Disease

The Impact of Stony Coral Tissue Loss Disease on the Northern USVI

Stony coral tissue loss disease (SCTLD) is a rapidly spreading disease in the USVI that is causing dramatic loss of coral cover and declines in species diversity. SCTLD was first sighted in the US Virgin Islands in January 2019 at the Flat Cay TCRMP monitoring site. The disease was identified by its characteristic stony coral species-specific susceptibility characteristics. By March 2019 the disease had spread to the north side of St. Thomas and by January 2020 had spread eastward to the St. Thomas East End Reserves.

Numerous local teams at the University of the Virgin Islands, the Department Planning and Natural Resources, the National Park Service, the Caribbean Oceanic Restoration & Education (CORE) Foundation and The Nature Conservancy have been coordinating monitoring, research, and response with national collaborators, such as the Florida Department of Environmental Protection, Woods Hole Oceanographic Institution, University of Texas Arlington, Louisiana State University, Mote Marine Lab, Rice University, and the National Oceanic and Atmospheric Administration. Updated details concerning SCTLD can be found at the following website: https://www.vicoraldisease.org

Detailed early impacts at TCRMP sites can be found in the site descriptions of the 2020 TCRMP annual report and are covered in more detail by Brandt et al. 2021. Since the 2020 monitoring period, SCTLD has spread to eastern St. John and as far as St. Croix. As of the 2020 TCRMP annual report, 85% of TCRMP locations have become impacted and are experiencing losses in coral species and cover. Ginsburg Fringe, Coral Bay, Buck Island STX, Great Pond, and Jacks Bay had no recorded instances of SCTLD during the 2020 monitoring surveys. The locations most adversely affected by SCTLD include Kings Corner, Seahorse Cottage Shoal, and Flat Cay with relative coral cover losses of 64.6%, 62.6%, and 61.5%, respectively, since before SCTLD arrived.

Other accounts of SCTLD research in the territory can be found in Meiling et al. 2020, Costa et al. 2021, and Meiling et al. 2021.

Monitoring locations unaffected by SCTLD have experienced relatively little change in coral cover since Hurricanes Irma and Maria (2017) to present. During their initial infection with SCTLD (“Year 1”), monitoring locations lost on average 14.1 ± 7.6% and 17.3 ± 3.1% coral cover in 2019 and 2020, respectively, relative to pre-SCTLD monitoring in 2017. It is also noteworthy that longer affected locations (“Year 2”) continued to lose coral cover after the initial appearance of SCTLD, resulting in average losses of almost 50% relative to pre-SCTLD monitoring. Coral species richness followed a similar pattern with large losses in number of species following initial appearance in 2019 and 2020 relative to 2017. However, the relative loss in number of species decreased during the second year, as the most highly susceptible species were extirpated in the initial wave of SCTLD.