Geology topics

Research about St. John

Source-linked reports with geographic coverage including St. John.

4 recordsLinked to original sources

USGS2024

Pathology of lesions in corals from the US Virgin Islands after emergence of stony coral tissue loss disease

Stony coral tissue loss disease (SCTLD) was first documented in Florida in 2014 and has since spread through the Caribbean causing unprecedented mortality in more than 20 species of corals. The cause of SCTLD is unknown, but bacteria are suspected based on regression of gross lesions in some corals treated with antibiotics. Limited pathology studies on SCTLD exist, but it is likely that ‘SCTLD’ is a general term encompassing tissue loss disease of unexplained origin. Here, we examined pathology of lesions in corals from the US Virgin Islands where SCTLD has recently emerged. The typical histologic lesion of SCTLD in Florida corals was lytic necrosis comprising vacuolation and necrosis of mucus cells with erosion of mesoglea and misshapen endosymbionts with variably sized intracytoplasmic granules and common occurrence of filamentous viral-like particles in endosymbionts visible on electron microscopy (EM). In contrast, USVI corals had mainly lytic mucus cell hypertrophy and necrosis with no involvement of mesoglea, endosymbiont pathology at the light microscopy level was less evident, and VLP were rarely seen on EM. We suspect SCTLD is likely more complex with multiple presentations and potential etiologies depending on geographic region. Further pathological studies from other regions might help refine the case definition of SCTLD.

St. John↗

USGS2013

Early signs of recovery of Acropora palmata in St. John, US Virgin Islands

Since the 1980s, diseases have caused significant declines in the population of the threatened Caribbean coral Acropora palmata . Yet it is largely unknown whether the population densities have recovered from these declines and whether there have been any recent shifts in size-frequency distributions toward large colonies. It is also unknown whether colony size influences the risk of disease infection, the most common stressor affecting this species. To address these unknowns, we examined A. palmata colonies at ten sites around St. John, US Virgin Islands, in 2004 and 2010. The prevalence of white-pox disease was highly variable among sites, ranging from 0 to 53 %, and this disease preferentially targeted large colonies. We found that colony density did not significantly change over the 6-year period, although six out of ten sites showed higher densities through time. The size-frequency distributions of coral colonies at all sites were positively skewed in both 2004 and 2010, however, most sites showed a temporal shift toward more large-sized colonies. This increase in large-sized colonies occurred despite the presence of white-pox disease, a severe bleaching event, and several storms. This study provides evidence of slow recovery of the A. palmata population around St. John despite the persistence of several stressors.

St. John↗

USGS2011

Data from in situ Observations of Fish Traps Set by Fishermen in St. John Waters, U.S. Virgin Islands, 1992-94

In order to estimate (1) the trapping pressure within Virgin Islands National Park (VINP) waters, (2) the effect of fish traps on park marine resources (both fishes and habitats), and (3) the effectiveness of park regulations in protecting marine resources, traps set by fishers were visually observed and contents censused in situ in 1992, 1993, and 1994, around St. John (U.S. Virgin Islands), within and outside of park waters. A total of 1,340 individual fish (56 species and 23 families) were identified and their lengths estimated for the 211 of 285 visually censused traps that contained fish. This dataset includes for each censused trap: location, depth, substrate/habitat, trap type and construction details, in or out of park waters, and species and estimated fork length (in centimeters) of each individual fish in a trap. Analysis and interpretation of this dataset are provided in previously published reports by the author.

St. John↗

USGS2009

High diversity and abundance of scleractinian corals growing on and near mangrove prop roots, St. John, US Virgin Islands

A narrow zone of red mangroves fringes the shorelines of four small bays in Hurricane Hole, within Virgin Islands Coral Reef National Monument (VICRNM) on St. John. In two of these bays, Otter Creek and Water Creek, a particularly high abundance and diversity of corals are growing directly on or near the prop roots (Fig. 1 a,b,c). To date, 28 coral species have been found: Stephanocoenia intersepta , Agaricia sp., Agaricia agaricites , Siderastrea siderea , S. radians , Porites porites , P. astreoides , P. furcata , P. divaricata , Favia fragum , Diploria strigosa , D. labyrinthiformis , D. clivosa , Manicina areolata , Colpophyllia natans , C. amaranthus , Montastraea annularis , M. faveolata , M. franksi , M. cavernosa , Oculina diffusa , Meandrina meandrites , Dendrogyra cylindrus , Scolymia cubensis , Mycetophyllia sp., Eusmilia fastigiata , Cladocora arbuscula , and Tubastrea coccinea . The size of many of the colonies, including some M. faveolata and C. natans colonies over 1 m across (Fig. 1 b), indicate that they survived the 2005/2006 bleaching and disease event that caused losses of over 60% of the coral cover on St. John reefs (Rogers et al. 2008 ). Shading by the mangroves possibly reduced the thermal and photic stress on these corals. The coral diversity in these mangroves may be higher than for other Caribbean mangrove systems. Few published papers include data on corals in these habitats. Two comprehensive reviews of the biology of mangroves make no reference to corals on or near prop roots (Kathiresan and Bingham 2001 ; Nagelkerken et al. 2008 ). The number of corals in Hurricane Hole, particularly the new recruits on the prop roots (Fig. 1 c), may have increased since the establishment of the VICRNM in 2001, as boaters are not permitted to overnight in these bays or to tie their boats to the mangrove trees as was done in the past.

St. John↗