Ring of Fire: how biofilms will help us understand the impacts of climate change

Our "commute to work". A 7.5km hike across mudflats, wetland, ice and rivers
Our “commute to work”. A 7.5km hike across mudflats, wetland, ice and rivers

Ring of Fire‘ is a NERC-funded research project that, over the course of four years and five geothermal sites in the Arctic Circle, investigates the impact of rising temperatures of global warming on freshwater ecosystems. Danielle Harris has just returned from an eight-day fieldwork trip in Svalbard, where she scrubbed nearly 300 rocks to see how temperature affects the community composition of biofilms, and the species interactions that occur within them.

As part of my PhD, I have been lucky enough to be part of the ‘Ring of Fire’ core sampling team – a team of six researchers from three different universities (University of Essex, Imperial College London and Queen Mary University of London) who travel across the Arctic to study ecological communities living in geothermal freshwater streams.

Getting to our field site in Bockfjorden, Norway, was the first test – particularly given that just two weeks before our departure date, the entire area was covered in sea ice. Fears of having to postpone the trip, or send a small team via helicopter, were only allayed when the ice melted just a few days before we flew. Each day, we hiked 7.5 kilometres from our camp at MS Farm to the field site and back again. It may have added an extra two hours to the start and end of each day, but it was a beautiful route that took us past an extinct volcano, along the coastline, and across mudflats, wetland, ice and rivers – a walk well worth doing to avoid camping overnight in polar bear country!

Our research focuses on the ecological and evolutionary responses of microbial communities to warming temperatures. The streams in Bockfjorden span a particularly broad temperature gradient of 1.5 – 24°C, making them the ideal natural laboratory. The complex communities we study are made up of hundreds of thousands of microbial species, such as; bacteria, viruses, algae and even microscopic nematodes (worms). To simplify matters, we isolate individual species of bacteria, and then build a ‘synthetic’ community in the laboratory. These synthetic communities are representative of the natural communities but are less complex, making it easier to study how the microbial communities respond to warming.

Collecting microbial samples from sediment, water and rock biofilms (the often ‘slimy’ layer covering the upper surface of rocks that is composed of a mixture of microbes) is a laborious process. Unwanted microbes are everywhere so, to avoid contamination, I scrubbed the rocks with sterile toothbrushes, while wearing gloves disinfected with ethanol, and placed my samples in sterilised tubes. Over the course of our Svalbard trip alone, we scrubbed 297 rocks – the start of a long journey of field and lab work, but one that will be worth it when I see the data!

Hot spring in Bockfjorden, Svalbard
Our field site – a hot spring in Bockfjorden, Svalbard

My PhD at the University of Essex focuses on how temperature affects these biofilms, from their diversity to the number of other species that interact with them. Biofilms are extremely complex communities, where species predate and compete with each other – much like more familiar ecosystems such as grasslands. Microscopic algae (microalgae), which make up the base of all food webs, are an important energy source for biofilms, supporting numerous other microbes that, in turn, fall prey to larger organisms. Microalgae are also primary producers (much like the grass in our field analogy), which means they photosynthesise to get the energy they need and produce oxygen as a waste product, something that is crucial for all other life in these streams. Research has already shown that warming impacts microbial communities. Furthering our understanding of how warming will affect biofilms means we will be able to make better predictions on how these changes will influence organisms further up the food web, and so better understand the impact of rising temperatures on freshwater ecosystems.

After six days of sampling biofilms for the project, we received news that there were polar bears in a neighbouring fjord. We leapt at the chance to see one in the wild so made a diversion to see them and saw four altogether, all feeding on a sperm whale carcass. Despite being a long way from them, I know it will be one of the best memories of my life.

For me, working in the Arctic Circle, seeing the wildlife and talking to the locals has brought home the very real impacts of climate change. In Greenland, residents told us that the sea ice has become noticeably thinner, no longer connecting Disko Island (a small island off the west coast of Greenland) to the mainland. While in Svalbard, we were told that Atlantic Mackerel have become more common in the coastal waters due to rising temperatures. Stories like these remind us how quickly the effects of warming are being exhibited, and why climate change research is so important.

polar bear

Find out more about the Ring of Fire research project.

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