Fast Moving Coral Disease Alert on Bonaire

[wind forecaster]

What would be more likely to spread Stony Corral disease, a diver or a parrot fish?

As a former marine biologist writing beyond my area of expertise, I would guess... Since gloves are not allowed on Bonaire the amount of pathogen spread by diver skin is probably tiny compared to Parrotfish coral sand excrement. But holding on to a living coral with your hand to a living coral is going to kill and damage hundreds of the living polyps and create an entry point for pathogens.

Stressors like temperature, soil runoff and ship pollutants and ocean warming increase vulnerability. Open water spread of a pathogen along island is probably a minor factor given the enormous dilution of the pathogenic spores. More likely the spread from coral to coral on a reef is by very local currents, grazing fish or divers.

We were at Something Special yesterday during the STINAPA survey and they are seeing continued spread of the disease. According to them Bonaire has not seen any long term water temperature changes in the the last decade.

I did notice lots of sponges covered with encrusting algae in the town area. So much algae that damselfish were actually defending the sponge algae crop. Again as a non-expert, I would guess this is due to runoff of household fertilizer from town. Which could be a disease stressor.

I am here on Bonaire for a month installing weather stations that will provide free information to divers, fishermen, windsurfers etc. With practice you can use such sensors to forecast local wind, swell and likely current in picking your dive location. In future months I will be writing blogs about this topic and will mention those on this board

Mike Godsey
weatherflow.com

 

[Hoyden]

I am sick about this for Bonaire, but I am afraid that this is the future for the entire area. Over the last few years Roatan, Honduras has been devastated by SCTL disease. It moves so fast. I didn't really notice it at all in Roatan in 2018. In 2019, maybe there was a little. We didn't go in 2020. In 2021, it was very noticable. In 2022, I cried on some dives. I saw no healthy pillar corals or brain corals at all. I am mostly a fish person and used to say that I only cared about corals because my fish needed them, but I was wrong. I think that if there is not some better solution (corals can be treated, but it is one at a time and in no way a real solution) the things that the dive tourism industry depends on will be gone. The fish populations reflected the loss of habitat and resources.

 

[Bernhelm]

Are they advising against all water activity in the affected area? (ie swimming, snorkeling in the shallows before getting to the reef, training, etc?)

 

[rmorgan]

There's solid evidence that SCTLD has moved from Florida to and throughout the Caribbean in the ballast water of vessels, as reported in the attached article from late 2022. I've read that "[t]he USDA reports that ballast water is 'one of the major pathways for the introduction of non-indigenous marine species,'" so this is not a novel proposition. This applies far more to cargo ships than cruise ships, of course--cruise ships never have cavernous empty holds. And it's not plausible to think that all vessels honor the requirements relating to discharge of ballast water well offshore of any ports. Also, dozens (hundreds?) of vessels from the Virgins and other islands in the hurricane belt relocate to Bonaire every year; given the savagery of SCTLD's takeover of those islands, perhaps it was transported that way.
These theories certainly mesh well with SCTLD first appearing on Bonaire close to where the ships--both cargo and cruise--tie up. But one of my pandemic pursuits was watching the progress of SCTLD around Grand Cayman. It started off of Rum Point, which is far from the port, and worked its way around the island in both directions. the port was actually one of the last places to be infected. So--who knows. An outlaw ballast-tank discharge at Rum Point? No doubt it happens.

But however it came to Grand, there was good real-time information of how it spread. It was first identified in early Summer 2020. By September 2020, it was like this:

And by November 2021--fewer than 18 months after the initial identification--it was like this:

This is not surprising, since the disease was found to progress at about 100m per day in the Florida Reef Tract. The same study reported that progression seemed to be consistent with local bottom currents, and in this respect, at least, perhaps the mild currents of Bonaire gives it bit of an edge. The finding that once in the waters of a given island, progression is consistent with currents on the floor, seems to support the measures STINAPA has put into place. But Grand Cayman closed 45 dive sites entirely in late 2020; the results seem to point more to the currents than the divers.

 

[scubadada]

Coral diseases are often caused by a combination of nonbiological and biological factors. I would imagine that SCTLD will follow that pattern. Most recent biological research reveals a rather complex, polymicrobial change in the coral microbiome rather than infection with a single identifiable pathogen.

In the article provided by @rmorgan, the laboratory transmission of SCTLD by infected water (treated or untreated with UV) or by direct contact is very interesting. However, I have not seen that SCTLD has been transmitted by actual ballast water. I welcome correction if I am wrong. It makes intuitive sense that ballast water taken on in a location with SCTLD would be at risk for containing potential pathogens.

Effective treatment of ballast water to prevent disease transmission would seem to be important area for additional research. The UV treatment, as performed in the above study, was not fully successful. Filtration, chemical disinfection, ultraviolet light, deoxygenation and heat are all used in ballast water treatment.

 

[rmorgan]

Roger that, Scubadada. I haven't seen anything identifying SCTLD in actual ballast water, or identifying ballast water as the source of transmission. Let's hope they figure it out before it manifests in the Pacific.

 

[Charred]

Based on the pictures, Cozumel went through this a few years ago. Its sad to see. Cozumel closed whole dive sites on a whim to try to stop it. It didn't. It was very fast moving and wiped out those impacted corals in a year. This year next time people will say Bonaire is much improved since there will be no more white spots but in reality all those susceptible corals will be dead and covered with some kind of new growth.

Instead of being sad, I remind myself all those corals are growling on coral skeleton. Plus Cozumel now has little baby ones growing

 

[rmorgan]

Ellen Muller, who many of you know to be a gifted and devoted photographer and marine scientist specializing in Bonaire's underwater magnificence, created a gallery of images which demonstrate the horrific speed with which SCTLD is attacking the hard corals on the island. Hard to see but important to understand, I think. Coral Disease by Ellen Muller

 

[scubadada]

Hi @rmorgan

Thanks for the post. I may have missed it, has this been confirmed as SCTLD, certainly looks like it. If so, looks like Something Special should be moved from caution to infected. This is just south of Front Porch, Bari Reef and Buddy's.

I can't seem to find updated information, have their been additional changes in diving recommendations or practices?

Very sad.

 

[rmorgan]

@scubadada I don’t think there’s any doubt about what it is, but as far as I know, there is not a definitive diagnostic test. Ellen’s pictures are dated and show progression on specific colonies—it’s dispiriting, to say the least, how fast the progression is over just a few days, which is certainly characteristic. Some of them also show the coral head actually blackening in the grooves as they die, unlike a bleaching event (which anyway would not occur in the relatively-cool water temps of late). Oh, Bonaire . . .