By: Staff Writer
May 3, 2022
A senior Caribbean marine scientist said that the dying off of the long-spined sea urchin (Diadema antillarum/Diadema) and the re-emergence of the Sargassum needs to be more closely evaluated to see if there are any links between both phenomena, but when added to the stony coral tissue disease these amount to a crisis in Caribbean waters.
Dr Krista Sherman, senior scientist with the Perry Institute for Marine Science (PIMS) with responsibility for the fisheries research and conservation programme, told Caribbean Magazine Plus that the Diadema loss is shocking, but not new, because the same phenomenon happened in the early 1980’s where the Caribbean experienced a “massive die-off” in sea urchins off of their grazing areas.
Dr Sherman said: “The diadema, or long-spined sea urchin, is a really important grazers and it was one of the most important grazers that helped to keep coral reefs healthy. So they helped to control the amount of microalgae cover for the algae that’s growing on reefs.”
She continued, “In the early 1980s, they experienced a massive die off throughout the entire Caribbean and in some instances that’s lead to what we call like a phased shift and a lot of reefs that were formerly really healthy and had lots of coral cover, we started noticing more algae growth and sort of a phase shift to being more algal dominated reefs. So it made reefs more susceptible to being overgrown, because they lost that really important, grazer.”
The Diadema is the second most important groups of grazers on Caribbean reefs behind parrot fishes and surgeonfishes that have already been “heavily fished” in some parts of the Caribbean.
She added: “It’s taken a long time. So it’s been about 40 years since all of this happened. But early this year, there started to be reports around the Caribbean, starting with the US Virgin Islands that there were extensive die offs of this same sea urchin happening again. So it has raised the alarm and cause for concern, because right now we’re having another crisis with reefs with stony coral tissue loss disease.”
She further remarked that while the Diadema die off was first spotted in the US Virgin Islands, it does not mean that it was the epicentre as there have been massive die-offs smattered around the entire Caribbean and in some instances more significant than that in the USVI.
The Caribbean is now being hit with a triple whammy as the stony coral reef tissue disease is taking hold along with the diadema die-off, now an old problem is resurfacing with a vengeance, the Sargassum problem in the Eastern Caribbean.
Dr Sherman, who is based in The Bahamas, said about the Sargassum spread: “So far, we have managed to escape the same problem that a lot of the islands in the Eastern Caribbean have and I think that’s just to do with ocean circulation patterns. But it’s something that they’ve been grappling with since 2011 and some years it’s worse than others.
She added: “In the southern and eastern part of the Caribbean, they have huge volumes of Sargassum that are inundating the coastlines. It means their waters are losing lots of oxygen. You’re having fish kills that’s releasing lots of gases when they decompose. So there are health hazards as well.
“Obviously, it’s an eyesore, so not really great for tourism and its obviously impacting fisheries. So they’ve been working to deal with that as well and they’ve worked on developing a monitoring protocol. They have outlook bulletins that they report in forecast what the situation is going to look like for the next three months and people have come up with really innovative ways of utilizing all that excess Sargassum.”
She added: “Some people use them for fertilizers. That’s one of the things that people have used it for just to repurpose it. Then there are some people that are experimenting with other ways that Sargassum can be used to generate income. So it’s something that’s happening in the Caribbean, we haven’t had the problems that they have had yet. We don’t know if that is going to change in the future. But it’s something that we need to be able to prepare for, and to be able to respond to, should that problem arise here.”