Tag Archives: climate change

Studying sea star sperm in Sweden

boy-urchinsHow many people would travel to one of the most beautiful coastal tourist destinations in northern Europe, at the height of summer, and spend three weeks sitting in a 10 degree cold room with their eyes glued to a microscope? Not many, I’d guess, but it’s exactly what I’ve done by visiting the Kristineberg Marine Station in Sweden.

I’ve swopped my tent on the Arctic ocean for another wonderful place to come and work, but yet again am nose to a microscope all hours of the day. Most of the world’s top marine biology stations are set in truly beautiful surroundings, but are generally full of people far too busy working to get out and enjoy the surroundings properly.

The Kristineberg Marine Laboratories, part of Gothenburg University, is situated in a really pretty part of the Swedish fjords, and is a fantastic place to come and do marine research as it has wonderfully clean seawater and an amazing array of marine species live here. I’m here to continue my ocean acidification research, looking at how the change in seawater pH caused by increased carbon dioxide in our atmosphere might affect the reproduction of small marine invertebrates, or more specifically, how it might impact the performance of their sperm.

Marine invertebrates makes up over 80% of the oceans biodiversity, and many of these small creatures reproduce by simply shedding their eggs or sperm straight into the water, often in synchronised spawning clouds, so that fertilisation happens ‘by chance’ in the open sea. This is often referred to as a fertilisation ‘lottery’, as the chances of sperm and egg meeting seems so small, yet these small animals have adapted to maximise the chances of this happening in numerous clever ways.

One such adaption shared by many species is the ability of the sperm to sense the egg and then swim towards it. But, how might a change in pH affect this swimming ability? That’s the main question I’m asking with my research, and I’m looking at a whole range of animals to see how their sperm ‘performance’ might be affected by future ocean conditions. By measuring sperm swimming speeds, respiration, and viability of sperm under future ocean conditions, I’m giving the sperm a future health check. So I’m basically doing the kind of tests that an IVF clinic would do, except on mussels and sea stars under future ocean conditions!

So how do you get a mussel or sea star to spawn and provide the valuable sample to be analysed? Well actually it’s pretty easy; most marine invertebrates store their eggs and sperm for a while before spawning, so that they can all release them at the same time and increase their odds in the fertilisation lottery. They then use a number of environmental signals to tell them all when to spawn, so all you have to do is mimic these signals to get them to spawn in the lab. Normally a good shake to mimic the tide coming in and some warmer seawater is all they need, but we can also use a small hormone injection to start spawning for some species. Sperm have a pretty short life span so it’s a mad dash to get as many measurements made as possible. I’m finding different species are showing quite different responses to the ocean acidification conditions, and it’s now my aim to understand why this is.

This kind of information will add another important piece to the puzzle in terms of our understanding of climate change impacts in our oceans, and really help us understand which species are going to be most susceptible to ocean acidification and which ones might be less affected. I have a lot of sperm to count and analyse for now though, whilst gazing out the window at the beautiful fjords. Still at least it’s not -40⁰C this time, and I can go and jump in the sea at the end of the day.

Posted by Dr Ceri Lewis, NERC Research Fellow (College of Life and Environmental Science).

Follow Ceri’s updates from Sweden via her Twitter feed @CezzaLew

Life on the Catlin Arctic Survey 2011

The Catlin Arctic Survey team

The Catlin Arctic Survey team

I’m writing this blog sat in a tent on the frozen Arctic Ocean at 78⁰46.4”N, 104⁰43.3”W, with just a meter and a half of frozen seawater between me and a 500m deep and very cold ocean. The temperature outside is -25⁰C today, which amazingly now feels almost warm after a week of camping out here in temperatures of -35⁰C to -44⁰C. Its blowing a gale today though and that makes it feel colder when out of the tents, -45⁰C wind chill factor, so just popping out still means covering every inch of skin up to stop frost bite and snow blowing in your face. As I sit in my tent writing this the wind is rattling the sides of the tent, the small jet-fuelled stove is struggling to keep the temperature in the tent above freezing and the generator is a constant drum in the background providing the only power we have out here.

I’m here for my second year running as part of the Catlin Arctic Survey, a scientific expedition that combines a multidisciplinary team of international scientists with a group of Arctic explorers to enable us to undertake important climate change research in the High Arctic during the harsh winter-spring transition period. My role in the survey is to look at ocean acidification processes in the Arctic and its potential effects on the small pelagic marine animals called zooplankton that live under the sea ice. Ocean acidification is the other carbon dioxide problem associated with climate change. Our oceans absorb over a third of atmospheric carbon dioxide, so as atmospheric carbon dioxide levels increase our oceans are absorbing more carbon dioxide and as a result are becoming more acidic. Carbon dioxide dissolves into cold waters more readily and so our polar regions are going to be affected first, hence our urgent need to study these remote seas. The dominant zooplankton in the Arctic ocean are small crustaceans called copepods, and it is the potential impact of ocean acidification on these tiny but important creatures that is the focus of my time on the ice.

Our window into the Arctic ocean beneath us is a metre square hole in the ice, through which we send all of our sampling kit, collecting information on the ocean’s physical and chemical properties, and collecting samples of the small plants (phytoplankton) and animals (zooplankton) that live beneath the ice and which support the larger marine animals of the Arctic food web. For me this means regular trawls using a plankton net, sending it down to 200m beneath the ice and then winching it back to the surface using our modified bicycle winch. I then take my samples back to the lab tent for hours of examining them down a microscope and counting out the copepods. I’m collecting data on what the zooplankton are doing at this time of the year, for which there is remarkably little data due to the harsh conditions, and relating their abundance and behaviour to the physical and chemical properties of the seawater. I’m also conducting incubation experiments, taking my copepods into the future by mimicking the warmer and more acidic seawater condition predicted for 100 years time and seeing how the copepods respond in terms of their physiology and behaviour. These experiments are extremely difficult to run in the freezing conditions, but we all pull together to come up with some ingenious solutions to every problem encountered, and work is progressing well.

Whilst this is my second year of working in these extreme conditions, it was still tough for the first few days of getting used to the cold. We sleep in unheated tents, to escape the Arctic’s biggest killer – carbon monoxide poisoning. This meant climbing into a sleeping bag at -40⁰C on the first few nights, and second year round this still felt horrid. Even with two hot water bottles, three sleeping bags and some tactically placed chemical hand warmers (not just for hands), I was still cold for the entirety of my first night back on the ice. I don’t think you ever get used to waking up with snow on your face, but I soon settled back into to the Ice Base way of life. Food is fuel here, so meal times are the highlights of the day and large amounts of chocolate, together with the great team atmosphere we have out here, help keep you warm and your sprits high. Your metabolism goes through the roof at these temperatures and it’s amazing how much more we all eat out here.

Whilst the Arctic is a tough and incredibly challenging place to do biological research, it is also a beautiful and hugely inspiring place to work. It’s a very dynamic place, and looks different every day according to the light and weather conditions. The snow on the ice is constantly moving depending on the wind, creating amazing shapes that constantly amaze us. It’s also a very humbling place to be, knowing that we are at the mercy of Mother Nature and that things can go wrong very quickly at these temperatures. Our only shelters are our tents, and a flight might take several days to get to us in any emergency. The contradiction between the power of the Arctic elements and its vulnerability to climate change impacts is striking and adds to its charisma. My time on the ice also reminds me of the beauty of the simple things in life. The luxuries we take for granted at home I am hardly missing, except for maybe a warm shower as it’s far too cold for a proper wash up here! I personally feel hugely privileged to be out here doing the science that I love and believe to be important in such a stunning environment.

Posted by Dr Ceri Lewis, NERC Research Fellow (College of Life and Environmental Science).

Follow Ceri’s updates from the Arctic via her Twitter feed @CezzaLew