Sweeper's Knoll: a demonstration of coral restoration
In 2019, the East End Marine Park, supported by The Nature Conservancy, established a restoration site in waters adjacent to Cramer's Park
The Caribbean is known for its turquoise blue sea, white sand beaches and colorful marine life which draw thousands of visitors every year to enjoy the beach, swim, sail, and scuba dive these waters.
But below the calm surface, the coral reefs in the USVI , and reefs worldwide, are facing a multitude of threats such as coral bleaching, overfishing pressures, nutrient run-off and coral-specific diseases. Currently, the most acute threat facing our local reefs is Stony Coral Tissue Loss Disease (SCTLD). SCTLD eats away at the tissue of the coral colony causing a 95% mortality rate if left untreated. Coral restoration efforts are ramping up world-wide in the face of these challenges.
The St. Croix East End Marine Park (STXEEMP) demonstration coral nursery was installed in March of 2019. This project was made possible through partnerships between DPNR’s Division of Coastal Zone Management and The Nature Conservancy (TNC), both supported by NOAA’s Coral Reef Conservation Program .
The site showcases, on a small scale, reef restoration efforts taking place in the Virgin Islands. The coral nursery is near a small patch reef, known as Sweeper’s Knoll, which rises from the seagrass meadows near Cramer’s Park. The nursery site is comprised of small structures that have been stocked with fragments of a variety of coral species. As coral fragments outgrow the table they are transplanted onto the adjacent reef.
The fragments are obtained by partners such as TNC and originate as fragments of opportunity (loose corals that have broken off due to storm events, groundings, etc.). The fragments may go directly on to the reef, on to a nursery structure, or be transferred to a land-based facility such as TNC’s Coral Innovation Hub in Estate Little Princess on St. Croix. All work is conducted under the necessary scientific permits.
A large Orbicella annularis anchors the southeast corner of the patch reef. The Glassy Sweeper fish for whom the reef is named live behind this magnificent coral head.
Here, three divers maintain the table by cleaning the algae which grows on it, and competes with coral for space.
In 2021, two undergraduate students from the University of the Virgin Islands , through the National Science Foundation-funded SEAS Islands Alliance program, helped the Park collect and summarize data on the condition and success of outplants at Sweeper's Knoll.
They found that of 66 outplants transferred to the reef since 2019, 97% have survived. The corals represent 8 species and 82% of the individuals range between 5 and 40 centimeters at their widest measurement.
The metrics they measured will be entered into the worldwide database maintained by the Coral Restoration Consortium .
In addition, a smartbuoy, which measures temperature, wind and wave conditions is also reporting data to a worldwide network of these buoys. Explore more at Aqualink.org or see data from this buoy at Sweeper's Knoll .
In this photo is an outplanted (2019) Acropora palmata with scale bar. Each colored increment is 10 cm.
The Cramer’s Park coral nursery is managed and maintained by East End Marine Park staff (DPNR-CZM) and volunteers. The Park also offers a quarterly nursery tour (check here or call the Park for dates!) which allows participants to learn more about the restoration efforts taking place, glimpse the progress made on the adjacent reef and experience some of the wildlife that inhabit the surrounding area. If you are a certified diver, ask about ways to get involved in monthly maintenance-watch this video made by our partners at Triton's Realm , to learn more!
Getting to the nursery requires a relatively short swim (0.15 mi) through open water conditions, thus participants are required to wear snorkel vests (either provided or personal) and must be ages 14 and up. Competent swimmers wishing to visit the site on their own can also stop by the Park’s Great Pond office for instructions. For more information regarding the coral nursery tour or other Marine Park educational events please contact Kelcie Troutman STXEEMP Environmental Outreach Coordinator at kelcie.troutman@dpnr.vi.gov or (340) 718-3367.
Come and experience a corner of St. Croix you haven't seen before!
