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Fifteen

International Perspective

Profiles of PhD students …

International Perspective

International Perspective

Profiles of PhD students

From jellyfish, dolphins and seals in the waters off Scotland to amphipods 10,000 metres down in the Kermadec trench near New Zealand, the research going on in Scotland is diverse and international – and the PhD students themselves come from countries all over world (including Scotland).

 

 

 

 

 

Chad Widmer
University of St Andrews

The effects of climate variability on life history stages of British jellyfish

Chad first came to St Andrews on vacation and liked it so much he is now a post-graduate there, writing his Thesis on jellyfish. In fact, it was his sighting of a blue fire jellyfish on the beach at St Andrews that first sparked his interest. Having spent 13 years working at an aquarium in California, Chad had also developed a strong interest in conservation. His research into jellyfish investigates “why we see them, where we see them” in relation to climate – e.g. they are more common after cold winters and grow more quickly during warm summers. What mechanisms drive this and what can we learn about climate (including temperature and salinity) by studying jellyfish?

Chad has also advised Scottish fish farms on how to control their jellyfish populations, which can harm their salmon. For example, the platforms used for cages can be ideal breeding grounds for jellyfish – home to ten polyps per square centimetre, each producing 20 jellyfish per year. Jellyfish are also a barometer of climate change, according to Chad, indicating when the ecosystem may be out of balance and reflecting short-term changes in climate.

Chad describes his project as follows: “Jellyfish play important roles in pelagic ecosystems, acting as zooplankton predators and food for a small host of organisms. Seasonally, they form blooms which facilitate their reproductive success, but these can sometimes be problematic for human enterprise. In the last few decades, the idea has arisen that the frequency and size of jellyfish blooms have been changing, increasing in some areas while decreasing in others. However, the direct causes for these changes are unclear. Jellyfish medusae abundance depends on success at all stages of the life cycle. Therefore, to better understand how climate variability may affect the timing of jellyfish blooms and their potential locations and magnitudes, it is important to study how factors associated with climate affect all jellyfish life history stages. I use the results from my laboratory experiments to generate basic statistical models which enable the prediction of the magnitudes of future jellyfish blooms. The general trend is that more jellyfish will be observed in British waters during summers following very cold winters, and fewer jellyfish will be observed following warm and mild winters.”

 

Silje-Kristin Jensen
University of St Andrews

Is toxin from harmful algae the reason for the Scottish harbour seal decline?

Harbour seal populations in some parts of Scotland have declined dramatically in recent years, and Silje is investigating if this is caused by particular toxins produced by algae and then passed along the food chain. How do these toxins accumulate in fish, the staple diet of seals?

We know the toxins are found in the gut of the fish, which humans do not tend to eat, but predatory seals consume the whole fish, including the gut, and thus can be used as “sentinels of ocean health.”

Along with Chad and eight of her colleagues at St Andrews, Silje regularly meets up with 40 other MASTS post-graduates from other institutions in Scotland. Back home in Norway, says Silje, a project such as MASTS could have a similar impact, and one day she would like to continue her work there.

Silje describes her PhD research as follows: “Phytoplankton are the most important organisms in the ocean and, under certain conditions, they can grow and reproduce quickly, forming what are known as algal blooms. Most of these blooms are beneficial to the ocean’s ecosystem and form the basis of the marine food chain, but ‘harmful algal blooms’ (HABs) produce toxins at certain times in their life cycle, including those responsible for shellfish poisoning in humans, while a neurotoxin called domoic acid (DA) has been associated with the deaths of hundreds of California sea lions on the US west coast every year since 1998.

“From 2000 to 2010, there was an 85% decline in harbour seal populations on Scotland’s east and north coasts, while populations on the west coast have largely been stable. The reason for these regional differences remains unclear, but one possible cause is ingestion of toxins from HABs. Preliminary results show that Scottish harbour seals are exposed to DA and other toxins, such as Saxitoxin and Okadaic acid, which have also been found in several species of their fish prey. By linking these findings with information on seal diet and foraging areas, we can begin to assess the health risk of HABs to harbour seal populations in Scotland.”

 

Lauren McWhinnie
Heriot-Watt University

Aquaculture site selection: a GIS-based approach to marine spatial planning in Scotland

When Lauren McWhinnie attended a recent conference on coastal GIS (geographical information systems) in Vancouver, she was the only marine biologist present in a field usually dominated by computer scientists and planners. This was no surprise, because Lauren is also doing something “unusual” in her field, using GIS to identify the best sites for fish farms at the same time as protecting the environment – on a bigger scale than previous studies, and closely integrated with planning.

Having done her first degree in Marine and Freshwater Biology at Edinburgh Napier University, Lauren chose to do her PhD at Heriot-Watt University, using huge amounts of data to build up a picture of the seas around Scotland, to balance the competing needs for increased commercial production and minimal environmental impact, especially for sensitive environments.

“GIS was an underdeveloped tool in marine spatial planning,” says Lauren, who has been working on her project for almost four years now, sponsored by Marine Science Scotland. “It had been used a lot on land, but not really tested in the marine environment.” In the past, there had been many smaller-scale, localised studies, but Lauren has taken a broader approach and also, where possible, increased resolution to zoom in on very fine details. The latest zoning model developed by Lauren now incorporates climate change scenarios to aid long-term planning, and the methods developed could also be exported from Scotland to countries worldwide. “Other countries are also just starting to look at these issues,” says Lauren, “and what works for Scotland could also work anywhere else, as long as you get the right data.”

Lauren describes her study as follows: “I am currently developing and testing approaches to the implementation of Marine Spatial Planning in Scottish waters, and ultimately aim to propose a decision support tool for aquaculture development. This research will outline the development and application of a new prototype zoning scheme designed and tested specifically for Scottish waters, using a geographical information system. The primary aim is to devise a large-scale, ecosystem-based zoning approach for managing activities, designating areas according to their ecological features and existing management mechanisms, and devising a series of goals, objectives and strategies for each of those areas. The ultimate aim is long-term protection of the marine environment, treating areas as whole ecosystems, whilst still enabling diverse activities to take place in a sustainable manner – to provide a tool to manage any potentially conflicting uses whilst still maintaining environmental integrity.”

 

Enrico Pirotta
University of Aberdeen

Assessing the population consequences of disturbances caused by human development on marine mammal populations: a case-study on bottlenose dolphins in the Moray Firth Special Area of Conservation

Enrico’s fascination with dolphins began when he was a young boy growing up in northern Italy, and today he is doing research which could help to explain their behaviour when human beings enter their environment. We may observe the dolphins moving away when a ship comes near, but what about the potential impact on their habitat of wind farms – and will they return? How long will they be displaced from their favoured feeding places?

After completing his first degree in biology in Italy and his Master's degree at the University of St Andrews, focusing on marine mammals, Enrico spent a few months working for a consultancy and doing wildlife conservation work in the Mediterranean Sea and in Africa, in Gabon and the Congo, where he was able to study the Atlantic humpback dolphin.

“I have always been fascinated by the complex social systems of dolphins.” he says, “and the way they interact with their environment.” Enrico acknowledges that dolphins are “charismatic” animals, but also points out that this makes them ideal for engaging the public when it comes to understanding the environment. “They are also very vulnerable to human development,” he adds. “And the more I get into it, the more interested I am.”

Enrico's work focuses on investigating the underwater acoustic behaviour of dolphins and modelling their distribution patterns to understand their habitat use and see how they're affected by human activities such as increased shipping or dredging in harbours. “We need to bridge the gap between short-term and long-term effects,” he explains. “We see them change their behaviour, but they may resume it later – and we may not be there to observe it.” To analyse this, Enrico has developed new modelling tools which help to map where the dolphins forage, overlapping this with shipping traffic and the behavioural effects of boat interactions, to quantify the overall impact and predict future effects. “The dolphins may stop foraging when ships arrive and lose energy moving away,” says Enrico, “but they may also compensate for this.”

The development is part of an international effort to study the impact of anthropogenic activity on marine mammals, and Enrico says that what makes this recent work different is the move away from merely studying changes in behaviour to the long-term effects.

Enrico describes his work as follows: “With the rapid rate at which human activities at sea are developing and diversifying, it is increasingly important to identify the potential consequences on marine life. However, for long-lived marine mammals, it is hard to detect effects at a population level. Therefore, although European legislation calls for the protection of the conservation status of populations of these animals, we are often limited to observing only short-term changes in behaviour, the significance of which is unknown. In the context of an international effort to address such problems, led by Professor John Harwood of the University of St Andrews, I am working with Dr David Lusseau at the University of Aberdeen to develop a modelling tool that can help to bridge this gap. My project focuses on a small population of bottlenose dolphins along the northeast coast of Scotland, which has been the object of intense study by Professor Paul Thompson and his team at the Lighthouse Field Station since the late 1980s. We have collected new acoustic data to investigate how dolphin foraging is impacted by boat traffic, and visual data to assess responses to coastal dredging. I am also using the existing long-term data to examine how individual dolphins use their habitat and which characteristics of the environment drive their foraging activity. By combining these elements with the distribution of boat traffic in the area, my aim is to develop a model that predicts the consequences of exposure to disturbance on individual dolphins. While considering the effects of boat traffic and coastal developments, these results could be adapted to other sources of disturbance of interest, such as offshore renewable energy developments. My work will hopefully help to guide management and conservation efforts, as well as streamline the consenting process for these important developments within Scotland and beyond.”

 

Thomas Linley & Niki Lacey University of Aberdeen

Novel technology and fauna of the hadal zone

They swarm like bees, devouring the corpse of a fish, and then a giant comes along about 40 times bigger, followed by the strangest-looking fish you've ever seen, who rip the corpse to shreds and pick it clean, leaving behind just the bones. But humans have no need to fear. We could not survive here at depths of up to 10,000 metres, and soon after the fish and the amphipods are brought to the surface, they turn to jelly or explode.

This is not a horror tale, however, but part of two PhD projects involving Thomas Linley and Niki Lacey of the University of Aberdeen, who are using autonomous landers – like high-tech lobster pots with cameras and traps on board – to film and gather samples from one of the most remote and inhospitable places on earth, the Kermadec trench near New Zealand.

While Lacey looks for amphipods, underwater invertebrates related to “sand-hoppers” which range in size from 4mm in length to “giants” almost 40cm long, surviving by eating dead matter which falls from above, Linley hunts for strange fish (with strange names like “rat tail”) that have never been seen before, except as bloated corpses caught in fishing nets.

“Neither humans nor these deep-sea creatures can survive where the other lives,” says Linley. “We can never co-exist.”

As well as studying the fish themselves, Linley also focuses on trying to improve or “update” the technology used for the dives – extremely strong structures with minimal weak points and minimal surface area, which are simply dropped into the water and sink to the bottom, then jettison their ballast to return to the surface. It’s a “smart approach” to deep-sea research which is significantly cheaper, says Linley, than using remotely operated vehicles (ROVs) – very few of which can operate at such extreme depths. In addition, several landers can be launched at the same time.

“It’s a technological challenge just to get down there,” says Linley, “and not much is known about life down there.” One advance in recent years has been the introduction of high-definition digital cameras with smaller, longer-lasting batteries, but at tens of thousands of pounds sterling per lander, including the payload, any further improvement is welcome.

The two researchers work very closely together, going together on missions about twice a year. Both are also interested in the same fundamental issues: what lives at the bottom of the trenches, where it lives and how it survives, as well as how the different creatures interact with each other. These deep-sea creatures have been known about since the 1950s, but largely neglected until recently in terms of research.

Linley and Lacey are also trying to establish connections between fauna in different places. Do groups stay in one place, and therefore evolve in a particular way, or manage to navigate over the undersea terrain which lies between trenches? Some amphipods seem able to survive at a wide range of depths – from 2,000 to 7,000 metres. How is this possible?

One obvious difference between their two projects is when the traps come back up to the surface and the crew get excited when they see the sometimes large and very strange-looking fish which appear, but hardly notice the amphipods because they are so similar looking and small.

When the bottom-dwelling creatures arrive on the boat, it’s a race to preserve them – e.g. the fish begin to “fizz” and turn to mush within 20 minutes unless samples are quickly frozen using liquid nitrogen. That is why these creatures were so little understood until very recently – the only specimens were grossly distorted in appearance.

The “super-giant” amphipods recovered by Lacey are just one of the achievements of her research so far, “adding to the diversity of the species discovered” as well as finding species in places where they've never been recorded before. Part of her work also involves analysing the fatty acids in the amphipods in the bid to understand how they manage to survive at different depths, including understanding their feeding habits. “We know so little about them,” she says, explaining that the same kind of organisms can also be found on land.

For Linley, one new area of future research would be to model the behaviour of the fish, which “pose for photos” in front of the lander, arriving to compete for the bait.

To discover an entirely new species would be a significant breakthrough – and who knows what is lurking at the bottom of the sea? “Every time a lander comes up,” says Linley, “we don't know what we'll get – either as an image on the memory card or a specimen inside the trap.”

 

 

 

 

 

"International Perspective". Science Scotland (Issue Fifteen)
Printed from http://www.sciencescotland.org/feature.php?id=228 on 23/06/17 12:59:11 PM

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