The end of October means only one thing for the PHATS team, it’s time for our winter field season on the Isle of May, Scotland. Every year from late October to mid December, thousands of grey seals arrive on the island to give birth to their pups and breed, and this gives us scientists at the Sea Mammal Research Unit (SMRU) and at Abertay University the chance to study all kinds of things about the seals, from their behaviour to immunology. Every year we are joined by researchers from other institutions across Europe, such as Durham University’s behavioural team (read more about their research here) and we also collect samples for collaborators to analyse back on the mainland. The PHATS team is specifically interested in the physiology of grey seal blubber and how it is affected by persistent organic pollutants (POPs), so we will be heading out to collect blubber samples from the seals to continue investigating how these chemicals impact on fat tissue function.
The last few weeks have been a blur of preparing all the lab gear we need for the 8 week field season and packing it securely for crossing to the island by boat. Running a remote tissue culture lab involves a lot of supplies, as everything from CO2 incubators to tiny sample tubes to liquid nitrogen has to be taken to the island so we have it to hand when we collect samples from the seals on the colony. We have so much large, delicate equipment and boxes full of supplies that every year we have to wait for a ‘weather window’ to take everything out on a large boat, the May Princess. This is the boat that usually takes visitors to the island in the summer (if you’d like to visit the island, their website is here, there are lots of sea birds like puffins to see at that time of year!) and it can carry far more gear than the smaller, faster RIBs (rigid-hulled inflatable boat) that take us to and from the island during the winter. It’s not only the lab equipment that gets taken out when we take this bigger boat to the island though. We need to take enough food to last the 8 week field season on the Isle of May too, so the night before our chance to take the Princess out to the island we did some monster food shops!
This year, the only day that looked calm enough to take the Princess out had high tides very early in the morning, so we left the harbour at 5am in the dark. There were several seals watching us arrive in the harbour at Kirkhaven on the Isle of May, and even a few mothers and pups on the surrounding rocks. In the coming weeks, Kirkhaven will completely fill up with mothers and their pups as it’s a major breeding site on the island. This makes landing large amounts of equipment later in the season impossible without causing lots of disturbance to the colony, which we want to avoid at all costs.
After some frantic unpacking about half of the team, including myself, headed back to mainland on the Princess while the other half stayed on the island to observe the colony while the seals are arriving. The rest of us headed back out four days later on the RIB to join them to start the fieldwork, and we were lucky enough to have a beautiful blue sky day to take the RIB out to the island. The PHATS team leader, Dr Kimberley Bennett from Abertay University, was with us for the dawn supply run and she will be coming out in November to join in the fieldwork fun. I have a new research assistant to help me this year with all the sample collection and lab work; Holly Armstrong. She is Dr Bennett’s PhD student and is writing up her thesis on cellular stress physiology in grey seal blubber tissue, so she has lots of experience on the island working with the seals and tricky tissue samples!
While we are on the island, the PHATS team is hoping to collect blubber samples from 30 grey seal pups at two time points in the field season:
- The first sampling time point is when the pups are big and fat, just before they wean from their mothers. This sample lets us investigate how fat tissue functions when the seals are generating fat reserves, as they are still nursing and drinking the fat rich milk their mothers produce. If POPs are disrupting the pup’s ability to store fat, these samples will allow us to detect this effect.
- The second sampling time point is when the pups are weaned from their mothers, during the 2-4 weeks they stay on the colony resting before going to sea for the first time. They do not feed during these weeks, so this sample lets us investigate how fat tissue functions when the seals need to utilise their fat reserves. If POPs are disrupting the pup’s ability to access stored fat, then these samples will allow us to detect this effect.
As POPs are considered obesogens (which are chemicals that prevent the fat tissue from responding to your body’s signals), we are especially interested in investigating the physiological differences we see across the two samples, which is why it is important to sample to same individual twice in one season.
In order to investigate the affect POPs have on fat tissue, Dr Bennett developed a novel technique which allows us to get the most information possible out of small tissue samples. By keeping the fat cells in the blubber sample warm and in specially prepared buffer solutions after sampling, we can use cell culture approaches to keep the fat cells alive for days. This allows us to split the sample into smaller pieces (called explants) which can then be used for lots of different experiments and analysis. By using this approach we can actually expose fat cells from the seals to elevated POP concentrations to see how the cells respond without subjecting the individual seal to those pollutants. This experimental approach means that we can detect causality (what is causing things to happen) rather than simply detecting correlations (what things are linked to each other).
But before any sampling for the PHATS project can take place, the grey seal mothers must arrive, have their pups and raise them successfully so they are big and fat. This gives the PHATS team about two weeks to get the lab set up and perfect our protocols before our first samples are collected and arrive in our field lab on the island. In the meantime, there is plenty happening here with all the other research that is going on at the same time as our project, and of course there is always interesting things happening in the seal colony. Now we’re on the island I’ll update this blog every week with what is going on here in the field, and hopefully in a few weeks time I will get to introduce you to our study animals! In the mean time, I better think about what I’m cooking for dinner for all eleven of the Isle of May team…