Tag Archives: caribbean

Kick-‘em-Jenny: Scientists get rare chance to study volcano as it’s erupting

A team of British researchers chanced upon something unexpected as they were carrying out a marine survey: an erupting underwater volcano. Their new study helps shed new light on underwater volcanoes, which are notoriously difficult to study.

Bathymetric map from the survey. Image credits: Imperial College London

Aboard the research ship R.R.S. James Cook, scientists from several UK universities, in collaboration with The University of the West Indies Seismic Research Centre, were collecting ocean-bottom seismometers, as part of a larger research project — when they got an alarm message. The culprit was an underwater volcano called ‘Kick ’em Jenny’, one of the Caribbean’s most active volcanoes.

Normally, when you’d hear that a volcano was erupting nearby, you’d want to get as far away as possible from it. But when you’re an Earth scientist aboard a research vessel, you might want to do the opposite: get as close as is safely possible.

Direct observations of submarine eruptions are extremely rare, but since the scientists were already nearby, they were able to get close enough to the volcano to record the immediate aftermath of the eruption, including the gas coming out of the central cone.

Survey of the cone with gas venting in April 2017. Image credits: Imperial College London.

It wasn’t the first time the volcano had been surveyed, but it was the first time one of its eruptions was imaged directly. Lead author and PhD student Robert Allen, from the Department of Earth Science & Engineering at Imperial College in London, said:

“There are surveys of the Kick-‘em-Jenny area going back 30 years, but our survey in April 2017 is unique in that it immediately followed an eruption. This gave us unprecedented data on what this volcanic activity actually looks like, rather than relying on interpreting seismic signals.”

The volcano has erupted on at least twelve occasions between 1939 and 2001 and it’s still quite active. The team found that Kick-’em-Jenny (a reference to the rough waters in the area) goes through a cycle of lava ‘dome’ growth, followed by landslides which trigger a collapse. A similar cycle has been observed with other volcanoes in the Caribbean, for instance on the island of Montserrat.

If a volcano as active as Kick-‘em-Jenny was on land, it would have been studied and monitored in great detail. But since it’s underwater, and thus both less dangerous and more difficult to study, geologists know far less about it than they’d like to. However, this study can also improve monitoring techniques to be used in the future. Co-author Dr. Jenny Collier, from the Department of Earth Science & Engineering at Imperial, concludes:

“Kick-‘em-Jenny is a very active volcano but because it is submarine is less well studied than other volcanoes in the Caribbean. Our research shows that whilst it has quite regular cycles, it is on a relatively small scale, which will help inform future monitoring strategies.”

The study has been published today in Geochemistry, Geophysics, Geosystems.

Scientists analyze 300 year old DNA from Caribbean slaves

Three hundred years ago, three African-born slaves from the Caribbean suffered a sad fate. No one knew who they are, no one knew what they went through, and until recently, no one knew where they came from. Now, researchers extracted and sequenced tiny bits of DNA to figure out where in Africa these people came from when they were captured and enslaved.

Image via MLK Task Force.

“Through the barbarism of the middle passage, millions of people were forcibly removed form Africa and brought to the Americas,” said Carlos Bustamante, one of the researchers, in a news release. “We have long sought to use DNA to understand who they were, where they came from and who, today, shares DNA with those people taken aboard the ships. This project has taught us that we cannot only get ancient DNA from tropical samples, but that we can reliably identify their ancestry. This is incredibly exciting to us and opens the door to reclaiming history that is of such importance.”

Indeed, it’s estimated that roughly 12 million people shipped from West and West Central Africa to the New World between 1500 and 1850, and very little else is known about the origin of these people. Hannes Schroeder, one of the study authors said:

“What’s new about our study is that we were able to obtain genome-wide data from really poorly-preserved skeletal remains using this new technique called whole genome capture. Those remains had essentially been lying on a Caribbean beach for hundreds of years so their preservation was really not good. But by enriching the poorly preserved DNA in those samples we were able to obtain enough data to be able to dig deeper into the genetic origins of those three individuals we analyzed.”

They used a technique called whole-genome capture to isolate enough ancient DNA to properly sequence and analyze – quite a challenging task, as the DNA was in a pretty bad state. They found that one of the former slaves had likely belonged to a Bantu-speaking group in northern Cameroon. The other two shared similarities with non-Bantu-speaking groups in present-day Nigeria and Ghana. All three of them were from between the ages of 25 to 40 years and lived sometime in the late 1600s.

“We were able to determine that, despite the fact that the three individuals were found at the same site, and may even have arrived on the same ship, they had genetic affinities to different populations within Africa,” said Maria Avila-Arcos, one of the researchers, in a news release. “They may have spoken different languages, making communication difficult. This makes us reflect on two things: the dynamics of the trans-Atlantic slave trade within Africa, and how this dramatic, ethnic mingling may have influenced communities and identities in the Americas.”

Journal Reference: Hannes Schroeder et al. Genome-wide ancestry of 17th-century enslaved Africans from the Caribbean. doi: 10.1073/pnas.1421784112

 

Caribbean Coral Reef

Only one sixth of the original Caribbean corals remain, but damage can be reversed

Caribbean Coral Reef

Photo: The Guardian

It’s estimated that only a sixth of the original coral reef that covered the Caribbean waters is still alive today, according to a recent report released by the Global Coral Reef Monitoring Network (GCRMN), the International Union for Conservation of Nature (IUCN) and the United Nations Environment Programme (UNEP). If no major interference occurs, most of the coral in the Caribbean might disappear in the next 20 years. There are some good news, too. The damage done so far can be reversed, if certain steps are made.

Titled “Status and Trends of Caribbean Coral Reefs: 1970-2012” (full PDF), the report is the result of three years worth of painstaking work that involved over 90 experts who studied more than 35,000 surveys conducted at 90 Caribbean locations since 1970, including studies of corals, seaweeds, grazing sea urchins and fish. Numerous insights that were missed until now have surfaced. For instance, we now know the Caribbean corals have declined by more than 50% since the 1970s.

There are a lot of voices who claim that this immense rate of degradation is mostly due to climate change. Most of the greenhouse gases released by human activity into the atmosphere eventually wind up into the world’s oceans, which act like huge heat sinks. This causes the waters to acidify and the corals to bleach. The report’s findings suggest that its not climate changer per se that is driving most of the coral fallout, rather an ecosystem destabilization. Namely, the loss of parrotfish and sea urchin – the area’s two main grazers – has, in fact, been the key driver of coral decline in the region.

“Even if we could somehow make climate change disappear tomorrow, these reefs would continue their decline,” says Jeremy Jackson, lead author of the report and IUCN’s senior advisor on coral reefs. “We must immediately address the grazing problem for the reefs to stand any chance of surviving future climate shifts.”

These two species are paramount if coral colonies are to thrive, as they feed on algae, clearing the ground so the reef doesn’t get smothered by the algae. But . An unidentified disease led to a mass mortality of the sea urchin in 1983, while extreme fishing throughout the 20th century has brought the parrotfish population to the brink of extinction. Protecting these species from overfishing, as well as pollution, tourism or coastal development will greatly improve reef quality and colony numbers.

parrot_fish

A parrot fish a coral. Photo: bugbog

The report also shows that some of the healthiest Caribbean coral reefs are those that harbour vigorous populations of grazing parrotfish. These include the Flower Garden Banks National Marine Sanctuary in the northern Gulf of Mexico, Bermuda and Bonaire, all of which have restricted or banned fishing practices that harm parrotfish, such as fish traps and spearfishing. Other countries are following suit. On the down side, reef that haven’t been protected suffered tragic declines, including Jamaica, the entire Florida Reef Tract from Miami to Key West, and the U.S. Virgin Islands.

“Barbuda is about to ban all catches of parrotfish and grazing sea urchins, and set aside one-third of its coastal waters as marine reserves,” says Ayana Johnson of the Waitt Institute’s Blue Halo Initiative which is collaborating with Barbuda in the development of its new management plan. “This is the kind of aggressive management that needs to be replicated regionally if we are going to increase the resilience of Caribbean reefs.”