All posts by Jill Studholme

Edits SCUBA News (ISSN 1476-8011), the monthly newsletter with articles on diving and marine science. She tweets as @SCUBANews. You can find her on Google+ at

Sensor sniffs out methane in deep-sea vents and cows

Methane is a potent greenhouse gas that traps heat about 20 times more effectively than carbon dioxide.

Understanding the sources of methane, and how the gas is formed, could give scientists a better understanding of its role in warming the planet.

Now a research team including scientists at the Massachusetts Institute of Technology, the Woods Hole Oceanographic Institution, the University of Toronto and elsewhere has developed an instrument that can rapidly and precisely analyse samples of environmental methane to determine how the gas was formed.

The method detects the ratio of methane isotopes, which can provide a “fingerprint” to differentiate between two common origins: microbial, in which microorganisms, such as might live in the guts of animals, produce methane as a metabolic byproduct; or thermogenic, in which organic matter, buried deep within the Earth, decays to methane at high temperatures.

The researchers used the technique to analyse methane samples from lakes, swamps, groundwater, deep-sea vents and the guts of cows, as well as methane generated by microbes in the lab.

“We are interested in the question, ‘Where does methane come from?’” says Shuhei Ono, an assistant professor of geochemistry in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “If we can partition how much is from cows, natural gas, and other sources, we can more reliably strategise what to do about global warming.”

The group noticed something surprising and unexpected in some samples. For example, based on the isotope ratios they detected in cow rumen, they calculated that this methane formed at 400 degrees Celsius — impossible, as cow stomachs are typically about 40 C. They observed similar incongruences in samples from lakes and swamps. The isotope ratios, they reasoned, must not be a perfect indicator of temperature.

Researching Methane Origins

Researching Methane Origins

Instead, study author David Wang and his colleagues identified a relationship between a feature of the bonds linking carbon and hydrogen in methane molecules — a quality they deemed “clumpiness” — and the rate at which methane was produced: The clumpier the bond, the slower the rate of methanogenesis.

“Cow guts produce methane at very high rates — up to 500 liters a day per cow. They’re giant methane fermenters, and they prefer to make less-clumped methane, compared to geologic processes, which happen very slowly,” Wang says. “We’re measuring a degree of clumpiness of the carbon and hydrogen isotopes that helps us get an idea of how fast the methane formed.”

Wang added “Now we have a baseline that we can use to explore how methane forms in environments on Earth and beyond”.

The study is published this week in the journal Science.

The ocean floor is teeming with methane, the natural gas that fuels our homes. According relatively modest changes in global ocean temperatures or sea level could trigger a massive release of oceanic methane. If a rise in water temperatures passes a certain threshold, sizable methane hydrate deposits could decompose rapidly and release a large quantity of heat-trapping gas back into the atmosphere.

Photos: Danielle Gruen (edited by Jose-Luis Olivares/MIT); MIT

Further Reading:
MIT News
When Seafloor Meets Ocean, the Chemistry Is Amazing, Oceanus Magazine, Vol. 42, No. 2, Apr. 2004

Basking shark Bali

Basking shark seen for first time in Indonesia

A recent stranding of a basking shark (Cetorhinus maximus) in north-western Bali is the first confirmed record of this large, filter-feeding shark species in Indonesian waters.

The shark was an adult male. It is possible that the Indonesian throughflow – the warm ocean current which moves water from the Pacific to the Indian Ocean – is an important route for basking sharks during their migrations.

Once thought of as a strictly cool-water species, basking sharks move to tropical seas each winter. While commonly sighted in surface waters in northern Europe and America during summer and autumn months, they disappear during winter. An article in 1954 even suggested that they hibernate on the ocean floor during this time.

Basking shark in European waters by Tim Nicholson

Basking shark in European waters (Isle of Man) by Tim Nicholson

More recently satellite tagging showed that basking sharks instead migrate through tropical waters, travelling at depths of 200 to 1,000 meters and unseen by humans.

The basking shark is the second largest shark after the whale shark (Rhincodon typus). It can grow up to 11 metres long and weigh up to 7 tonnes. It feeds by filtering plankton through its gills whilst swimming with its huge mouth open.

Basking shark

Basking shark and snorkellers by Chris Gotschalk

Further Reading
Marine Biodiversity Records / Volume 8 / 2015DOI:, Published online: 28 January 2015

Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean. Skomal, Gregory B.; Zeeman, Stephen I.; Chisholm, John H.; Summers, Erin L.; Walsh, Harvey J.; McMahon, Kelton W.; Thorrold, Simon R.

Images: Green Fire Productions CC by 2.0, Tim Nicholson, Chris Gotschalk

Green Turtle, Chelonia mydas.

Warming seas stop turtles basking

Green sea turtles may stop basking on beaches around the world within a century due to rising sea temperatures, a new study suggests.

Naturalists as early as Darwin observed beach basking in green turtles (Chelonia mydas). It helps the threatened animals regulate their body temperatures and may help their digestion and immune systems.

After analysing six years of turtle surveys and 24 years of satellite data, researchers from Duke University, the National Oceanic and Atmospheric Administration (NOAA) Pacific Islands Fisheries Science Center and the University of Ioannina in Greece found the turtles bask less often when sea surface temperatures rise.

If global warming continues, they may stop basking altogether by 2102. Or even earlier in some places like Hawaii where you might stop seeing turtles sunning themselves on the beach in less than 25 years.

The cut-off point for Green Turtles is 23 °C at the sea surface. Warmer than this and they don’t need to get out to get warm.

Not all green turtles bask on land. Though the turtles are found in tropical and subtropical oceans around the world, beach basking has only been observed in Hawaii, the Galapagos Islands and Australia. Sea surface temperatures at these sites have been observed to be warming at three times the global average rate.

It is not yet clear whether populations that currently bask on land during cooler months will adapt to warming sea temperatures and begin to bask exclusively in the water, as do some other populations around the world.

Further Reading
Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns, Kyle S. Van Houtan, John M. Halley, and Wendy Marks. Biology Letters, January 14, 2015. DOI: 10.1098/rsbl.2014.0744

Photo credit: Tim Nicholson

Loggerhead Turtle, Caretta caretta

Loggerhead turtles home in on nests magnetically

Mother turtles find their way back to nesting beaches by looking for unique magnetic signatures along the coast, according to a new study published in Current Biology.

Loggerhead turtles, for example, leave the beach where they were born as hatchlings and traverse entire ocean basins before returning to nest, at regular intervals, on the same stretch of coastline as where they started. How the turtles accomplish this natal homing has remained an enduring mystery until now.

Loggerhead Sea Turtle

Loggerhead Sea Turtle. Photo credit: Brian Gratwicke, (CC by 2.0)

Several years ago, Kenneth Lohmann, the co-author of the new study, proposed that animals including sea turtles and salmon might imprint on magnetic fields early in life, but that idea has proven difficult to test in the open ocean. In the new study, Brothers and Lohmann took a different approach by studying changes in the behavior of nesting turtles over time.

“We reasoned that if turtles use the magnetic field to find their natal beaches, then naturally occurring changes in the Earth’s field might influence where turtles nest,” Brothers says.

The researchers analysed a 19-year (1993–2011) database of loggerhead nesting sites on the Atlantic coast of Florida, an area encompassing the largest sea turtle rookery in North America. Their analyses confirmed the predictions of the geomagnetic imprinting hypothesis.

In some times and places, the Earth’s field shifted so that the magnetic signatures of adjacent locations along the beach moved closer together. When that happened, nesting turtles packed themselves in along a shorter stretch of coastline, just as the researchers had predicted. In places where magnetic signatures diverged, sea turtles spread out and laid their eggs in nests that were fewer and farther between.

Turtles are long lived, and females undertake reproductive migrations periodically throughout their adult lives. Thus, the population of turtles that migrate to a given beach to nest each year consists of two subsets: a group of first-time nesters, and another, typically larger group of older “re-migrants” that have nested in the area during previous years.

Loggerhead turtles are thought to reach adulthood when they are between 23 and 29 years old. Much younger than this they return to coastal areas from the open sea and continue to mature there.

Sea turtles likely go to great lengths to find the places where they began life because successful nesting requires a combination of environmental features that are rare: soft sand, the right temperature, few predators, and an easily accessible beach.

“The only way a female turtle can be sure that she is nesting in a place favorable for egg development is to nest on the same beach where she hatched,” Brothers says. “The logic of sea turtles seems to be that ‘if it worked for me, it should work for my offspring.'”

These findings, in combination with recent studies on Pacific salmon, suggest that similar mechanisms might underlie natal homing in diverse long-distance migrants such as fishes, birds and mammals.

Further Reading
Evidence for Geomagnetic Imprinting and Magnetic Navigation in the Natal Homing of Sea Turtles, Brothers, J. Roger et al., Current Biology DOI:

Casale P, Mazaris A, Freggi D (2011). Estimation of age at maturity of loggerhead sea turtles Caretta caretta in the Mediterranean using length-frequency data. doi: 10.3354/esr00319

Wildlife Photographer of the Year Contest now Open

Enter the Wildlife Photographer of the Year Contest

For 50 years the Natural History Museum in London has run the Wildlife Photographer of the Year competition – harnessing the power of photography to inspire greater understanding of the natural world, challenge perceptions and encourage change to preserve the beauty and diversity of the Earth.

They are looking for photos that represent the natural world as faithfully as possible, free from excessive digital manipulation and with total regard for the welfare of the animals and their environment.

This year’s categories include

  • Earth’s Environment: Underwater
  • Earth’s Diversity: Reptiles, Amphibians and Fishes
  • Earth’s Diversity: Mammals
  • Earth’s Diversity: Invertebrates
  • TIMElapse Special Award

The TIMElapse category looks for unexpected insights or surprising views of the natural world. Photographers can submit up to three multi-image sequences–lasting between 45 and 90 seconds–to tell a story, reveal unique behaviour, uncover hidden processes or portray a dramatic event that may otherwise be overlooked.

Prizes include £10000 for the Wildlife Photographer of the Year and £1,250 for each category winner.

Amongst the judges is Dr Alexander Mustard who is a regular columnist and features writer for many publications in the marine, wildlife, diving and photographic media. In 2013, he was named European Wildlife Photographer of the Year, the first time an underwater photograph had ever won this award.

For more details, or to register, visit the The Natural History Museum site.

Humpback Whale

Humpback Whales Sing for their Supper

Whales may sing for their supper, a study in the open access journal Scientific Reports suggests.

Humpback whales (Megaptera novaeangliae) work together whilst foraging on the bottom for food – but how do they co-ordinate their behaviour? Susan Parks of Syracuse University believes she may have the answer.

Her research group have been monitoring humpback whales for a decade.

This study used digital acoustic tags to record sounds made by the whales when feeding on the bottom (at around 30-35 m depth) of the Northwest Atlantic. The data showed that whales often feed on the seafloor in close co-ordination, matching diving and behaviour on the seabed. The researchers heard the whales making a previously undescribed sound which sounded like “tick-tock”.

The scientists noticed that the bottom-feeding sounds, were only produced under low-light conditions whilst other humpback whales were nearby.

Why the whales make the noises is unclear. It may be to co-ordinate timing of feeding activities under low light conditions, to alert other humpback whales to the location of particularly good patches for feeding – acting like a dinner bell – or to flush out the prey.

“Hints of behaviour suggest that other whales who overhear the sounds are attracted to them and may eavesdrop on other whales hunting for food,” Professor Parks says.

Dinner for the humpbacks feeding on the bottom was mainly sand lance. These are eel-like fish which bury themselves in the sand of the ocean floor.

Sand Lance

Sand Lance

Humpback whales forage across habitats on a wide diversity of prey, ranging from krill to larger schooling fish species, using a variety of feeding strategies. This novel acoustic cue used whilst foraging on a bottom-dwelling prey provides yet more evidence of the learning abilities of humpback whales.

Scientific Reports is a primary research publication from the publishers of Nature.

Further Reading:
Parks, Cusano, Stimpert, Weinrich, Friedlaender & Wiley. Evidence for acoustic communication among bottom foraging humpback whales Scientific Reports 4, Article number: 7508 (2014)
Biologist reveals how whales may sing for their supper

Diver on wreck

Diving incidents down again

The British Sub-Aqua Club (BSAC) has published its Annual Diving Incident Report for 2014. The 2014 report records a total of 216 incidents.

BSAC have monitored and reported on diving incidents since 1964. Their report contains both details of UK diving incidents occurring to divers of all affiliations, and incidents occurring world-wide involving BSAC members.

In the last three years the number of reported incidents has declined by approximately 60 per year.

BSAC conclude that the decline may be because a normal amount of diving has taken place but:

  • either it has been safer and fewer incidents have occurred,

  • or a normal number of incidents have occurred but fewer have been reported.

Alternatively, less diving may have taken place and thus fewer incidents occurred.

There are some trends identified in the report that indicate that there are improvements to diver safety with respect to decompression illness and buoyancy control, and also a reduction in boating incidents.

BSAC say that most of the incidents reported could have been avoided had those involved followed a few basic principles of safe diving practice. Several incidents involved rapid ascents due to panic and a rush for the surface, poor buoyancy control, out of air, delayed surface marker buoy issues or a weight-related issue. Interestingly, there was also an increase this year in the number of cases which identified the malfunction of inflation or dump valves on a BCD or drysuit.

The “Incident Year” in the report ran from 1st October 2013 to 30th September 2014. Of the 216 incidents, 16 were fatal. Six cases probably involved divers who suffered a ‘nondiving’ related medical incident (for example a heart attack) whilst in the water. Four cases involved a separation of some kind. One case involved a diver who died as a result of breathing poisonous gas in a dry passage in a partially flooded mine.

Full details of each incident are covered in the report.

Further Reading:
BSAC Diving Incident Report 2014

Global Fishing Watch

Global Fishing Watch shows you ships fishing in protected areas

In the last 60 years the fishing industry have caught nine out of every ten large fish. That’s only 10% of large fish like tuna, cod, swordfish and halibut remaining on the planet. International fleets still pursue what is remaining. According a 2014 report by the United Nations Food and Agriculture Organization, over 90% of the world’s fisheries are fully exploited or over-fished.

This week Oceana, Skytruth and Google launched The Global Fishing Watch. This can identify individual fishing vessels and track their fishing activity, shining a light on fishing activity worldwide.

Global Fishing Watch Map

Global Fishing Watch Example Map

The prototype anlayses data from the Automatic Identification System (AIS) network. This was designed to avoid collisions and gives information about a ship’s identy, location, speed and direction of travel. Global Fishing Watch uses the data to map the who, where and when of commercial fishing around the world.

Global Fishing Watch will be available to anyone with an internet connection to monitor when and where commercial fishing is happening around the globe. The designers hope that people will use the tool to see for themselves whether their fisheries are being effectively managed. Seafood suppliers can keep tabs on the boats they buy fish from. Media and the public can act as watchdogs to improve the sustainable management of global fisheries. Fisherman can show that they are obeying the law and doing their part. Researchers will have access to a multi-year record of all trackable fishing activity.

The systems aims to make fishing activity more transparent and identify illegal fishing. It will be able to monitor any fishing activity in closed, protected areas. For example, in tests the Komarovo, a trawler registered in Russia, appeared to be fishing five times inside the Dzhugdzhursky State Nature Reserve in September 2013. The nature reserve is an International Union for Conservation of Nature (IUCN) category 1a protected area, meaning it has the highest, and strictest, protection level possible. However, at least five vessels, all registered in Russia, entered the Nature Reserve and exhibited behavior suggestive of fishing in 2013.

There are currently 6,600 marine protected areas (MPAs) covering about 2 percent of the world’s oceans. An even smaller area of the global oceans, about 1 percent, has been protected with a “No Take” designation where all fishing is prohibited.

“Global Fishing Watch is designed to empower all stakeholders, including governments, fishery managers, citizens and members of the fishing industry itself, so that together they may work to bring back a healthy, bio-diverse and maximally productive ocean,” said Andrew Sharpless, CEO of Oceana. “By engaging citizens to hold their elected officials accountable for managing fisheries sustainably and for enforcing fishing rules, Global Fishing Watch will help bring back the world’s fisheries, protecting and enhancing the livelihoods of the hundreds of millions of people who depend on ocean fisheries for food and income.”

Although the Global Fishing Watch promises to be a fantastic tool, it is not perfect. Many smaller fishing vessels are not included in Global Fishing Watch as vessels below 300 gross tonnage are not currently required to operate AIS in many areas. It is hoped that the AIS will be expanded to smaller ships.

SkyTruth is a nonprofit organization using remote sensing and digital mapping to create stunning images that expose the environmental impact of natural resource extraction and other human activities. Oceana is the largest international advocacy group working solely to protect the world’s oceans. Google Earth Outreach is a team dedicated to leveraging and developing Google’s infrastructure to address environmental and humanitarian issues through partnerships with non-profits, educational institutions, and research groups.

Further Reading:
Global Fishing Watch

Frog Fish, Great Barrier Reef

Great Barrier Reef: Australia to ban Sediment Dumping on Part of Reef

Australia has declared that it will ban dumping of sediment in the marine park area of the Great Barrier Reef, but not in the entire World Heritage Site. This matters because, according to environmental pressure group Fight for the Reef, in recent years 80% of dumping has been in World Heritage waters just outside the Marine Park.

During a speech in Sydney at the World Parks Congress, Environment Minister Greg Hunt said that the government will legislate a ban on dumping.

Spoil will still affect Coral and Seagrass

A ban in just the Marine Park, though, would still allow millions of tonnes of spoil to be dumped where plumes can easily drift onto coral and seagrass.

The expansion of Abbot Point, to make it one of the world’s biggest coal ports in middle of the Great Barrier Reef is still going to go ahead – this time with the dumping of toxic sludge on wetlands. Wetlands are the filters and the fish nurseries for the Reef.

Groups press to protect entire World Heritage Area

Environmental groups are pressing for the government to protect the entire World Heritage area or risk an ‘in-danger’ listing for the Reef from the World Heritage Committee.

Practically the entire Great Barrier Reef was inscribed as a World Heritage site in 1981. It contains the world’s largest collection of coral reefs, with 400 types of coral, 1,500 species of fish and 4,000 types of mollusc. It also contains habitats of species like the dugong and the large green turtle, which are threatened with extinction.

Green Turtle

Green Turtle, Chelonia mydas

In June 2015 the World Heritage Committee will decide whether to place the Barrier Reef on the List of World Heritage in Danger.

Fight for the Reef is a partnership between WWF-Australia and the Australian Marine Conservation Society.

Further Reading
Fight for the Reef
World Heritage List: Great Barrier Reef

Whale shark

Beth Tierney on Diving the World

Along with her husband Shaun, Beth Tierney is co-author of the popular Diving the World. Jill Studholme interviewed her for SCUBA News.

What makes your book different from other books about diving around the world?

There are two principals we have stuck to ever since the first edition. Right from the start, we asked other divers where they had been and where they were diving next. And then we focused on those places people actually want to go to and can afford to go to. Let’s face it, we would all love to dive the Antarctic, but few of us will win the lottery this week! The other thing is that we can say – hand on heart – that there is nothing in the book that we haven’t personally done. If we haven’t dived the country or a specific site, we don’t write about it or pass opinion. It makes the guide unique. Yes, it is personal to us and our experiences but at least readers know we have said it because we have done it!

Blue ringed octopus

Blue ringed octopus

Whale Shark

This is the third edition – did you have to revisit all the dive
sites in the original book and have you added any new areas to the book?

Wouldn’t that be a wonderful thing! I love the idea of going back to everywhere again, but sadly, that’s not practical for every edition. However, we have dived almost everywhere more than once and revisited some places specifically to make sure we are up-to-date. Jordan is a good example, it was our first ever foray into the Red Sea but it didn’t go into the first two editions. However, this time around, we found it was hitting more wish lists so we went back and checked it out. And yes, it was as good as we remembered it.

Where would you like to dive next?

Always a hard one as we tend to hold off making plans to see what new things crop up – if a different destination or new liveaboard appears, we can just hop on. However, we are both quite keen to go back to Papua New Guinea where there is a mix of reefs and wrecks and it is never that busy. We would both like to revisit Truk Lagoon or perhaps explore the Malpelo in the Eastern Pacific.

Do you have a worst diving experience?

We have been fortunate to never have any really serious dramas, although there have been plenty of small ones that make hilarious dinnertime tales. As for bad dive experiences, the hardest one was a dive in the far south of Indonesia in the Indian Ocean. We were heading for a pinnacle beyond the surf zone with no land in sight. When we reached it and entered the water, all was calm but as soon as we reached about 25 metres there was a phenomenal tidal change that hit the pinnacle as a 5 or 6 metre surge. One minute we would be at 24 metres, and then in seconds were thrown up to 18 before dropping rapidly to over 30 metres. It was terrifying and hilarious all at once. Trying to abort a dive like that is nigh on impossible too as our computers screeched non-stop. We ended up clinging to rocks on the pinnacle and slowly working our way up, ending with just 12 minutes of deco-time. Phew.

Great photos are a hallmark of your books, what photographic equipment do you use?

The images in the book have been taken over quite a few years so some were on film. Way back when, Shaun used a Nikonos V and a Nikon F90 in a Sea and Sea Housing. When he went over to the dark side (oops, digital), he stuck with Sea and Sea housings as he feels they are the most ergonomic and simple, incredibly well built but good value. His first digital SLR camera was a Nikon D200 and he has a D300 as well.

Now that the new book is finished, what projects have you in the pipeline?

At the moment, we are working on converting our previous guide, Diving Southeast Asia to a digital version. This means going back over all the factual content to ensure it is still correct (or fix what has changed) then we also updating the operator listings. We are hoping it will be available before Christmas this year.

What do you do for recreation when you are not diving?

We’ve recently bought a new house in the wilds of Dorset (UK), so life is currently all to do with renovating and gardening. We are lucky enough to have a stream though, with all sorts of wonderful wildlife – crayfish, kingfishers and water voles – so we are not completely missing the marine world. I am contemplating putting my Canon S110 in it’s housing to see what I can get when I go paddling!

Most people would like your job – diving exotic places and writing about it – how did you get into it?

Way back in the 80s we did a round-the-world trek spending long spells in the tropics, floating over vivid coral reefs and wishing we were down below with the divers. At the time our budget didn’t extend to learning to dive but within months of returning to London we signed up for a BSAC course, did our first open water dives in the Maldives and our qualification dives in Cyprus.

As the years went by, we became increasingly involved in the diving world as a photojournalist team: Shaun’s first career was as a studio photographer and Beth worked in advertising and marketing as a consultant to the travel industry. In the early ’90s, we took a ‘career break’ and aimed to dive our way around the world. We didn’t manage to see as much as we wanted but it was a great year.

Since then, we have become PADI Master Scuba Divers and our work has become increasingly focused on dive travel books plus we run

Diving the World Third Edition

Diving the World

You can order a signed copy of Diving the World from the Tierneys’ Sea Focus website. It is also available with 49% off from Amazon.

As well as information about over 275 dive sites, the book covers: local customs; suggestions for dive centres, accommodation and restaurants; information on what to do when you’re not diving (useful for non-divers travelling with you) and anecdotes about the diving. The authors have dived, reviewed and photographed every site in the book.

The new edition is out 12 November.

Further Reading:
More interviews with diving authors, and scuba book reviews.