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
Sea Urchin

Sunscreen nanoparticles harm sealife

Materials commonly used in clear sunscreens harm marine life. Research shows sea urchin embryos, plankton and coral all affected.

Sea Urchins at Risk

According to a study published in the journal Environmental Science and Technology, nanoparticles commonly used in sunscreens are making sea urchin embryos more vulnerable to toxins,

Researchers from the University of California showed that Zinc Oxide Nanomaterial (ZnO) made developing sea urchin embryos more sensitive to other chemicals, blocking transporters that would otherwise defend them by pumping toxins out of cells.

Nanozinc oxide is used as an additive not only in sunscreens but in toothpastes and beauty products as well. Another nanoparticle commonly used in sunscreen is titanium dioxide (TiO2).

Nanomaterials are tiny chemical substances, which are about 100,000 times smaller than the diameter of a human hair.

Plankton also affected

When people wearing sunscreen go to cool off in the sea, the nanoparticles in sunscreen wash off. Research by Spanish scientists David Sánchez-Quiles and Antonio Tovar-Sánchez has shown that titanium dioxide and zinc oxide nanoparticles from the sunscreen produce significant amounts of hydrogen peroxide, a strong oxidizing agent that generates high levels of stress on marine phytoplankton.

Conservative estimates for a Mediterranean beach reveal that tourism activities during a summer day may release on the order of 4 kg of TiO2 nanoparticles to the water, with direct ecological consequences on the ecosystem. The researchers concluded that titanium dioxide from sunscreen was largely responsible for a dramatic summertime spike in hydrogen peroxide levels in coastal waters.

And Coral

Titanium dioxide nanoparticles also increase stress in reef-building corals. Adding to the warming pressures they already face in parts of the world.

Coral Reef

Photo credit: Tim Nicholson

Why Nanoparticles?

Zinc oxide and titanium dioxide have been used in sunscreens for decades, but in the form of big particles. They reflect not only ultra-violet light but visible light making them and the sunscreen appear white. When used as minute nanoparticles, the sunscreen looks clear. This type of sunscreen is popular because people can spray it on, it feels lighter and it needs reapplying less frequently. But evidence is mounting of the harm it does to marine life.

Further Reading

Copper Oxide and Zinc Oxide Nanomaterials Act as Inhibitors of Multidrug Resistance Transport in Sea Urchin Embryos: Their Role as Chemosensitizers
Bing Wu, Cristina Torres-Duarte, Bryan J. Cole, and Gary N. Cherr
Environmental Science & Technology 2015 49 (9), 5760-5770
DOI: 10.1021/acs.est.5b00345

Sunscreens as a Source of Hydrogen Peroxide Production in Coastal Waters
David Sánchez-Quiles and Antonio Tovar-Sánchez
Environmental Science & Technology 2014 48 (16), 9037-9042
DOI: 10.1021/es5020696

Tovar-Sánchez A, Sánchez-Quiles D, Basterretxea G, Benedé JL, Chisvert A, Salvador A, et al. (2013) Sunscreen Products as Emerging Pollutants to Coastal Waters. PLoS ONE 8(6): e65451. doi:10.1371/journal.pone.0065451

Jovanovi?, B. and Guzmán, H. M. (2014), Effects of titanium dioxide (TiO2) nanoparticles on caribbean reef-building coral (Montastraea faveolata). Environmental Toxicology and Chemistry, 33: 1346–1353. doi: 10.1002/etc.2560

Grouper recovery graph

US Makes Progress on Over-Fishing: Fish Stocks Recovering

The number of US fish stocks listed as overfished, or subject to overfishing, has dropped to an all-time low since NOAA Fisheries began monitoring began in 1997. Their report, released this week, highlights the United States’ continued progress towards sustainably managing fish stocks.

NOAA Fisheries maintain three lists: Overfishing, Overfished and Rebuilt. A fish stock is on the overfishing list when the annual catch rate is too high. It’s on the overfished list when the population size of a stock is too low, whether because of fishing or other causes. The Rebuilt list holds stocks that have previously been on one of the other lists but have now recovered.

“This report illustrates that the science-based management process under the Magnuson-Stevens Act is working to end overfishing and rebuild stocks,” said Eileen Sobeck, assistant NOAA administrator for fisheries. “While we have made tremendous progress, we know there’s more work to be done — especially as we continue to document changes to our world’s oceans and ecosystems. We will continue to strive toward sustainable management of our nation’s fisheries in order to preserve our oceans for future generations.”

Twenty-six fish stocks, though, are still on both the Overfished and Overfishing lists. These include bluefin tuna, bigeye tuna, striped marlin, Atlantic cod, red snapper, white marlin, blue marlin, scalloped hammerhead, Atlantic halibut and Atlantic salmon.

Further Reading

Status of Stocks 2014. Annual Report to Congress on the Status of U.S. Fisheries by NOAA Fisheries


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