Reef Collapse at Keepsake Dive Site, Klein Bonaire
Keepsake dive site at Klein Bonaire experienced an underwater collapse in January, 2017.
At Keepsake on the southern side of Klein Bonaire, a large section of the reef recently collapsed in an underwater landslide. On the morning of January 20th, 2017, STINAPA personnel investigated the site and made their assessment.
Precautions should be taken when diving and snorkeling at Keepsake.
The site is unstable and STINAPA advises that divers and snorkelers stay away from the area both to protect people as well as prevent further collapse of the reef.
Details of the underwater landslide.
The collapsed area is approximately 65″/20m southwest of the mooring buoy, starting at a depth of 40″/12m. The collapsed zone extends to a depth of at least 130″/40m. The total length of the collapsed zone is at least 100″/30m, if not longer. The width of the collapse is approximately 52″/16m near the top, and 92″/28m wide at a depth of 75″/23m, widening further at deeper depths.
Unfortunately, there were very few living corals left within the affected area. STINAPA personnel attempted to right a few toppled corals that remained, but deemed that the area was too unstable to work safely, as there is a risk of further reef collapse.
Reasons why reefs may collapse.
These types of reef collapses on steep slopes are a natural occurrence on such sloping reefs as at Keepsake, and they are most likely caused by reef bio-erosion. Living organisms such as sponges, worms, urchins and fish break down coral structures by boring, drilling, rasping and scraping the reef. There is speculation that sound waves from large passing ships may exacerbate this reef instability and trigger the collapse. However, there is no evidence to support this claim at the moment. Another attributing factor could be a 4.8 magnitude earthquake that occurred east of the ABCs on December 28th, 2016 at a depth of .27 mile/440m, which may have played a role in destabilizing the reef shelf. At the moment there is no singular, clear cause of this collapse.
Specific measurements of collapsed area.
The collapse begins at depths ranging from 40-43″/12 to 13m, and extends beyond 131″/40m. There is an outcrop of coral that divides the start of the collapsed zone; the northwest side is 20″/6m wide, the dividing coral ledge is 13″/4m wide, and the southeast side is also 20″/6m wide (these measurements were taken at a depth of between 42-46″/13 and 14m). STINAPA personnel measured the width of the collapsed area at 60″/18m where the collapsed zone was 85″/26m wide, and at 92″/28m where the collapsed zone was 75″/23m wide.
Once again, the reef at Keepsake dive site at Klein Bonaire is not considered stable at this time due to the collapse. For their own safety, as well as the reef area, it is recommended that divers and snorkelers avoid this dive site for the time-being.