Eyes in the sky: how drones are helping marine researchers

It turns out drones can be used for more helpful things than just shutting down major international airports. Marine biologists are using the technology to monitor marine life in new and exciting ways. But how do they aid researchers and what are the future possibilities? I talked to an expert to find out.

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Eleuthera from the air (photo by Alex Smith)

Last January I was lucky enough to visit the Bahamas as part of a University of Exeter field course. We visited the Cape Eleuthera Institute (CEI) and for two weeks we were immersed in an amazing array of hands on research activities. As a group we learnt so much about the local marine life and the work that goes into studying it. But on a personal note one of my favourite activities was a drone survey of a nearby mangrove creek. I wanted to know more about how researchers at CEI have been using drones, how much the technology helps them with their work and what the potential uses are for the future. I was lucky enough to talk to Dr Nathan Robinson a lead researcher at CEI to find out.

Nathan has been working with drones in his professional career for over four years and was kind enough to talk to me over skype about all things drone related in his work in the Bahamas. His knowledge of the technology and enthusiasm for the field was inspiring. He enjoys working with drones because he believes “for me it’s a new way of looking at the world around us and that’s why it’s so beneficial to science”.

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Smile for the drone! Our research group from UofE with Nathan (centre controlling the drone)

At CEI drones have been an active part of their research for the last two years. One of the first projects they ran was the one I briefly took part in during my visit last year. The study took place in mangrove creeks, which are important shallow water habitats that act as a nursery ground for juvenile fish, sharks, turtles and rays. The aim was to compare the effectiveness of aerial drone surveys in monitoring the abundance of those species compared to traditional methods such as snorkelling surveys.

The field work begins with a researcher like Nathan doing a drone survey from the shore. The drone used by CEI is the DJI phantom 4 which Nathan described as “a little bit like the small portable ones you shove in a backpack but with a longer battery life and a bit more rugged”. He told me that it is capable of flying in winds up to 20 knots but that it does not operate in the rain as it is not fully waterproof. Fortunately weather conditions in the Bahamas allow for lots of opportunities to fly year round.

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A juvenile lemon shark spotted by the drone (photo by Alex Smith)

After the drone survey is completed the team on the shore will begin a snorkel survey of the same area using underwater slates to count how many of each species they see. The results of both surveys can then be analysed to see how effective drones are compared to the more traditional method. One of the big differences in the methods is time. Nathan told me “snorkelling for most of our surveys would generally take about 20 minutes, but the same survey by a drone would take a quarter of the time.” It’s also not just saving time that is helpful, Nathan explains that “what used to be done by a team of people snorkelling through the habitat can now be achieved by one person with a drone”.

So logistically it is quicker to use drones and requires less people, but how effective is it? I asked Nathan if using drones meant it was easier to spot certain species. He replied “when snorkelling the species you tend to miss are the skittish species that scare easy, such as bone fish. You very rarely see bone fish because they can hear you coming from miles away. The same goes for juvenile lemon sharks, you might see some while you’re out there but you will see more in a drone survey.” It is also very good for picking out larger rounded animals like turtles and rays.

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Green turtles are easily spotted by drones (photo by Alex Smith)

However there are some drawbacks to using drones as well. Nathan explained “other species like juvenile barracudas you see more on visual surveys compared to drone surveys, that’s probably because they’re so small it’s harder to spot them from high up.” I also asked if there was any chance of misidentifying species from higher up. He answered “so that’s a risk, especially with smaller organisms. Things like ripples on the surface can really affect your ability to see them.” So whilst drones are an effective way of identifying species, they are not perfect.

But overall it is believed that the drone surveys are as effective as snorkelling surveys and potentially capable of identifying more species. Perhaps the real benefit though is the time saved and ease of which you can complete a drone survey. I asked Nathan about whether drones allow for a greater amount of data collection and he replied “Yes completely, 100 %” and went on to elaborate saying “that’s one of the big advantages of drones in that they are replacing human effort” and can be done in “less than half the time”.

Having established the drone surveys as an effective and easy way to collect data the research has switched to answering more practical questions. The work done with drones at CEI is now focused primarily on sea turtles. Nathan says they are “starting to observe behaviours by tracking individual sea turtles for a longer period of time, looking at how long they spend foraging or escaping from predators”. He also says they are “now using them to investigate how sea turtles react to boat traffic” because “boat strikes is a big threat to sea turtles in many coastal habitats”.

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Shallow water coastal regions like this are a likely area of turtle collisions with boats (photo by Alex Smith)

The results of these studies are not published but Nathan took me through the preliminary results of the boat traffic study. He explained “when we’re doing our boat surveys we will record them from above using drones and see at what distance turtles start to panic when a boat comes nearby” so they can “figure out how different sized turtles react to different levels and proximity of boat traffic”. Surprisingly they have found there is no real difference between sizes of turtles but that “in some creeks where there is higher boat traffic the turtles don’t respond quickly” compared to areas where they rarely encounter the noises.

Nathan told to me that the results meant “we might be changing turtle behaviours in these areas without even realising it because of boat traffic”. This was a really interesting result that would have been hard to find if the team couldn’t observe the turtle/boat interactions from above. I was pleased to see how the drone work had evolved in the last year and was starting to be used to answer serious research questions. But I also wanted to know what the future holds for the technology.

I asked Nathan what studies he would like to do involving drones going forward if money was no object. He told me that “being able to observe across longer distances would be useful”. Compared to the drones they are using now he says “some are more like mini planes and those can go to distances of tens of kilometres”. He went on to tell me “we could use those to monitor surrounding deeper waters and track things like sharks, cetaceans and other marine mammals”. In particular he explained to me how he wanted to track whales in the surrounding deeper waters and monitor health and well being through body condition.

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In the future it may not just be the juveniles that are tracked (photo by Alex Smith)

I finished off by asking how working with drones has affected Nathan’s career. He told me “it has been a huge benefit personally to me for my research and a field that’s been growing a lot throughout my career”. Like a lot of other researchers who work with the technology he has high hopes for its future. He ended by saying “I don’t know, the potentials are endless. We’re already seeing drones being used more in ecological research worldwide, but within 2 or 3 years it will be commonplace at every research station.”

To sum up drones are starting to make a big difference in the lives of marine research scientists. A big benefit of the technology is that it reduces the time taken to survey a large area and the amount of people and effort required to do it. This results in a greater amount of data that can be collected increasing the amount of studies a researcher can conduct. They are also providing a fresh perspective that can start to answer important questions in new and exciting ways. Drones are not perfect but they have come a long way in a very short space of time and their future in marine biology is bright. As the technology continues to improve who knows what researchers might be able to accomplish with them in the future.


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