A recent article (November 2022, attached) "confirms the potential for ship-born spread" of SCTLD in ship-ballast water. Cruise ships carry a lot less ballast water than cargo ships; I assume this is because their displacement is not radically altered by loading or offloading cargo. There are plenty of cargo and fuel ships coming into Bonaire, of course. I haven't found a reference for the number of cargo vessels or cruise ships which come to the island, but it seems quite likely that the greater volume of ballast water comes from cargo vessels.
One of my pandemic pursuits was watching with dismay as SCTLD moved around Grand Cayman. It started off of Rum Point in June 2020, and over the next few months it moved around the entire island, with Seven-Mile Beach succumbing last. The entire circumference of the island impacted by November 2021. Rum point is not at all close to the cargo and cruise-ship ports, which are not only well around the island from Rum Point, but are, in fact, quite close to Seven Mile Beach. Grand Cayman has about 400 cargo-vessel visits per year. (AGRRA has a SCTLD map here).
Cuba is not far from the Caymans. To date, there are no published reports of SCTLD in Cuban waters. While this could be related to a lack of information, there are recent reports and videos of healthy reefs on the south side of Cuba, and there are also no reports of SCTLD on either Little Cayman or Cayman Brac, which are ENE of Grand Cayman and SW of Cuba. The ocean currents prevail from the east. There are also many fewer ships--cargo or cruise--coming to Cuban ports, despite an enormously-greater population. (We are visiting Jardines de la Reina in January and will report first-hand).
This all suggests to me--and this is certainly stitching together a number of inferences--that SCTLD has perpahs moved from island to island in vessel ballast, mostly cargo ships, and then circulated around the islands through local currents, boats, and divers. An early study of the progress of the disease once established found that it was "spreading at about 100 meters per day to the north and about 92 meters per day to the south" in the Florida Reef Tract. That seems more like currents and boats than recreational users, but that's my conjecture.
There is so much left to learn. The large and growing cast of researchers has not yet nailed down whether SCTLD is viral, bacterial, or (as seems most likely) an opportunistic stew of both. Or the impact of ocean warming, which of course is known to weaken the resistance of corals to disease and so likely plays some role. Treatment methods are limited to treatment colony-by-colony once infection is detected. Fortunately, it has not yet been found off the east coasts of Nicaragua, Costa Rica or Panama, but work is already being done to evaluate the risk to Pacific corals.
Ugh.
One of my pandemic pursuits was watching with dismay as SCTLD moved around Grand Cayman. It started off of Rum Point in June 2020, and over the next few months it moved around the entire island, with Seven-Mile Beach succumbing last. The entire circumference of the island impacted by November 2021. Rum point is not at all close to the cargo and cruise-ship ports, which are not only well around the island from Rum Point, but are, in fact, quite close to Seven Mile Beach. Grand Cayman has about 400 cargo-vessel visits per year. (AGRRA has a SCTLD map here).
Cuba is not far from the Caymans. To date, there are no published reports of SCTLD in Cuban waters. While this could be related to a lack of information, there are recent reports and videos of healthy reefs on the south side of Cuba, and there are also no reports of SCTLD on either Little Cayman or Cayman Brac, which are ENE of Grand Cayman and SW of Cuba. The ocean currents prevail from the east. There are also many fewer ships--cargo or cruise--coming to Cuban ports, despite an enormously-greater population. (We are visiting Jardines de la Reina in January and will report first-hand).
This all suggests to me--and this is certainly stitching together a number of inferences--that SCTLD has perpahs moved from island to island in vessel ballast, mostly cargo ships, and then circulated around the islands through local currents, boats, and divers. An early study of the progress of the disease once established found that it was "spreading at about 100 meters per day to the north and about 92 meters per day to the south" in the Florida Reef Tract. That seems more like currents and boats than recreational users, but that's my conjecture.
There is so much left to learn. The large and growing cast of researchers has not yet nailed down whether SCTLD is viral, bacterial, or (as seems most likely) an opportunistic stew of both. Or the impact of ocean warming, which of course is known to weaken the resistance of corals to disease and so likely plays some role. Treatment methods are limited to treatment colony-by-colony once infection is detected. Fortunately, it has not yet been found off the east coasts of Nicaragua, Costa Rica or Panama, but work is already being done to evaluate the risk to Pacific corals.
Ugh.
