Predators, good for other Bahamas reef fish

This 2017 video says about itself:

Inside the Struggle to Save an Endangered Grouper Species | National Geographic

Follow dedicated wildlife authorities in Belize as they strive to protect the endangered Nassau grouper.

From North Carolina State University in the USA:

Predators and hidey-holes are good for reef fish populations

October 1, 2019

New research highlights two factors that play a critical role in supporting reef fish populations and — ultimately — creating conditions that are more favorable for the growth of both coral reefs and seagrass.

“Previous work has shown mixed results on whether the presence of large predator species benefits reef fish populations, but we found that the presence of Nassau grouper (Epinephelus striatus) had an overall positive effect on fish abundance,” says Enie Hensel, a former Ph.D. student at North Carolina State University and lead author of a paper on the work. “We also found that habitat complexity benefits both fish abundance and species richness, likely because it gives fish a larger variety of places to shelter.” This is consistent with previous work.

“One of the surprises here was that the effect of predator presence on fish abundance was comparable to the effect of habitat complexity,” Hensel says.

To better understand the effect of these variables, researchers constructed 16 artificial “patch” reefs in shallow waters off the coast of Great Abaco Island in The Bahamas. Eight of the reefs consisted of cement-filled cinder blocks, mimicking degraded reefs with limited habitat complexity. The remaining eight reefs consisted of unfilled cinder blocks and branching pipe structures, mimicking the more complex physical environment of healthier reefs.

Once in place, the researchers waited for groupers to move in and claim the new reef territory. The groupers were large juveniles, ranging in size from 16-33 centimeters. The researchers then removed the groupers from four of the degraded reef sites and from four of the complex reef sites. Groupers that were removed were relocated to distant reefs.

Researchers monitored the sites for 60 days to ensure that the grouper-free reefs remained free of groupers. At the end of the 60 days, the researchers assessed the total number of fish at each reef site, as well as the total number of fish species at each site.

The differences were significant.

Fish abundance, or the total number of fish, was highest at sites that had both a resident grouper and complex habitat. Abundance at these sites ranged from 275 fish to more than 500 — which is remarkable given that each reef was less than a meter long in any direction. By comparison, sites that had simple structures and no grouper had fewer than 50 fish on average. Simple structures with predators had around 75 fish, while complex sites without grouper had around 100.

“We think the presence of the grouper drives away other predators, which benefits overall fish abundance,” Hensel says. “And a complex habitat offers niches of various sizes and shapes, which can shelter more and different kinds of fish than a degraded, simple habitat.”

The presence of grouper had little or no effect on species richness, or the number of different species present at each site. However, habitat complexity made a significant difference. Complex sites had 11-13 species, while degraded sites had around seven.

“We found that the sites with complex habitats and the presence of predators had fish populations that were actually larger than what we see at surrounding, similar-sized natural reefs,” Hensel says. “That’s because the natural reefs in the area are all degraded due to a variety of stressors.

“We also found that the presence of grouper on complex reefs led to a significant jump in the population of Tomtate grunts (Haemulon aurolineatum),” Hensel says. “That’s good news, because Tomtates are a species that provides a lot of ecosystem services, which would be good for creating conditions that are more amenable to both coral reef growth and seagrass growth.

“Currently, my colleagues and I are building from these findings in two directions. We’re measuring long-term community and ecosystem level responses to coral restoration or the reintroduction of structurally complex habitat; and we are also measuring long-term biological and physiological responses of fishes residing on restored reefs. For the latter, Haley Gambill, an undergraduate at NC State, is measuring changes in the age and growth of grunts.

“It’s also worth noting that this is an area that was hit hard by Hurricane Dorian. Because we’ve done so much reef population work in that area, I’m hoping to return to do some work that can help us understand how extreme weather events can affect these ecosystems.”

The work was done with support from the National Science Foundation under grants 0746164 and 1405198.

Hurricane Dorian, from Bahamas to USA

This 6 September 2019 NBC TV video from the USA says about itself:

Dorian Bears Down On South Carolina, Hundreds Of Thousands Without Power | NBC News

Hurricane Dorian is slamming the South Carolina coast, making its way to the Outer Banks of North Carolina. NBC News’ Molly Hunter reports from Myrtle Beach, SC, where hundreds of thousands of people are without power.

USA: Core of Hurricane Dorian barrels ashore in North Carolina with ‘Life-threatening’ impacts extending into Virginia: here.

From the World Socialist Web Site:

Death toll mounts in Bahamas as Hurricane Dorian lingers off Carolina coast

By a reporter

6 September 2019

Officials in the Bahamas said Thursday that the confirmed death toll had risen from seven to 20 and was expected to “increase significantly” as rescue crews and aid workers go further into the two islands, Grand Bahama and Abaco, that were the hardest hit by Hurricane Dorian.

Meanwhile the storm continues to cause damage along the southeast Atlantic coast of the United States, with flooding, high winds and occasional tornados reported in South Carolina, as well as a storm surge of 7-8 feet along both the South Carolina and North Carolina coasts.

The Bahamian government transported hundreds of police, marines and health care workers to the affected area Thursday, and they were joined by international support from the Red Cross, the United Nations, the US Coast Guard and the British Navy.

The biggest single need was for emergency shelter, because nearly every home on the two islands has been damaged and many are smashed to splinters. Grand Bahama was the second most populous of the island chain and Abaco was the third most populous, with a combined total of about 73,000.

The Bahamas have a total population of 400,000, with more than 70 percent living in Nassau, the capital and largest city, which was well south of the route taken by Dorian through the island chain.

Dorian is the strongest hurricane to make landfall from the Atlantic since 1935, with Category 5 winds of 185 miles per hour and wind gusts of up to 220 miles per hour. The storm virtually came to a stop when it reached Grand Bahama Sunday, its eyewall, where the strongest winds are located, stalling over the island for 38 hours.

Meteorologists said that there is no comparable instance in recorded history of wind and rain of such intensity and duration combined at a single location. The barometric pressure of 910 millibars is lower (more intense) than that recorded by Hurricane Andrew, which laid waste to south Florida in 1992.

There is little doubt that the growing frequency of the strongest hurricanes—at least one category 5 storm in each of the last four years, an unprecedented streak—is powered by global warming. Water temperatures are 1 degree Celsius higher in the ocean region where Dorian originated. Climate change is also believed to be linked to the tendency of such large storms to stall in place, thus increasing the damage they can cause to a particular location.

As much as half of the land surface of Grand Bahama is still covered by water, from the combination of endless rain and storm surge. According to press reports, the island’s airport is destroyed, the only public hospital is damaged, the two main supermarkets in Freeport, a city of 25,000, are under water, as are the warehouses that supply them.

Grand Bahama had a population of 52,000 before the storm, and only three deaths have been confirmed, but more than half the housing on the island has been smashed to pieces. There is every likelihood that there are many bodies still to be recovered.

Long lists of missing persons—one with more than 5,500 names—have been uploaded to social media sites established to allow survivors to make connection with displaced family or friends.

On Abaco, the airport remains under water, the Haitian refugee shantyown at The Mudd has been obliterated, and many parts of the island look, in aerial photos, like debris fields from saturation bombing.

Survivors told harrowing stories to the media about fleeing the 25-foot storm surge that swamped homes up into their second storeys, and seeing windows, doors and even walls explode from the force of the powerful winds.

They used words like “total devastation,” “apocalyptic,” “generational,” “decimation,” while maintaining that these were completely inadequate to describe the damage.

The first private ships loaded with relief supplies were expected to leave Nassau Friday for the two islands. They will have difficulty unloading because harbor facilities were heavily damaged and the waters at Marsh Harbour and Freeport are filled with debris.

Property damage in the Bahamas was estimated at $7 billion, not including infrastructure, which is a total loss on both islands, and automobiles and boats, many of which were thrown hundreds of yards by the force of the storm.

In the face of such need, the amounts of aid promised by the main imperialist powers with ties to the country, the United States, only 50 miles away at some points, and Great Britain, the former colonial ruler, are a drop in the bucket.

Dorian is also causing extensive damage in Florida, Georgia, South Carolina and North Carolina, although it has stayed offshore about 50-60 miles, and its wind velocity has dropped to 115 miles per hour near the eyewall, and 7 5 miles per hour at the shoreline.

The National Weather Service warned of rainfall rates reaching three inches per hour with “widespread flash flooding, some of which may be significant” along the coast of South Carolina

About 225,000 customers were without power in the Carolinas and Georgia, with Duke Energy, the main private utility, projecting 700,000 customers without power by the time the hurricane passed through.

On Thursday the hurricane pushed up the Georgia and South Carolina coast and reached Wilmington, North Carolina by the evening. It was expected to pound the southeast portion of North Carolina on Friday, including the Outer Banks, before continuing northeast into the open sea.

Virginia Governor Ralph Northam declared an emergency in anticipation of the storm affecting the Norfolk-Virginia Beach area, likely its last point of contact with the US before it passes northeast into the open Atlantic. It may eventually make landfall in several days in the Atlantic Provinces of Canada, although it would be a much weaker storm by then.

Hurricane Dorian, Bahamas death toll at 20

This 4 September 2019 video, about Hurricane Dorian, says about itself:

The death toll in Abaco, in the Bahamas, has risen to 7 according to Prime Minister @minnis_dr who provided an update late Tuesday.

DORIAN WREAKS ‘APOCALYPTIC’ DEVASTATION Relief officials reported scenes of utter ruin in parts of the Bahamas and rushed to deal with an unfolding humanitarian crisis in the wake of Hurricane Dorian, the most powerful storm on record ever to hit the islands. At least seven deaths were reported, with the full scope of the disaster still unknown. [AP]

HURRICANE DORIAN STRENGTHENS The devastation wrought by Dorian in the Bahamas came into focus as the passing of the strongest hurricane on record revealed a muddy, debris-strewn landscape of smashed and flooded-out homes on Abaco and Grand Bahama islands. The official death toll jumped to 20, and looks likely to climb. Now a Category 3, Dorian is pushing its way up the U.S. Southeastern coast. [AP]

TRUMP’S HURRICANE MAP FIASCO It’s well known that Trump doesn’t like to admit he’s wrong, but somebody may have gone to extreme lengths to protect his ego. During a hurricane briefing, the president showed a Sharpie-altered weather map suggesting Dorian was previously on track to hit Alabama, which it wasn’t. [HuffPost]


Hurricane Dorian destruction on Bahamas

This 1 September 2018 video is called Bahamas feeling the wrath of Hurricane Dorian.

Translated from Dutch NOS TV today:

Dorian ashore at Bahamas as a very heavy hurricane

Hurricane Dorian went ashore as a very heavy hurricane, with category 5, in the Bahamas. Dorian reached the mainland with wind speeds of 285 kilometers per hour. The hurricane is expected to cause high waves, strong gusts of wind and a lot of rain on the islands in the coming two days.

According to residents of the islands, trees have been blown down and quays destroyed. A meter of rain may fall in some places in the coming days.

Residents of the Bahamas have withdrawn to schools, churches and specially designed shelters. People who fail to get to safety may experience “catastrophic” consequences, the prime minister warned today. Almost all tourists have left.

After passing the Bahamas, Dorian is expected to bend north and continue his journey along the Atlantic coast.

Life threatening circumstances

The US authorities have issued mandatory evacuations for parts of Florida. These apply to the residents of peninsulas, people in low-lying areas and those who live in a caravan.

The National Hurricane Center has warned of “life-threatening conditions”. In Florida, Georgia, and North and South Carolina, residents prepare by depositing sandbags.

It is unclear whether the hurricane will actually land in Florida: it is also possible that the storm will linger above the sea and then skim along the coast.

5 DEAD AFTER DORIAN DEVASTATION Bahamas Prime Minister Hubert Minnis says at least five people have died in the Abaco Islands as Hurricane Dorian continues to pound the region as a Category 4 storm. Minnis added that rescue crews will respond to calls for help as soon as weather conditions allow. [AP]

Extinct Bahamas caracaras, new DNA research

This 2017 video from Florida in the USA says about itself:

The gods of birding and photography were with me on this day. I stopped to capture some shots of a Crested Caracara Family feeding on a carcass in an open field. They were soon in competition with a Vulture and then a Bald Eagle. It was amazing to witness.

From the Florida Museum of Natural History:

Extinct Caribbean bird yields DNA after 2,500 years in watery grave

August 15, 2019

Scientists have recovered the first genetic data from an extinct bird in the Caribbean, thanks to the remarkably preserved bones of a Creighton’s caracara from a flooded sinkhole on Great Abaco Island.

Studies of ancient DNA from tropical birds have faced two formidable obstacles. Organic material quickly degrades when exposed to heat, light and oxygen. And birds’ lightweight, hollow bones break easily, accelerating the decay of the DNA within.

But the dark, oxygen-free depths of a 100-foot blue hole known as Sawmill Sink provided ideal preservation conditions for the bones of Caracara creightoni, a species of large carrion-eating falcon that disappeared soon after humans arrived in the Bahamas about 1,000 years ago.

Florida Museum of Natural History postdoctoral researcher Jessica Oswald extracted and sequenced genetic material from a 2,500-year-old C. creightoni femur from the blue hole. Because ancient DNA is often fragmented or missing, Oswald had modest expectations for what she would find — maybe one or two genes. But instead, the bone yielded 98.7% of the bird’s mitochondrial genome, the set of DNA that most living things inherit only from their mothers.

“I was super excited. I would have been happy to get that amount of coverage from a fresh specimen,” said Oswald, lead author of a study describing the work and also a postdoctoral researcher at the University of Nevada, Reno. “Getting DNA from an extinct bird in the tropics is significant because it hasn’t been successful in many cases or even tried.”

The mitochondrial genome showed that C. creightoni is closely related to the two remaining caracara species alive today: the crested caracara, Caracara cheriway, and the southern caracara, Caracara plancus. The three species last shared a common ancestor between 1.2 and 0.4 million years ago.

At least six species of caracara once cleaned carcasses and picked off small prey in the Caribbean. But the retreat of glaciers 15,000 years ago and the resulting rise in sea levels triggered extinctions of many birds, said David Steadman, Florida Museum curator of ornithology.

C. creightoni managed to survive the sweeping climatic changes, but the arrival of people on the islands ultimately heralded the species’ demise, as the tortoises, crocodiles, iguanas and rodents that the caracara depended on for food swiftly disappeared.

“This species would still be flying around if it weren’t for humans,” Steadman said. “We’re using ancient DNA to study what should be modern biodiversity.”

Today, the islands host only a fraction of the wildlife that once flourished in the scrubland, forests and water. But blue holes like Sawmill Sink can offer a portal into the past. Researchers have collected more than 10,000 fossils from the sinkhole, representing nearly 100 species, including crocodiles, tortoises, iguanas, snakes, bats and more than 60 species of birds.

Sawmill Sink’s rich store of fossils was discovered by cave diver Brian Kakuk in 2005 in his quest for horizontal passages in the limestone. The hole was not a popular diving spot: Thirty feet below the surface lay a 20-foot-thick layer of saturated hydrogen sulfide, an opaque mass that not only smells of rotten egg, but also reacts with the freshwater above it to form sulfuric acid, which causes severe chemical burns.

After multiple attempts, Kakuk, outfitted with a rebreather system and extra skin protection, punched through the hydrogen sulfide. His lamp lit up dozens of skulls and bones on the blue hole’s floor.

Soon after, Kakuk and fellow cave diver Nancy Albury began an organized diving program in Sawmill Sink.

“This was found by someone who recognized what it was and never moved anything until it was all done right,” Steadman said.

Though the hydrogen sulfide layer presented a foul problem for divers, it provided excellent insulation for the fossils below, blocking UV light and oxygen from reaching the lower layer of water. Among the crocodile skulls and tortoise shells were the C. creightoni bones, including an intact skull.

“For birds, having an entire head of an extinct species from a fossil site is pretty mind-blowing,” Oswald said. “Because all the material from the blue hole is beautifully preserved, we thought at least some DNA would probably be there.”

Since 2017, Oswald has been revitalizing the museum’s ancient DNA laboratory, testing methods and developing best practices for extracting and analyzing DNA from fossils and objects that are hundreds to millions of years old.

Ancient DNA is a challenging medium because it’s in the process of degradation. Sometimes only a minute quantity of an animal’s original DNA — or no DNA at all — remains after bacteria, fungi, light, oxygen, heat and other environmental factors have broken down an organism.

“With ancient DNA, you take what you can get and see what works,” Oswald said. “Every bone has been subjected to slightly different conditions, even relative to other ones from the same site.”

To maximize her chance of salvaging genetic material, Oswald cleans a bone, freezes it with liquid nitrogen and then pulverizes it into powder with a rubber mallet.

“It’s pretty fun,” she said.

While previous studies required large amounts of bone, Oswald’s caracara work showed ancient DNA could be successfully recovered at a smaller scale.

“This puts an exclamation point on what’s possible with ancient DNA,” said Robert Guralnick, Florida Museum curator of bioinformatics. “We have new techniques for looking at the context of evolution and extinction. Beyond the caracara, it’s cool that we have an ancient DNA lab that’s going to deliver ways to look at questions not only from the paleontological perspective, but also at the beginnings of a human-dominated planet.”

Steadman, who has spent decades researching modern and extinct biodiversity in the Caribbean, said some questions can only be answered with ancient DNA.

“By understanding species that weren’t able to withstand human presence, it helps us better appreciate what we have left — and not just appreciate it, but understand that when these species evolved, there were a lot more things running and flying around than we have today.”

Other co-authors are Julia Allen of the University of Nevada, Reno; Kelsey Witt of the University of California, Merced; Ryan Folk of the Florida Museum and Nancy Albury of the National Museum of the Bahamas.

Diver woman petting Bahamas sharks, video

This 29 March 2019 video says about itself:

Petting Sharks like Dogs?! | Blue Planet Live | BBC Earth

Cristina Zenato is the woman who isn’t afraid to hug sharks.

Cristina Zenato caresses her sharks in the warm Bahamas waters, the animals seem to like the suit’s touch on their skin and stop in her lap for a quick stroke.