RSGS Seminar: Rod Downie, WWF UK Chief Polar Advisor
Disclaimer: This blog is completely rock free and a little different to my other posts. The seminar had a mix of biology (polar bears) and environmental science (climate change), which was nice to write about. This will be my last blog from semester one, but it is certainly my favourite and I hope that it comes across as interesting to others as it does to me!
What was the talk about?
The Arctic is being affected by global warming and is, in the words of Rod Downie “ground zero” for climate change. In all the chaos of reducing sea ice in the arctic live the polar bears – traversing this harsh and ever-changing terrain to hunt and survive. They truly are the epitome of the arctic, representing everything we stand to lose with climate change; the true “icons on ice” the public imagine and support, yet we really don’t know very much about them.
How many are there? How will they respond to climate change? WWF want to answer these questions to better understand polar bears in the future by better understanding them now. The seminar focussed on current projects involved in answering these questions and what the future may hold for the polar bear.
Climate change and its effect on sea ice in the arctic
To explain this, I need to explain what global warming is:
The earth is warming at a rapid rate. The average temperature on earth rose by 2 degrees fahrenheit in the 20th century and will continue to rise throughout our lifetime. A small change in temperature doesn’t seem like a big deal, but it can cause large changes to the environment. We can already bear witness (a terrible pun) to some of the changes taking place on the planet because of this temperature rise: glaciers are receding, sea ice is melting earlier in the summer and forming later in the winter, heatwaves are longer and more intense and sea levels are rising.
How does this affect sea ice? Follow this link to NASA for a time series of sea ice extent since 1979: https://climate.nasa.gov/vital-signs/arctic-sea-ice/
Why is it an important topic?
Estimates of polar bear numbers range from 22,000 to 31,000; a very imprecise estimate. At present this is the best we have at knowing how many bears there are.
What we do know:
· 60-80% of bears are found in the Canadian Arctic
· There are 19 discrete subpopulations of bears
· 6 of these populations are stable
· 1 is increasing in number
· 3 are decreasing
· 9 populations are deficient in data – we do not know what is happening in these areas
There has been a rapid decline in arctic sea ice in all seasons. We will have lost 13% of sea ice by the end of the next decade. How do we know this? The use of the CryoSat 2 satellite which has recorded arctic sea ice extent. Follow the link to find out more: http://www.cpom.ucl.ac.uk/csopr/science.html
By 2040 the arctic is predicted to be free of sea ice in the summer months and polar bear numbers are predicted to decline by 30% by 2050.
Why is this important? Because polar bears depend on the sea ice to hunt and without it they struggle to find enough food for themselves and their cubs. It is therefore of vital importance to understand how these bears will respond to these changes. This is why we have to try and understand them right now.
What techniques were used and why were they suitable?
To better understand the polar bears in the future we need to try and study them today. The seminar discussed some of the new ways in which the WWF are trying to count polar bear numbers.
The main ways to count bears:
1. Genetic mark and recapture
2. DNA from bear footprints
3. Thermal imaging
Genetic mark and recapture in Nunavut
There are an estimated 280 bears in the Canadian arctic territory of Nunavut. The area covers over 300,000 square miles (about the size of the United Kingdom) and the project wanted to find and tag all the bears.
The mark and recapture project occurred as follows:
· A team of scientists will fly around in a helicopter searching for bears.
· When a bear is found the team circle it and prepare to fire a dart.
· The non-lethal darts are fired from the helicopter at a bear.
· The dart hits the bear and will then fall off.
· Attached to the dart is a fur, skin and fat sample from the bear.
· Someone from the helicopter must then retrieve the dart while being careful to avoid the aggravated bear.
· The skin sample is dried and then taken for DNA analysis at a laboratory.
· The genetic identity or fingerprint of the bear is then recorded in a database. The bear will then be recognised if it is encountered in another survey.
· The fat sample is frozen and sent for diet analysis, so that the bears diet over the last few months will be known.
· Capturing enough bear samples over the project will allow an estimate of the subpopulation size and trends to be recorded.
Mark and recapture results:
The project worked for a couple of months and captured a total of 90 bears. This was less than estimated but the data has been collected and have helped to plug in gaps in subpopulation knowledge. Unfortunately, the reports based on Rod’s expedition to Nunavut are not available online, so I cannot comment on the precise results gathered from the scheme.
To read about Rod’s experience you can follow this link: https://blogs.wwf.org.uk/blog/habitats/polar/icons-ice-part-two/
You can also read a little bit about the scheme here: https://www.polarbearscanada.ca/en/research/population-inventories/physical-mark-recapture
DNA from bear footprints in Svalbard
In 2014, WWF and the Norwegian Polar Institute conducted a survey of polar bear tracks in Svalbard. The project wanted to extract environmental DNA from the tracks to find out about the diet and lifestyle of a bear.
You can watch a short video from WWF about the survey here showing how the snow is collected and prepared for analysis: https://youtu.be/8uHove9cMgs
Footprint results
The company Spygen analysed the snow track samples for one polar bear and found 3 genetic markers present in the snow. They found DNA from a ringed seal, a gull and from the polar bear. This allowed scientists to recreate the recent history of the bear – the bear had hunted and fed from a ringed seal, which gulls had also fed from.
In time, the project wants to identify individual animals to track their movements and diets (like creating a genetic fingerprint).
Thermal imaging of bears in the Chukchi Sea
The area of the Chukchi sea covers 600,000 square km (about two times the size of the United Kingdom). There is no data whatsoever for bears in this region and so the project wanted to use thermal imaging to conduct an aerial count of bear numbers in the region.
The survey was conducted by flying a plane 1000 feet above the ice to estimate the bear population in that area. High resolution images were taken from cameras mounted to the plane. Thermal images from an infrared camera were also taken of the same spots. Any mammal shows up as a shiny blotch on the infrared. Zooming in on these blotches on the high resolution image can identify bears. They are then counted, one by one, this way.
Results
Can you spot the bear?
Here is the same image from the thermal camera – can you spot the bear now?
Sadly, this could be anything – how do you know that the blotch is a bear? Zooming in on the high resolution image to the area where the blotch is will reveal the bear.
The technique will be used by scientists to monitor population trends over time.
How did the talk advance our knowledge?
The talk advanced our knowledge of how climate change is reducing sea ice cover, and how this will affect polar bears. The talk highlighted how little we know about bear populations and how it is crucial to study them now, so we can implement measures in the future to help protect them from human induced climate change.
The talk showed the new innovative ways in which we are slowly building up population records about polar bears, and hopefully with more public interest, we can help save these iconic creatures from an ice-free future.
You can read more about Rod’s work on his blog posts at WWF, or just follow this link: https://blogs.wwf.org.uk/blog/habitats/polar/icons-ice-part-1/
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