About Niki Diogou

I am a Ph.D student at ORCAA Lab and I mainly work with high frequency ocean acoustic recordings. My study focuses on identifying and classifying odontocetes by the sounds they make. I am obsessed with sperm whales and I like to "play" with oceanography to understand what is it that my favorite whales love. I am also interested in photography, creative writing and creative everything, public awareness, I fear life without snow and skiing, and I am an acro-yoga addict.

(A story that follows the adventures of Niki Diogou, the first person that hitchhiked at the Aegean Sea to record dolphin “voices” before somebody else does it)

Since it has been suggested that the idea of leaving the oceans (and then coming down from the trees) was not a wise thing to do, I decided to return to our distant ancestor’s water element for this summer. I spent 2 weeks of late

Let’s go back

July and early August at the remnant of the ancient Sea Tethys, where also happens to be my motherland. Tethys Sea, prior to its closure into the Mediterranean Sea, it was the one of the 2 world oceans during the Earth’s early life, when geography class would had been so much simpler (history too) with Pangaea being a unique super-continent. Greece was covered by the

The super-continent and the Oceans before they broke up

Tethys and nowadays there are fossils at the Aegean islands to prove this intimacy. The Tethys Sea was named by Eduard Suess  (don’t get confused, this is a different Dr. Suess ) after the Greek goddess Tethys. She was the daughter of Uranus (Sky) and Gaia (Earth), both sister and wife of Oceanus (there are no taboos if you are a god).

After praying to all the Greek sea gods that I could remember for an opportunity to collect the data I needed for my 3rd thesis chapter, the opportunity arose. Well to be accurate, didn’t really arise itself. I did push it a bit to come up…

The history of every major marine research has passed through 3 recognizable stages, those of: Survival, Enquiry and Sophistication. Otherwise known as the How, Why and Where phases. For instance the first phase is characterized by the question “how can I get funding”. The second, by the question “why do I do this research”, and the third “where in the world is the seawater warmer and clearer”.

To answer the first question I wrote this post.

To answer the second question, I wrote my previous blog.

And for the third ultimate question about the meaning of life, universe and absolutely everything, eeeh I meant the sampling site, the ultimate answer: Greece!

Concerning the second question, I will give you a summary of my field work purpose. Though, Douglas Adams  has already expressed the importance of my research:

Man had always assumed that he was more intelligent than dolphins because he had achieved so much — the wheel, New York, wars and so on — whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man — for precisely the same reasons. The last ever dolphin message was misinterpreted as a surprisingly sophisticated attempt to do a double-backwards-somersault through a hoop whilst whistling the ‘Star Spangled Banner’, but in fact the message was this: So long and thanks for all the fish”.

To avoid this sort of misunderstandings, bio-acousticians have been feverishly working on decoding the dolphins’ vocalizations.
First step towards this direction is telling the voices of different species apart.

Different species of cetaceans are known to produce different types of sounds, resulting from various factors such as morphology, genetics, ecology, sociality, and culture. For example, the calls that sperm whales, humpbacks and common dolphins produce are significantly different from each other in so many ways that are clearly distinguishable by an expert ear (and eye that inspects the spectrograms). This fact makes the lives of the bio-acousticians easier because it helps us to identify different species of whales and dolphins by just listening to them.

Things though are more complicated than this. It has been shown that within the same species, some cetaceans tend to produce different sounds when they live in different areas. So the sperm whales in the Pacific produce codas (a type of vocalization indicative of sociality and communication) that are different to the ones of the Mediterranean sperm whales. Similar is the case for pods of killer whales that use different habitats and target different prey. Likewise, different geographic populations of dolphins that belong in the same species have different call characteristics. It is like speaking dialects or simply having an accent. The differences seem to be greater when the geographical distance increases.

The geographic variations of cetacean sounds are usually divided microgeographically and macrogeographically. For instance the striped dolphins in the Mediterranean Sea produce different whistles than the ones in the Atlantic. Also the striped dolphins that live in the western Med sound differently than the ones that dwell in the eastern side. Applying the same logic, the ones that inhabit the Aegean Sea will have a different “accent” than the Ionian Sea habitants. Past studies have revealed the existence of variations in the whistle acoustic structure of a striped dolphin within the different regions of the Mediterranean Sea. However the Aegean Sea is still an acoustically pristine place. The dolphins we encounter there (common, striped, bottlenose, and risso) have not been acoustically recorded (during visual encounters) and classified. YET!

Maps always help

Being a communicative creature myself, I feel the need of these dolphins in the Aegean to be understood. 🙂

And the same time I will use this information to identify different dolphin species in my N. Aegean acoustic dataset. 😉

I return to the first survival question.  If you have read my previous post you will probably remember my public invitation for funding to achieve the acoustic sampling in the area of my interest. In case you are not fortunate enough to study and work on the field with the charismatic megafauna, I should enlighten you into the specific  requirements of cetacean research: HIGH BUDGET! Cetacean research is particularly expensive. Money for renting a boat, gas money for the boat, money for the boat crew (a captain at least is required) and money for the acoustic instrumentation.

Because the times are hard and funding appears dimly or not at all in the horizon, I had to recruit some old skills of mine to make this happen. Hitchhiking skills (contacts also help, so get your selves out to these conferences)!

I first thumbed a ride when I was doing my undergraduate at the island of Lesvos, in Greece.  With my friends we would hitchhike to the university which was slightly further from downtown. Too far to walk when you are already late for the morning lecture, too close to wait for the bus that has a very irregular schedule, too expensive for taxi while being a student, and just the right distance to be given a lift! That is when my hitchhiker’s career commenced. Now that I have reached a Ph.D level and I only possess a bicycle, my hitchhiking skills have equally improved and can be utilized for science. In this case, the thumb got replaced by emails, phone calls and meetings.

Not too far from the area that I have my hydrophone deployed and I get part of my acoustic data; there is the island of Alonissos. T

Blue: where Niki’s Dolphin Quest took place

here, it is founded the first Marine Protected Area in Greece that happens also to be the biggest in Europe. The marine area around Alonissos Island, together with 6 more islands, 22 islets and rocky outcrops is one of the few remaining habitats of the Mediterranean monk seal; the only seal specie in Med. In the past, the monk seal was very common all along the Mediterranean coasts.

Nowadays, it is on e of the world’s most endangered marine mammals and

half of its current population lives in Greece. For this reason in 1992, the National Marine Park of Alonissos, Northern Sporades was established and is dedicated to the protection of this rare species. There are laws a

Too cute to go extinct

nd regulations that limit certain anthropogenic activities that could interfere with the animals’ welfare and the population’s survival. To impose these regulations and ensure the good management of the reserve, the guards of the Marine Park patrol daily the marine protected area. And this is where my thumb comes up. The lovely people that work for the Marine Park accepted me on their daily patrols, allowed me to get on their boat and look for dolphins while they were looking for any illegal activity.

At work with the National Marine Park of Northern Sporades' team
At work with the National Marine Park of Northern Sporades’ team

So I bought a big hat, I got my dipping hydrophone, swimming suit as my uniform and my Dolphin Quest began!

First day on the boat was mind blowing! Traveling with 35 miles/hour, stop every now and then to exotic locations, blue caves, a long break to rest the engine and the guards, have some drinks and swim  in turquoise water coves. Marvelous sites that few have had the chance to visit.

And you will rightfully ask: did you find the dolphins?

No. But it was a good way to break the ice!

The following days were much more effective. I explained that for the purposes of my research we would have to go slower. As a hitchhiker I hesitated to reinforce my own rules to my hosts but soon our zodiac was going with 15 miles/hour and had 2 extra visual observers on board scanning the horizon for dorsal fins and splashes.

Still though, no dolphins in sight.

You see, the ocean is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to ocean. Searching for dolphins there is not an easy job. It is fun but not easy. It can take unpredictable amount of time until you get to see them. And I had only a few days before my flight back to USA…

Fortunately dolphins are curious creatures and if the boat is not too noisy they will swing by for a bit to check it out and hopefully play with its wake. Just like this. Eeeeeh, I wish.

A couple of days went by without any dolphin luck. And the thump comes out again for extra rides. I needed more time in the sea.

Lucky me, the same time period, the NGO MOm, the Hellenic Society for the Study

and Protection of the Monk seal  who has been monitoring the monk seal population and promoting the establishment of a Marine Park for almost the last 30 years also operates in the same area. The last 2 years Mom has been running the Northern Aegean Dolphin Project . A team of volunteers and their lovely project leader, also called Niki, perform daily visual transect surveys to study the population and ecology of the dolphins in the Marine Park region. I

Aviary Photo_130519860083407122
The MOm team and I, happy after an exciting sighting

hitched a ride with them too. Success from our very first cruise! A monk

seal sighting first thing in the morning and a big group of striped dolphins that we were able to stalk for a while. Stalk and eavesdrop on their conversations! This raised my expectations.

Stalking a groups of striped dolphins
Stalking a groups of striped dolphins

My days passed with me jumping from the one vessel to the other exploring extensively the N. Aegean Sea. But without enough dolphin sightings. And while I was trying to compromise with the idea of having only striped dolphins’ recordings and thinking of the shift I would give to my research, disappointingly looking for any dolphins, the common dolphins appeared and gave me hope again! Fortunately, trustworthy hope. Later on the same day a mixed group of common and bottlenose dolphins was having a long dinner close to our boat. After recording them for long time, I did not resist jumping in to the water. There were far enough to not be interrupted by my presence but close enough to hear them while I had my head underwater. I was shaking with excitement. Dream comes true. Check.

My field trip ended with recordings from 3 different dolphin species, 2 monk seal encounters, countless seabirds, and 3 illegal spear-gun divers. The sea CSI in action!

The only problem was that I had to go. Too soon I think. But would there ever be a right time to leave this heavenly place?

Take me back!
Take me back!

And now I am back in Newport, my skin has still some tan left and all the Greek memories are still fresh with strong salty flavor. My suggestion is the following:

Do you want to implement research but you don’t have funds to do it? DON’T PANIC. There are ways and alternatives. Consider the hitchhiking method.  It is an inexpensive way to do your sampling and it essentially means collaborating, meeting people, working together, sharing and having a common direction. I assure you, it’s the journey not the destination that matters.

My gratitude to the National Marine Park of Northern Sporades and MOm, the Northern Aegean Dolphin Project, for their hospitality and help. Definitely worth a visit and I am already craving my return!

So long and thanks for all the dolphins!


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.



I am going to start with a stereotype. The term stereotype is derived from the Greek words στερεός (stereos), meaning “firm, solid” and τύπος (typos), meaning “impression,” hence “solid impression”. The stereotype of Greeks relating the definition of every word to Greek origin. I know, stereotype in the stereotype, right? The Matryoshka Principle (MP) in effect!

Some people like to generalize a lot. Most of us criticize this behavior but overall it is hard to avoid it. Stereotypes result from peoples’ effort to understand the world by categorizing. As long as the stereotypes are not accompanied by prejudicial or discriminatory reactions I can, sarcastically, use them and self-stereotype.

Stereotype that does NOT apply
Stereotype that does NOT apply


I enjoy looking into the history, the origin of things, the etymology of words. The word itself derives from the Greek word ἐτυμολογία, etymologia, from ἔτυμον, etymon, meaning “true sense” and the suffix -logia, denoting “the study of”. MP again!

I regularly (quite always) find myself asking people, especially here in the US, where they come from. Where they originally come from, you know, not where they were born but their ancestors origin. In the case that I cannot directly ask people questions, I ask myself.

Where my studies’ subjects come from, where and when cetecean and bioacoustic rese

Roman copy in marble of a Greek bronze bust of Aristotle by Lysippus, c. 330 BCE.
Roman copy in marble of a Greek bronze bust of Aristotle by Lysippus, c. 330 BCE.

arch was initiated. You would (not) be surprised to discover that Cetology (from κῆτος, kētos, “whale”; and -λογία, -logia), has Greek origin, and I am not just referring to the word. It was 2364 years ago when the ancient Greek philosopher Aristotle published the History of Animals. He was only 34 when he wrote these 10 books! I don’t want to make any comparisons here, it would be inaccurate because I am also younger (!!!!), but just for reference: I struggle with just one publication.

Aristotle was the first to study and record dolphins (from Greek δελφίς (delphís), “dolphin”, related to the Greek δελφύς (delphus), “womb” and referred to as “a ‘fish’ with a womb”) and dolphin behavior. He made observations, he took notes and then he scientifically published them. He even reported his methods! Sounds like what everybody does, right? Well yes, but not 2.5 thousand years ago! It is also startling that he came up with 2 common research methods used nowadays in cetology: photo-identification and tagging. He did not have a camera or any tag equipment, but he collaborated with the fishermen and they would create artificial notches on the dorsal fins of the dolphins that were entangled alive in their fishing nets and then they were able to identify different individuals, monitor their movements and get information on their age and span of their lives.

In his writings, he correctly claimed that dolphins were mammals, he observed that they bore their live young and suckled them, breathed air and communicated by underwater sounds:

“The dolphin has a blow and lungs… it sleeps with the snout above the water and when it sleeps, snores. None produces any eggs but they give birth directly to an embryo like in the case of human and the viviparous quadrupeds.  The gestation period lasts for 10 months and gives birth in the summer. The dolphins produce milk and they suckle the young which they accompany for long periods. The caring for their young is remarkable. The young grow up fast and becomes adult at the age of 10 years old. It lives for many years, even above 25 or 30The voice of the dolphin in air is like that of the human in that they can pronounce vowels and combinations of vowels, but have difficulties with the consonants.” (Aristotle, HISTORIA ANIMALIUM, 350 BC)

It is interesting to think how much more information we have (or have not) acquired the last couple thousands of years. Especially as far as acoustics are concerned as it was not before the 1950s when new observations were made. In 1949, William E. Schevill and B. Lawrence used their hydrophones (from Greek ὕδωρ = water and φωνή = sound) into the Saguenay River of Quebec to make the first underwater recordings of the sound of cetaceans, belugas in this case, in the wild.

The use of hydrophones started at wartime too, used during WWII by

Passive Aquatic Listener (PAL): my hydrophone to eavesdrop the sperm whales and the dolphins at the Gulf of Alaska and the Greek Seas.
Passive Aquatic Listener (PAL): my hydrophone to eavesdrop the sperm whales and the dolphins at the Gulf of Alaska and the Greek Seas.

the submarines to detect underwater targets. Since it became declassified and available, it has been widely used today to study the underwater soundscapes and reveal a non-Silent World. While Jacques-Yves Cousteau’s title was a misnomer, Professor Huxley, in 1869, stated in his essay on the “Physical Basis of Life”:

“The wonderful noonday silence of a tropical forest, is, after all, due only to the dullness of our hearing; and could our ears catch the murmur of these tiny maelstroms, as they whirl in the innumerable myriads of living cells which constitute each tree, we should be stunned, as with the roar of a great city.”

making a point on the information we can get from soundscapes and the essentiality of the right equipment. Thus hydrophones become a favorite tool for cetologists and bioacousticians to record, understand and accurately study the charismatic marine-megafauna.

Being able to hear the whales and dolphins “voices”, opened a discussion whether these intelligent animals can actually talk, use their sounds to communicate with each other in a language context. I’m not sure which is the answer but I don’t see why we should give such an anthropocentric meaning to their vocalizations just to consider them intelligent and worthy of our protection and conservation efforts…

But the languages have further significance even within the human society. Anthropologists, linguists and psychologists have done research around the world and looked into many different languages to understand the importance of the use of certain languages and words in our minds performance. Results of these studies show that the words and language that we use represent and  shape what and how we think. Thus who we are! Very cool research has shown that human languages shape the way we think about space, time, colors, and objects.  Just like what cetaceans do using sound to navigate and locate food over long distances!

In fact, an interesting example of how  words change the way we view the world is this one of Shakespeare who is known to have created a whole bunch of new words and phrases  that have unarguably affected the way we sense our surroundings. “It’s all Greek to me” has been introduced by him, but I know that after reading this post this phrase has no use for you! In fact Greek is not really that hard, of medium difficulty. After 44 posts you will be proficient…

I will close by quoting Marcel Proust  who said that the real voyage of discovery doesn’t consist in seeking new landscapes but having new eyes. And to paraphrase that, as far as my field of studies is concerned, the voyage of discovery consists in seeking soundscapes instead of landscapes, in listening to the deep sea, deep listening and understanding what we hear of the sounds in the oceans.

Every fourth week of the month I will be sharing with you, thoughts, ideas, everyday lessons and concerns, more related to bioacoustics than the Greek language 😉