New Irish research reveals the secret lives of tiger sharks

JUNE 7, 2019

by Thomas Deane, Trinity College Dublin

A team of scientists led by experts from Trinity and a US-based NGO have just returned from the Bahamas where they learned all about the secret lives of the region's tiger sharks.

Cutting-edge bio-logging devices fixed to the sharks are providing a suite of biological information that has never been collected before, which will help the team assess how the global climate crisis may impact these apex predators.

Tiger sharks are classified as 'near threatened' by the International Union for the Conservation of Nature, with commercial and artisanal fishing pressure and infrequent (once every three years) reproduction contributing to this status. Several countries continue to cull populations of tiger sharks given perceived risks to human swimmers, despite some regions having seen declines in shark abundance of ~ 75% in recent decades.

These huge (up to 5m in length) animals are found in tropical and sub-tropical oceans worldwide but have always been difficult to study given their aquatic lifestyle. The scientists involved in the current study got around this issue by using their biologging devices on the sharks—with sensors recording video, body temperature, swimming activity and orientation as the animals went about their normal routine.

By measuring how temperature influences the sharks' behaviour and swimming performance, the team will be better placed to predict how these animals will respond to future climate change.

Read more and watch video

Four new species of plume moths discovered in Bahamas

JUNE 7, 2019

by Natalie Van Hoose, Florida Museum of Natural History

Deborah Matthews hunts for plume moths in darkness, waiting for the halo of her headlamp to catch a brief flicker. About the size of mosquitoes, the delicate, feathery moths fly only a few feet at a time. Matthews must watch for that short flight while keeping clear of poisonwood, cracks in the limestone and sinkholes, common hazards of fieldwork in the Bahamas.

Her vigilance, deftness with a net and more than 30 years' experience working on plume moths and their host plants helped her discover four new species, bringing the number of known plume moth species on the islands to 23.

Plume moths are microlepidoptera, another name for tiny moths, and are understudied compared with larger, more charismatic species. But when Matthews, a biological scientist at the Florida Museum of Natural History, first joined a plume moth research project in 1987, she got hooked.

Read on

Ocean channel in Bahamas marks genetic divide in Brazilian free-tailed bats

Date: August 18, 2017

Source: Florida Museum of Natural History

Summary:

Brazilian free-tailed bats are expert flyers, capable of migrating hundreds of miles and regularly traveling more than 30 miles a night. But they pull up short at a narrow ocean channel that cuts across the Bahamas, dividing bat populations that last shared an ancestor hundreds of thousands of years ago.

Continued

Smuggled endangered iguanas fly back to the Bahamas

Twelve critically endangered San Salvador rock iguanas seized from smugglers at London’s Heathrow Airport have been returned home to the Bahamas.

The reptiles were discovered stuffed inside socks in the baggage of Romanian nationals Angla-Alina Bita, and Vitora-Oliva Bucsa by staff carrying out customs checks.

Following the seizure, officers from Border Force’s specialist CITES team worked with the Bahamas High Commission in London to arrange their return to their native islands.

They have been transported to a government research station on the island of San Salvador where they will be monitored by experts, with the eventual aim of retuning them to the wild.

Continued

Lemon Sharks Return to Their Birthplace to Have Babies

By Megan Gannon, News Editor | December 05, 2013 10:35am ET

Female lemon sharks in the Bahamas seem to "remember" the place where they were born and return to the spot after years of wandering to give birth to their own young, a new study found.

This kind of homing behavior has been observed in other aquatic animals — salmon famously swim upstream to get back to their own spawning grounds and sea turtles return to the nesting beaches where they were born. After years of speculation, the researchers say this is the first time it's been confirmed that shark moms-to-be also go back to their own nurseries.

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Key island in the Bahamas cleared of mice

Key breeding island for Audubon's Shearwaters & Iguanas cleared of invasive mice

July 2013. Allen Cay in the Bahamas, an important breeding site for Audubon's Shearwater and home of an eponymous endemic iguana, has been declared free of the invasive house mice which were threatening both species.

"This announcement is a major milestone for the recovery of Allen Cay, and we plan to replicate this success on other islands being damaged by invasive alien species," said Eric Carey, Executive Director of BirdLife Partner the Bahamas National Trust (BNT).

The cay was de-moused by a partnership including BNT, Island Conservation, Dr John Iverson of Earlham College, and Dr Will Mackin, Seabird Co-Chair of the Society for the Conservation and Study of Caribbean Birds.

Audubon's Shearwaters & Iguanas

Allen Cay is one of three cays in the Allen's Cays Important Bird and Biodiversity Area (IBA), in the northern Exuma Islands 60 km southeast of Nassau. The IBA supports the third largest breeding population of Audubon's Shearwaters in the Bahamas, as well as the Allen Cay Rock Iguana, which is listed as Endangered by the IUCN.

Barn owl invasion

The inadvertent introduction of non-native house mice led to an artificially high population of normally transient Barn owls, which stayed to eat the mice, but ate shearwaters and young iguanas too. The shearwater mortality rate was twice as high on Allen Cay as nearby cays without mice.

Beginning in 2009, the partners conducted extensive planning, field trials and public outreach. The Bahamas Ministry of Environment authorised the project in April 2012, and the mice were removed in the following month. In the first week of June 2013, the partners visited the Cay, confirmed the absence of mice, and noted early signs of a recovering island ecosystem. Preliminary findings suggest a significant drop in shearwater mortality.

Mouse removal is part of a larger effort to restore the natural environment of Allen Cay. To minimise the risk of mouse reintroduction, BNT will develop a biosecurity plan, and work with recreational boaters and fishers.

"Invasive species are the leading threat to the Caribbean's rich biodiversity", said David Wege, BirdLife's Caribbean Programme Director. "By building local partnerships and training practitioners in the region in invasive species removal techniques, we are increasing capacity for island restoration

http://www.wildlifeextra.com/go/news/bahamas-shaearwater.html

Endangered sharks return to Bahamas 'home'

By Ella Davies, Reporter, BBC Nature

Oceanic whitetip sharks return home to protected Bahamas waters, surprising scientists.

Previously thought to be wide-ranging animals, a tagging survey has revealed that the sharks frequently revisit the same areas around the island.

Conservationists have listed the sharks as Vulnerable globally and Critically Endangered in parts of their range.

Experts suggest that the island nation's marine protected area is assisting the species.

The findings are published in the online journal PLoS One.

Oceanic whitetips are named for the distinctive white flashes at the end of their fins.

They are opportunistic predators with powerful jaws and as such are considered one of the more dangerous sharks to humans, although the number of unprovoked attacks on people is small.

Continued: http://www.bbc.co.uk/nature/21497049

Bahamas shark station comes under attack - but the monster isn't Jaws, it's a foot-long woodlouse from 8,500ft down

When 'teeth marks' appeared in cables of an underwater camera system in the Bahamas and the camera cut out, the scientists in charge began to look around for a cuplrit. 

Edd Brooks of the Bahamas Cape Eleuthera Institute took a closer look at the cables and found that the teeth marks looked like a huge crustacean had gnawed on them. 

The truth was even stranger: they were under attack from a foot long undersea woodlouse. 

'There’s nothing else with mandibles that sharp,' says Brooks. 'It was a Bathynomus attack.'

The beast normally lives 8,500ft under water. Called the Bathynomus Giganteus, it is a super-sized cousin of the humble woodlouse.

Its legs are arranged in seven pairs, and its front two are able to manipulate and bring food to its four sets of jaws. 

It is a scavenger that feeds on dead whales, fish and shrimp.

Continued:  http://www.dailymail.co.uk/sciencetech/article-2156416/Bahamas-shark-station-comes-attack--monster-isnt-Jaws-foot-long-woodlouse-8-500ft-down.html#ixzz1xHojNcZy

Castaway Lizards Provide Insight Into Elusive Evolutionary Process, Founder Effects (via Herp Digest)

ScienceDaily (Feb. 2, 2012) 

A University of Rhode Island biologist who released lizards on tiny uninhabited islands in the Bahamas has shed light on the interaction between evolutionary 

Jason Kolbe, a URI assistant professor of biological sciences, and colleagues from Duke University, Harvard University and the University of California at Davis, found that the lizards' genetic and morphological traits were determined by both natural selection and a phenomenon called founder effects, which occur when species colonize new territory.

Their research was published recently in the journal Science.

"We rarely observe founder effects as they happen in nature, but we know that it happens because islands are colonized by new species over time," said Kolbe. "What we didn't know was how these evolutionary mechanisms interact with each other. What we learned is that the differences caused by the founder effects persist even as populations adapt to their new environments."

The founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It often results in the new population becoming genetically or morphologically different from the original population.

The scientists randomly collected brown anole lizards from a large island near Great Abaco and released one pair on each of seven nearby islands whose lizard populations had been cleared by a recent hurricane. The source island is forested while the other islands have short, scrub vegetation. 

Previous research found that anoles living in forests had longer hind limbs than those found in scrub habitat. Lizards with longer limbs can run faster on the broad perches available in forests, while short-limbed lizards are more adept at moving on the narrower perches found in lower vegetation.
The scientists revisited each of the islands over the next four years to measure the lizards' limb length and collect tissue samples for genetic analysis. All of the new populations survived and increased an average of 13-fold in the first two years before leveling off.

"We noticed a founder effect one year after starting the experiment, which resulted in differences among the lizards on the seven islands," Kolbe said. "Some of the islands had lizards with longer limbs and some had lizards with shorter limbs, but that was random with respect to the vegetation on the new islands."

Because the structure of the vegetation on the islands differed from that of the source island, the scientists predicted that natural selection would lead the lizards to develop shorter limbs.
"Over the next four years, the lizards on all the islands experienced a decrease in leg length that is attributable to natural selection," Kolbe explained. "But those that started out with the longest hind limbs still had the longest hind limbs. The fact that the populations maintained their order from longest to shortest limbs throughout the experiment means that both founder effects and natural selection contributed to their current differences."

According to Kolbe, founding effects are rarely observed in nature, with most previous studies being conducted in the laboratory. "Ours is the first to study this process experimentally in a natural setting, and we were able to account for multiple evolutionary mechanisms through time," he said. "We manipulated the founding of these islands, but everything else about it was natural."
The next step in the research will be to determine how long the founder effects persist before other factors erase its signature.

The study was funded by the National Science Foundation and the National Geographic Society.