The Museum at sea | Darwin Tree of Life

Adventuring to the west coast of Scotland in search of DNA

Laura Sivess, Research Assistant for the Darwin Tree of Life project, shares the experience of being on a Museum field trip.

The Natural History Museum (NHM) Darwin Tree of Life (DTOL) team recently returned from Millport, Scotland, where in just over four days we encountered over 150 species and took 266 tissue samples for whole genome sequencing!

Preserving biodiversity

Based at the NHM, in partnership with the Wellcome Sanger Institute, we are attempting to sequence the DNA barcodes and full genomes of all 66000+ species found in the British Isles.

Preserving biodiversity is critical to safeguard and conserve ecosystems. Genomics can be used to describe and understand species, and this knowledge can contribute to conservation measures that are mitigating the impacts of negative environmental change.

We can work towards securing and protecting biodiversity for future generations through the combination of historic and contemporary natural history collections alongside new technologies.  

In search of marine invertebrates

A woman holds seaweed against a grey sky
On Millport’s beaches we studied the intertidal community. By digging holes we located worms and bivalves while inspecting rocks and seaweed uncovered Bryozoa. Image by Laura Sivess

Millport is on the Isle of Cumbrae, which is an island nestled beside the West coast of Scotland and has the distinction of being one of the oldest marine stations in the United Kingdom. It is now run by the Field Studies Council (FSC) which operates a series of important nature centres, working towards their mission of ‘Bringing environmental understanding to all’. Every year, families, school groups and scientists alike visit these outposts, found as far North as the Cairngorms in Scotland and as far South as Devon in England.

The earliest NHM collections from Millport were collected in 1860 by David Robertson, the Scotsman, who would go on to start the marine station thirty years later.  

We set off for Millport in search of marine invertebrates, the majority of which live in the ocean.

Our focus creatures included: Bryozoans, colonial organisms with over 300 UK species. Polychaetes, segmented marine worms which are dominant organisms in anoxic mud. Irregular sea urchins, yes urchins also come in ‘regular’, all of which have pentaradial symmetry. Amphipods, a diverse group of brooding crustaceans usually under one centimetre yet more abundant than crabs or lobsters in the marine environment.

A person collecting seaweed
Sampling often involved wading in the water to continue the great species search. Image by Laura Sivess

Why did we collect these groups of marine creatures?

It is what we are good at. Contrary to popular belief, the Museum doesn’t have experts in every group of animals. Our present marine staff have a great interest in the identification, taxonomy and applied research of these target animals.

The material collected will contribute to both the genomic research with our field and project partners Sanger and to further research at NHM.

Our study of UK organisms extends to the blue carbon sequestering, changes in distributions with climate change, documenting invasive fauna, skeletal and neural development and revising scientific classification, which for some groups, such as the Caprellid amphipods, has not received scientific attention in the UK since the 1940s. 

A race against tides

Picture a beach, its smooth sand occasionally pitted with small holes, easy to miss but unmistakable, each hole belonging to a marine worm or amphipod. Every time you step on a beach, they are just inches from your feet. 

In intertidal environments timing is crucial. Heading out at low tide we raced against the sea, sampling the beaches, the rocky shores and associated algae. Every low tide brings a new race, a race for terrestrial animals to forage for food and a race for scientists to collect. Our intertidal activities are not unlike those of the local gulls, which tap and dig on the beach, following the tide out with us. 

Sea stars cling to the bottom of a rock on the sea shore
Turning over a stone on a rocky shore beach revealed five sea stars. These animals use hydrostatic pressure to move the tube feet which line their ventral surface (that’s the pale underside which is touching the rock). Image by Laura Sivess

Collecting from the ocean floor

Offshore, we had a boat team on the RV Actinia setting out every morning to collect from greater depths. Using a combination of both trawling and benthic grabbing, sand and muddy sediment was collected from the bottom of the sea. What did they find?  You guessed it, more worms but importantly different worms!

Amongst the worms were sea stars, sea urchins, crabs and even the occasional Nephrops, a historically overfished genus of lobster with limitations on the local catch number. On the boat, the weather really counts as does wearing bright, visible colours. Unlike the many buckets, sampling pots, microscopes, reference books, liquid nitrogen and archival labels – which were meticulously planned and packed – the weather was not something we could guarantee in advance. Luckily, the choppy sea was mostly on our side, and the boat returned with an interesting catch of fauna on all planned days. 

Bryozoans are aquatic invertebrates found living in colonies which can contains thousands of individuals! This was a common species we encountered named Electra pilosa. When building natural history collections, it is incredibly important to collect and record common species to accurately represent the flora and fauna encountered. This allows us to review changes in species composition over time – what is common in one time period may be rare in another! Image by Laura Sivess

What did we find?

Upon returning to the NHM a total of 192 specimens were processed for DNA barcoding. Several of these were new species to the Barcode of Life Data System (BOLD), a global online repository of DNA barcodes. Half of the specimens collected at Millport have been sent to the Wellcome Sanger Institute for whole genome sequencing, which will be conducted over the coming months.

What was our most interesting find of the expedition? Each of our 10 strong team may have different opinions – the sea urchins, where only a few species are yet to have whole genome sequencing, the pycnogonid sea spiders which were more abundant than expected near the boat wharf or the continually increasing number of Bryozoa species that are still being identified from the several kilograms of rocks we collected. Perhaps the most iconic was the polychaete marine worm, Arenicola marina, collected on the 15th August 2021. On the shelves here at South Kensington, it will join the first polychaete from the region, the David Robertson specimen collected at Millport in 1860. The Museum collection is an ever-expanding research infrastructure for natural history, the only things that have changed are the tools and methods with which scientists study the world around us. In 2021, liquid nitrogen is the innovative method of choice used for preserving collections, in another hundred years when genomes of many species have been published and long known, it is exciting to think what might come next. 

Millport felt worlds away from our usual base in South Kensington, London. Whether you’re travelling or not this year, remember there is wildlife all around you, be it in an urban park, a woodland glade or, perhaps, a nearby beach. So, what are you waiting for? The great outdoors awaits.