenous Species Act of 1990, and internationally by the Convention of International Trade in Endangered Species. Beyond legislation, active management of sea turtle nesting beaches have lead to increases in many local populations including the leatherback sea turtles on Sandy Point, as well as greens and hawksbills at Jacks and Isaac Bays, and on Buck Island, St. Croix. Also, in the USVI the Sea Turtle Assistance and Rescue network actively works to rescue and rehabilitate injured sea turtles throughout the territory. Contact STAR at (340) 690-0474 to report injured or dead sea turtles. The research and conservation of sea turtles in the USVI demonstrates that positive human intervention can help to improve the resilience of sea turtles species.
CORAL REEF COMMUNITIES
Extremely bio-diverse, coral reefs communities are productive resources for many marine fishes, invertebrates, reptiles, and other marine organisms. Coral reefs are built from many small coral polyps reproducing to form colonies and building calcium carbonate skeletons. The colorless corals receive color from the pigmented zooxanthellae with which it shares a symbiotic relationship. In the mutualistic relationship, corals receive nutrients from the photosynthetic zooxanthellae, which receives shelter from the coral. Like mangroves and seagrass beds, coral reefs may serve as nurseries for juvenile marine organisms but are also foraging, mating grounds, and shelter for mature organisms. Coral reef ecosystems also support a variety of human needs and uses including fisheries, tourism, shoreline protection, and medicines and also have local cultural and spiritual value.
Threats to coral reefs include warm water temperatures that lead to coral bleaching, coral disease, ocean acidification, land-based sediments and pollutants, marine-based toxins and hydrocarbons, overfishing, and physical damage from boats and anchors. The combination of these threats has led to high coral mortality in the Virgin Islands. Marine protected areas such as the St. Croix East End Marine Park and the St. Thomas East End Reserves help manage and protect coral reef ecosystems. Mooring buoys systems installed for boats prevent anchor damage to coral reefs. The recent development of the Virgin Island Reef Resilience Program plans to reduce or eliminate human impacts in the face of global climate change, while restoring degraded coral reef sites and recovering important coral reef species. The Nature Conservancy’s Coral Restoration Program in the USVI is actively working to restore degraded USVI reefs and help to recover the threatened Elkhorn and Staghorn coral species. These strategies will help to build the resilience of coral reefs so that they retain the many benefits that they provide to people and marine organisms alike.
Mangroves are salt-tolerant plants that grow along tropical and sub-tropical coasts. They require warm temperatures, calm near shore waters, and low-lying coastal land. Their unique structures serve several important roles in marine ecosystems. The dense root system, especially prevalent in the red mangroves, protects coral by filtering land-based sediment that would otherwise flow into the ocean and obstruct sunlight from reaching the coral. The roots also provide nutrient-rich detritus and protection for larvae and juvenile fish, resulting in an ideal fish and shellfish breeding ground and nursery. Mangrove trees are also home to various species of birds. Furthermore, mangroves are valuable to humans, especially in times of severe weather. The roots are able to absorb high levels of wave energy; and boaters often protect their boats by docking them within the mangroves. The mangroves also protect the land behind them from erosion and flooding.
The largest mangrove stand in the US Virgin Islands is located within the St. Thomas East End Reserves (STEER), a marine protected area on the southeast side of St. Thomas. This region, the Mangrove Lagoon-Benner Bay (MLBB), supports local tourism and is also a comercially important area for marine related business and has historically been a boating hub. The MLBB has been designated one of six Areas of Particular Concern on St. Thomas due to potential threats to the ecosystem from its location beneath the largest watershed on the island and proximity to the Bovoni landfill. Encroachment of human activity (e.g., development) often limits the mangrove extent, particularly along the northern edge of the mangrove lagoon. The mangrove delta in the Inner Mangrove Lagoon was altered during the construction of the Clinton Phipps racetrack leading to a channelization of the Turpentine Run drainage. This has both reduced the habitat extent of the mangroves in the northern portion of the Mangrove Lagoon and led to much of the sediment being delivered from the watershed down Turpentine Run and its tributaries, bypassing most of the mangroves and resulting in infilling of the Inner Lagoon. The western edge of the MLBB is below the Bovoni landfill and the mangroves along this shoreline often have debris caught within their prop roots. Leaching from the dump also has the possibility to influence the growth and productivity of the mangroves along this region of the Reserves. Both improper mooring to mangroves and derelict vessels moved during storms and hurricanes can damage the most shoreward portions of the mangrove stands within STEER and affect both the recovery of the mangroves and the extension of nursery and feeding habitat available for commercially and ecologically important species. Mangroves are protected by Virgin Islands law. The Virgin Islands Department of Planning and Natural Resources (DPNR) Division of Fish and Wildlife has installed a mooring system to protect mangroves from damage by boats when the area is used as a refuge during storms. Additionally DPNR Department of Environmental Enforcement reduces marine debris that can damage mangroves removing derelict vessels. These strategies have been put in place to protect and conserve mangroves well into the future. Image Provided by “For the Sea Productions”
Marine Debris includes discarded trash and plastic; derelict vessels, mooring and docking materials; monofilament fishing line; etc. Marine debris, which has accumulated over decades of periodic hurricane events and illicit activity, poses substantial ecosystem-wide threat to species and nursery habitat through the leaching of chemicals, entanglement, and asphyxiation. Marine-based sources of pollution have been identified in the Management Plan of the St. Thomas East End Reserves as a significant threat to coastal resources including coral reef communities, seagrass beds, mangrove stands and sea and shore birds.
Efforts to reduce marine debris include beach cleanups that are conducted regularly by a variety of organizations throughout the Territory. Additionally the Virgin Islands Department of Planning and Natural Resources Division of Environmental Enforcement reduces marine debris by removing derelict vessels and docking materials. Campaigns to encourage fishers not to cut their lines have also been initiated to reduce monofilament entanglement of sea birds. Efforts to reduce and eliminate marine debris make our islands beautiful and reduce the detrimental impacts to natural resources.
Lionfish, The Beautiful Outlaw
Seagrass beds are most prevalent in lagoon areas and play an integral role in the well-being of a marine ecosystem. Seagrass beds trap and stabilize sediment, resulting in better water clarity and light penetration that are necessary conditions for coral reefs to flourish. The extensive root system of seagrass beds limits erosion by holding the sand substrate together, preventing extensive shifting of sand during storms. Seagrass also provides important habitat and refuge from predators for juvenile reef fish. Furthermore, green sea turtles, several herbivorous fish, echinoderms, mollusks, and birds feed on the seagrass.
The major threat to seagrass beds is direct physical damage or disturbance done by boat anchoring in seagrass habitat and to a lesser degree by prop scarring by boats in the shallow waters of the Reserves. Anchoring within seagrass beds in particular can cause extensive damage by creating ‘blowout’ holes that can migrate and expand after the initial disturbance, taking years to recover. Coastal development can also have a major impact on nearshore eelgrass beds, especially the construction of docks and marinas that project into the shallow waters and shade any seagrass present. Activities that can alter water quality conditions are another major threat to seagrass habitats. The changes in water clarity and nutrients can favor macroalgal and epiphytic growth that reduces seagrass cover.
The St. Thomas East End Reserves (STEER), a marine protected area on the southeastern side of St. Thomas, contains extensive seagrass beds. A mooring system for boats was installed by the Virgin Islands Department of Planning and Natural Resources Division of Fish and Wildlife in Christmas Cove to protect seagrass from improper anchoring. Boat owners can avoid damage to seagrass by using established mooring balls, anchoring in sand patches and ensuring that anchors, hulls or propellers do not physically scar seagrass. These strategies have been developed to protect and conserve seagrasses.