Stony Coral Tissue Loss Disease on a species of coral.
PHILIPSBURG–St. Maarten Nature Foundation has been monitoring the impact of Stony Coral Tissue Loss Disease (SCTLD) on St. Maarten coral reefs in the last months to determine the current presence of the disease compared to data from March. The ongoing surveys indicate that the disease is still strongly impacting the coral colonies and most corals that became infected have either perished or are still showing visible signs of the disease, said the foundation.
The coral disease was first discovered on St. Maarten reefs in October 2019. Healthy-looking colonies of “highly susceptible species” such as the Meandrina, Dendrygya, Dichocoenia, Pseudodiploria, and Diploria genera have become very scarce on the reefs, said the foundation.
SCTLD is a relatively new issue that has been plaguing coral reefs in the Atlantic Basin for the last year. The disease manifests itself through the creation of white blotches on stony coral, eventually leading to the loss of tissue and eventual death in the coral colony.
The disease affects 20 different coral species and can kill entire colonies within several weeks.
In the last two months, the foundation found an average of 30 per cent infection rates of susceptible stony corals in the Marine Park’s “Man of War Shoal.” On coral reefs outside the Marine Protected Area, a lower average was found. There, about 20 per cent of susceptible corals species are currently diseased.
However, certain susceptible coral species show much higher disease rates, such as species from the genus Orbicella. About 50 per cent of these coral colonies are infected with SCTLD.
“The higher proportion of diseased Orbicella species in a later stage is the typical trend when tissue loss disease infects coral reefs, as these species take longer to pass away,” said the foundation in a press release.
“We found lower infection rates compared to previous surveys done in March this year. However, this does not mean that the disease [and – Ed.] its effects [have] decreased. Most coral colonies which were infected with the disease already died in the last months, leaving less diseased corals behind.
“During the recent surveys we hardly found any coral colonies from the species which are marked by experts as ‘highly susceptible’ to the disease, which indicates that these species already perished and have been overgrown by algae and other marine life.
“It is time that we panic about the health of our reefs, as coral reefs are of great importance to our tourist industry, the health of our fish stocks, clarity of our waters, and the protection from storms,” said St. Maarten Nature Foundation Manager Melanie Meijer zu Schlochtern.
The foundation used the Roving Diver methodology to establish the impact of SCTLD. During the research, scientific divers swam around designated sites, focusing on species that are primarily impacted by the disease outbreak. All stony coral species and their level of disease progression were recorded.
“This research provided insight in the order in which species are affected, the rate of spread of the disease, and the frequency across different coral reef sites,” said the foundation.
“The disease has been moving very fast on our coral reefs, affecting many corals in a short time period. Our coral reefs were already highly threatened due to pollution, wastewater and nutrient input, Hurricane Irma, and rising ocean temperatures. Wastewater, and even plastic presence, can easily decrease the resilience of our corals.
“The fast rate of this disease shows that our corals are more susceptible. Therefore, it is of high importance to keep our waters clean, ban single-use plastics, and … obstruct further sewage and pollution run-off in our waters,” said Meijer zu Schlochtern.
The disease may potentially be spread by diver gear, according the Florida Disease Advisory Committee. The committee advises divers in the Caribbean and Florida to soak their gear in a five-per-cent chlorine bleach solution for 30 minutes and to rinse well after, especially when moving between diving locations.
Nature Foundation reminds all divers to be vigilant to avoid spreading the disease. It also advises divers to be aware of their fins and to not touch any coral.
Source: The Daily Herald https://www.thedailyherald.sx/islands/91972-nature-foundation-coral-still-strongly-impacted-by-disease
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