Planet Earth Winter 2013

www.planetearth.nerc.ac.uk

Winter 2013

RRS Discovery The ship that never stops

Meteotsunami • Bat navigation • Copepod predation • Cleaning ecosystems

About us NERC – the Natural Environment Research Council – is the UK’s leading funder of environmental science. We invest public money in cutting-edge research, science infrastructure, postgraduate training and innovation.

Our scientists study the physical, chemical and biological processes on which our planet and life itself depends – from pole to pole, from the deep Earth and oceans to the atmosphere and space. We work in partnership with other UK and international researchers, policymakers and business to tackle the big environmental challenges we face – how to use our limited resources sustainably, how to build resilience to environmental hazards and how to manage environmental change.

Contact us To give us your feedback or to subscribe email: requests@nerc.ac.uk or write to us at Planet Earth Editors, NERC, Polaris House, North Star Avenue, Swindon SN2 1EU. NERC-funded researchers should contact: editors@nerc.ac.uk Editors Adele Walker, 01793 411604 admp@nerc.ac.uk Tom Marshall, 01793 442593 thrs@nerc.ac.uk Science writers Tamera Jones, Harriet Jarlett, Alex Peel Design and production Candy Sorrell, 01793 411518 cmso@nerc.ac.uk ISSN: 1479-2605

Front cover: RRS Discovery

2

PLANET EARTH Winter 2013

NERC is a non-departmental public body. Much of our funding comes from the Department for Business, Innovation and Skills but we work independently of government. Our projects range from curiosity-driven research to long-term, multi-million-pound strategic programmes, coordinated by universities and our own research centres: British Antarctic Survey British Geological Survey Centre for Ecology & Hydrology National Oceanography Centre National Centre for Atmospheric Science National Centre for Earth Observation

Planet Earth is NERC’s quarterly magazine, aimed at anyone interested in environmental science. It covers all aspects of NERC-funded work and most of the features are written by the researchers themselves.

For the latest environmental science news, features, blogs and the fortnightly Planet Earth Podcast, visit our website Planet Earth Online at www.planetearth.nerc.ac.uk.

Not all of the work described in Planet Earth has been peer-reviewed. The views expressed are those of individual authors and not necessarily shared by NERC. We welcome readers’ feedback on any aspect of the magazine or website and are happy to hear from NERC-funded scientists who want to write for Planet Earth. Please bear in mind that we rarely accept unsolicited articles, so contact the editors first to discuss your ideas.

In this issue Winter 2013

14

20

16

12 Blind as a bat

On finding your way home in the dark.

14 The 2011 UK meteotsunami

A study in science.

16 Full steam ahead

Building NERC’s new research ship.

20 Monitoring Earth’s canary

How important is Arctic methane for global climate change?

22 Fixing broken ecosystems

A microscopic solution to a big problem.

25 Climate research helps fight terror threat

A new way to find explosives.

26 New for old

Turning quarries into nature reserves.

28 Sex, plankton and

28

predators

The marine mystery of the missing males.

30 Sky high – what’s going on

up there?

Maths skills help interpret climate change.

PLANET EARTH Winter 2013

3

www.planetearth.nerc.ac.uk

News Editorial

New investments in ocean monitoring

W

elcome to the winter edition of Planet Earth.

Our stunning cover picture gives a clue to one of our top stories – in fact a top story for NERC this year. It’s not a poster for a new Cunard liner but a prelaunch shot of our equally stunning research ship – the new RRS Discovery.

Discovery has been years in the making and represents a significant capital investment in UK environmental science.

She’s a fine example of cutting-edge engineering meeting cutting-edge research facilities and is robust enough to take marine scientists into some of the most hostile seas on the planet. The ship can accommodate researchers across a range of disciplines; together they will bring back new understanding of our enigmatic oceans – how they support marine ecosystems, regulate our climate and ultimately maintain life on Earth.

One particularly unusual oceanic event featured elsewhere in this edition is a tsunami that struck Britain’s south coast in 2011. Dave Tappin explains how marine geologists and meteorologists turned sleuth to solve the mystery of how it happened.

Another researcher-turned-detective, Anna Senkevich, explains how she applied maths modelling skills to a climate puzzle, while Damien Weidmann tells us how climate research techniques are being adapted into technology that could help fight terrorism.

Back in the water, we hear from Jags Pandhal about a new low-cost technique for dealing with algal blooms that starve water of oxygen – an expensive and potentially toxic problem which is on the rise worldwide.

Meanwhile Richard Holland goes nocturnal to uncover the tools bats use to find their way home – sometimes from hundreds of miles away.

All that, and the sex life of plankton too!

We hope you enjoy it.

4

PLANET EARTH Winter 2013

N

ERC has joined forces with the US’s National Science Foundation (NSF) and National Oceanic & Atmospheric Administration (NOAA) to fund two projects worth around £44m to monitor crucial ocean currents in the North Atlantic which shape Britain’s climate.

Science Minister David Willetts announced the projects when he delivered the Mountbatten Memorial Lecture at the Royal Institution in October.

The projects should ultimately improve long-term climate predictions and weather forecasts. During one of them, the fiveyear £20m Overturning in the Subpolar North Atlantic Program (OSNAP), scientists from seven countries will set up an array of moored instruments and use autonomous gliders across the North Atlantic, along a line running from Scotland to Canada via Greenland. These will measure ocean temperature, salinity and current strength in an area called the North Atlantic Subpolar Gyre.

The currents here are part of the so-called ocean conveyor belt, a system of currents moving heat around in the world’s oceans.

In the Atlantic, warm upper-ocean water travels north, to the high northern latitudes, where it loses heat to the atmosphere. This process keeps the UK relatively mild compared to other countries at similar latitudes. This water cools then sinks and returns southwards at great depth.

The strength of currents in the global conveyor belt can vary significantly. The OSNAP array aims to understand the connection between these variations and our weather.

NERC, NSF and NOAA will also continue funding the RAPID array of moored instruments between the Canary Islands and Florida, providing around £24m. This collection of instruments has continuously monitored the strength of the North Atlantic portion of the global conveyor belt since 2004. RAPID will now run for six more years.

Daily updated news @ www.planetearth.nerc.ac.uk

Antarctica under ice wins mapping award

A

n innovative representation of the bedrock beneath the Antarctic ice has won the British Cartographic Society’s Bartholomew Award for best small-scale or thematic map.

The colourful map is the result of an international effort led by NERC’s British Antarctic Survey and assembled using data from many sources by its MAGIC (Mapping and Geographic Information Centre) team. It provides a fascinating glimpse into how the

frozen continent might look if it were stripped of its ice cap. The roundels at each corner of the map provide extra information on ice-sheet surface, ice thickness and on the many data sources it incorporates.

Peter Fretwell of BAS received the award at the BCS 50th anniversary symposium awards dinner in September.

PLANET EARTH Winter 2013

5

www.planetearth.nerc.ac.uk

News 3D fossils now online R

esearchers at the British Geological Survey have been hard at work on a collaborative project to scan many of the UK’s finest fossil specimens to produce the first ever 3d virtual fossil collection – an important step towards being able to put perfect replicas of even the most precious examples into classrooms all over the world.

The fruits of their labours are now available at www.3d-fossils.ac.uk. There are thousands of high-resolution photos, 3d models and stereoscopic images of the fossils – the database isn’t fully populated yet and scanning work continues, but more information is being added all the time. Also included is comprehensive data about each one – where it was found, what species it comes from, its place in the tree of life, and even the paper in which it was first described.

The 3d models are particularly innovative. The files can be downloaded and read using open-source modelling software, and they’ll work with 3d printers – the revolutionary technology that lets computers create real, physical objects by building up layer upon layer of plastic. Until recently these cost so much they were out of reach for almost everyone, but prices have plummeted in recent years.

It may not be long before they are within the budget of the average school, and students will be able to handle exact replicas of some of the most important fossils ever discovered and find out about how they were found and what they tell us about the story of life.

BGS is collaborating on the project with the Natural History Museum, the Sedgwick Museum of Earth Sciences, the Oxford University Museum of Natural History, the National Museum Wales and the Geological Curators’ Group. Funding came from Jisc, the public body that supports the use of IT to improve education.

Lost home of last Neanderthals rediscovered in Britain

A

record of Neanderthal archaeology, thought to be long lost, has been rediscovered by NERC-funded scientists working on the Channel island of Jersey.

The study, published today in the Journal of Quaternary Science, reveals that a key archaeological site has preserved geological deposits which were thought to have been lost through excavation 100 years ago.

The discovery was made when the team undertook fieldwork to stabilise and investigate a portion of the La Cotte de St Brelade cave, on Jersey’s southeast coast.

Much of the site contains sediments dating to the last Ice Age, preserving 250,000 years of climate change and

6

PLANET EARTH Winter 2013

archaeological evidence.

The site, which has produced more Neanderthal stone tools than the rest of the British Isles put together, contains the only known late Neanderthal remains from north-west Europe. These offer archaeologists one of the most important records of Neanderthal behaviour available.

‘In terms of the volume of sediment, archaeological richness and depth of time, there is nothing else like it known in the British Isles. Given that we thought these deposits had been removed entirely by previous researchers, finding that so much still remains is as exciting as discovering a new site,’ says Dr Matt Pope of University College London, who

helped lead the research.

The team dated sediments at the site using a technique called Optically Stimulated Luminescence, which measures the last time sand grains were exposed to sunlight. This was done at the Luminescence Dating Research Laboratory for Archaeology and the History of Art at the University of Oxford.

The results showed that part of the sequence of sediments dates between 100,000 and 47,000 years old, implying that Neanderthal teeth discovered at the site in 1910 were younger than previously thought, and probably came from one of the last of the group to live in the region.

Daily updated news @ www.planetearth.nerc.ac.uk

Princess Royal

names new research ship

Amazon

dominators identified

T

H

er Royal Highness The Princess Royal has named the new Royal Research Ship – RRS Discovery – at NERC’s National Oceanography Centre (NOC) in Southampton.

Around 200 guests including the Science Minister David Willetts, local MPs, civic guests and senior figures from the UK marine science community were present to see a bottle of champagne smashed in the traditional manner on the vessel’s bow.

After the naming ceremony and a blessing from the Bishop of Southampton, Her Royal Highness toured the ship, meeting officers and crew, representatives of Freire shipbuilders and members of the Discovery replacement team, whom the Minister praised for completing the project on time and on budget.

The Office of Government and Commerce Gateway Review made a similar point, noting that ‘The project team has delivered a high quality ship on time for the key science programme to begin and under budget. This has been achieved in a challenging economic climate. This level of project management achievement is not typical across government and should be recognised and built upon.’

Discovery is the latest in an illustrious line of vessels bearing the name that date back to 1602, when the East India Company commissioned the first Discovery to explore the waters now known as the Hudson Strait in the long search for the Northwest Passage. In the 20th century, a new Discovery was specially commissioned for the British National Antarctic Expedition of 1901-04, which included Antarctic heroes Captain Scott and Ernest Shackleton.

The new ship’s immediate predecessor ended a 50-year career in 2012, and was the platform for some of the most important marine science carried out during that period – truly a half-century of discovery.

See pp16-19 for much more information about the new ship and its capabilities.

he Amazon basin, home to the richest collection of plant species on Earth, turns out to be dominated by just 227 tree species.

A paper in Science says more than half of the forest’s 390 billion trees belong to just 1.4 per cent of its species. And of the 16,000 species that populate the forest, the rarest 11,000 account for just 0.12 per cent of tree cover.

Accounting for more than half the world’s remaining rainforest, Amazonia is often called the lungs of the planet. But until now, its sheer size has restricted researchers to studying local or regional pockets of forest.

‘In essence, this means that the largest pool of tropical carbon on Earth has been a black box for ecologists,’ says Dr Nigel Pitman of The Field Museum in Chicago, one of the study’s authors. ‘Conservationists don’t know which Amazonian tree species face the most severe threats of extinction.’

The NERC-supported research involved more than 100 researchers from around the world working across all nine countries of Amazonia.

Led by Dr Hans ter Steege from the Naturalis Biodiversity Center in the Netherlands, they surveyed half a million trees across six million square kilometres, giving the first estimates for the whole Amazon basin.

‘The most common species of trees in the Amazon now not only have a number, they also have a name. This is very valuable information for further research and policy-making,’ says ter Steege.

A thin palm tree called Euterpe precatoria is the commonest in the forest, with an estimated five billion or more individuals across the basin.

But there were some more worrying findings. Almost 6000 species seem to have fewer than 1000 individuals remaining.

Some of those species are unique to the region, and could be classified as globally threatened.

The researchers hope their work will help conservationists identify vulnerable tree species in unprotected areas.

PLANET EARTH Winter 2013

7

www.planetearth.nerc.ac.uk

News New light on bee colony failure

L

8

PLANET EARTH Winter 2013

AA) Robert Pitman (NO

ong-term exposure to pesticides can destroy bee colonies even at levels too low to kill the bees immediately, according to new research published in Ecology Letters.

Scientists from Royal Holloway University of London found that when bees are exposed to small amounts of neonicotinoid pesticides – too small to kill them instantly – their behaviour changes and they stop working properly for their colonies. This shows that exposure to pesticides at levels bees encounter in the field has subtle impacts on individuals, and can eventually make colonies fail.

It’s an important breakthrough in identifying the reasons for bees’ recent global decline, which has baffled beekeepers and scientists.

‘One in three mouthfuls of our food depends on bee pollination,’ says lead author Dr John Bryden from Royal Holloway. ‘By understanding the complex way in which colonies fail and die, we’ve made a crucial step in being able to link bee declines to pesticides and other factors, such as habitat loss and disease, which can all contribute to colony failure.’

‘Exposing bees to pesticides is a bit like adding more and more weight on someone’s shoulders. A person can keep walking normally under a bit of weight, but when it gets too much they collapse. Similarly, bee colonies can keep growing when bees aren’t too stressed, but if stress levels get too high the colony will eventually fail,’ he adds.

The research is part of the £10m Insect Pollinators Initiative (IPI) set up to understand the causes of pollinator declines and safeguard future pollination services. The IPI is funded by NERC, the Biotechnology & Biological Sciences Research Council, Defra, the Scottish Government and the Wellcome Trust, as part of the Living With Environmental Change programme.

Killer whales may have menopause so grandma can look after the kids K

iller whales are one of only two species apart from humans that continue to live long after they can no longer reproduce. But scientists still don’t know why these animals evolved this unusual menopausal trait.

In a bid to find out, NERC has agreed to fund a project worth nearly £500,000 to look at why killer whales stop reproducing a third of the way through their lives, dedicating the rest of their days to protecting and caring for children and grandchildren.

The researchers suspect that the menopause, which the whales experience in their 30s or 40s, is related to the animals’ social structure.

‘Killer whales have a very unusual social system whereby sons and daughters don’t disperse from their social group but instead live with their mother her entire life,’ says Dr Darren Croft of the University of Exeter, a lead investigator on the study.

‘As a female ages, she shares more genes

with group members, and theory predicts that older females can benefit more from helping their offspring and grand-offspring than reproducing themselves.’

To discover why the menopause developed in the whales, the team will use information collected over the last 30 years about two populations of killer whales with more than 550 individuals between them.

The unique dataset includes birth and death dates as well as more complex data, like the genetic and social relationships between the different animals.

They will then look at how a female who has undergone menopause helps offspring survive. They suspect it is because older females take a leadership role in the social group and know more about where and when food is available. After preliminary work they expect to find that having a female around who no longer reproduces greatly increases a calf’s chance of survival. The research may even shed light on the menopause in humans.

Daily updated news @ www.planetearth.nerc.ac.uk

Frozen limit for life found

S

cientists have pinpointed the lowest temperature at which simple life can live and grow.

The study reveals that below -20°C, single-celled organisms dehydrate, sending them into a vitrified – glass-like – state during which they can’t complete their life cycle.

The researchers propose that, since the organisms cannot reproduce below this temperature, it’s the lower limit for life on Earth.

They placed cells in a watery medium and cooled it. As the temperature fell, the medium started to turn into ice and as the ice crystals grew, the water inside the organisms seeped out. This left them first dehydrated and then vitrified. Once a cell’s reached this state, scientists no longer consider it ‘living’ as it cannot reproduce, but it can be brought back to life when temperatures rise again.

‘The interesting thing about vitrification is that in general a cell will survive, where it wouldn’t survive freezing – if you freeze internally you die. But if you can do a controlled vitrification you can survive,’ says Professor Andrew Clarke of NERC’s British Antarctic Survey, lead author of the study. ‘Once a cell is vitrified it can continue to survive right down to incredibly low temperatures. It just can’t do much until it warms up.’

More complex organisms can survive at lower temperatures because they can control the medium their cells sit in to some extent.

This goes some way towards explaining why preserving food by freezing it works.

Most fridge freezers operate at nearly -20°C. This study shows this keeps food fresh because moulds and bacteria can’t multiply and spoil food when they’re this cold.

This study was supported by funding from NERC, the European Research Council, and the Institut National de la Recherche Agronomique. It appears in PLoS One.

NERC scientists contribute to Fifth IPCC Report

T

he Intergovernmental Panel on Climate Change (IPCC) has published its fifth Assessment Report (AR5), providing the most up-to-date summary yet of the scientific evidence for climate change and how our actions are contributing to these changes.

‘Climate Change 2013: the Physical Science Basis’ projects that by the end of the century global surface temperatures will rise at least 1.5°C above those seen in 1900 – perhaps by more than 2°C. ‘Warming in the climate system is unequivocal,’ the IPCC said in a statement.

AR5 firmly establishes human activity as a major cause.

‘Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions,’ says Thomas Stocker, co-chair of the IPCC Working Group l. ‘Heat waves are very likely to occur more frequently and last longer. As the Earth warms, we expect to see currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions.’

AR5 is the latest in a series of reports on climate change, synthesising peerreviewed studies from around the world. It is curated by leading experts in climate science, and plays a vital role in informing the climate policies adopted by governments.

The UK provided 30 of the AR5’s authors – around 11 per cent of the international panel. Many of these are highly-regarded NERC-funded scientists.

A significant portion of the science feeding into the report is supported by NERC; for example the pan-European ice2sea programme, coordinated by scientists at the British Antarctic Survey, made significant contributions to improving our understanding of how melting polar ice will affect future sea-level rise.

in brief . . . ➤ Reports of fish’s demise prove greatly exaggerated Britain’s rarest freshwater fish, the vendace, has made an unexpected reappearance in Bassenthwaite Lake in northwest England, more than a decade after being declared locally extinct. A survey led by CEH researchers turned up a single young specimen. The vendace is a relic of the last ice age, and only four native populations have ever been recorded in Britain. Of these only one in Derwent Water was thought to remain, along with another that was introduced last decade using eggs from elsewhere. This means the news that there are still vendace in Bassenthwaite is particularly welcome.

➤ Gravity satellite mission comes to an end The European Space Agency’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite has come to the end of its four-year life, running out of fuel and breaking up in the atmosphere. During that time it’s mapped variations in the Earth’s gravity in unprecedented detail. Although its planned mission was finished by April 2011, fuel consumption had been so much lower than expected that ESA could squeeze years more life out of it.

➤ Timelines highlight UK

contributions to eight great technologies

Research Councils UK has launched new timelines to highlight UK contributions to the eight great technologies. Science Minister David Willetts identified these as areas of great potential economic importance, in which UK research is particularly strong. They are: big data and energy-efficient computing; satellites and commercial applications of base space; robotics and autonomous systems; life sciences, genomics and synthetic biology; regenerative medicine; agri-science; advanced materials and nano-technology; and energy and its storage. The timelines chart UK contributions in each area up to the present day, including many that arose from NERC funding. They can be found at http://bit.ly/17qkHp1.

PLANET EARTH Winter 2013

9

www.planetearth.nerc.ac.uk

News

NSP-RF / Alamy

Mangrove carbon credits to help Kenyan communities A

new initiative is raising money for community projects in Kenya by protecting and restoring the country’s dwindling mangrove forests.

The plan is to sell carbon credits earned by preserving mangrove swamps to companies and individuals aiming to offset their emissions.

The Mikoko Pamoja (‘Mangroves Together’) project aims to bring in some $12,000 a year, around a third of which will fund projects in areas like education and clean water, selected by a local council. The rest covers the cost of protecting the mangroves and planting new seedlings to replace lost trees.

‘Mangrove forests are one of the world’s most threatened natural ecosystems, with 20 per cent lost in Kenya over the last quarter-century,’ says Professor Mark Huxham of Edinburgh Napier University, one of the project’s leaders. ‘When mangroves are destroyed, the carbon that has been stored in the forest soil and in biomass, built up over thousands of years, is released to the atmosphere and contributes to climate change.’ Mangroves

10

PLANET EARTH Winter 2013

also protect the coast from erosion and act as nurseries for fish and shellfish on which local people depend; cutting them down destroys these benefits.

The project focuses on Gazi Bay, a mangrove-rich coastal area south of Mombasa that’s home to around 3000 people. Initially it’ll cover 117 hectares of mangrove, but Huxham and his colleagues hope this will expand over time, and that communities in Kenya and beyond will be inspired to set up similar initiatives.

It’s the brainchild of Huxham and Dr James Kairo from the Kenya Marine and Fisheries Research Institute, with backing from international NGOs including the Earthwatch Institute and the World Wildlife Fund, from UK insurer Aviva and from the Ecosystem Services for Poverty Alleviation programme, which is partly funded by NERC. By working with local people and ensuring they see immediate benefits, Huxham hopes the initiative will encourage them to take more care of their mangroves, and particularly to be more vigilant about reporting illegal logging.

Daily updated news @ www.planetearth.nerc.ac.uk

Online tool boosts Algae forecasting service wins award ash cloud forecasts A

A

system to provide advance warning of harmful algal blooms has won an award for the most beneficial Earthmonitoring service.

The Harmful Algal Bloom (HAB) Forecast service is the first of its kind, and combines information from on-site monitoring, satellite data and both physical and biological ocean models to provide weekly alerts for fish farmers and regulators along Europe’s Atlantic coast. These provide early warning of the likelihood of toxic algal blooms over the following week. This lets them take steps to minimise the damage.

The system was developed by the European-funded Applied Simulations and Integrated Modelling for the Understanding of Toxic and Harmful algal blooms (ASIMUTH) project, and includes scientists from 11 research organisations and businesses from five European countries.

Among them are researchers at the Scottish Association for Marine Science.

Algal blooms cause enormous problems for fish farmers; each of the partner nations has experienced prolonged closures – up to ten months – of aquaculture areas, often with large losses of farmed fish. For example, in 2006 an exceptionally large bloom off Scotland’s west coast killed many bottom-dwelling animals.

HAB Forecast won the award for Best Service Challenge from Copernicus Masters, a European Earthmonitoring competition that awards prizes for innovative Earth-observation-based solutions to problems faced by businesses and society as a whole. As winner, the service will receive €40,000 worth of satellite data, made available with financial support from the European Commission.

new online tool for predicting the amount of ash pumped into the atmosphere during a volcanic eruption has been made freely available to scientists around the world.

PlumeRise, created by University of Bristol researchers, will help forecast the spread of ash clouds more accurately, paving the way for better management of airspace during volcanic crises.

It has already revealed that the 2010 eruption of Iceland’s Eyjafjallajökull volcano, which grounded planes across Europe, may have unleashed up to ten times more ash than originally thought.

‘Our research represents an important development in our modelling of volcanic plumes,’ says Dr Mark Woodhouse, one of the creators of PlumeRise and lead author on the study, published in Journal of Geophysical Research. Until now, estimates of the amount of ash an eruption releases have relied solely on measurements of the height of its volcanic plume. But that approach is only reliable in still air. To account for the wind, mathematicians and Earth scientists at the University of Bristol created a new mathematical model.

It shows that strong winds stop ash plumes reaching as high as they otherwise would. This means ash estimates relying on plumeheight measurements alone can be far too low.

The team have now turned their model into an online tool that scientists around the world can use to predict how much ash an eruption releases. That information enables better prediction of how an ash cloud will spread, and how airspace must to be managed accordingly.

PlumeRise has been tested by several Volcanic Ash Advisory Centres (VAACs) around the world including the Met Office London VAAC which covers the UK, Iceland and the north-eastern part of the North Atlantic. It is also being used by institutions in Japan, Italy and Iceland.

PLANET EARTH Winter 2013

11

Tracking bats’ movements after release.

Blind as a bat

How do bats navigate by night? Richard Holland has been doing ingenious experiments to find out.

12

PLANET EARTH Winter 2013

‘B

lind as a bat,’ the saying goes. Bats have small eyes and are nocturnal, so the idea is that they have little need for vision at night. Like many popular sayings, this is a misconception; bats actually see well in the dark compared to other mammals of a similar size. Yet it does highlight one question. How do bats find their way around at night when it is dark and visual cues are not available?

Of course, bats use echolocation, making sounds and then listening for the echoes. This system, essentially the same as the SONAR system used by ships, is sophisticated enough for them to detect and hunt small insects at night, out in the open air, and perhaps even navigate around a familiar place.

Echolocation has its limits though. Sound fades very quickly in air, and even though bat echolocation calls are some of the loudest sounds produced by an animal (130 decibels), the maximum range for detecting large landmarks is around 30m. However, we know that bats travel over much greater distances than this, finding their way home from as far away as 700km. Some bats even migrate, making journeys of over 1000km between their summer and winter roosts.

Echolocation can’t explain these feats of navigation.

So how do they do it? When I started to get interested in this question in 2006, the only clues I had were from bird navigation, my original area of research. Birds can navigate using a two-step process that is

Finding your way home in the dark

Bat nav In 2006 I did an experiment to test whether big brown bats also use this system, and found to our surprise that they did. We placed bats in an altered magnetic field at sunset, using a device called a Helmholz coil, which works by passing current through two parallel coils to generate a magnetic field. When the bats were released 20km north of their roost, they would fly off at 90° to their unmanipulated peers. This suggested that they were using the Earth’s magnetic field as a compass to take a bearing.

Experiments I later carried out in Bulgaria on greater mouse-eared bats confirmed this. By fitting bats with a small radio transmitter, we could follow their direction after release. Sure enough, bats that observed sunset in an altered magnetic field were shifted by around 90° compared to a control group. But if they got the same treatment after sunset, there was no difference – both groups flew away from the release site in the same direction, towards home.

This tells us that bats use the sunset to

Fitting a bat with a GPS tracker.

Both images: Stefan Greif

effectively like our navigation with map and compass. They first work out where they are – the map step – and then they fly in the right direction to reach their destination – the compass. In an area they already know the ‘map’ is made up of familiar landmarks, but birds can return from unfamiliar places as well. Here it is less certain what provides the stimulus, but we think the birds may be able to sense changes in the Earth’s magnetic field strength, or subtle differences in smell.

The compass cues birds rely on are much better known – we know they use the sun, the stars and the magnetic field’s direction to take a bearing. Evidence suggests they use these different compasses to calibrate their direction-finding system. In particular it seems that birds calibrate the magnetic compass to the sunset. If the magnetic field shifts at sunset, they miscalibrate and fly off in the wrong direction.

calibrate the Earth’s magnetic field for use as a compass. But the story may be still more complicated. In birds, it’s not the sun itself that is responsible for this calibration, but the polarised light it creates in the atmosphere as it sets. Experiments on birds show that if they view the sunset from behind a polarising filter that rotated the light by 90°, then they fly off at right angles to their normal direction.

With that in mind, I have returned with postdoctoral researcher Stefan Greif to the Tabatchka Bat Research Station in Bulgaria, aiming to test whether bats also set their compass with polarised light cues. As I write this ‘live from Tabatchka’, I am living a nocturnal lifestyle, having got out of bed at 2pm. Last night we were releasing bats until 4.30am, having started the experiment at sunset, when we exposed some bats to an altered magnetic field and others to a shifted pattern of polarisation.

I got to bed at around sunrise. Working on bats is a bit like being a student again.

As well as our experiment on the polarisation, we are also collaborating with Yossi Yovel and Ivo Borissov of Tel Aviv University. They have developed small GPS tracking devices to track bats’ homing

routes. While GPS tracking is widely used on birds, it is much rarer on bats, partly because most bats are too small to carry even lightweight devices. However, Yossi and Ivo have arrived with GPS trackers weighing just 3 grams – the lightest ever built.

The trouble with these devices is we need to recapture the same bat in order to recover the data, but we have already recovered 19 of 24 of these devices so far.

Although the data are preliminary, they are also exciting. Soon we may know as much about bat navigation as we do about how birds find their way around. We’ll no longer be in the dark about how these fascinating animals navigate.

i Dr Richard Holland is a lecturer in Animal Cognition at Queen’s University Belfast.

Email: r.holland@qub.ac.uk.

PLANET EARTH Winter 2013

13

When reports started coming in that southern Britain had been hit by a tsunami, they were hard to believe. But it turns out there really had been one – just not the kind we usually hear about.

Dave Tappin describes the scientific detective work that uncovered the truth.

The 2011 UK meteotsunami

A study in science

14

PLANET EARTH Winter 2013

If the wave starts Video screenshot of the Yealm tsunami, 9.30GMT, 27 June 2011. off in deep water it is very small, maybe just a few centimetres high.

But when it travels into shallow water, it grows taller, especially when the atmospheric disturbance moves at the same speed as the tsunami – we call this ‘resonance’.

But the wave may still be only 20-30cm high. It’s in the final in Devon two days earlier; an amazing period of travel, when the wave approaches video showed a 40-50cm high wave the shore and enters a harbour or estuary, passing upstream. UK tide gauge data that it becomes dangerous, because here from farther east in the English Channel further resonance or the ‘focusing’ effect confirmed the wave had affected a long of more and more water being forced into stretch of coastline. At St Michael’s Mount an ever-smaller channel can create a wave in Cornwall, the causeway was suddenly several metres high. flooded and people reported their hair standing on end. Near Marazion, Simon Spotting the tsunami Evans was digging for bait and compared We first learned about the tsunami from it to a horror movie; it was foggy, and newspaper articles on 29 June reporting suddenly the sea disappeared; he knew a strange event in the Yealm Estuary what it meant and got out of there quickly.

Simon Fitch

‘W

hen you have eliminated the impossible, whatever remains, however improbable, must be the truth,’ Sherlock Holmes said. This was always in my mind after a ‘tsunami’ struck south-west England. My work on the subject is usually overseas, studying the Indian Ocean tsunami of 2004 and Japan in 2011, but in June 2011 we got to investigate an event much closer to home.

Two years on, I still get a kick when I think of this event and how we worked it out – elementary, my dear Watson. Our initial conclusions met with disbelief, but now after a really exciting journey we know they were correct. It is the UK’s first proven example of a meteorological tsunami.

What do I mean by that? Most tsunami are geological, generated from the bottom up by earthquakes, submarine landslides or volcanic collapses that make the seabed move vertically. This causes an ocean wave that travels outward from its source.

By contrast, a meteorological tsunami wave is generated from the top down by a change in air pressure, with the wave being pushed along ahead of the atmospheric disturbance.

HOW A METEOTSUNAMI FORMS A 3 millibar pressure jump over the ocean causes a 3cm wave. As it travels, this increases in height due to resonance. By the time it reaches the head of an estuary it is nearly 5m high.

480cm 280cm

3 mbar

130cm

Estuary

3 mbar pressure jump

45cm

Continental shelf

16cm

3cm wave

Ocean

At St Michael’s Mount in Cornwall, the causeway was suddenly flooded and some people reported their hair standing on end.

The monitoring system of the British Geological Survey (BGS) hadn’t picked up an earthquake, so the first suggestion was that the wave came from an undersea landslide far to the west. Yet the wide extent of the event and the sensation of hair standing on end didn’t fit with a landslide.

After checking the weather conditions on the 27th, my colleague Dave Long at BGS in Edinburgh and I both independently suggested that a storm in the Channel was to blame.

The initial results were posted on the BGS website, and we immediately received an email from a French colleague at the Naval Hydrographic and Oceanographic Service (SHOM) in Brest. He agreed with our overall conclusions, but said the tsunami had been recorded on French tide gauges from the southern part of the Bay of Biscay all the way to Calais in the eastern English Channel – a distance of over 1000km. It was staggering.

More UK tide gauge data confirmed the tsunami extended from Wales to Dover.

I contacted some friendly meteorologists about getting hold of satellite weather data. Luckily, the son of a BGS colleague runs the surfers’ weather site www. magicseaweed.com. The meteorologist there was intrigued and at first dismissive of a tsunami, but after some research agreed it was a possibility.

What about the weather?

Met Office scientists had also been following the event, and Andrew Sibley in Exeter provided meteorological data that quickly began to support the oceanographic model we had produced.

Satellite and radar imagery revealed that on the 27th there was a major low-pressure weather system west of the UK, and that storm cells to the south-west were tracking north-eastwards from Spain to England. It turned out that they passed at exactly the same time as the unusual readings from the tide gauge data.

Some simple calculations on the tsunami’s expected speed supported these observations. But we still didn’t have the whole picture. One of the missing aspects was the rapid change in atmospheric pressure needed to generate the tsunami.

Andrew managed to get hold of data from buoys off Brittany and south-west England. These measurements showed rapid pressure changes as the storm cells passed overhead. Measurements of temperature, pressure and wind speed and direction over Coruna, Spain, taken from a weather balloon, revealed an unstable air mass that would produce downdraughts, again supporting our idea about how the tsunami was generated.

Pulling it all together Although we’d already established the overall picture of the relationships between the weather systems, the tide gauge data and the tsunami, once we had all the data we could see some very interesting details.

The weather system that originated over Portugal/Spain created the tidal anomalies there, and simple calculations of their speed matched the way we knew the wave had moved.

Yet this weather system could not explain the tidal anomalies along the east coast of France or in the English Channel. For these the source had to be off Brittany, as recorded by the rapid atmospheric changes and seen in the satellite imagery and buoy data. But the timing of the tsunami in the Yealm ruled out a source off Brittany – there had to be a local source, and the radar imagery of the weather system over the western Channel showed there was one.

So there were three weather systems, and three separate tsunamis. It was brilliant and unexpected how it all fitted together, and very exciting building the model as the data came in.

Thankfully the UK event wasn’t destructive, but we do know that in the western Mediterranean meteotsunamis can cause serious damage. In the Great Lakes region of North America, an event the previous year created a wave six metres high.

As the oceans warm with climate change, 2011’s meteostunami may be a taste of what’s to come. We now need to consider how we might better record, model and predict these events.

For example, UK tide gauges take measurements every 15 minutes, compared to the continuous recording of our nearest European neighbours. The UK also has highly-developed models to forecast storm surges and tides, but we need to link them to high-resolution weather forecast models. All possible; it just costs money. If meteotsunamis are going to become more common, and perhaps more damaging, this could be money well spent.

i

Dave Tappin is a marine geologist at the British Geological Survey, and Visiting Professor at University College London, with a particular interest in tsunamis.

Email: drta@bgs.ac.uk.

PLANET EARTH Winter 2013

15

In 2010 the UK government committed £75m to a new ship that would lead the world’s marine research capability. As the vessel neared completion, Adele Walker took a trip to Southampton to see how our money has been spent.

Full steam ahead 16

PLANET EARTH Winter 2013

I

’m sitting in an office in the National Oceanography Centre in Southampton, staring at a plan of NERC’s new research ship, RRS Discovery. The plan reveals a marriage of cutting-edge marine engineering and research facilities, with home comforts to boot.

Project Officer Edward Cooper has been involved from the outset of the six-year project which has brought Discovery from a twinkle in NERC’s eye to the dockside at Southampton, her home port. As we talk it’s clear that this £75m baby is more than just a day job.

‘I almost feel bereaved at the prospect of the project ending,’ he confides. And the reality of this endeavour dawns on me; the vision, skill, tenacity, blood, sweat and quite possibly tears that are invested in her.

If you’re not a ship buff you might not give Discovery a second look, but she’s worth it.

Almost 100m long, Discovery is packed with state-of-the art scientific equipment, the infrastructure needed to deploy it, and facilities to keep 28 scientists and 24 crew comfortable at sea for up to 50 days at a time – although the vessel may be away from the UK for six months or more.

‘The ship was designed from the outset to be world-class, world-reaching and flexible,’ says Professor George Wolff from Liverpool University, senior scientist on the Discovery replacement project. Flexibility in this case means a master of all trades, able to work in the most testing conditions and cater for the multidisciplinary marine science for which the UK is renowned.

Physical, biological and chemical oceanography, marine geology and geophysics, ocean engineering and atmospheric science research can all be carried out on board, in some of the planet’s most remote ocean areas. And in an age when no single discipline can fully address our big environmental challenges, the flexibility and breadth of Discovery’s facilities gives scientists from different fields the chance to work alongside each other. Their work will help us address those challenges – such as how we predict and respond to natural hazards, how we manage the effects of environmental change, and how to manage our oceans sustainably so they can flourish and continue to provide us with the resources and services we rely on.

All this is achieved through a suite of built-in or ‘bolt-on’ equipment. Standard are the multi-beam echosounder and acoustic doppler current profilers which use sound to map the sea floor, marine habitats and ocean currents. The largest of these,

Princess Anne meeting the crew.

Below: Princess Anne being presented with a memento by Ed Hill, Director of NOC. Bottom: The bottle smashing ceremony.

VITAL STATISTICS Length: 99.7m Beam: 18m Max draught: 6.6m Gross tonnage: 5952 tonnes Total installed power: 57920kW Top speed: 15 knots Stern/side lift limit: 20 tonnes Fuel capacity: 900,000 litres Fresh water capacity: 210,000 litres Total accommodation: 52 an 8x8m echosounder array, fits in a novel blister on the bottom of the ship; others are fitted on two drop keels which can be lowered 2.5m below the hull, out of the way of interference from bubbles drawn along the hull by the ship’s motion.

Also standard is a CTD – conductivity, temperature, depth sensor – to study the physics of the water column. A second containerised CTD with a Kevlar cable can be used for sampling minute concentrations of trace metals in water without the risk of contamination by a steel cable. Seismic surveys, to investigate the structure and movement of the ocean crust, use equipment towed behind the ship. Discovery also has deep-water, trawling, dredging and coring capabilities, and can take sediment cores up to 20m into the seabed.

And of course there’s all the data-logging and computing equipment to analyse and display the information captured by the sensors.

Some of this capability can be extended beyond the reach of the ship itself using remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) which can be programmed and set off on their own independent mini-missions for months on end. Autosub6000 – designed and built by NOC – gives scientists eyes down to 6000m (nearly 4 miles) to explore and sample otherwise inaccessible habitats and record the creatures living there. Combined with Discovery’s ability to venture into some of the most challenging seas on the planet, this technology will literally take us into new territory.

PLANET EARTH Winter 2013

17

THE SCIENCE The first research to take advantage of the new ship will be NERC’s Shelf Sea Biogeochemistry programme, led by scientists at the universities of Liverpool and Southampton, and Plymouth Marine Laboratory.

Our shelf seas are incredibly rich and important for global fisheries and biodiversity, as well as providing us with carbon cycling, waste disposal, nutrient cycling, renewable energy resources and recreation. They are under considerable stress from things like pollution, overfishing, habitat disturbance and climate change, but we still don’t understand these areas as well as we need to. This programme will address that gap, and provide evidence to support marine policy such as the Marine Strategy Framework Directive and Marine and Climate Acts.

18

PLANET EARTH Winter 2013

This technology will literally take us into new territory.

Wolff’s job was to make sure all the researchers’ needs were built into the design and in particular to address some issues that have the potential to compromise the quality of data collected. For example, NERC’s other ship RRS James Cook has a bulbous bow designed for fuel efficiency but which is susceptible to trapping air bubbles which then run under the hull and interfere with its acoustic sensors.

Discovery’s streamlined, deeper bow and the blister are designed to overcome this.

The ship’s dynamic positioning (DP) abilities are critical to the deployment of scientific equipment. DP keeps the ship in one place using a combination of thrusters controlled by a computer. Discovery can hold her position in sea state 6-7 (waves up to 9m high) and winds gusting to 40 knots which is around 46mph – enough to break twigs off trees and make it tricky to walk.

Discovery has nearly 400m2 of permanent lab space and more exacting research environments can be created in one of the specially designed 20-foot container-labs. A matrix of sockets on deck means that up to 18 of these can be carried, though generally only three will be plugged in and working at any one time. A bit like hooking up

your caravan, there are ports for electricity and freshwater supply, drainage and waste disposal, phone, internet and fire alarms.

As well as adding flexibility, the containers ensure that highly sensitive work can be conducted in very controlled conditions without risk of cross contamination and compromise of results.

The research equipment might take the limelight but there’s a plethora of equally marvellous behind-the-scenes stuff that’s critical for deploying it safely and effectively. There’s a vast room on the main deck devoted to a complex suite of electric winches, for lowering or towing different equipment along the seabed or through the water. These handle five cables ranging from 8000m of synthetic rope to 15,000m of steel wire (yes that’s 15km – a three-hour walk), as well as a 10,000m fibre-optic tow cable. Heave compensation on some of the winches protects ROVs from damage should the ship move suddenly and allows the delicate instruments to be held steady in the water column.

The ship’s cranes and gantries have to take the weight of the equipment and also of the cables, which can experience quite violent forces as the ship moves with

wave and swell action. A double gantry on the starboard deck makes it possible for one piece of equipment to be ready to be lowered almost as soon as another is landed. Everything has its own specific storage, deployment and recovery needs, and Discovery can cater for them all. The ROV Isis comes with its own gantry, six containers of kit and a two-container

GOODBYE TO THE OLD DISCOVERY When the previous Discovery was built she was expected to last for 25 years. A 1992 refit gave her another 15; when she came home to Southampton after her last voyage in December 2012 she had surpassed this by an additional five years and overall had been plying the seas for half a century.

The UK’s oldest research vessel had carried out 382 missions.

Her final voyage was to Ghent in Belgium to be recycled.

Many researchers, officers and crew associated with the ship have shared their memories of expeditions and life on board this venerable vessel on a blog http://memoriesofdiscovery. blogspot.co.uk/

control room – some 90 tonnes of equipment.

NERC accepts applications for research cruises based on scientific excellence, and researchers then book facilities and equipment. It can take up to three years from first applying for a grant to the cruise setting sail. The programme is full for the foreseeable future.

Geraint West is Director of National Marine Facilities, which as well as the ships, includes the National Marine Equipment Pool – £20m-worth of equipment that NOC looks after on behalf of the UK science community. He explains how costs are reduced through an international barter system, in which each nation’s research facilities and equipment are worth a number of points per day.

Over recent years it has saved millions in reduced fuel costs, with the added benefit of enabling science and technology interactions between countries.

West and his team are also responsible for the ship’s material state, as well as liaising with bodies such as Lloyds and the Maritime and Coastguard Agency to ensure that she is properly certified to operate worldwide. They are also on standby whenever Discovery is at sea; if there’s an incident they’ll take control and provide support to the ship.

Discovery is self-sufficient at sea for 50 days, carrying around 210,000 litres of fresh water which is topped up with desalination in the ship’s vacuum evaporators after around three weeks. For a six-month cruise she carries as many nonperishable goods as possible and the purser organises resupply with local agents. This means setting off with around 50 tonnes of food on board; it sounds a lot, but it’s not much on top of the hundreds of tonnes

(getting on for half a million pounds-worth) of fuel; then there’s around 35,000 litres of lubricating oil and all the spare parts that are needed to keep the ship running.

As for the scientists and crew, they’re maintained with regular meals prepared in the substantial galley, and have a mess, bar/lounge, video room and fitness suite.

There’s an internet café, a conference room and library, and everyone has their own cabin to escape to when it’s time to get some shut-eye. Spending upwards of 40 days out of sight of land can be pretty stressful, and relaxation, exercise and creature comforts are essential to make sure everyone ‘decompresses’.

There’s also a well-equipped hospital – Discovery doesn’t normally carry a doctor but there are officers with medical training on board, and 24/7 access to expert medical advice from shore.

The hospital, we hope, won’t see much use. But Discovery herself operates 24/7, with the continuous demands on infrastructure and home comforts of a floating village.

‘The ship never stops,’ says West. ‘Even in harbour there’s always something going on’.

i

Discovery was funded by NERC and the Large Facilities Capital Fund which is administered by NERC’s parent department, the Department for Business, Innovation & Skills.

Contact Project Officer Edward Cooper ebc@noc.ac.uk Web address: http://noc.ac.uk/research-at-sea/ships

PLANET EARTH Winter 2013

19

There has been a lot of noise lately about the role of Arctic methane emissions in global climate change. But we need repeated measurements and careful analysis of the results before we’ll know for sure how important these emissions are.

Sam Illingworth describes a current project that’s trying to do just that.

I

n days gone by, miners would take canaries down into the mineshafts with them, not as pets but as biological detectors of harmful gases that may be present underground. Signs of distress from the bird indicated that concentrations of these gases were too high, and that conditions had become unsafe.

Because of a series of positive feedbacks – for example, a loss of sea ice makes the sea darker and less reflective, so it absorbs more sunlight, melting still more ice – the Arctic feels the effects of global warming more strongly than anywhere else. So it can be thought of as the Earth’s canary: signs of distress indicate that we are approaching unsafe conditions.

The Arctic is also home to large reservoirs of methane, in the form of permafrost soils on the land and methane hydrates beneath the seabed – a hydrate is a substance that contains water. A warming climate may destabilise both. Methane in the Earth’s atmosphere is an important greenhouse gas; over 100 years, its impact on climate change is over 20 times greater than that of carbon dioxide, on a moleculefor-molecule basis. The melting of these

Monitoring Earth’s canary

Rugged Arctic landscape of Svalbard, seen from the FAAM atmospheric research aircraft.

20

PLANET EARTH Winter 2013

large Arctic reservoirs and their subsequent release into the atmosphere could therefore have potentially catastrophic implications for Earth’s climate. This means it is crucial that we to try to understand the relative strengths of these potential sources of methane.

As well as possible large-scale emissions of methane from these permafrost soils and hydrates, the Arctic wetlands – land consisting of marshes and swamps – are also thought to be significant sources of methane, thanks to a species of microorganisms known as methanogens.

Methanogens produce methane as a byproduct of respiration, and need lowoxygen conditions to thrive. Wetlands are an ideal breeding ground for such bacteria; another is the digestive tract of humans, where they are somewhat delightfully responsible for flatulence.

Further complicating matters is the issue of transport, in which methane from sources as far away as Canadian wild fires can be transported high into the atmosphere and across to the Arctic. So even if we know there are high levels of methane over the Arctic, we can’t be sure if

Wetlands of Sodankyla in northern Finland, showing the walkways where the team make ground-based measurements.

Dave Lowry

it comes from wetlands, melting permafrost and hydrates, or from another part of the world entirely. All this means we urgently need consistent and precise measurements of Arctic methane, coupled with a detailed and thorough analysis of the results. This will let us say not only how much methane is being emitted, but also exactly where it has come from.

The Methane and other greenhouse gases in the Arctic – Measurements, process studies and Modelling (MAMM) campaign, part of the NERC Arctic Research Programme, aims to address these issues. As well as ground-level measurements of how much methane is emitted and absorbed over both the land and sea, part of the campaign has involved measuring atmospheric composition using the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 atmospheric research aircraft.

This is a commercial jet that has been modified to carry a large suite of scientific instruments, enabling it to make precise measurements of greenhouse gases including methane, carbon dioxide, water vapour, carbon monoxide and nitrous oxide. It has a range of over 3000km, can reach heights of about 10km, and can fly for more than five hours carrying 21 crew and scientists.

MAMM included three separate flight campaigns, one in July 2012 and two more in August and September the next year. In each case, measurements were made over similar locations, with the idea being that repeated measurements at different times of the year would give us a better idea of the effect of seasonally differing variables such as temperature, as well as increasing confidence in our findings.

One of the key tools in analysing the data is to perform isotopic analysis on bags of air that have been sampled in mid-flight.

Isotopes are simply variant forms of the same element. They have equal numbers of protons but different numbers of neutrons in their nuclei. For example in the case of MAMM we are primarily interested in the ratio of Carbon-12 to Carbon-13; the Carbon-12 isotope contains six protons and six neutrons, whilst the slightly heavier Carbon-13 isotope has six protons and seven neutrons.

The ratio of Carbon-12 to Carbon-13 in a sample of air varies depending on where it originally came from. This method effectively lets us ‘fingerprint’ the atmosphere; by analysing the sampled bags we can then say whether the air in them has come directly from the wetlands that were below the aircraft at the time of sampling (‘isotopically light’), or if

instead we are looking at a parcel of air that contains methane originating from a North American fire (‘isotopically heavy’).

By comparing these fingerprints to other measurements that are made on the aircraft and on the ground, we can better understand both the concentrations and sources of methane emissions in the Arctic. In turn this will provide insight into the present and future effects on Earth’s climate as a result of global warming – hopefully before Earth’s canary stops singing for ever.

i Dr Sam Illingworth is a post-doctoral research assistant in the Centre for Atmospheric Science at the University of Manchester. Email: samuel.illingworth@ manchester.ac.uk. The MAMM project is led by Professor John Pyle of the University of Cambridge.

Further details of the MAMM project can be found on the blog: http://arcticmethane. wordpress.com.

A series of audio field diaries and interviews hosted by the Barometer podcast (http://thebarometer.podbean. com/) give further insight into the project and the people behind it.

Jennifer Müller

PLANET EARTH Winter 2013

21

Fixing broken

ecosystems

22

PLANET EARTH Winter 2013

The world’s growing population is increasing demand for resources like food and clean water – but more people means more waste, and that’s having a direct impact on those resources. But all is not lost: Jags Pandhal and colleagues describe a new technique for cleaning up ecosystems that has knock-on economic benefits too.

W

ith Earth’s population predicted to exceed nine billion by the middle of this century, providing enough food, water, medicines and renewable energy is becoming a major challenge. At the same time, global economic growth means more waste from industry and agriculture is making its way into the environment, and this pollution damages the ecosystems that we rely on for so many of our resources.

One very visible example is eutrophication. This happens when too many nutrients such as phosphorus and nitrogen reach our water systems, causing a bloom of overfed algae. Algal blooms make water undrinkable and starve it of oxygen. This damages wildlife and biodiversity and in turn affects fisheries and tourism, and the toxins released can be a severe health hazard.

2013 saw China’s largest algal bloom on record and the Chinese government has pledged £400 billion over the next decade to meet increasing drinking-water demand. But blooms are on the increase everywhere; more than three-quarters of England’s freshwater systems are classified as eutrophic, with estimated clean-up costs of up to £114 million a year.

Climate change could add to the problem, as warmer temperatures and changing rainfall patterns can encourage algal growth.

A fisherman wades in Chaohu Lake, covered in blue-green algae, in Chaohu city, Anhui province. REUTERS/China Daily

No silver bullets There are several ways to prevent or treat eutrophication, though each has limitations. Legislation to control the nutrients coming from industry, sewage or agriculture has made the future look brighter, but because stored phosphorus continues to be released it can take decades before we see any improvement.

There’s ecological engineering, for example chemically fixing nutrients to the sediment to stop them causing damage, or protecting our natural wetlands so the plants can soak up excess nutrients before they can cause a bloom. Or there’s biomanipulation, for example encouraging the growth of algae’s natural predators. Alternative methods include barley straw and ultrasound (see Planet Earth Summer 2013, pp30-1).

An attractive option is to remove the algae, but doing this efficiently is a challenge. The good news is there are economic as well as conservation reasons to get better at it; but despite the algal biofuel industry’s efforts over the last decade, harvesting still accounts for as much as 30 per cent of industry costs. One of the most popular harvesting methods, dissolved air flotation (DAF), widely used by the water treatment industry, is considered too expensive to use on a large scale. But all that could be about to change.

PLANET EARTH Winter 2013

23

Eco-technology: Microflotation with bubbles DAF clarifies wastewater by removing solids suspended in it. It works by saturating water with air under pressure, then releasing it through a diffuser which causes bubbles to form. A chemical flocculent is added to make suspended particles in the water clump together, and the bubbles float the solids to the surface where they can be more easily removed. It works, but it uses a lot of energy.

Now our team at Sheffield, led by Professor Will Zimmerman, has developed a cheaper alternative. The breakthrough has been in how the bubbles are made. Conventional DAF mechanisms depend on their diffuser to generate microbubbles, which break off when they are big and buoyant enough.

Our system, microflotation (MF), has no moving parts but instead uses the dynamic properties of the water itself. As air enters the system the water flows from side to side due to the so-called Coanda effect, which dictates the direction of fluidic flow. This fluidic oscillation releases bubbles at the infant stage, much sooner than if they had to break free by themselves.

With just a small amount of flocculent, these tiny bubbles can float microscopic particles like algae cells to the surface of the water.

Traditional bubble-based separation systems are expensive because they have to pump both gas and liquid to make their bubbles, and pumping liquid takes a lot of energy. MF only pumps gas so it uses a fraction of the energy. It doesn’t use large saturation tanks and needs none of the expensive safety certification required for operating in high-pressure conditions; in fact it has no moving parts. Essentially, MF can produce the same effect as a standard DAF system but at just 5–10 per cent of the capital and operating costs.

So far so good: MF works well in the lab but how do we scale up the process to make it commercially viable? MF bubbles last for a long time and can efficiently process around 200l of water. Where a large body of water needs treating one option would be to have MF operating in a lagoon from which treated water is released. We’re also looking at the use of organic flocculants and how these can be chosen to complement water characteristics, for example pH, and the

Microflotation can produce the same effect at just 5–10 per cent of the cost.

i

Jagroop Pandhal is the NERC/TSB Research Fellow for the Algal Bioenergy Special Interest Group (AB-SIG) and based in the Department of Chemical and Biological Engineering at the University of Sheffield. Email: j.pandhal@sheffield.ac.uk Professor Will Zimmerman is an expert in microfluidics and inventor of the technology, in the same department.

James Hanotu is a Consulting Project Engineer for Perlemax Ltd, working on microflotation trials and the application of microbubbles in bioreactors.

24

PLANET EARTH Winter 2013

types of algae being removed. Once these questions are resolved, microflotation could be a crucial tool for both conservation and the biofuel industry.

Good for the environment …

Many environmental problems we face today are an indirect result of mankind’s engineering progress, so it’s fitting that our engineering proficiency should help solve them. But before we use microflotation in the environment, we need to use all our scientific expertise to assess the possible effects on biodiversity and ecosystems, and make sure the technology does good and not more harm. As an important first step, we are developing techniques using proteins to give us a snapshot of what is happening to the water biology in lab experiments. We’re combining this data with more traditional ecology approaches that will help us predict and control the effects of microflotation in the environment. Laboratory experiments must be moved into the field as natural ecology is a much more complex system. … Good for the economy The secret to making biomass removal even more cost effective is to find other ways of making money out of the process – and there are many. Microalgae grow very fast and are very efficient at converting the sun’s energy into forms we can readily use.

They store energy as lipids or fats (some species are up to 76 per cent lipids), which can be converted to bio-diesel and jet fuel, or used in cosmetics and drugs. Algal protein can be turned into animal feed or food supplements, and the carbohydrates can be converted to ethanol and methanol.

The algae themselves can be directly fed into anaerobic digesters to produce methane, or used as a fertiliser which helps restore the structure of eroded soils.

In an age when we have to balance protecting the environment with the challenge of sustaining a growing human population, we need innovative technology more than ever. Algal blooms are becoming more prevalent around the world as a direct result of human waste and carelessness.

Stopping them happening is paramount, but with smarter technology and the right financial drivers we can start to fix these broken ecosystems and benefit both the environment and the economy.

Climate research helps fight terror threat The fatal incidents at the Boston marathon earlier this year highlighted yet again the threat of terrorist bombs and chemical attacks. Security forces will be on high alert at such events but how can they be sure someone is carrying explosives until the damage is done? Damien Weidmann explains how climate change research could give them the upper hand.

D

ecades of research into climate change have led scientists to develop a range of techniques for measuring the levels of greenhouse gases in the atmosphere. These include remote sensing, using instruments flown on satellites which can accurately measure even very low concentrations of gases across large distances, using radar or lasers.

Because explosives emit tiny amounts of gaseous chemicals, they have potential to be detected in the same way as greenhouse gases but until recently there were no equivalent instruments for detecting these chemical traces at ground level.

Funded by the Centre for Earth Observation Instrumentation (CEOI), a collaboration of academic and industry researchers, scientists at the Rutherford Appleton Laboratories have now adapted a remote-sensing instrument called an Active Coherent Laser Spectrometer (ACLS) to do just that.

ACLS works on the principle that different chemicals have a unique effect on the wavelength of light that passes through them.

It directs a beam of laser light towards the area of interest, which is reflected off buildings and other surfaces back to the spectrometer.

Any chemicals present in the laser’s path will change the properties of the returning light so the spectrometer can detect exactly which chemicals are present and their concentration.

The technology is already effective at a distance of 50 metres from its target and it will be able to operate up to several hundred

metres, so it can be used with no risk to the operator. The laser is harmless to eyes and the trolley-mounted kit is compact (with plans to produce a tripod-mounted version), robust and cost effective. It’s also quick, giving results in seconds to a minute depending on the accuracy needed. ACLS has wider applications too. It can be used by fire services to check for hazardous chemicals at accidents and fires, and by the military to monitor for chemical warfare agents. Environment agencies can use ACLS to remotely monitor pollution from factories and local councils will be able to use it to check air quality.

CEOI is behind a wide range of innovative new instruments that measure our weather, our atmosphere, the ice caps and many other aspects of the natural environment. The Active Coherent Laser Spectrometer is just one example which is finding fascinating and potentially life-saving applications in everyday life.

i

ACLS project lead is Dr Damien Weidmann, STFC Rutherford Appleton Laboratory. Email: damien.weidmann@stfc.ac.uk.

For more on this technology and others funded by the CEOI visit www.ceoi.ac.uk

PLANET EARTH Winter 2013

25

The noise and wasteland of a gravel quarry and the serenity of a nature reserve – all in one place. Sue Nelson meets a group of people with a shared interest in Cambridgeshire’s Paxton Pits Quarry.

New for old Sue Nelson: I’m with David Payne from the Mineral Products Association, at Paxton Pits, an old sand and gravel quarry.

David, what normally happens at the end of a quarry’s life?

David Payne: These days, there are usually legal agreements that require the quarry company to restore the land to fit in with the landscape. That can be agriculture but more often than not these days it means creating habitats for wildlife. Most of this site is now a nature reserve.

Sue Nelson: Let’s head over to the nature reserve now… what a difference between the masses of gravel and noisy diggers where we were to what is now a very serene lake with water lilies, bulrushes, birds flying overhead. It’s absolutely beautiful.

Jim Stevenson, you’re a senior warden here.

It’s hard to believe that this waterside was once a quarry.

Jim Stevenson: Yes it is. This is the Star Lake – we’ve had bitterns in here, we’ve got otters and there’s a good chance of seeing

26

PLANET EARTH Winter 2013

a grass snake today or a kingfisher flying past. And the meadows past the briars and wild rosebushes there, were also quarry land that was first backfilled to restore it to agriculture, and now it’s the heart of the nature reserve.

Sue Nelson: Helen King from Cranfield University, you’ve been working on a report on ecosystem services and part of it relates to quarries. Ecosystem services sounds very corporate and jargony – what does it mean?

Helen King: In the past we only considered the value of land in terms of static resources, like minerals, timber or food. The ecosystem services approach also considers the natural processes that we benefit from effectively for free, such as water cycling or carbon storage. If we can formally assess the value of these we can make better decisions relating to the environment.

Sue Nelson: OK, so how do you apply the ecosystem approach to a quarry?

Helen King: In several ways. You can use it when planning how you’re going to restore the land, then in how you manage that restored land to encourage the generation of different ecosystem services. Then to actually put a value on the ecosystem services that land is providing.

Then you can see whether those services are increasing, and communicate to others the services a piece of land is providing.

Sue Nelson: Cas Jewell, you work for Nature After Minerals, a partnership between Natural England and the RSPB. What do you think when you see an area like this?

Cas Jewell: It’s a fantastic example of what restoration can provide for wildlife.

We’ve got reedbeds, wet grass and lowland meadows – all are important habitats for biodiversity. And today we’ve seen families looking at wildlife, school groups doing pond dipping, people birdwatching. This shows just some of the ecosystem services that quarry restoration can give – not only nature conservation but health and

Images Boffin Media

In some ways our image of quarrying is stuck in the Dark Ages. wellbeing for local communities too.

Helen King: We call these cultural services, things like relaxation and education. There are three other ecosystem services in the approach: things like food, materials, timber and minerals we call provisioning services; then you’ve got regulating services such as cycling of water and air, pollination and carbon storage.

And then you’ve got supporting services that underpin all the others; these are biophysical processes, like soil regeneration.

Sue Nelson: Cas, how easy is it to transform a completely bare quarry, with no green in sight, into something like this?

Cas Jewell: One thing we’re keen to promote is that you can actually support wildlife before, during and after extraction.

It’s possible to create nursery beds for plants while extraction is still going on. Then at the end of the quarry’s working life you can reshape the hole and either wait for natural regeneration – because habitats like heathland regenerate very well on their

own – or use the nurseries to repopulate the land.

Sue Nelson: David, the Mineral Products Association is a key partner on this report.

What are you going to do with Helen’s findings?

David Payne: We’re going to use them to educate our members and translate ecosystem services into simple language for companies to use, for example, applying for planning permission for a new site and they need to think about the wider potential benefits right from the beginning. It will also be important for demonstrating to various communities the benefits that can be delivered through a working quarry and its restoration.

Cas Jewell: And we’ll use it in some EUfunded work the RBSB is doing, as part of a toolkit to measure ecosystem services in quarries and try to put some relative economic value on different restorations, which we hope will help operators in their planning.

i This Q&A is adapted from the Planet Earth Podcast, 6 August 2013. The full podcast and transcript are on Planet Earth Online http://planetearth.nerc.ac.uk/multimedia/ story.aspx?id=1297 Paxton Pits Nature Reserve www.paxton-pits.org.uk/ Mineral Products Association www.mineralproducts.org/ Nature After Minerals www.rspb.org.uk/ourwork/policy/planning/ mineralsplanning.aspx The Ecosystem Services Approach to Quarry Restoration report can be downloaded from http://dspace.lib. cranfield.ac.uk/handle/1826/8024

Helen King: The ecosystem services approach has massive potential for quarry restoration. Restoration work has been going on for a long time and the companies are already familiar with things like the Nature After Minerals project. What will be new is giving them the opportunity to record, assess and communicate these benefits to the wider public and to policymakers. In some ways our image of quarrying is stuck in the Dark Ages – we think of noise and the dust but there’s a huge amount of good stuff coming out at the end.

PLANET EARTH Winter 2013

27

Moon jellyfish.

Sex, plankton and predators Tania FitzGeorge-Balfour has been looking into why females rule the marine lonely-hearts column.

28

PLANET EARTH Winter 2013

C

opepods are small (1-4mm) crustaceans with elongated bodies and large antennae. They dominate the plankton in the marine environment, which is why they are often called the insects of the sea. Like other crustaceans, they have an armoured exoskeleton – a hard outer casing that protects their soft bodies. They moult as they grow, leaving their old exoskeleton behind. Like many other animal plankton, copepods are often near-transparent. We think this helps them avoid predators in an environment where there is nowhere to hide.

Don’t be fooled by copepods’ tiny size – they are a vital part of the marine food web. Copepods are usually the dominant animal in the plankton – in fact, they are the most abundant animal on the planet – and are the main prey of many larger marine animals such as fish, jellyfish and whales. Scientists have long recognised their significance in the marine ecosystem,

but while their growth, reproduction and feeding habits have been well studied, there is still a lot we don’t know.

A curious phenomenon – occasionally reported, but not well studied – is that adult female copepods often outnumber the males, sometimes by more than 10 to 1. It is important to understand what causes this, because at times there are not enough males to fertilise all the females. This restricts population growth, even when all other factors, such as the abundance of food, favour a population boom. In turn, this limits the copepods available as food to fish and other predators.

Why are there so many more females?

First, we need to be certain that equal numbers of females and males are born. This is true for most species, for reasons explained by the evolutionary scientist Ronald Fisher in The Genetical Theory of Natural Selection, published in the 1930s. He starts from a scenario

Close up of a moon jellyfish Aurelia aurita.

where male births are less common than female. A newborn male then has better mating prospects than a newborn female, because he has more females to choose from. Males with genes that cause them to have more male offspring are at an even bigger advantage. This means the genes for male-producing tendencies spread, and male births become more common. The advantage associated with producing males then dies away as the sex ratio reaches equilibrium. A recent study examining sex ratios in juvenile and adult copepods has shown this is as true for copepods as for other animals – female dominance only appears in adulthood, after the last moult of the exoskeleton; the younger developmental stages have equal sex ratios.

In the mid-2000s, scientists spotted a pattern in the species of copepods exhibiting adult female dominance.

The females of these particular species can store sperm. This may have evolved because of the difficulty of finding a mate in the vast three-dimensional ocean. The ability to store sperm changes the dating game – mating with such a female is very advantageous to a male. One successful reproductive encounter could lead to many offspring, all with his genes.

Observations of how these copepod species behave have shown males and females exhibit different swimming patterns. The females swim slowly, only moving rapidly to feed, while the males seem to search constantly for a mate. In fact, a 16-fold difference in swimming speed between males and females has been reported in some species. However, while swimming faster may increase the chance of finding a female, it will also increase the risk of an encounter with a predator.

So have the missing males died through predation, on the quest for a mate?

Unfortunately, it is more complicated than this, as male copepods develop faster and naturally die sooner. However, after we accounted for differences in lifespan and development rates, the evidence still suggested that males suffer from much higher predation. This left us asking which marine predators are responsible for eating all the male copepods? The next step was to examine feeding rates on male copepods directly.

Jellyfish gender control We focused on the moon jellyfish Aurelia aurita, common in coastal waters worldwide. Jellyfish are good predators to study because we need to understand their impact on the wider ocean ecosystem

Both images: Alexander Semenov/Science Photo Library

– some studies suggest their numbers are increasing. We know they are voracious predators, often outcompeting others, such as fish, for food. However, we do not know if some prey are more likely to be caught than others – for example, does the size and speed of prey increase or decrease their risk of being eaten?

We used Aurelia provided by the aquarium at the Horniman Museum and Gardens in London, which enabled us to perform many single experiments using similar-sized jellyfish. This would have been challenging if we had relied upon natural Aurelia populations. It is hard to collect them from the wild, as jellyfish blooms can be difficult to predict and do not last long.

Our experiments examined how quickly the moon jellyfish fed on the males and females of two different species of copepod.

The first, Acartia tonsa, has as many males as females in the marine environment, and the two sexes swim in a similar way.

In contrast, the males and females of the second copepod, Oithona similis, have very different swimming speeds, and the population is often female-dominated.

We found that predation rates on the males and females of both copepods were similar. This suggests the large difference in the number of males and females observed in natural populations of Oithona cannot be caused by predation by jellyfish like Aurelia.

To try to understand why fasterswimming male Oithona similis were eaten in the same numbers as the females, we estimated how often males and females encounter the jellyfish, taking into account the size and swimming speed of both predator and prey. We found encounter rates differed only by 9 per cent, despite the 16-fold difference in swimming speed between the male and female Oithona similis. The jellyfish’s much larger size (45mm compared to less than 1mm for the

copepod) and faster swimming overrides the comparatively smaller differences in swimming speed between the males and females. Essentially, what seems like a large difference in swimming speed in the copepod world is nothing compared to the large jellyfish, cruising rapidly through the water column.

Jellyfish are just one type of copepod predator. Other predators use different methods to detect their prey. For example, many fish are visual predators and may spot a faster-moving male copepod; however, females are often larger and more pigmented, which may also increase their risk of being eaten.

Chaetognaths, commonly known as arrow worms, are voracious predators of copepods and detect their prey by sensing their movements in the water. This might mean that faster-moving prey, such as some male copepods, are more vulnerable. There is some anecdotal evidence to back this up – analysis of chaetognaths’ stomach contents suggests they eat male copepods more often than females.

What we need now is more research on other predators and their relationship with different kinds of copepod prey. In the meantime, our study takes us a step closer to solving the mystery of the missing males.

i This work was completed while Dr Tania FitzGeorge-Balfour was a postdoctoral researcher at the Queen Mary University of London (QMUL), supervised by Dr. Andrew Hirst of QMUL and Dr Cathy Lucas of the National Oceanography Centre in Southampton.

Email: t.fitzgeorgebalfour@gmail.com

PLANET EARTH Winter 2013

29

what’s going on up there?

30

PLANET EARTH Winter 2013

The upper atmosphere can have a major impact on our increasingly high-tech lives, but what factors influence its state?

Maths student Anna Senkevich took a placement at the British Antarctic Survey and set out to investigate.

E

mbarking on my first research project was both exciting and terrifying. I had taken up the opportunity of a summer placement at the British Antarctic Survey (BAS), which would give me research experience and the chance to apply my maths programming and analysis skills to something new: climate change.

My first task was to brush up my basic atmospheric physics. Wading through the alien terminology was hard at first, but I soon began to recognise more and more words and acronyms – seeing a familiar term became like meeting an old friend.

And before I realised it, I knew exactly what this research was about and why it is so important.

We might not give much thought to the upper atmosphere (roughly 50–800km above the surface) as we go about our business, but what happens up there can affect the space-based technologies on which we increasingly depend.

Among the many layers in the atmosphere, a critical one for modern communications is the ionosphere, about 85-600km up. The Sun’s radiation strips electrons off atmospheric molecules in this layer and creates a mixture of electrons and ions known as plasma. The height and electron density of the ionosphere depend on the amount of solar radiation, so these characteristics vary with geographical location, season, time of day and solar activity.

The characteristics of the ionosphere have a strong influence on the movement of radio waves, so global navigation systems like GPS and high-frequency radio communication systems are particularly susceptible to changes there. Satellites are

also at risk from changes in the density of the atmosphere, which affects drag and can send them off course.

One thing we know to be affecting the upper atmosphere is climate change.

While the average global temperature at Earth’s surface has increased over the last three decades, the upper atmosphere has cooled. This is thought to be mainly due to an increase in the concentration of greenhouse gases; these trap heat in the lower atmosphere but remove it from the upper atmosphere by emitting infrared radiation into space. As the atmosphere cools it contracts and the layers move downwards. If cooling is the only influence on the atmosphere we would expect it to have the same effect on the height of the ionosphere everywhere, and the electron density should not be affected much.

My job at BAS was to see whether these models of atmospheric change are borne out by actual observations from data stations around the world – to see whether cooling alone can explain changes in the upper atmosphere. In particular I would focus my maths skills on identifying trends in the height and density of the F2 layer, the most dense layer of the ionosphere.

Previous observations – of changes in atmospheric temperature at a fixed height, changes in satellite orbits and of the decrease in the height of the F2 layer – all seemed to agree with the model.

When data from more stations around the globe were analysed, it was clear that the height of the F2 layer varied from station to station, both in the size and direction of the change. We also found unexpected changes in its electron density.

This didn’t necessarily mean the model was wrong, but it did mean that cooling

400 Altitude (km)

What happens in the upper atmosphere can affect the space-based technologies on which we increasingly depend.

350

F2 LAYER 300

geomagnetic activity (occurring when the solar wind buffets the Earth’s magnetic field) – can’t be tested until we have longer datasets and better global coverage. The key to better understanding lies in close monitoring and analysis of global data, for which international cooperation is crucial.

This research experience was incredibly rewarding and timely.

Learning new skills and tackling problems gave meaning to my parents’ words: ‘It’s not the grades that matter, but the knowledge.’ I will return to university with more confidence in working and learning independently.

As for my results, they confirmed that the changes in the upper atmosphere are not as simple as they seemed initially. Further analysis of my findings will, I hope, shed more light on the correlation between those influences and the local variability in the ionosphere that could be so critical to predicting and avoiding harm to our space-based technologies.

250

F1 LAYER

200

150

Ionosphere begins

E LAYER Thermosphere 100

Mesosphere 50

Stratosphere

i

Electron density (Logarithmic scale)

PLANET EARTH Winter 2013

31

1,000,000

0

100,000

Her eight-week research placement at BAS was sponsored by NERC.

0

10,000

E-mail: as225@st-andrews.ac.uk

Troposphere 1,000

Anna Senkevich is a mathematics student at the University of St Andrews.

100

alone wasn’t enough to explain what was happening – if it were then the changes in the ionosphere would be more consistent across the data stations.

Finding out exactly what is going on is complicated by the dependence of the ionosphere on solar radiation, not least the effects of the 11-year solar cycle. Our data only covered a relatively small number of cycles, so I had to find a way of detecting patterns of change that were happening independently of the Sun’s activity.

One approach is to look at the timing, rather than the actual values, of the daily peaks in F2 height and electron density; both are expected to occur at a particular time of the day, depending on the season and location. This involved analysing large amounts of data of varying quality, dealing with gaps and accounting for trends that didn’t have an obvious cause – now my maths modelling experience was critical. It was worth the effort. My analysis revealed shifts in the timing of the height and density peaks, which varied from station to station and in size and direction. So the changes were real, and cooling could not be the only cause.

I had confirmed the question, but we still need to answer it. One important factor could be magnetism: my supervisor at BAS had previously found that changes in the Earth’s magnetic field could be even more important than greenhouse gases in explaining trends in F2 layer height. This is because ionospheric plasma tends to flow along magnetic field lines and horizontal winds can cause the plasma to move up or down, changing the height of the F2 layer.

However the real significance of magnetism – and other possible factors like long-term changes in solar and

Back issues

Available as downloads from www.planetearth.nerc.ac.uk

Natural Environment Research Council, Polaris House, North Star Avenue, Swindon, SN2 1EU, UK. Tel: 01793 411500

www.nerc.ac.uk