Sarah Marley is a Scottish marine biologist studying whales and dolphins in Western Australia. She’s particularly interested in how anthropogenic noise in the ocean environment affects dolphin behavior and communication. Here she tells us about days spent dolphin spotting, what it’s like to manage lots of volunteers and how to get into marine biology.
Name: Sarah Marley
Species: Bottlenose and Snubfin dolphins
Location: Western Australia
Bio: I’m originally from Scotland, where I was lucky enough to start exploring nature at a very young age. I grew up chasing squirrels in the woods, watching sea birds nest from clifftops, and fishing for tadpoles in streams. But one of my favourite things was observing dolphins in the Moray Firth. Every school holidays, my family would go to stay with relatives up in northern Scotland, and I would spend the majority of my time perched on the walls of the local coastguard station looking for dolphins. So even as a 7-year-old I was happiest sitting on a wind-blown hill with my binoculars and notebook – looking back, I was on-track to being a scientist before I even realised it!
You’ve managed to turn your passion into a job, which is certainly something a lot of people aspire to. Can you tell us a bit about how you made that happen?
Since my early days as an amateur naturalist, I’ve turned it into a career. I gained an undergraduate degree in Zoology from the University of Aberdeen, where my honours project focused on the same bottlenose dolphins I’d grown up watching in the Moray Firth. It was then that I realised marine mammals were my passion, so I specialised further by completing a Masters in Marine Mammal Science from the University of St Andrews, this time focusing on grey seal behaviour for my dissertation. By then I felt pretty confident on the general knowledge part, but wanted to develop my field skills more. So I spent a year in Australia with my partner (who is also a marine biologist), where we worked on several research projects involving dolphins, humpback whales, and blue whales.
Working with blue whales with the Southwest Whale Ecology Study (SouWEST) was amazing – there is a particular point down in south-western Australia where the pygmy blue whales migrate really close to the coast. You can literally stand on the beach and watch them swim by only a couple of hundred meters from shore. On this project, I met my current supervisor and we started discussing PhD projects. I then spent a couple of years working in science communication whilst applying for international scholarships to study in Australia – and here I am!
The ocean has never been a quiet place. It is full of ambient noise (wind, waves and currents) and biological sounds (crustaceans, fish and marine mammals). Light doesn’t travel very far underwater, so as a result many marine organisms have evolved to use sound, rather than vision, to explore the world around them. But over the last few decades, the ocean has been increasingly filled with another sound source – anthropogenic noise, such as boats, dredging, seismic surveys, pile-driving, and so on.
Some of those marine species with the most elaborate and extreme acoustic specialisations are dolphins. They use sound to communicate with each other, find food, avoid predators, and even have echolocation to sense objects underwater. But for many coastal dolphin species, their habitat overlaps directly with ours, making them subject to increasing levels of man-made noise.
For my PhD, I am studying coastal dolphins in noisy environments. I want to investigate the soundscape of their environment to characterise how noisy dolphin habitats are. From this, I can start to investigate dolphin communication space – or, how far they can communicate with each other in different scenarios of “noisiness”. I also want to investigate what strategies dolphins have for dealing with noisy environments – maybe they make changes to their physical or acoustical behaviour in response to high levels of underwater noise.
Can you tell us more about the dolphin species you are studying?
I am focusing on two coastal dolphin species – bottlenose dolphins (Tursiops aduncus) and snubfin dolphins (Orcaella heinsohni). Bottlenose dolphins are a wide-spread species around Australia, but exist in small communities with limited genetic exchange rates, which make these communities vulnerable to environmental changes and anthropogenic pressures. Snubfin dolphins are endemic to Australia, occurring in fragmented populations across the north of the country. They are currently listed as ‘near threatened’ on the IUCN Red List, but there is insufficient data to assess whether they should be listed as ‘threatened’ or ‘specially protected’ under Australian legislation. However, given the near-shore distribution of snubfin dolphins, they appear particularly vulnerable to human activities.
I have two field sites in Western Australia – for bottlenose dolphins research occurs in the Swan River which flows through Perth, and for snubfin dolphins the fieldwork occurs in Roebuck Bay, up north in the Kimberleys.
Since I live in Perth, fieldwork here is relatively straight forward! Since November 2013 I have been using underwater noise loggers to record sounds in the river. These are deployed at several locations along the Swan River, and each month I go out to recover data, swap batteries, and redeploy the loggers to a new site. For visual observations, I have two main land-based vantage points which I try to do 3hr shifts at several times a week with a team of undergraduate volunteers. So a typical day in the field for me is getting up around 5:30am to meet the vollies at Field Site 1 at 6:30am. We set up our gear and begin observations, with the shift lasting from approximately 7 – 10am. I’ll pack up, head to uni to charge the laptop and download data, then go to meet the next group of vollies at Field Site 2 around 2pm, where we do observations until around 5:30pm. Then it’s time to head home, charge batteries and download more data, before an early night to do it all again the next day! Visual observations in the river last from January – June, so I manage to rack up quite a few field hours!
Up in Roebuck Bay it’s a little bit different. There are not really any suitable land-based vantage points, so in the past we have done boat transects and conducted visual observations from moored vessels. The latter is particularly good for behavioural observations, as we have used an ex-pearling vessel that has been moored in the area for a long time. The animals are used to its presence, and don’t even realise we’re there, so we can be confident that we are recording undisturbed behaviours. Because we are out on the water though, we are a bit more restricted by the weather – if it starts to get too windy, then we have to pack up and head in. This means we seize whatever weather windows we can, which can require some rather early starts and long days on the water to maximise our opportunity for data collection.
It sounds like a great lifestyle, if a bit hectic! Can you tell us about the highlights of studying dolphins?
Obviously the main highlight is the animals. I’ve been conducting marine mammal research for over seven years now, but I still get excited whenever I see them! It actually takes the new volunteers a while to get used to me breaking off the middle of a seemingly-normal conversation to suddenly scream “Dolphins!” and start grabbing equipment. Turns out some of them are quite easily startled, but they are soon trained out of it! I have a real passion for learning new things, so I thoroughly enjoy the chance to spend so much time observing these animals to learn more about their behaviour and ecology. Branching out into acoustics has made that even more fascinating – it’s one thing watching the animals at the surface, but acoustics gives us an idea of what they are experiencing beneath the surface too!
I’ve always enjoyed meeting new people, and the first thing I get new volunteers on the project to do is share their life story. During quiet periods in the field, you get to learn all about a person and we’ve had some pretty interesting conversations! A lot of the volunteers who get involved are ones I have taught in my capacity as a lecturer and tutor at local universities, and for many it is their first taste of fieldwork. So there is also quite a sense of pride in watching these students move from the classroom to the field, grow their skills, develop confidence, and start to become researchers. So far this year I’ve had over 40 volunteers involved with various aspects of the project and I look forward to following their future careers, especially knowing that I was able to play a small role in that.
People management can be pretty tricky. I can’t do this field work alone – there are too many things to do! So having lots of volunteers available and willing to help is a real benefit. But organising dozens of people can be rather challenging at times! Finding out everyone’s availability, arranging them into shifts, and organising training takes up quite a bit of my time each week. And each night I worry that someone will cancel at the last minute or sleep-in and miss the morning shift!
Of course, another challenge is the heat! Coming from Scotland, I’m not exactly built for warm temperatures… So spending several hours a day out in 40⁰C heat, baking in the Australian sun, can be pretty exhausting!
Many dolphin populations live in close proximity with human activities, so it is likely that some individuals are habituated to the presence anthropogenic noise. But there may still be a ‘critical limit’ of noise that invokes an acoustic or behavioural reaction in these animals. By learning more about the responses of dolphins to underwater sound and what criteria are required before an environment becomes ‘too noisy’, we will be better placed to manage human activities and minimise their effect on coastal dolphins. In some cases, this could be as simple as introducing different speed limits for vessels or restricting activities to certain places or times of year to have the least effect, or maybe even feed into vessel design to help develop quieter vessels.
Well, first we have to determine if it is indeed a problem, and if so how big a problem it is!
Underwater noise levels have definitely been increasing over the past few decades, but the effects of this on marine fauna are still being studied. Research from other projects has suggested that underwater noise can potentially contribute to other environmental pressures on sensitive populations of animals. For example, if animals are already food limited and they rely on sound to detect their prey, then noise from boats can make foraging even more difficult for these individuals.
Many marine industries have already adopted protocols to reduce their potential impacts on wildlife, which is great. But another under-appreciated source of underwater noise in coastal areas is actually from recreational boat traffic. There are over 95,000 recreational vessels registered in Western Australia, and more than half of these are located around the Perth metro area. So you can imagine that when everyone takes to their boats to go out on the Swan River during the holidays, it can result in a pretty noisy river!
A lot of the students I teach are really keen to get some marine biology work experience, and each week I receive emails from people looking for internships and volunteering opportunities. It can seem pretty daunting as an undergraduate wanting to gain more field skills and research experience, but not knowing where to start. So here are my top tips to aspiring marine biologists:
1) Follow your passion: Nobody goes into biology for fame or money – instead, what drives you forward is passion for your subject. The thrill of discovery, the satisfaction of knowledge, the excitement of learning new things. Sure it has its ups-and-downs (just like every other job), but if you’re averaging out pretty happy by doing what you love, then you’re onto a winner! When I am recruiting volunteers, I would choose high enthusiasm over high grades any time.
2) Start Local: The grass is always greener on the other side, and overseas projects always sound more exciting. But they are often expensive and competitive. Check if there are any local projects that would give you some foundation skills before you branch overseas. Not only will this give you an edge over other applicants, but you will get more out of the project if you enter it with a bit of experience and know-how.
3) Network, network, network: There are so many amazing opportunities out there, it is difficult to hear of them all! But one of the best ways is just through word-of-mouth. Speak to other people in your field about what they have done in the past, and what projects they know of that might need volunteers.
4) If you don’t ask you won’t get: Don’t be afraid to send out enquiry emails – you never know who could be looking for help, but just hasn’t found the time to advertise it yet! But put some effort in and be sure to personalise the email. Batch emails with the same content sent to dozens of researchers are pretty obvious; instead, read up on the person you are contacting and their institution. Then not only can you personalise the email, but you can make an informed choice about the right opportunity for you.
5) Try new things: The only way to find where your strengths and interests lie is to try new things – and lots of them! Maybe you are a great diver or perhaps you feel more comfortable on-shore. You could have sharp-eyes for spotting animals at a distance or you could be better at accurately recording data. No matter where your skills lie, there is a place for you out there. It might just take some time and experience to figure out exactly where that is.
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