Scientists at Sea Podcast: Sail Against Plastic

Show Notes




Guests – Flora Rendell and Lowenna Jones




Sail Against Plastic started as an idea to simply undertake a sailing expedition, over just a few months it developed into an Arctic mission to investigate unseen pollutants, namely microplastics and noise pollution.


“We are a collaborative expedition hoping to unveil and reveal the invisible pollutants of the arctic”


The Sail Against Plastic team. Photo credit – Ben Porter


Why the Arctic?

It is well documented that plastic debris has been circulating around our oceans via 5 ocean gyres. It is now thought there maybe a sixth gyre that carries plastic up into the Arctic circle. Recent discoveries supporting this theory have shown that plastic has been found in sea ice.


“As sea ice melts that could be opening up more microplastics that have been trapped in that sea ice… it shows that we’ve been influencing the world for a long time”


A selection of plastics found on mainland Svalbard. Photo credit – Ben Porter


A view from the Blue Clipper: Photo credit – Ben Porter

These pieces of plastic aren’t necessarily what you would expect, while there plastic bottles and bags found in these areas, there may be an even greater prevalence of microplastics, tiny pieces of plastic debris resulting from the breakdown of consumer products and industrial waste.


“It’s not these big large pieces of plastic, it’s not a floating island that we’re going to find’


At the time of recording, the team, a diverse group of scientists, artists, environmentalists, photographers and videographers, were just a few days away from setting sail on the Barents Sea from Svalbard aboard the Blue Clipper.



The team’s manta trawl, used to collect microplastics. Photo credit – Ben Porter



“I think the main thing is making issues that are so strongly linked to humans… making you feel emotive about them… through art and through film, people will feel emotive about it and will care, we hope”


“And make it relevant to people in the UK and Europe and connect communities that are halfway across the world that have similarities and can work together to find a solution to our crazy plastic addiction”







Website –

Blog –

Facebook – @amessagefromthearctic

Instagram – @amessagefromthearctic

Twitter – @Sail4seas

Art – Jess Grimsdale & Further info


Hosted by Ethan Wrigglesworth and Molly Meadows

Episode and show notes produced by Ben Toulson


#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!


Scientists at Sea Podcast: What’s in the water? With Dr. Anne Leonard

Show notes

Ethan and Molly talk to Dr. Anne Leonard about her work studying antibiotic resistant bacteria in the waters around our coasts. How did it get there? Is it dangerous? Where are the cleanest places to swim? All these questions and more are answered in the podcast linked above.

If people are worried about where and when they should go to beaches… going to ones that regularly meet good water quality standards is probably a good way to go.

Follow Anne on Twitter – @dr_anne_leonard


Read Anne’s open access (free) systematic review here:

Is it safe to go back into the water? A systematic review and meta-analysis of the risk of acquiring infections from recreational exposure to seawater

You can also find out more about the Beach Bum Survey here (again, open access)!



Links to more of Anne’s work (membership to journals required)

A coliform-targeted metagenomic method facilitating human exposure estimates to Escherichia coli-borne antibiotic resistance genes

Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters



Bathing Water Quality Near You

Blue Flag Beaches

Environment Agency – Bathing Water Quality

Surfers Against Sewage – Safer Seas Service



The Jargon Buster

If there’s anything that came up in the episode that you would like to know more about, get in touch via our Facebook and Twitter pages.

Antibiotic medications

  • Drugs used to treat bacterial infections. These are used to treat a whole range of conditions such as acne, bronchitis, and skin infections.

Antibiotic resistant bacteria

  • Bacteria that are not controlled or killed by antibiotic medications.


  • A living organism that cannot be seen by the naked eye, but can be observed under a microscope.

MRSA – Methicillin-resistant Staphylococcus aureus

  • An example of antibiotic resistant bacteria.

E. coli – Escherichia coli

  • A type of bacteria that usually live in the intestines of people and animals which can cause food poisoning.

Pathogenic bacteria

  • Bacteria that is capable of causing disease.

Agricultural run-off

  • The portion of rainfall that runs over agricultural land and then into streams as surface water rather than being absorbed into ground water or evaporating.

Systematic review

  • A systematic review has multiple stages and is aimed at the identification of all reliable evidence regarding a specific clinical problem.

Next Generation Sequencing

  • A quick way of analysing DNA.


Get in touch via our Facebook and Twitter pages.

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!

My #ExeterMarine PhD: Clams and Climate Change

Author – Sarah Holmes, PhD Researcher – Geography and Earth System Science

Arctica islandica (also known as ocean quahog) clam shells. Oldest animal known to science, abundant and widely distributed throughout North West European Shelf.
Photograph by Thom Holmes [].
Yes, clams.

Admittedly, telling people that my PhD research is using clams doesn’t always get “ooo’s” and “aah’s” that perhaps my fellow researchers working on whales and dolphins might get, but before you write me off as having a boring PhD, let me tell you a few…



  1. Clams are the oldest animal known to science. Certain species are extremely long-lived. In 2006, scientists at Bangor University (these scientists have now moved to the University of Exeter, Penryn Campus) found a clam that was 507 years old. 507! That means this humble little mollusc (see picture above) was around when Shakespeare was putting pen to paper, when Henry VIII was beheading wives, when your great-great-great-great-great grandparents were born!


  1. Clams can record information about the environment in their shells. Certain species form annual growth bands on their shells, just like tree rings. During winter months, the clams grow more slowly and build up a denser layer of shell that looks like a defined band under the microscope (see picture below). Just like trees, the amount a clam (and so its shell) grows depends on the environment it lives in. In general, warm temperatures and plenty food (e.g. algae) means lots of growth and so a wide growth band. The opposite is true in less favourable conditions such as low temperatures or lack of food. As you may already know, using tree records in this way is called dendrochronology; using clam records is called sclerochronology.

    Microscope image (25x mag.) of acetate peel of internal portion (umbo) of clam shell (species Glycymeris glycymeris). Clear growth bands visible, yellow line shows direction of growth (d.o.g).


  1. Clams in the same area grow synchronously. Since clam growth is affected by environment, it makes sense that clams from the same location (that are affected by the same environmental conditions) have very similar growth patterns. This means that it is possible to match up and combine the growth records of multiple clams to create what is called a ‘master sclerochronology’ – you can even incorporate ‘dead-collected’ clams that have an unknown date of death.


Cool, right? Well even more interestingly, these features mean that clams are an extremely valuable proxy* for the marine environment and are therefore of great interest to climate scientists like me. Previous research has shown that the clams are recording a multitude of environmental information in their shells such a sea water temperature, the amount of plankton present in the water and even large-scale climate variability such as North Atlantic Oscillation (which is like a measure of storminess in Northern Europe). Researchers can therefore (to an extent) reconstruct past ocean conditions using these records.

Clams also look really beautiful under the microscope (photographs of Glycymeris glycymeris by Thom Holmes [])
It is of vital importance to know how the ocean has changed in the past as this can help us understand how it might change in the future, especially considering the many threats of climate change. The shelf seas (the shallow oceans that surround the land, e.g. the North Sea) are hugely important as they sustain the majority of global fisheries (the North Sea is a major UK fishing ground) and are the main way that we interact with the marine environment (e.g. tourism). Although we do have some direct observational measurements of the shelf seas available, these are both spatially and temporally limited.

Scientists generally use shelf sea models** (of places like the North Sea) to predict future change, however to check if these models are representing reality correctly, they must be compared or ‘validated’ with these limited observed measurements.

Therefore, for the first time, my research is attempting to combine the records of long-lived clams with ocean models in order to better understand past and future change in the North Sea. The aim is twofold – first, to use the clam records to better validate the model and second, to use the model to give greater insight into the factors controlling clam growth in order to better interpret these proxy records.

So, I think we can all agree, this humble little clam is pretty exciting and could hold the key for better predictions of future ocean climate change – not bad for a squidgy, slimy lump that doesn’t even have a brain!

*Proxies are indirect measurements of the environment preserved in natural recorders of climate variability such as tree rings, pollen, ice cores or the rings on marine clams.

** Models are mathematical representations of the real world. Ocean models such as the one I am using (the European Regional Seas Ecosystem Model (ERSEM)) attempt to quantitively describe the physics, chemistry and biology of the shallow ocean that surrounds Europe (known as the Northwest European shelf seas).

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!

Scientists at Sea (Episode 1): Do crabs have ears? with Emily Carter



Show notes


Emily Carter – @E_E_Carter

How does noise pollution impact one of our coastal favourites? Ethan and Molly talk to Masters by Research student Emily Carter about her current work which investigates how the presence of ship noise affects the rate of colour change in shore crabs.


Other behaviours that don’t rely on noise at all can be quite drastically affected by noise pollution

Useful links from this episode:

Fiddler crab

Selfish herd hypothesis

Shore crabs

Crabs hearing noise

Gylly beach

Penryn Campus

Steve Simpson, Matthew Wale, Andrew Radford

Martin Steven’s Group/Sensory Ecology





#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!








SOPHIE website launched

Author – Alexander Smalley

Research in the field of Oceans and Human Health gets a big boost this week, as the Seas, Oceans and Public Health in Europe project launches its new website.

Designed to encourage debate between different sectors, Seas, Oceans and Public Health in Europe (SOPHIE for short) will build a community of researchers and practitioners to explore the links between our oceans and our health.

The new website will share information about the project and provide a platform for bringing marine specialists together with experts from medicine and public health. The site also provides wider opportunities for the public to get involved, with researchers keen to hear from those with an interest in marine issues, ‘blue’ tourism, or healthcare.

In one example, members of the public are being encouraged to share their experiences of interventions which harness the benefits of interacting with the ocean, in the hope of inspiring similar initiatives.

The project is led by a team from the University of Exeter’s European Centre for Environment and Human Health, and has attracted €2 million in funding from the European Union’s Horizon 2020 programme. It is a collaboration between several partners across Europe.

You can view the new website at and follow SOPHIE on Twitter here

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!


Laying strong foundations for sustainable small-scale fisheries and marine conservation

Author – Dr Ana Nuno, Research Fellow and Project Coordinator for Omali Vida nón

A remote and poorly known small island located in the Gulf of Guinea, off the coast of Central Africa, Principe (Sao Tome and Principe) and its people rely heavily on small scale fisheries. “I’m a fisherman with great pride! I am not afraid to say it anywhere in the world: I am a fisherman!” says one of the men during our project workshops. In a similar workshop organized for fish traders, an occupation mostly done by women, one of them tells us: “being a fish trader is good because we do not depend on our husbands… we can buy what we want… eat and drink what we want…support our children’s education… it’s very good for us”. It is clear than more than simply providing food (average annual fish consumption in the country is one of the highest in Africa) and income, fishing is intrinsic to these local communities’ lives and the status of marine resources affects all of them.

a fisherman’s catch (credit: Ana Nuno)

When these same communities report having to travel farther away, spend more time at sea and increase the amount of fishing gear in order to get similar amounts of fish that they used to catch near the coast some years ago, the usual suspects come to mind. Scarce alternative sources of income, lack of resources and capacity for marine conservation and fisheries management plus limited monitoring and enforcement mean that overfishing and habitat degradation are affecting the viability of Principean fishing livelihoods. For example, in 2012, the entire island of Príncipe and its surrounding waters was designated a UNESCO Biosphere Reserve for its global biodiversity significance. However, in reality, there is no enforcement to support this designation (and there is no formal protection provided to any marine areas around the neighbour island of São Tomé).

Tia, one of the project focal points, conducting landing surveys (credit: Guillermo Porriños)

This project aims to improve marine biodiversity and livelihoods of coastal communities in Principe, based on collaborations among researchers (University of Exeter, UK), a local NGO (Principe Trust Foundation), the Regional Fisheries Department and the Biosphere Reserve Management Unit, and with support from Forever Principe (a collaborative conservation alliance that finances conservation through tourism activities) and the Halpin Trust. From July 2016 (when the project started) until now, much has been learnt and, more importantly, fishers and fish traders have remained central to all interventions. Due to limited governmental control, there is a strong need for participatory approaches involving local men and women in any management measures, since they will be the future enforcers of such measures. Fishers and fish traders have thus been actively involved in: identifying project priorities and target areas of intervention; landing surveys data collection (e.g. focal points from different communities record information on fishing gear, effort and catch twice a week); and mapping their own fishing areas (e.g. fishers take GPS trackers when they go out fishing and contribute to identifying important fishing grounds and potential conflicts with other uses, such as industrial fishing).

Fishing community in Principe (credit: Ana Nuno)

One of the highlights of the project so far has been the discussions and identification of “community ideas” with a positive impact on the sustainability of artisanal fisheries. Several months of project meetings and discussions at each of the six fishing communities allowed us to identify the best locally-suitable ideas to improve management of marine resources and benefit fishers and fish traders. These ideas, identified and proposed by each of the communities following specific criteria and judged by all project partners, include, for example, developing a crafts center, building a community headquarter or providing better fish storage equipment. With its implementation just beginning, we look forward to learn from each investment made possible thanks to Darwin Initiative funds and use them as catalysers for community dynamism and capacity building.

Fishers describing important and common fish species in Principe (credit: Litoney Matos)

Our emphasis on participatory approaches and local capacity building is starting to pay off. Project efforts are increasingly recognized by the wider community and discussions about potential future measures (e.g. co-managed areas) and project expansion to neighbour island are on the table. With much progress still to be made, it’s very encouraging to see that this project, only possible thanks to funds from Darwin Initiative, Forever Principe and the Halpin Trust, is creating momentum for sustainable small-scale fisheries and marine conservation on this small island nation.

#ExeterMarine is a interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!

Changing storminess and global capture fisheries

Author – Nigel Sainsbury, PhD researcher, Environment and Sustainability Institute

Potential changes in the frequency and intensity of storms over the world’s oceans could have a catastrophic impact on global fisheries, risking the lives, livelihoods, food security and health of billions of people around the world.

In a new commentary article published in Nature Climate Change, I argue, along with my co-authors from ExeterMarine, Cefas, Willis Towers Watson, Met Office and the University of Bristol, that a new global research effort into changing storminess and global capture fisheries is required to help fisheries adapt to this aspect of climate change. We outline a research roadmap encompassing aspects of climate modelling, fisher behaviour, marine ecosystems and fishery vulnerability and adaptation.

There is growing evidence that storminess will alter in the future with climate change. There are great uncertainties in both future predictions and reanalyses of historic storms, owing to a lack of historic data and the limitations of storm representation in climate models. Whilst the number of studies is growing in both number and coverage of the world’s ocean basins, research is required to develop projections of future storminess at local scales with significantly more confidence.

Storms have the potential to cause extensive socio-economic impacts on fisheries. It is estimated that every year, night-time thunder storms kill between 3,000 – 5,000 fishers every year on Lake Victoria. When Cyclone Nargis struck Myanmar in 2008, 28,000 fishers were killed or missing and over 100,000 fishing boats were destroyed. Closer to where I am based, at the University of Exeter’s Penryn campus, the winter of 2013-2014, the stormiest on record, caused an estimated £7 million loss of income, £400,000 in lost fishing gear and £1.1 million in fisheries onshore infrastructure damage.

Our knowledge of how storms impact marine ecosystems is limited. There is evidence that storms damage mangrove forests, seagrass beds and corals and cause the redistribution of fish and mass fish mortality events. However, this is taken from a handful of studies. Research is required in different ecosystem contexts around the world to identify how storms will impact ecosystems and how this links to socio-economic impacts on fisheries.

Changing storminess differs from other climate stressors affecting fisheries, such as ocean warming and acidification, because it has a direct social dimension as well as causing ecological impacts on target fish species. Whilst a myriad of social and economic factors have been shown to affect fishers’ decisions about where and when to fish, the role of weather in fisher behaviour has received little attention. Exploring how fishers perceive weather risks and how the uncertainties of physical danger and financial outcomes factor in fishers’ decision making in different social and cultural contexts will be important to predict the future fishing disruption caused by changing storminess.

If the scientific community is to help fisheries adapt to changing storminess, research into the ecological, socio-economic and climate aspects of changing storminess must translate into assessments of fisheries vulnerability to this environmental change.  This will support national governments in assessing the threat their fisheries face and, if required, help them to prioritise where to focus adaptation efforts. Social scientists can also support this effort by identifying and evaluating adaption actions in different contexts. Financial mechanisms currently being used in terrestrial agriculture to improve farmers’ resilience to environmental shocks, such as drought, may offer potential. It must also be considered that fisheries in areas of projected reduced storminess may experience an increase in potential fishing days, bringing socio-economic benefits but also increasing the challenges of unsustainable natural resource use.

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!

My #ExeterMarine MSc: Skates on thin ice: a phylogenetic study of vulnerable elasmobranchs

Author – Maisie Jeffreys, MSc Student – Molecular Ecology and Evolution group

Elasmobranchs (sharks, skates and rays) are more vulnerable to extinction than any other vertebrate group, meaning their protection is more important than ever. However, confusion remains surrounding the taxonomy of many species- making conservation difficult. Hence, more research needs to be done to answer taxonomic questions that still surround these endangered species.  

Elasmobranchs are some of the most fascinating creatures of the underwater world. Currently, there are at least 1,118  extant species of sharks, skates, and rays found throughout all corners of the globe: from depths of up to 4,000m in the deep sea and the icy waters of the Arctic, to shallower habitats in estuaries and freshwater lakes. Indeed, this group of cartilaginous fish can be found in just about every aquatic ecosystem on the planet, where they play vital roles in maintaining ecosystem balance.

Unfortunately, elasmobranchs are a group at high risk of extinction; due to habitat destruction, overfishing, and being caught as bycatch, an estimated 25% of species are thought to be threatened worldwide. The impact of elasmobranch decline is poorly understood, but given their important roles in aquatic ecosystems, the consequences are likely to be far-reaching.

Of all the elasmobranchs, the batoids (skates and rays) are the most vulnerable, with around 20% now threatened with extinction. Despite this, effective conservation of batoid fish has been hindered by a lack of accurate scientific data; many species are now listed as ‘data deficient’ on the IUCN red list, making establishing accurate conservation methods difficult.

This lack of data can be partially attributed to the large degree of morphological and ecological similarities among living orders of skates and rays. These similarities cause high amounts of cryptic speciation (animals that look alike but are genetically distinct), which results in taxonomic confusion and unstable nomenclature.

A classic example of cryptic speciation can be found in the Manta rays. Currently, there are two species of Manta ray; the larger species, Manta birostris, can grow up to 7 m in width, while the smaller, Manta alfredi, reaches 5.5 m. However, these were thought to represent just one species until 2009, due to their morphological similarities. This discovery has been vital in the conservation of mantas, particularly as it has allowed the clarification of the two species’ ranges. Since M. birostris is thought to migrate across open oceans, while M. alfredi tends to be resident and coastal, conservation efforts have now been targeted accordingly.

My Masters by Research focusses on resolving taxonomic questions that still surround several other species of endangered rays and skates, including the ‘common skate’ complex (Dipturus cf. flossada and Dipturus cf. intermedia), the Norwegian skate (Dipturus nidarosiensis), the longnose skate (Dipturus oxyrinchus), the thornback ray (Raja clavata) and the Madeiran skate (Raja maderensis). In order to answer these questions, I will be using restriction-site associated DNA sequencing (nextRAD) and mitochondrial DNA (mtDNA) sequencing to build phylogenetic trees for analysis. This work could potentially lead to the discovery of new species of endangered skate and has important conservation implications for batoid fish.

This project, supervised by Dr Andrew Griffiths and Dr Jamie Stevens, forms just one part of a host of exciting work being done by the Molecular Ecology and Evolution group (MEEG) here at Exeter University. Several other marine projects are currently underway, including research into the population genetic variation of brown trout (Salmo trutta) and Atlantic salmon (Salmo salar), and genetic connectivity in tropical corals and temperate invertebrate systems.

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!


My #ExeterMarine PhD: Marine Turtles of the Bijagós, Guinea-Bissau

Author: Dr Rita Patricio. Rita is now a postdoc jointly between MARE – Marine and Environmental Science Centre – ISPA, Portugal and the University of Exeter, in the project ‘Consolidation of Marine Turtle Conservation in Guinea-Bissau’, funded by the MAVA foundation.



For my PhD in Exeter I conducted fieldwork at the Bijagós Archipelago, Guinea-Bissau, where I had the chance to study one of the most impressive sea turtle populations in the world under the supervision of Prof Annette Broderick, Prof Brendan Godley and Dr Paulo Catry  from MARE – ISPA, Portugal. I finished my PhD at the University in 2017, and I continue to work in this amazing site as post-doctoral fellow. My work in Guinea-Bissau is very rewarding because it is rooted in participation with local communities, and in strong collaboration with the national authorities for biodiversity conservation (Institute for Biodiversity and Protected Areas – IBAP). Our co-developed scientific outputs inform the management of marine turtles and their habitats.

Our team

The Bijagós Archipelago and Poilão Island

The Bijagós Archipelago, and Poilão Island (encircled)

Located offshore Guinea-Bissau (West Africa), the Bijagós Archipelago is a sanctuary for iconic fauna, such as marine turtles, manatees, hippopotamus, and several species of migratory sea birds and waders. This biodiversity led to the designation of the Bolama-Bijagós UNESCO Biosphere Reserve in 1996.

The beaches of the archipelago are used by four species of sea turtles for nesting: the green turtle Chelonia mydas, the olive ridley Lepidochelys olivacea, the hawksbill Eretmochelys imbricata and the leatherback Dermochelys coriacea, and important foraging grounds for green turtle juveniles have also been identified in the area.


Poilão: home of Africa’s largest green turtle rookery

A small island in the southernmost end of the Bijagós, Poilão Island (10°52’N, 15°43’W), with a beach extending for only 2 km, hosts the third largest green turtle rookery in the Atlantic, the largest in Africa, with an average of 27000 clutches laid per year (2013 – 2017).




Our findings

Green turtle hatchling begining its first large-scale migration.

Through my PhD research, we have learnt a great deal about the major green turtle rookery in Poilão and hopefully contributed towards raising awareness as to its importance.

Using genetic analysis, we estimated that the connectivity of Poilão goes well beyond the African continent, with some juveniles dispersing across the Atlantic, reaching South American foraging grounds. This is a major undertaking for the small turtles and underlines the regional importance of this population.

Fieldwork was conducted with local community collaborators

During the nesting season I used temperature dataloggers to record the incubation conditions at the nesting beach, as this defines the sex of the hatchlings. If temperatures are above a certain limit only females are ‘born’, and extreme temperatures can cause embryo mass mortality; worrying attributes with the undergoing climate change. We found that the native forest at Poilão is key to keeping ‘healthy’ hatchling sex ratios and predicted that this rookery is likely the largest source of male green turtle hatchlings in the Southern Atlantic.

We also realized that there were different preferences in nesting habitats among nesting females in Poilão, but that they are very faithful to their nesting site, typically returning to the same habitat (i.e. either the exposed beach or the forested sand) and within less than 50 metres of their first nest! This is a really fine-scale philopatry, and turtles seem to maintain this fidelity across nesting seasons.

Female green turtle coming ashore to nest at Poilão

Another potential threat associated with climate change is sea-level-rise leading to increase flooding of the nesting beach. Using a drone coupled with a digital camera we collected aerial photos at Poilão and with photogrammetry analysis we created digital elevation models of the nesting beach, to estimate impacts of projected sea level rise. Taking current IPCC scenarios, as much as 33.4 to 43.0% of the current nesting habitat could be underwater by 2100.

Miguel Varela, PhD student at the University of Exeter, flying the drone at Poilão

Under future climate change scenarios, females nesting in the upper shaded areas of the beach should have higher fitness, because their nests will be more protected from the impacts of both extreme temperatures and sea-level-rise. Individual consistency in nesting microhabitat should provide opportunity for natural selection to occur.

Future research
For my post-doc I will be looking into the post-breeding migratory paths of nesting green turtles from Poilão, using satellite tracking devices. We will deploy these in August 2018, so soon we will have more information that will help us to assess the connectivity of this major population and the potential threats outside the nesting beach. I will also be monitoring a feeding ground for juvenile green turtles located in the most offshore islands of the Bijagós, Unhocomo and Unhocomozinho, and engaging the local communities in our research work.

#ExeterMarine is an interdisciplinary group of marine related researchers with capabilities across the scientific, medical, engineering, humanities and social science fields. If you are interested in working with our researchers or students, contact Michael Hanley or visit our website!

My #ExeterMarine PhD: Connectivity Between Marine Protected Areas

Author: Tom Jenkins (PhD Student) – Biosciences, Streatham Campus


Natural England Case Partner

I started my PhD study under the supervision of Dr Jamie Stevens at the University of Exeter in October 2014 on a NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP) studentship.  This programme was appealing to me because it encouraged collaborations among academic and non-academic partners to achieve mutual research objectives in environmental science. Natural England, the UK government’s advisor for protecting the natural environment in England, is the official non-academic partner linked with my PhD.  In our research group, the Molecular Ecology and Evolution Group (MEEG), we use a variety of molecular techniques to examine variations in the DNA of various aquatic and terrestrial species in an effort to answer questions about the population biology and ecology of these animals. Of particular interest to me is the application of such data to inform and address matters of marine conservation and management.


Marine connectivity

Study species: Pink sea fan

Connectivity is generally defined as the degree to which individuals/larvae/eggs are exchanged between populations, the study of which allows us to estimate dispersal distances and explore patterns of immigration between populations of a species. For some marine species, high connectivity can be extremely important for the persistence of isolated populations or for (re)colonising habitats that become available.  One of the aims of marine conservation is therefore to establish Marine Protected Areas (MPAs) of adequate size and spacing to help maintain natural connectivity by reducing human disturbance in key or vulnerable areas.

Study species: European lobster

My research

My PhD centres on assessing the connectivity of two bottom-dwelling marine invertebrates around UK and western European coasts, the pink sea fan (Eunicella verrucosa) and the European lobster (Homarus gammarus). To do this, I am using molecular markers to study patterns of population genetic structure across both species’ geographical ranges.  These data allow us to detect genetic similarities or differences between populations, which we can use as a proxy for indirectly estimating the amount of connectivity between discrete populations (i.e. ↑ similarity = ↑connectivity – but evolutionary processes other than connectivity can also influence the genetic structure of populations which can complicate interpretations of the data!).

Pink sea fan

The pink sea fan (Eunicella verrucosa) is a cold-water soft coral that is protected in the coastal waters of England and Wales by the UK government, and it is listed as Vulnerable on the IUCN Red List.  Because of its rarity across the UK, several Marine Conservation Zones (MCZs) have been specifically designated around southwest Britain with the protection of pink sea fan colonies in mind (e.g. The Manacles MCZ).  Our published research found that at distances of >500 km, pink sea fan colonies are likely to follow a stepping-stone model of connectivity, such that colonies which are closer together are more connected than those further apart.  In contrast, at distances <500 km, we found that populations were genetically quite similar, suggesting high connectivity between areas at this spatial scale.  For the colonies sampled across southwest Britain, high connectivity was apparent which suggests that the network of MPAs in southwest England and Wales appears to be sufficient for maintaining connectivity in this species! We think that this could be useful evidence to support the existing MCZs designated around southwest England and Wales.

Pink sea fan population genetic structure (Holland et al. 2017).  Strong genetic differences between populations from Portugal, Ireland and France/Britain suggests low connectivity at this spatial scale; low genetic differences within countries (i.e. within southwest Britain) suggests high connectivity between populations at this scale.

European lobster

European lobster fishing pot (image from the National Lobster Hatchery)

The European lobster (Homarus gammarus) is a crustacean typically found hiding in crevices on rocky substrates at depths from the low tide mark to 50-150 metres.  Their high market value means they are targeted by fishermen and therefore it is important that these fisheries are managed sustainably.




Sampling lobster pleopods at Looe Harbour, Cornwall


For this lobster study, I have been fortunate enough to collaborate with the National Lobster Hatchery (Padstow, Cornwall) and members of the public (e.g. local fishermen/shellfish merchants) which has massively helped me to collect tissue samples for genetic analysis across most of the range of European lobster (from the Mediterranean to the British Isles and Scandinavia).

European lobster sampling locations








At this stage, I have isolated variations in DNA sequences known as single nucleotide polymorphisms (SNPs) from across the genome – this panel of SNPs was recently published and will hopefully be a useful resource for future genetic studies of European lobster.  My ongoing work is using this SNP panel to explore the population genetic structure of European lobster across our sampling sites.  For me, it will be very interesting to find out what patterns of connectivity are present across these geographical areas and, moreover, the results may help the National Lobster Hatchery decide where they can release their Cornwall-bred juvenile lobsters without impacting the natural genetic make-up of the lobster population being restocked.

This blog accompanies a new paper in Marine Policy, read here.


Hatchery-reared juvenile lobster (image from the National Lobster Hatchery)

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