Summertime!

And the living is not necessarily easy but certainly more easily entertaining. Besides the wedding season it’s also conference season. All the lab-mates travel on the other edge of the country (USA) for summer schools, meetings, exciting field trips and pilot classes (stay tuned and Selene has some stories to tell). I made it to the other end of the Atlantic and all the way to my beloved motherland. My first time participating at the Underwater Acoustics meeting, an international conference that took place at the Island of Rhodes in Greece, just a few days after the meeting of the Acoustical Society of America that took place at Rhode Island in USA. Appears that the islands of roses (Rhodes derives from the Greek: rhodo which means rose) were acoustically active this summer. Coincidences are fun.

Four exciting projects were presented by OSU people.

Haru Matsumoto, had a presentation with the imaginative title: “Antarctic’s Siren Call: The Sound of Icebergs”. I absolutely love it when people use a cool title for their scientific projects! His talk and his project was as exciting as it sounds and it was by far my personal favorite non-bioacoustics talk of the conference. Haru showed how the sound of melting icebergs affects the noise budgets in the South Pacific Ocean. The disintegration of two large icebergs at Antarctica produced low frequency sounds, so loud that they propagated and got recorded across the equator up to 8o N, 10.000 km away from the icebergs! He measured an increase of the noise level by 6 dB and 3 dB in comparison to baseline years (when the melting icebergs were absent). If 3 and 6 dB doesn’t sound like a significant increase to you then you are probably not aware of the decibel scale. This Radiolab podcast “The Walls of Jericho” will entertain you and will explain in a simple and funny way how this scale works.

Lately we have been seriously concerned about the shipping, airguns, naval sonars and other prominent man-made noise in the ocean and how they interfere with marine life. Haru’s presentation opened a window to think how a non-anthropogenic sound source can have such an impact to the marine soundscape, and potentially impact specifically the largest baleen whales (blue and fin whales) that also vocalize at low frequencies (below 100 Hz). Even though natural, the melting of the icebergs can be effected by anthropogenic activities, in particular the human induced climate variability and global warming. No need to be more specific, feel free to consider further potential ecological implications.

Bob Dziak presented, through Haru (unfortunately Bob was not able to make the Oregon-Greece 20 hours long travel), the “Sources of long-term ambient ocean sound near the Antarctic Peninsula”. Bob’s project was one step more general and inclusive. He described the contribution of a variety of sound sources to the soundscape of the frozen South. Acoustic data were collected during 4 years using 2 hydrophone arrays and the results indicate that the main factors of sound production or “noise” (depending from which point of you look at it: the biologist’s or the geophysicist’s) around the Antarctic Peninsula are the icequakes (acoustic signal derived from fracturing of large free-floating icebergs or ocean front icesheets) and the whale calls!

The whales confuse the icequakes with ice cakes!
The whales confuse the icequakes with ice cakes!

The weather conditions are too rough for sound-measurable human activities and both the blue and fin whales seem to take advantage of this human-almost-absent corner of the world. The sound of the ice breakup and grounding is clearly the most prominent sound source in the Southern Ocean Basin but it varies seasonally. Bob’s presentation (same as Haru’s) made me switch my perception of summer and winter for a bit. In Antarctica, during the austral summer the increased temperatures result increased icequakes and the release of acoustic energy. The opposite happens during the austral winter when the icesheets form, even though the wind speed increases. The giants of the Antarctic Peninsula seem to follow the freeze-thaw cycles and their peak season matches the sea-ice-cover-minimum of the austral summer. Consequently if you want to see fin and blue whales when in the North Hemisphere is still winter, chase the summer down as south as it gets…

This conference was an excellent opportunity to reunite with ORCAA’s favorite Naysa. It had been almost a year since Naysa left Newport, after her few-months stay and collaboration with the CIMRS, and it was an indescribable pleasure to spend some warm Greek time with her and watch her awesome presentation on “Acoustics as a tool to reveal population structure of the elusive blue whale”. Naysa talked about the smallest subspecies of the largest animal on earth. The pygmy blue whale. She used 5 sites in the SE Indian and the SW Pacific Oceans to collect 3 years of acoustic data to

determine the occurrence of pygmy blue whale in these locations. Apparently th

Pygmy blue whale on it's belly
Pygmy blue whale on it’s belly

is species produces 5 regionally-specific calls: the Madagascan, Sri Lankan, Australian, New Zealand and Solomon type. Naysa used an automated method (detector) and was able to detect the “Australian” and the “New Zealand” dialects at the SE Indian and the SW Pacific Oceans respectively and her results provide evidence of a previously unknown population, the latter one! Naysa’s study is an excellent example of the numerous applications of acoustics, particularly to the population and movement patterns of marine mammal species over large spatial and temporal scales. The more I enter into the acoustics field the more excited I get about the knowledge and information that the sound solely can reveal us, especially about elusive cetaceans, like Naysa’s pygmy giant.

In the Ocean it is a common truth that what the eyes cannot see the ears can hear!

After seeing Naysa’s presentation I have one technical advice for presenters. Go simple or go home! She managed with minimum text, probably no text at all, pretty slides with most of the times just one picture, to get across her messages and keep the attention of her audience! Focus on the gist of your talk and feel confident to leave the details out giving the opportunity to people to ask for them if needed.

For my presentation we move back to the North Hemisphere and head eastwards. I presented my work at the Greek seas with the title: “Passive acoustic detections of odontocetes in the Ionian and Aegean Seas, Greece”.  Even though cetology was born in Greece (as mentioned in my first post: The philosophy of sound) 2500 years ago, little research has been done in the Greek seas since then. Mainly the Ionian Sea (west of continental Greece) has been investigated and almost exclusively during the warm summer season, while the cetacean populations in the Aegean (east of continental Greece) are largely unknown. I used 2 hydrophones during 19 and 10 months to assess the seasonal occurrence of different species in these two regions and determined the seasonality of especially the sperm whales (that I particularly love, usually dream of, and I am overall obsessed with) and the delphinids. I am proud to have performed the first long-term bio-acoustic monitoring study in Greece and looking forward to going out to the clear blue Greek waters to collect ground truth data necessary that will allow us for first time to tell apart the different dolphin species that dwell the Aegean! Any funding suggestions anyone…? If you do, you are welcome to join me at an Aegean cruise chasing dolphins!

Me and my poster!
Me and my poster!

My presentation was a poster and even though I am usually not very fond of this form of communicating my work, there is no way that I could have had a better result/impact and feedback. While I was thinking that 3h of a poster session would be dull and endless, I ended up spending more than 5h chatting about gender determination, localization of my animals with one single hydrophone (!), acquiring more acoustic data, using my spectral information for species detection, and getting inspiration from wonderful colleagues coming from Italy, Australia, China, Israel, San Diego, Boston, Pennsylvania and around the globe.

Poster take home message: if the number of posters is low  (<10), dare to submit one, especially if the number of parallel oral presentations is high (>=3).

This has been a wonderful and productive meeting!  5 days of underwater acoustics bliss. Listening and talking about the sound in polar areas (always fascinating environments), about bubbles (it might not be as etheric as it sounds but still interesting), oil and gas, renewable energy, hydrophone calibration, soundscapes, ships and noise, sonars, super-cool technologies that make me want to be an engineer, a bunch of marine sound-related stuff and of course whaaaaaaaaaales! Besides the days, the nights were equally exhilarating but in a more social way.

Science on tab
Science on tab

I met people from all around the world with whom I shared scientific ideas, PhD and work related concerns, personal perspectives and liters of raki 😉 It is always good to combine work and fun. Even better when work is fun. That is certainly true for my case and I bet for my ORCAA mates too. Lucky people!

See you all again at the next Underwater Acoustics meeting in Greece.

Preparing for some underwater acoustic experiments with fellow scientists.
Preparing for some underwater experiments with fellow scientists…

Next blog-post will include some of the Greek summer sunlight, the salty flavor of the Mediterranean and the sound of cicadas.

Happy and bright summer to y’all.

 

 

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