Living in the Acoustic Environment

Last month, I attended the Acoustical Society of America (ASA) conference in Minnesota. I prepared a conference report for the Journal of Animal Ecology Blog, which I have reposted below.

Animal Ecology In Focus

Our Blog Editor, Dr Sarah Marley, reports back on last month’s Spring Meeting of the Acoustical Society of America (ASA) in Minnesota, USA. Find out what made it such a successful conference, and why she did not end up being the loner she expected to be…

Last month, several hundred acousticians descended on Minneapolis, Minnesota for the 175th Meeting of the Acoustical Society of America (ASA). I was among them, attending this conference for the first time. Although I have been conducting research in acoustics for over five years, I still feel very new to this field and was nervous about presenting to ‘hardcore’ acousticians rather than my normal audience of biologists. And, although I was an invited speaker, I did not actually know many people attending this primarily American conference beyond my PhD supervisor and a few Twitter acquaintances. So the 27hr plane ride over from Western Australia…

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New Job!

I am excited to announce that I have a new job! Starting in August, I will be a Lecturer in Marine Biology at the University of Portsmouth. This means a big change in more ways than one, as – after 8yrs down under – we will be moving back to the UK.

I think our friends and families on both sides of the world are still in shock, with one side having given up hope of us returning and the other thinking they’d managed to claim us for keeps. I’m still feeling pretty shocked myself, alternating between being Extremely Excited  and Totally Terrified. The positives are obviously the idea of going home and being closer to family, all to do a job that sounds perfect for me. I love teaching, and this position will allow me to broaden that by developing new materials and supervising students, as well as continuing my research activities. However, moving means saying goodbye to some amazing people, a big lifestyle change, and an overwhelming amount of logistics. As I wander around our house, mentally categorising items as ‘sell’ or ‘ship’, I can’t help but think how much simpler it was when we first came out here with just a backpack each. If it wasn’t for the fact we’re going to need so many layers whilst our internal thermostats adjust, that might still be an option.

close up photo of three sweatshirts

Photo by Daria Shevtsova on Pexels.com

What makes the logistics particularly challenging is that neither of us have ever actually been to Portsmouth before. The whole hiring process (including an interview, a mock lecture, and a presentation about my research) was all conducted over skype. So whilst all these virtual meetings have gone well and my new colleagues seem lovely, it is still a bit disconcerting to be moving to the otherside of the world to a place you’ve never been. Although saying that, I did the same thing in 2010 by coming to Australia… Maybe I’m just getting old.

However, this issue will soon be rectified! Phil and I are both presenting at the International Statistical Ecology Conference next month, which conveniently enough is being held in St Andrews. This not only allows us both to tie in a trip to see our parents, but means we’ll also have the chance to visit our new home.

It does mean my life at the moment has been pretty FIFO (Australianism: fly-in, fly-out). Last month I was over in the US to present my research at the Acoustical Society of America conference in Minnesota. After a 27hr flight and 13hr time difference, I had an amazing trip despite being wrecked by jetlag. The fact that I was only there for a week meant that by the time my body clock got its act together it was time to go home and spend another week temporally confused! Now, after a month back home, we’ll be heading to Europe for a month, followed by a month back in Oz before the Big Move over to Portsmouth. Crikey.

It is a lot to take in, but there is no doubt in my mind that this going to be a great experience! So stay tuned for posts about moving dramas, culture shock, and academic adventures!

 

Laborastory Talk – My Science Heroes

A couple of months ago, I was invited to participate in the Perth Laborastory event. The Laborastory is a science storytelling event usually held in Melbourne that comes to tell the stories of science – “the heroes, the egos, the breakthroughs and the mistakes of genius”. This was the second time it had been held over West, and I was delighted to be involved!

Laborastory quote

My science story revolved around two of my heroes – David Attenborough and Gerald Durrell. Whilst you are no doubt well aware of the first, you might not be so familiar with the second. In my story, I describe my failed close encounter with Attenborough, my captivation with Durrell, and how both men contributed to my zoological career.

Hear the full story below. Unfortunately the acoustics are a little on the quiet side, so you’ll need to turn it up! And yes, I swear the audience is laughing in those quiet pauses…!

Sound Science in the Swan

On Monday, I gave a presentation about dolphin acoustics in the Swan River at a free public seminar called “Sound Science in the Swan“, supported by Acoustics2017, the annual conference of the Australian Acoustical Society.  Over 60 people attended the two-hour seminar, with the audience containing both scientists and members of the public.

The evening kicked off with an introduction by the organiser, Dr Miles Parsons from Centre for Marine Science and Technology (CMST) at Curtin University, who explained what sound is and how animals use it underwater.  I then demonstrated this through my interactive Soundscape Game, where the audience members are each allocated the role of a different underwater sound source and produce them together to create a ‘soundscape’.

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Me yelling at some audience members to “make snapping shrimp noises” (Photo: Sylvia Parsons)

Miles then explained more about some of the anthropogenic (man-made) sound sources in the Swan River system, including things like vessels, pile-driving, airplanes, drones, and even human swimmers!

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Miles presenting experiments examining sounds produced by swimmers (Photo: Sylvia Parsons)

This was followed by Dr Iain Parnum (also of CMST) who explained his work using underwater acoustics for the purposes of habitat mapping within the Swan.

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Iain using acoustics to ‘see’ underwater (Photo: Sylvia Parsons)

After the break, I was up to present about dolphins!  I started with examples of the different sounds dolphins make and why underwater sound is vital for their survival.  I then applied this to the Swan River, by showing it as a busy, noisy environment – and therefore rather challenging for dolphins!  However, as I explained, my research shows that the dolphins don’t necessarily leave noisy areas, although they might have strategies for dealing with them.

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Me showing some theodolite tracks of dolphins and vessels within the Swan River (Photo: Sylvia Parsons)

I was then able to present some research on dolphins and pile-driving, on behalf of my PhD supervisor Dr Chandra Salgado Kent, who was unable to attend that evening.

The evening finished back with Miles, who spoke about mulloway and some of the research surrounding the calls made by these fish.

A thoroughly enjoyable way to spend an evening!

SMM 2017 Conference Presentation

I’m now safely home after attending the Society for Marine Mammalogy’s biennial conference in Halifax, Nova Scotia.  It was an amazing eight days of conference talks and workshops, interspersed with plenty of networking.  As well as meeting lots of interesting new people, it was particularly wonderful to catch up with so many old friends.  Totally worth the 35hrs of one-way travel and 12hr time difference jetlag!

I’m currently preparing a detailed conference report for the Journal of Animal Ecology’s blog, but in the meantime I wanted to make my conference presentation available online.  To download a PDF version, click here.  The full abstract is provided below.  Feedback welcome!

SMM 2017 - Sarah Marley

Acoustic habitats and behavioural responses of bottlenose dolphins in Western Australia

Marley, S.A., Salgado Kent, C.P., Erbe, C., Parnum, I.M. and Parsons, M.J.G.

As human activities continue to expand across the marine environment, anthropogenic ocean noise is also rapidly increasing.  This is of concern to acoustically-specialised species, particularly those displaying a high degree of habitat overlap with anthropogenic activities, such as bottlenose dolphins (Tursiops sp.).  There is a need to describe the soundscape of coastal dolphin habitats and examine how prominent anthropogenic noise sources may impact these animals.  The Swan River in Western Australia flows through the state capital of Perth, containing over 1.4 million people, and consequently experiences a range of anthropogenic activities.  However, the river is also extensively used by a resident community of Indo-Pacific bottlenose dolphins (T. aduncus).  Autonomous underwater acoustic recorders were used to collect data throughout the Swan River, which were analysed via weekly spectrograms, power spectrum density percentile plots, octave-band levels, broadband noise levels, and generalised estimating equations.  Land-based theodolite tracking at two sites provided information on vessel traffic and dolphin behaviour, which were assessed using generalised additive models and Markov chains.  Acoustic datasets collected from 2005 to 2015 indicated that the Swan River was comprised of multiple acoustic habitats, each with its own characteristic soundscape and temporal patterns in underwater noise.  The ‘noisiest’ site from an anthropogenic perspective and in relation to dolphin communications was the Fremantle Inner Harbour (mean broadband noise level: 106 dB re 1 µPa rms [10 Hz – 11 kHz]).  Theodolite tracking at this site found that dolphins remained present during periods of high vessel traffic.  However, behavioural observations indicated significant alterations to dolphin movement speeds and activity states at high vessel densities.  Furthermore, whistle characteristics varied in conditions of high broadband noise.  This work suggests that dolphins maintain occupancy at key foraging sites within the Swan River despite the presence of vessels, but alter their behaviour in periods of high vessel traffic.

New Paper: A Tale of Two Soundscapes

I am a little bit behind in posting about my various PhD publications.  But a pretty cool one that came out in the August edition of Acoustics Australia focused on comparing the acoustic characteristics of urban versus pristine coastal dolphin habitats.

I’ve previously spoken about the need to define the soundscape of dolphin habitats and examine patterns of when and where noise occurs.  But whilst we can monitor dolphin acoustic habitats and describe how they are now, in many cases it is hard to say how they were in the past.  We simply don’t have enough long-term datasets that capture the expansion of human activities into the marine environments – i.e. datasets that go far enough back in time to capture when the habitat was pristine and free of human influence.  Understandably, this can also make it hard to decide how we best manage man-made noise in these habitats into the future.  It’s hard to determine what noise mitigation measures are necessary when you don’t know how quiet an area is ‘supposed’ to be.

A potential solution to this conundrum for managing ‘urban’ areas is to find comparable ‘pristine’ areas which are also used by the study species, and see what differences exist.  Of course, this is reliant upon pristine areas still existing in the first place.  However, in Western Australia we are fortunate enough to have some areas up in the remote north of the state.

The Kimberley region in north-western Australia is one of the most remote, pristine wildernesses in the world.  The largest town in the region is Broome, which has a permanent population of only 16,000 people (although the temporary population can increase to 45,000 in the tourism season).  Broome is located on the shores of Roebuck Bay, with a relatively large population of snubfin dolphins and is also regularly used by bottlenose dolphins and humpback dolphins.  This area offers a nice contrast with the busy, urban environment of the Swan River, which flows through the Western Australian state capital of Perth.  This river is also used by bottlenose dolphins.  To create successful noise mitigation strategies for coastal dolphins, there is a need to compare ‘quiet’ and ‘noisy’ acoustic habitats.  Roebuck Bay and the Swan River offer the perfect opportunity to do just this.

Prepping the Roebuck Bay acoustic gear

I chose to compare the pristine soundscape of Roebuck Bay with the Swan River’s anthropogenically-noisiest site, the Fremantle Inner Harbour.  I used autonomous underwater acoustic recorders to monitor the soundscape at these sites, and assessed these using a combination of weekly spectrograms, power spectrum density percentile plots and probability densities, octave-band levels, broadband noise levels, and generalised estimating equations – i.e. a shedload of nifty acoustic analyses.

What these essentially showed were that these two sites are very different in their acoustic characteristics.  In Roebuck Bay, biological sounds (such as crustaceans and fish) were the most prevalent sound sources, with very few instances of vessel noise.  However, in the Fremantle Inner Harbour, man-made noise dominated.  This worked out to a 20 dB difference between sites on average, and the frequencies used by dolphins for communication were more likely to be masked in Fremantle Inner Harbour based on elevated noise levels.

In this study, I was also lucky enough to get some acoustic recordings of sounds produced by snubfin and bottlenose dolphins in Roebuck, and could use these for a comparison with the sounds produced by bottlenose dolphins in Fremantle.  This helped me to discuss the potential consequences on Roebuck Bay dolphins if noise levels were to increase at that site.  Such information is going to be useful going into the future, as several coastal developments are currently planned for Roebuck Bay.

To find out more, check the paper out online or contact me!

Snubbies are happy little dolphins – hopefully they stay that way! (Photo: Sarah Marley)

 

New paper: Behavioural and acoustical responses of dolphins to vessel traffic and noise

Last night, my sixth (and final) PhD paper was published in the journal Scientific Reports!

In earlier papers, I established that the Swan River is a pretty noisy place.  One of the noisiest sites from an anthropogenic perspective is the Fremantle Inner Harbour, which experiences high levels of vessel traffic.  However, during my initial visual observations I discovered that dolphins continued using the harbour, even though it was a busy noisy environment.  So in this latest paper, I searched for evidence of dolphins responding to boats and noise at a subtler scale.

To do this, I used a combination of visual and acoustic monitoring techniques.  I found that dolphins significantly increased their movement speeds when vessel traffic occurred at high levels.  Similarly, dolphins also changed their behavioural budgets at high vessel densities, spending more time travelling and less time resting or socialising.

I monitored dolphin movement speeds and behaviours, to see how these changed as vessel traffic increased

I also looked for acoustic responses, by measuring nine characteristics to describe the shape and frequencies of dolphin whistles in different noise scenarios.  I found that all nine of these characteristics varied with increasing levels of broadband noise, and that the response was particularly strong for low-frequency noise.

I used nine characteristics to describe dolphin whistles

I’ve spoken before about the importance of scientific publishing, in terms of career brownie points for researchers.  So I’m pretty chuffed to have completed publishing my PhD!  To view the full list of papers from this and other projects, check out my Publications page.  Now to deal with all the ‘leftover’ PhD data that I collected, but didn’t get around to including!

Associate Editor of Austral Ecology

Today I received my first email addressed to “Dear Dr Marley…

And as if that wasn’t enough of a buzz, the email itself was to welcome me onboard as a new Associate Editor for the scientific journal Austral Ecology!

The daunting world of academic publishing…

Most scientific work is published in an academic journal.  The idea is that a piece of work is reviewed by your peers, who can either reject it as unacceptable or recommend it for publication (often after implementing some improvements).  So everything that appears in academic journals has generally been vetted by at least two experts in the field through this ‘peer review’ system. This is to ensure the quality of work being published, as researchers are judged by their publications when applying for jobs and grants.  In some cases, the survival of whole university departments depends on their publication records.

But it’s not just about churning out article after article.  There are thousands of journals out there for different scientific fields, each of which with its own level of prestige.  And your success as a scientist depends on getting your work published in good-quality journals.

Austral Ecology is the official journal of the Ecological Society of Australia (ESA), and is the premier journal of basic and applied ecology in the Southern Hemisphere. This includes experimental, observational or theoretical studies on terrestrial, marine or freshwater systems.  ESA is the main professional association for ecologists in Australia, with over 1,500 members across the country.

The most striking ecological system I’ve ever worked in – the Kimberley of NW Australia

As an Associate Editor, I will be responsible for managing several manuscripts per year.  This involves finding suitable peer reviewers for each article, and making recommendations of the suitability of that article for publication based on the reviews received.

From my own experience, I know that a good editor makes all the difference.  When publishing my first paper, I received excellent support from the journal editor, who guided me through this overwhelmingly daunting process.  I have also received support from an editor in the past when a peer reviewed behaved less-than-professionally when assessing my work.  I believe having a good editor can make all the difference for authors – and I look forward to contributing to this process.

Introducing Dr Marley!

Last week, I received official notification that my PhD was conferred!  In normal-speak, this means that Curtin University has fully accepted my PhD and that I can now use my new title!

In a nice coincidence, that same day my printed and bound thesis copies were ready for collection.  So I had the double pleasure of holding my academic babies AND referring to myself as Dr Sarah Marley!

In that moment, all I could remember were the highlights and golden times.  The amazing experiences, friends and discoveries that happened along the way.  The opportunity to do something novel and exciting.  I was reminded of how happy I was to start my PhD, giving my top three reasons for doing so to be curiosity, love of research, and enjoyment of being challenged.  And although the end of the PhD was certainly challenging, when I was holding the final, finished project as an official Dr of Dolphins, all I could think was:

Totally. Worth. It.

New Paper: Spatial and temporal variation in dolphin acoustic habitats

There is a growing awareness of underwater noise in our oceans and the potential impacts of such noise on marine life, an issue which was the major theme of my PhD thesis.  This is particularly relevant for “acoustically-specialised” species, such as dolphins.  However, before we can start investigating the effects of noise on these animals, we first need to define the soundscape of dolphin habitats and examine patterns of when and where noise occurs.

We get a glimpse of them at the surface – but what about their acoustic habitat beneath the surface? (Photo: Sarah Marley)

This description of noise in dolphin habitats formed my third PhD chapter, which has now been published online in the scientific journal Frontiers in Marine Science.  In this paper, I examine spatial and temporal variability in the soundscape of the Swan River using over 11,600 hours of acoustic data collected from five sites within the river system across eight years.  Multiple sound sources were recorded at these sites, but the prevalence of these sounds at each site differed, giving each location a characteristic soundscape.  Consequently, some sites were ‘noisier’ than others.

Deploying acoustic recording equipment with help from Fremantle Ports. Spot the dolphins in the background! (Photo: Jeanette Murray)

Want to know more?  The full paper is available online! I’d love to hear your thoughts 🙂

Marley et al. (2017) Spatial and temporal variation in the acoustic habitat of bottlenose dolphins (Tursiops aduncus) within a highly urbanised estuary.  Frontiers in Marine Science, 4: 197.

And watch this space, as the remaining three PhD papers should be going up online in the next few months!