Simple behavior classification of tracking data with residence in space and time

By Rachael Orben PhD., Postdoctoral Scholar in the Seabird Oceanography Lab and the Geospatial Ecology and Marine Megafauna Lab 

At 2pm, Jan 3, our paper entitled “Classification of Animal Movement Behavior through Residence in Space and Time” was published. At 14:03 I clicked on the link and there it was, type-set and crisp as a newly minted Open Access scientific contribution.

So, what is this paper about? It presents a simple – yes simple – method of identifying simple behaviors states in two-dimensional animal tracking data (think latitude and longitude). Since the paper is open access you can go find the methods there. Categorizing these “dots on a map” into behaviors allows us to ask questions about how often, why, when and where simple behaviors happen. These behaviors really are simple (hopefully the somewhat grating repetitiveness of the word ‘simple’ has driven that point home by now!). We are identifying three basic, but fundamental, states:

1) transit, characterized by fast somewhat straight line movement from a to b,

2) a sedentary state characterized by relatively more time spent in an area with little distance traveled (such as resting behavior) and

3) an active state characterized by lots of time spent in an area where an animal is also moving around a lot and covering a lot of ground.

This new method, that we termed Residence in Space and Time (RST), can assist the fast-growing, sophisticated, big-data generating, conservation-orientated field of animal movement ecology. One of the first hurdles is data exploration and visualization. Modern ecologists deploy tracking devices that collect location data remotely to understand animal distribution and behavior. But at first glance tracks (like the figure below) can look like spaghetti dinner. Identifying movement behaviors can help to us see patterns in the tangles.

24 GPS tracks of grey-headed albatross incubation foraging trips; tracked from Campbell Island, New Zealand.

So how might this method work? First lets start with a track. Below is a very short foraging trip from a thick-billed murre tracked with a GPS logger during chick rearing from St. Paul Island in Alaska (see Parades et al 2015).

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A thick-billed murre (Uria lomvia), St. Paul Island, Alaska.

The track below has points every second and we can imagine the murre flying from the colony, landing on the water, and then diving (indicated by the lack of GPS position data when the bird dives below the water to forage). Then the bird flies back to the colony to feed its chick. This trip is roughly 14 minutes long.

murretrack

So I can take this track and run RST to identify three behavior states. As color-coded below, the black points indicate transit, red indicates relatively stationary behavior, and blue indicates points where the bird was flying in a less direct manner than pure transit potentially circling around before landing and moving between dives. The high resolution of the GPS data really helps us to understand how this bird was moving. Such behavior information is easily conserved in a high-resolution track like this. Though in this case the bird did a lot of transiting and only exhibited different movement behaviors in the vicinity of the two dives.

murretrack_1sec_rst-copy

Logging locations at 1 second intervals is a stretch for the battery life of these miniaturized GPS loggers (~15g), and more often than not we would like the loggers to last much longer than 14 mins. So instead of 1 second we typically have tracks with less frequent locations. To me this is akin to taking a 1 second track and then taking off my glasses and trying to see the same behaviors. Deciphering behavior states becomes a bit (or a lot) fuzzier. In the case of this murre track, when we down-sample the locations to every 10 seconds much of the resolution of this track is lost (see plot below). What happens when we run RST?

murretrack_10sec_rst-copy

As you can see some of the behavior is maintained and some of it is a bit fuzzier.

A good rule of thumb is that if a behavior happens faster than the sampling interval the logger is recording at, then the behavior is not recorded. Seems simple, but it is an important consideration when programming loggers and designing animal movement studies. For murres these quick trips to forage for their chicks are easily lost even at a 5 minute sampling interval, which is often used in seabird tracking studies where the birds are at-sea for days. Often we work with such lower resolution location data and, instead of one trip from one bird, we have many trips from many individuals. RST allows a fast way to quickly and accurately identify simple behaviors in order to help with initial data exploration efforts and for answering more complex questions such as behavior specific habitat models.

So, if you have some tracking data – of birds, marine mammals, or your dog! – you can learn how RST works (basically by summing up time and distance covered within a circle). The R code, a short guide, and example dataset are available as links at the end of the paper.

Here is the spaghetti from above (really tracks of Grey-headed albatrosses) with the behavioral states labeled using RST:  93,481 points and this behavior classification took only 14 seconds to run!  albatrosstracks_rst

How we craft our messages

By: Erin Pickett, MSc

Communicating science has become more important than ever as major social and political issues, such as climate change, require increasing input from scientists. In a recent article published by the Proceedings of the National Academy of Science, a research group from the University of Cologne in Cologne, Germany, explores how social cognition influences our ability to market science.

This article, titled “Past-focused environmental comparisons promote pro-environmental outcomes for conservatives” focuses specifically on understanding why there is a political divide in the United States regarding the issue of climate change (Baldwin & Lammers 2016). While our research in the GEMM lab focuses on spatial ecology (rather than social science) I thought this article was worth sharing because of its insights about “framing science”. The conservation science that we conduct in the GEMM lab will not be effective if we cannot properly communicate our objectives and our findings to funders and stakeholders.

“Framing” is a term in psychology that describes how you craft a message based on your intended audience. It is important to note that use of the term framing (or marketing) science doesn’t imply misrepresentation of facts (Nisbet & Mooney 2007). Rather,“Frames organize central ideas, defining a controversy to resonate with core values and assumptions” (Nisbet & Mooney 2007). Baldwin & Lammers (2016) demonstrated that subtle differences in framing significantly affect how environmental messages are perceived. These authors investigated the effect of framing with regards to temporal comparisons, environmental attitudes and behavior.

The specific problem these authors address is the failure of climate change advocates to bridge the political divide between liberals and conservatives in the United States. The authors hypothesize that the temporal comparisons used in arguments for action on climate change explain the dichotomy between liberal and conservative views on this issue (which garners less support from conservatives).

The primary hypothesis guiding this study is that conservatives are more likely to favor a “past-focused” message rather than a “future-focused” message about climate change. The authors surmise that this framing bias is rooted in a conservative ideology that favors past traditions over a progressive future, which is more favored by liberals. Many pro-environmental arguments and appeals to address climate change are future focused, e.g. Balwin & Lemmers (2016) quote UN Secretary-General Ban-Ki Moon, speaking about climate change:

“…We need to find a new, sustainable path to the future we want”.

If temporal comparisons do elicit framing bias, then our framing of the issue of climate change, and possibly other environmental issues, could be more effective if presented to conservatives as past-focused messages.

The authors tested these hypotheses on participants in a series of online studies. You can find more details on methods in the papers supporting information found here. In the first three studies, the authors investigated the effect of temporal comparisons on pro-environmental beliefs. Study participants were asked to read messages, or view images, that addressed the issue of climate change by comparing the present to the past, or the present to the future. Following these comparisons, participants ranked their pro-environmental attitudes. Examples of these comparisons were statements such as, “Looking forward to our Nation’s future… there is increasing traffic on the road” (future-focused), and, “Looking back to our Nation’s past…there was less traffic on the road” (past-focused).

You can see examples of past and future-focused images below.

Images of past, present and future conditions (Baldwin & Leemers 2016-Supporting information Fig. S1)

The authors found significant evidence to support their hypothesis that presenting conservatives with past-focused messages is more effective in terms of promoting pro-environmental messages than presenting future-focused messages. Temporal comparisons did not affect the pro-environmental attitudes of liberals.

Liberals pro-environmental attitudes remain similar between conditions, while conservatives pro-environmental attitude is higher given a past-focused condition (Baldwin & Lammers 2016, Fig. 2)

The authors also investigated the temporal focus of environmental organizations and found that overall, environmental charities promote future-focused messages. Study participants were allotted small amounts of cash to donate to these charities, and conservatives gave more to past-focused charities than to future-focused charities. You can see examples of charities with differing temporal focuses below.

Examples of future and past-focused environmental charities (Balwin & Lammers 2016-supporting information Fig. S3)

In a final meta-analysis, these authors found that employing past-focused comparisons nearly made up for the difference between liberals and conservatives in terms of their pro-environmental attitudes. The implication of these findings is that we can improve the way we communicate about controversial issues such as climate change by subtly altering our arguments. For example, in one study that was cited by Baldwin & Lammers (2016), conservatives favored the words ‘purity’ and ‘sanctity’ over ‘harm’ and ‘care’ (Fienberg & Willer 2012). Based on these studies, an example of an effective message for a conservative audience would be, “It is important that we restore the Earth because it has become contaminated”.

These findings could be true for other environmental issues as well, and so it is worth thinking critically about how to craft messages about our scientific findings for our intended audiences. We need to carefully frame our messages whether we are writing grant proposals, peer-reviewed manuscripts, press releases, or posts intended for social media.

I originally discovered this paper after listening to a short radio interview that was conducted by CBC Radio, and if you are interested in this research I encourage you to check it out! You can following this link: how to convince a climate change skeptic.

References:

Baldwin, M., & Lammers, J. (2016). Past-focused environmental comparisons promote proenvironmental outcomes for conservatives. Proceedings of the National Academy of Sciences113(52), 14953-14957.

Feinberg, M., & Willer, R. (2013). The moral roots of environmental attitudes. Psychological Science24(1), 56-62.

Nisbet, M. C., & Mooney, C. (2009). Framing science. Science316.

GEMM Lab 2016: A Year in the Life

By Dawn Barlow, MSc Student, Department of Fisheries and Wildlife, Oregon State University

The year is rapidly coming to a close, and what a busy year it has been in the Geospatial Ecology of Marine Megafauna Lab! In 2016, our members have traveled to six continents for work (all seven if we can carry Rachael’s South African conference over from the end of 2015…), led field seasons in polar, temperate, and tropical waters, presented at international conferences, processed and analyzed data, and published results. Now winter finds us holed up in our offices in Newport, and various projects are ramping up and winding down. With all of the recent turmoil 2016 has brought, it is a nice to reflect on the good work that was accomplished over the last 12 months. In writing this, I am reminded of how grateful I am to work with this talented group of people!

The year started with a flurry of field activity from our southern hemisphere projects! Erin spent her second season on the Antarctic peninsula, where she contributed to the Palmer Station Long Term Ecological Research Project.

Erin collecting a crabeater seal scat sample.
Erin in action collecting a crabeater seal scat sample along the West Antarctic Peninsula.

 

Aerial image of the research vessel and a pair of blue whales during the 2016 New Zealand survey.
Aerial image of the research vessel and a pair of blue whales during the 2016 New Zealand survey.

The New Zealand blue whale project launched a comprehensive field effort in January and February, and it was a fruitful season to say the least. The team deployed hydrophones, collected tissue biopsy and fecal samples, and observed whales feeding, racing and nursing. The data collected by the blue whale team is currently being analyzed to aid in conservation efforts of these endangered animals living in the constant presence of the oil and gas industry.

Midway atoll is home to one of the largest albatross colony in the world, and Rachael visited during the winter breeding season. In addition to deploying tracking devices to study flight heights and potential conflict with wind energy development, she became acutely aware of the hazards facing these birds, including egg predation by mice and the consumption of plastic debris.

Laysan albatross equipped with a GPS data logger.
Laysan albatross equipped with a GPS data logger.
Fledgling from last year with a stomach full of plastic.
Fledgling from last year with a stomach full of plastic.

Early summertime brought red-legged kittiwakes to the remote Pribilof Islands in Alaska to nest, and Rachael met them there to study their physiology and behavior.

Rachael with a noosepole on St. George Island, Alaska
Rachael with a noosepole on St. George Island, Alaska
Solene with Dr. Claire Garrigue during fieldwork at the Chesterfield Reefs, New Caledonia.
Solene with Dr. Claire Garrigue during fieldwork at the Chesterfield Reefs, New Caledonia.

As the weather warmed for us in the northern hemisphere, Solene spent the austral winter with the humpback whales on their breeding grounds in New Caledonia. Her team traveled to the Chesterfield Reefs, where they collected tissue biopsy samples and photo-IDs, and recorded the whale’s songs. But Solene studies far more than just these whales! She is thoroughly examining every piece of environmental, physical, and oceanographic data she can get her hands on in an effort to build a thorough model of humpback whale distribution and habitat use.

A humpback whale in New Caledonia's South Lagoon.
A humpback whale in New Caledonia’s South Lagoon.

Summertime came to Oregon, and the gray whales returned to these coastal waters. Leigh, Leila, and Todd launched into fieldwork on the gray whale stress physiology project. The poop-scooping, drone-flying team has gotten a fair bit of press recently, follow this link to listen to more!

The overhead drone captures a pair of gray whales surfacing between kelp beds off Cape Blanco, Oregon, with the research vessel nearby. Take under NOAA/NMFS permit #16111 given to John Calambokidis.
The overhead drone captures a pair of gray whales surfacing between kelp beds off Cape Blanco, Oregon, with the research vessel nearby. Take under NOAA/NMFS permit #16111 given to John Calambokidis.

And while Leigh, Leila, and Todd followed the grays from the water, Florence and her team watched them from shore in Port Orford, tracking their movement and behavior. In an effort to gain a better understanding of the foraging ecology of these whales, Florence and crew also sampled their mysid prey from a trusty research kayak.

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Florence and the summer 2016 gray whale field team.
DSCF0758
Kelli Iddings sampling mysid near Port Orford.

With the influx of gray whales came an influx of new and visiting GEMM Lab members, as Florence’s team of interns joined for the summer season. I was lucky enough to join this group as the lab’s newest graduate student!

All summer 2016 GEMM Lab members.
All of the summer 2016 GEMM Lab members.

Our members have presented their work to audiences far and wide. This summer Leigh, Amanda, and Florence attended the International Marine Conservation Congress, and Amanda was awarded runner-up for the best student presentation award! Erin traveled to Malaysia for the Scientific Convention on Antarctic Research, and Rachael and Leigh presented at the International Albatross and Petrel Conference in Barcelona. With assistance from Florence and Amanda, Leigh led an offshore expedition on OSU’s research vessel R/V Oceanus to teach high school students and teachers about the marine environment.

Amanda with her award!
Amanda with her award!
Science Party musters in the dry lab for safety debrief aboard R/V Oceanus.
Science Party musters in the dry lab for safety debrief aboard R/V Oceanus.

Courtney fledged from the GEMM Lab nest before 2016 began, but the work she did while here was published in Marine Mammal Science this year. Congrats Courtney! And speaking of publications, additional congratulations to Solene for her publication in Marine Ecology Progress Series, Rachael for her four publications this year in PLOS ONE, Marine Ecology Progress Series, Marine Ornithology, and the Journal of Experimental Biology, and Leigh for her five publications this year in Polar Biology, Diversity and Distributions, Marine Ecology Progress Series, and Marine Mammal Science!

Wintertime in Newport has us tucked away indoors with our computers, cranking through analyses and writing, and dreaming about boats, islands, seabirds, and whales… Solene visited from the South Pacific this fall, and graced us with her presence and her coding expertise. It is a wonderful thing to have labmates to share ideas, frustrations, and accomplishments with.

No heat in the lab can't stop us from solving a coding problem together on a wintery evening!
Solving a coding problem together on a wintery evening.

As the year comes to a close, we have two newly-minted Masters of Science! Congratulations to Amanda and Erin on successfully defending their theses, and stay tuned for their upcoming publications!

Amanda's post-defense celebration!
Amanda’s post-defense celebration!
Erin's post-defense celebration!
Erin’s post-defense celebration!

We are looking forward to what 2017 brings for this team of marine megafauna enthusiasts. Happy holidays from the GEMM Lab!

Happy GEMM Lab members.
Happy GEMM Lab members, enjoying one another’s company and playing Evolution.

Feed from the scientific network: the digital library of a millennial student

Solène Derville, Entropie Lab, Institute of Research for Development, Nouméa, New Caledonia (Ph.D. student under the co-supervision of Dr. Leigh Torres)

If you are a follower of our blog, you may have noticed that bioinformatics and statistics hold a very important role in the everyday life of the GEMM Lab. As good-old field observations remain essential to the study of animal behaviour and ecosystems, the ecology field has greatly benefited from advances in information technologies. In fact, data analysis is now a discipline in itself, as innovative solutions must continuously be developed to cope with the challenges of ever increasing dataset size and complexity.

communications-jpg-800x600_q96Artist’s impression of a complex network. ©iStock.com/Vertigo3d

So how does a poor biology student find her/his way in this digital and mathematical world? Most ecology departments will provide classes to learn the basics of statistical modelling and data analysis, but there is only so much you can learn through formal education. In practice, we ultimately always run into a problem, an exception that we have never heard of, and we have to figure it out on our own. As my initial training was in fundamental biology, self-teaching of other disciplines (statistics and bioinformatics) has taken a lot of my time as a Master’s student and now as a PhD student. This has made me feel lonely and a bit lost at times when I run into challenges that always seemed too big for me. But in the end, there is nothing more rewarding then solving problems by yourself after long hours of mind-scrambling.

Oh, sorry, did I say by myself? Nothing could be more wrong and more true at the same time! Because the place where I find all the answers to my questions, is in fact born from the contribution of thousands of scientists, which, despite not actually knowing each other, all work together to develop innovative solutions to modern world scientific challenges. The internet scientific network has been my best colleague over these past years and here I would like to share my enthusiasm for some of its best features that have helped me in my research.

If you look at my Firefox toolbar you will find two types of websites: let’s call them the “practical” and the “reflectional”.

The practical websites:

These are the websites I consult if I have a specific and practical question. Many forums exist where people exchange their experiences solving a great variety of problems. But sometimes conversations get lost in never-ending exchanges of opinions, some of which are not always scientifically well-founded. On the contrary, the StackExchange platform launched in 2009 has a strict policy on how questions should be asked (as precise and focused as possible) and should be answered (in an objective, opinion-free way). This makes it a very powerful tool to find quick and practical solutions to your everyday problems. This platform includes 136 different websites, each dedicated to a different topic. In my field, I mostly use: CrossValidated for statistical issues (e.g., Why does including latitude and longitude in a GAM account for spatial autocorrelation?) and StackOverflow for programming (e.g., plotting pie graphs on map in ggplot).

The latter will usually provide you with codes in the programming language of your choice (R, python, java, sql, etc.). Interestingly, even with more queries regarding Python to StackOverflow in 2015, R was the fastest-growing language between 2013 and 2015 on this same platform. If you haven’t decided on the language you want to “speak” yet, check out this fun infographic. But always remember that these tools keep evolving

4a9d355949d9cb77f8128dd517395405Academia can also be useful for questions regarding publications. For instance: How to reference multiple authors of a chapter from a book [APA]? Why might a journal editor reject a submission, but suggest submission to a sister journal? Or, how to best kill a manuscript as a peer reviewer?

And finally, if you’ve always wondered, “Why don’t we remove door handles and let doors open both ways (inwards, outwards)?, you’ll be pleased to know that other out-of-the-box-thinking people are sharing their opinion on the web…

Coming back to serious matters, it is important to recognize that you need the right key-word to access this gold-mine of website knowledge and sharing. The accuracy of your search answer will only be proportional to the quality of your question. In R for instance, if you keep googling “table” instead of “dataframe”, “list” instead of “vector”, or “size” instead of “dimensions”, you will likely get quickly drowned in the google-limbo. One way to be more efficient at your search strategy is to make sure you know your basics. Most of the programming languages used in ecology (e.g., R, Python, Matlab) share a similar vocabulary and structure, but before you start to run all sorts of crazy statistical analysis it is important to know what types of objects you are working with and how you want to format them. In R, I have found Hadley Wickham’s book, Advanced R, particularly useful to understand what happens back-stage.

Another good reference in the spatial ecology field is ZevRoss “Technical Tidbits From Spatial Analysis & Data Science. This website is a particularly up-to-date blog for data processing and visualization in R.

More generally, I regularly check R-bloggers or simply the Comprehensive R Archive Network. A note on the latter: I know it doesn’t look pretty and the reference manuals for R packages are rather intimidating but it is still the number one reference to check when encountering a problem with a given function. Some authors make a special effort to write more user-friendly tutorials to their packages. Check for those by looking at the CRAN page of a given package, in the “downloads” section, “vignettes” subsection (e.g., for the adehabitatLT package vignette).

4f5429df5ea6361fa8d3f08dfcdccdf9

 The reflectional websites:

The web is also an amazing media to reflect on our scientific practices, learn about current ecological theories, and acquire general knowledge across disciplines. In the scientific network, many blogs and forums exist where scientists can converse and debate ideas without the pressure of publication requirements. As a student trying to find my way in the great world of statistical modelling, I find these discussions and blogposts most useful to put my methodological choices in perspective and progressively build myself an opinion (still rather vague I’ll admit). Some of my most recent findings are: Dynamic Ecology Multa novit vulpes and From the bottom of the heap, the musings of a geographer. I am sure each of you has your own “rock star of the web”, so please share your favorite sites with us in the comments below.

Science not longer needs to wait for publication to be shared between peers and with the general public. The web offers us a new space to communicate, not only on that small part of our work that led to positive results, but also our negative results, frustrations and failures, which can at times be as informative and useful to the scientific community than our successes. So, wherever you stand, tell us about your ideas, and tell us about the challenges you have encountered, where you failed and where you succeeded. Because, this is what ecology is all about. Sharing knowledge across borders and cultures to understand the planet we live on and together take better care of it.

Reflecting on the graduate school experience

By: Amanda Holdman, MS student, Geospatial Ecology and Marine Megafauna Lab & Oregon State Research Collective for Applied Acoustics, MMI

This Thanksgiving I had a little something extra to be thankful for; two and a half weeks ago I successfully defended my master’s thesis, “Spatio-temporal patterns and ecological drivers of harbor porpoise off the central Oregon Coast”. It’s a good thing too because I think it was starting to turn me into a harbor porpoise. The last month, I was solitary, constantly eating, and I think I was starting to sleep with one hemisphere of my brain, while the other kept working.

In the weeks leading up to the submission of my thesis, I daydreamed about my life on the ‘other side’.  As a means of pushing myself over the final hurdle I envisioned what it would be like to be free of a thesis, to reclaim my weekends, and how relieved I would feel to hand over the culmination of two and a half years of work – and at last here I am:  on the other side, well almost.

The first week after my defense was just about as busy as the weeks leading up to my defense. I spent my time filing paperwork and moving things, packing up my office and house to head back to my home state of Indiana for the holidays, and tying up loose ends in Newport. For the past couple of weeks, I have been finishing up revisions on my thesis and formatting my work for publication, all while starting to look for a new job. After defending my masters I found time to “actually breathe” – I’m still as busy as always but now with a more consistent sleep schedule. The shift from all-research-and-writing-all-the-time has given me time to reflect a bit on what I’ve gained from the graduate school experience and what I know I still want or need to learn from it. Graduate school has supplied me with a tool box of skills that I didn’t realize I was acquiring day to day. Now, however, looking back over the years I realize how much I’ve grown as both a scholar and a person and in more ways than just learning how to craft scientific tweets in less than 140 characters (this really does take some skill).

Perseverance and Diligence

One big thing I learned from graduate school was how to transition from “panic” to “problem solving”. There were endless days of back breaking work that I had nothing to show for and days when I succumbed to imposter syndrome. I learned to pick myself up and solve the problems at hand though and find a way to move forward, sometimes even scratching my original idea to move towards something that worked in the end. That’s life. Things go wrong, plans don’t work out and yet our ability to pick ourselves up and carry on is one of the best skills we have. In graduate school you learn to never give up.

Time Management

I now assume that anyone who has been to graduate school is essentially an expert at multi-tasking. Between running a field season, taking and teaching courses, submitting research proposals, and trying to balance a social life, I didn’t realize how much of a pro I became at juggling many things at once. In other words, gaining a fundamental skill for being a working scientist

Resourcefulness

Graduate school taught me how to find the information I need. Every day I had a moment where I didn’t know an answer. In the beginning, I thought all you had to do was ask, but sometimes the first person you ask doesn’t know the answer either. Over time, I learned to dig through the literature, ask an expert in the field, or my favorite “try several different things and see how they differ”. Once I learned the hard lesson that there isn’t always an easy way out, I had subconsciously created an order of operations to figure it out.

Collaboration (and giving back the help to others who struggle where you once did)

Not many jobs teach us to work with a bunch of different minded people, but grad school does! I learned to work as a team, with scientists within and outside my lab who had personalities different from mine. Graduate school taught me to collaborate as much as possible and, more importantly, help someone with less experience to figure out their coding problems, or help them get their research proposals or publications out. Offering advice or expertise for a certain skill or method when I was busy helped me develop my team-building skills and proved to myself that I had skills to share.

There are good moments within bad moments

When a bad moment presented itself, I learned to focus on the good and recognize the moments that things worked out because I didn’t give up. These included following a bad presentation with a strong one, sparking the interest of collaborators, receiving an award for a conference presentation, or just the simple self-satisfaction of getting an R code to work properly. There are a lot of good moments in grad school, and it became important for me to celebrate them when they happened, but also not to take them for granted because they don’t come as often as the bad ones.

Importance of a strong support system

Unlike a harbor porpoise – I am very social person. Some can get through graduate school without any social interaction or encouragement from others, but there was no way that would have worked for me. Everyone copes with bad moments in graduate school in different ways – so my friends and family were my life-raft, especially those living in Newport. Mental and physical health are important to maintain in graduate school and it was beneficial for me to form a community early to help me through the tough moments. Although friends and family cannot completely relate to your situation (unless maybe they are also a graduate student) they will hear you out, care, listen and pull you out of a slump. Accepting their support and help drastically improved my mental health.

Work smarter, not necessarily harder, and forge your own path

When I look back at my past 2.5 years of graduate school now, I realize how hard I did truly work. I worked nights, weekends and evenings on weekdays. But in my last few months,  I became more competent as my productivity peaked. I learned how to multi-task and plan better – not just in school, but also in my daily life. Graduate programs force you to do unique research, as you can’t write a thesis by reproducing someone else’s work. You have to learn from what others have done and then get creative. Creating something original demands trust in yourself, and avoiding trying to compare yourself to others. Forging your own path can be uncomfortable, but necessary.

I am confident to say that graduate school overall made me a better scientist, and a better person. I value the training and education that I was fortunate enough to receive. It seems everyone starts graduate school with stars in their eyes, and then sometime in the middle we get weighed down by the failures and frustrations of graduate life, and we can fail to remember what brought us here in the first place: Intense curiosity, a desire to learn, and a chance to improve the world. These factors made me opt for this experience and in spite of all the hardships along the way, grad school gave me a set of life skills. So if you are contemplating graduate school, currently working toward a graduate degree, or in a transitional phase of job-seeking or career-changing, I suggest taking a minute to reflect on what you have already, or could gain, from graduate school.

My days as a current GEMM lab member are dwindling down as finish my edits, preparing publications, search for jobs, and rekindle my network – but I look forward to being a long distance cheerleader for the current and future members of the GEMM lab.

When I entered graduate school – one of my committee members told me I would go through the five stages of grief – and she was right – but the end reward was more than worth it.

“Being a graduate student is like becoming all of the Seven Dwarves. In the beginning, you’re Dopey and Bashful. In the middle, you are usually sick (Sneezy), tired (Sleepy), and irritable (Grumpy). But at the end, they call you Doc, and then you’re Happy.”

Challenges of fecal analyses (Round 1)

By Leila Lemos, Ph.D. Student, Department of Fisheries and Wildlife, OSU

Fieldwork is done for the year and lab analyses just started with some challenges. This is not unexpected since no previous hormonal analysis has been conducted with any gray whale tissue, and whale fecal sample analysis is a relatively new technique. So, I have been thinking, learning, consulting, and creating a methodology as I go along. I am grateful to the expert advice and help from many great collaborators:

  • Kathleen Hunt (Northern Arizona University, AZ, United States)
  • Shawn Larson (Seattle Aquarium, WA, United States)
  • Amy Green (Seattle Aquarium, WA, United States)
  • Rachel Ann Hauser-Davis (Fiocruz, RJ, Brazil)
  • Maziet Cheseby (Oregon State University, OR, United States)
  • Scott Klasek (Oregon State University, OR, United States)

I have learned that an important step before undertaking fecal a hormonal analysis is the desalting process of the samples since salts can interfere in hormonal determinations, leading to false results. In order to remove salt content, each sample was first filtered (Fig. 1A), to remove a majority of the salt water content (Fig. 1B) that is inevitably collected along with the fecal sample. Each sample was then re-suspended in ultra-pure water, to dilute the remaining salt content in a higher water volume (Fig. 1C).

Figure 1: Analytical processes: (A) Filtration of the samples; (B) Result from filtration; (C) Addition of pure water to the samples.
Figure 1: Analytical processes: (A) Filtration of the samples; (B) Result from filtration; (C) Addition of pure water to the samples.

After these steps were completed for each sample, the samples were centrifuged (Fig. 2A) to  precipitate the fecal matter and leave the lighter salt ions in the supernatant (the liquid lying above a solid residue; Fig. 2B). After finishing these two phases, the water was removed with aid of a plastic pippete (Fig. 2C), and I was left with only desalted fecal at the bottom of the tubes (Fig. 2D).

Figure 2: Analytical processes: (A) Samples centrifugation; (B) Result from the centrifugation; (C, D) Results from separating water and sample.
Figure 2: Analytical processes: (A) Samples centrifugation; (B) Result from the centrifugation; (C, D) Results from separating water and sample.

The fecal samples were then frozen at -80°C (Fig. 3A & 3B) and then freeze-dried on a lyophilizer for 2 days to remove all remaining water content (Fig. 3C). Finally, I have what I need: desalted, dry fecal samples, ready for hormone analysis (Fig. 3D).

Figure 3: Analytical processes: (A) Freezing process of the samples; (B) Frozen samples ready to go to the lyophilizer; (C) Samples in the lyophilizer; (D) Final result of the lyophilizing process.
Figure 3: Analytical processes: (A) Freezing process of the samples; (B) Frozen samples ready to go to the lyophilizer; (C) Samples in the lyophilizer; (D) Final result of the lyophilizing process.

Writing this now, this process seems simple, but it was laborious, and took time to find the equipment needed at the right times. The end product is crucial to get a good final result, so my time investment (and my own increased stress level!) was worth it. This type of analysis is very new for marine mammals and our research lab is still in the learning the best methods. Along the way we were unsure of some decisions, some mistakes were made, and we were afraid of losing precious fecal material. But, this is the fun and challenge of working with a new species and new type of sample and, importantly, we have developed a working protocol that should make the process more efficient and reduce our stress levels next time around.

At the end of this sample preparation process, our 53 samples look great and are ready to be analyzed during my training at the Seattle Aquarium. We are also planning to analyze the water that was removed from the samples (Fig. 2D) to see if any hormone leached out from the poop into the water.

Results from this process will aid in future whale fecal hormone studies. Perhaps only the centrifugation step is needed and we can discard the water without losing hormone content. Or, perhaps we need to analyze both portions of the sample and sum the hormones found in each. We shall know the answer when we get our hormone metabolite results. Just another protocol to be worked out as I move ahead with the hormone analysis of these fecal samples. And through all these challenges I keep the end goal of this work in my mind: to learn about the reproductive and stress hormonal variation in gray whales and to link these variations to nutritional status and noise events. Onward!

 

 

 

Good news: You are Brilliant, the Earth is Hiring

By: Erin Pickett, M.S. Student, Oregon State University

GEMM lab UPDATE: Amanda Holdman successfully defended her master’s thesis this week!

Amanda wisely planned her defense date for November 7th, 2016, the day before Election Day. As I anxiously watched the New York Times election forecast needle bounce back and forth, from left to right on Election night, I thought to myself, why didn’t I think of that? If you are unfamiliar with what I am talking about, this “forecast needle” was an animated graphic on the NYT website that bounced constantly all night between the two Presidential candidates. It caused a great deal of unease for those of us that found it difficult to look away. The animation sparked some debate online among bloggers and tweeters, my favorite comment being, “it borders on irresponsible data visualization”. I came to the realization pretty quickly on Tuesday night that despite the outcome of the election, I would still need to turn in my thesis the following week.

Personally, I did not feel motivated to get out of bed on Wednesday. I wasn’t feeling inspired, or overcome with positive thoughts about what my day of thesis writing would bring. Thankfully, here at OSU, we graduate students have good leaders to keep us on track. Wednesday afternoon, we received an encouraging email from our Department Head, Dr. Selina Heppell. I took away two important points from this email. The first: stay positive, and remember that we do great work with great people and that our work matters. Secondly, think about the lessons that we have learned from this election. For those of us that were shocked about who our country has chosen as the next President of the United States, one important lesson is that we need to focus more on engaging people who exist outside of the echo chambers of our scientific communities.

The recent election has left many scientists and environmentalists concerned about what the future political climate will bring in terms of research funding, job opportunities, and environmental protection. More so now than ever it is important to remain positive and hopeful, and to reconsider the way we communicate our research and engage outside communities whose views are unlike our own. Both of these tasks are particularly challenging due to the long list of environmental problems we face. As it turns out, having a hopeful outlook is important for tackling seemingly insurmountable conservation issues, and empowering others to want to do the same (Swaisgood & Sheppard 2010, Garnett & Lindenmayer 2011).

The title of this blog comes from an eloquent commencement speech by Paul Hawken about the importance of remaining optimistic when the data tells us otherwise. While the address was given to the University of Portland class of 2009, I think it is worth reading because it is a relevant and moving reminder of why hope is important.

But, before you read that, take a look at what has been done recently to protect biodiversity around the world-

Photo credit: Mark Sullivan NMFS Permit 10137-07/NOAA

President Obama quadrupled the size of a marine national monument in Hawaii. You can read more about the significance of this monument, called Papahānaumokuākea, in a previous blog of mine.

Photo credit: Northeast U.S. canyons expedition science team and NOAA Okeanos Explorer Program (2013)

Soon after announcing the expansion of Papahānaumokuākea, President Obama established the first marine national monument in the Atlantic. You can read more about the aptly named Northeast Canyons and Seamounts Marine National Monument here.

Photo credit:  Ari Friedlaender

And finally, to top it off, an international body comprised of 24 countries, called the Commission for the Conservation of Antarctic Marine Living Resources, recently came to a consensus to designate a vast portion of the Antarctic’s remote Ross Sea as the world’s largest marine reserve.

 

References

  • Garnett, S. T., & Lindenmayer, D. B. (2011). Conservation science must engender hope to succeed. Trends in Ecology & Evolution, 26(2), 59-60.
  • Swaisgood, R. R., & Sheppard, J. K. (2010). The culture of conservation biologists: Show me the hope!. BioScience, 60(8), 626-630.

 

“Evolution”: a board game review

By Florence Sullivan MSc student, Department of Fish and Wildlife.

Another grad student once told me that in order to survive grad school, I would need three things:

(1) an exercise routine, (2) a pet, and (3) a hobby. My Pilates class on Wednesdays is a great mid-week reminder to stretch. I don’t have a pet, so that advice gets fulfilled vicariously through friends. As for my hobby, I think you’ll find that even when scientists take a break from work, we really don’t get that far away from the subject matter…..

Board games have evolved significantly since the early ‘90s when I grew up on such family staples as Monopoly, Risk, Sorry!, Candyland, and Chutes and Ladders, etc. Now, table-top games tend to fall into three loose categories – “Euro-games” that focus on strategy and economic themes as well as keeping all players in the game until the end, “American-style” that tend toward luck and direct player contact so that not everyone plays until the end, and “Party” that are easy to learn and are often played in large groups as social icebreakers or to provide entertainment.

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A few of my favorite games.

As board games proliferate, we see the use of many themes and often, there are valuable educational lessons included in the game design!  There are militaristic or survival games (Betrayal at the House on the Hill, Dead of Winter), economic and engineering (Settlers of Catan, Istanbul, Ticket to ride, Carcassonne), fantasy and art (Small World, Dixit), cooperative vs competitive (Hanabi, Forbidden Desert vs. 7 Wonders), and some of my favorites – the sciences (Compounded, Bioviva, Pandemic).

Today, let’s talk about my current favorite – Evolution. It is immediately obvious that the game designers responsible are either giant nerds (I use this in the most loving way possible) or have spent some quality time with ecologists.  Not only is the art work beautiful, and the game play smooth, but the underlying mechanics allow serious ecological theories such as ‘predator and prey mediated population cycles’, ‘co-evolution’ and ‘evolutionary arms-races’ to be acted out and easily understood.

Players set up their species around the watering hole, and contemplate their next moves.
Players set up their species (1 green/yellow tile = 1 species) around the watering hole, and contemplate their next moves.

In game play, as in life, the point of the game is to eat – victory is achieved by the player who has managed to ‘digest’ the most food tokens. All players begin with a single species, and with each turn, can either add traits (ie. fat tissue, scavenger, etc.) to the species, increase the body size of a species, gain a population level, or gain additional species.  Next, players take food from a limited, random supply until there is no food left. Species that have not been fed to their full capacity (population levels) will starve, and can even become extinct – much like the reality of environmental cycles.  Finally, all food that has been ‘eaten’ is digested, and the next round begins.

Since a player can never be sure how much food will appear on the watering hole each turn, it is a good strategy to capitalize on traits like foraging which allows a species to take twice as much food every time it feeds.  If your species cooperates with another, that means that it gets to eat every time you feed the first species. A player who combines foraging traits with multiple cooperating species in a “cooperation chain” can quickly empty the watering hole before any other players get a chance.  Much like a species perfectly adapted to its niche in the real world will out compete more generalist species.

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The pack-hunting carnivore on the left can easily take down the fertile defensive herding species in the upper right. The efficient foraging species in the middle is protected by its horns, and cooperates with the next species to the right. The burrowing species is protected from carnivores only as long as it is full (and presumably no longer needs to venture out of its burrow).

One way to avoid the competition for food at the watering hole is to play the carnivore trait.  This species must now consume other species in order to feed itself.  A few caveats; a carnivore must be larger in body size than anything it tries to eat, and can no longer eat plant food as it is an obligate carnivore. As soon as a carnivore appears on the board, the evolutionary arms-race begins in earnest!  Traits such as burrowing, climbing, hard shells, horns, defensive herding and warning calls become vital to survival.  But carnivores can be clever, and apply ambush to species with warning call, or pack-hunting to a species with defensive herding.  In everything, there is a certain balance, and quickly, players will find themselves acting out a classic ‘boom and bust population growth cycle’ scenario, where herbivores go extinct due to low food supply at the watering hole and/or high predation pressure, and carnivores soon follow when there are no un-protected species for them to feed upon.

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A flying creature must first pay the ‘upkeep cost’ of its body size in food, before it can feed its population. Good thing it has the extra cliff-side food source that is only accessible to other species with wings!

An expansion has been released for the game – it is called Flight – and introduces traits such as flight, camouflage, good eyesight, and others.  From an ecologist’s perspective, it fits the original game well both scientifically and thematically.  To achieve flight, a higher price must be paid (in terms of cards discarded) to gain the trait card, and unlike other species, an ‘upkeep cost’ must be gathered in food tokens before the species actually eats any food tokens during the round.  However, flight also gives access to a cliff-side watering hole that is not accessible to earthbound species. This neatly mirrors the real world where flight is an energetically costly activity that also opens new niches.

The next expansion is just arriving in stores, and I can’t wait to play it! It’s called Climate, and adds traits such as nocturnal, claws, and insectivore. Perhaps more exciting though, are the ‘event cards’ which will trigger things like desertification, cold snaps, heatwaves, volcanic eruptions and meteor strikes. A climate tracker will keep track of whether the planet is in an ice age or a warming period, and certain traits will make your species more or less likely to survive – can you guess which ones might be useful in either scenario? I think it will be enormously fun to play through different climate scenarios and see how traits stack and species interactions evolve.  Perhaps this new addition to the game will even cause a new game review in Nature – check out their initial assessment here: http://www.nature.com/nature/journal/v528/n7581/full/528192a.html

Games like evolution are useful thought exercises for students and researchers because they promote discussion of adaptive traits, predator-prey cycles, climate, and ecosystem dynamics as related to our own projects. Watching a story unfold in front of you is a great way to truly understand some of the core principles of ecology (and other subjects). This is especially relevant in the GEMM lab where we continuously ask ourselves why our study species act the way they do? How do they find prey, and how are/will they adapt(ing) to our changing climate?

Assembling a Toolbox

By Dawn Barlow, MSc student, Oregon State University

toolbox
Source: https://www.ohrd.wisc.edu/home/portals/0/toolbox.jpg

The season has shifted since the post I wrote this summer about diving into the world of New Zealand blue whales and the beginnings of my masters research. My fieldwork will take place during the upcoming austral summer, which will require me to miss the winter term here on campus. This quarter, I have put my research on the back burner for the time being in favor of a full load of coursework. But my project is still there, simmering subtly and persistently, and giving relevance to the coursework that I’m focusing my energy on this fall term.

As an undergraduate student, I acquired a broad scientific background and had the opportunity to dabble in the areas of biology that piqued my interest. I arrived here with a basic understanding of chemistry, physics, cell biology, anatomy, marine ecology and conservation biology. I gained experience working in the field with intertidal sea stars, snails, mussels, crabs and barnacles, with bottlenose dolphins and with humpback whales. But now my focus has narrowed as I’ve honed in on the specific questions that I will pursue over the next two years. My passion lies in marine ecology and conservation. Now, as a graduate student studying the ecology of a little-known population in a highly industrial area, this passion can come to fruition. For my masters, I hope to do the following:

A) Use photo-identification analysis to obtain a population abundance estimate for blue whales in New Zealand

B) Investigate blue whale residency and distribution patterns in New Zealand waters

C) Develop a comprehensive blue whale habitat use model for the South Taranaki Bight region of New Zealand, which incorporates physical and biological data

Down the road I hope to have implemented a capture-recapture abundance estimate model that best fits the dynamics of this population of blue whales, to have mapped where sightings have occurred and where the highest densities of blue whales are found in both space and time, and to have paired blue whale presence and absence with prey distribution, remote-sensed environmental data, and in situ oceanographic data. But how does one accomplish these things? I need a toolbox to draw from. And so this fall, I am assembling my toolbox, learning programs and analytical skills. I am taking methods courses—statistics, data management in R, analysis in GIS, methods in physiology and behavior of marine megafauna—that are no longer explorations into the world of natural science, but rather tools for exploring, identifying, and interpreting specific phenomena in ecology. While each comes with its own hiccups and headaches (see Florence’s post about this…), they are powerful tools.

Aside from coursework, the research I’m conducting has gained weight and relevance beyond being an investigation in ecology. My study area lies in the South Taranaki Bight of New Zealand, which is a contentious proposed seabed mining site for iron sands. As an undergraduate student I read case studies and wrote papers on the environmental impacts of industry, and I decided to go graduate school because I want to do research that has direct conservation applications. Last week I compiled all the data I’ve processed on blue whale sightings, seasonal residency, and photo identification for the South Taranaki Bight, which will be included as evidence submitted in environmental court in New Zealand by my advisor, Dr. Leigh Torres. “Applied conservation science” has been an abstract idea that has excited and motivated me for a long time, and now I am partaking in this process, experiencing applied conservation science firsthand.

And so my toolbox is growing, and the scope of my work is simultaneously narrowing in focus and expanding in relevance. The more tools I acquire, the more excited I am to apply them to my research. As I build my toolbox this fall, this process is something I look forward to enhancing while I’m in the field, when I dig deeper into data analysis, and as I grow as a conservation scientist.

A blue whale dives in the South Taranaki Bight, New Zealand. Photo by Leigh Torres.
A blue whale dives in the South Taranaki Bight, New Zealand. Photo by Leigh Torres.

The seamounts are calling and I must go: a humpback’s landscape

Solène Derville, Entropie Lab, Institute of Research for Development, Nouméa, New Caledonia (Ph.D. student under the co-supervision of Dr. Leigh Torres)

The deep ocean is awe-inspiring: vast, mysterious, and complex… I can find many adjectives to describe it, yet the immensity of it prevents me from picturing it in my mind. Landscapes are easy to imagine because we see them all the time, but their hidden ocean counterparts of seascapes with several kilometer-high seamounts and abyssal trenches are hard to visualize.

When I started a PhD on the spatial ecology of humpback whales, a species typically known for its coastal distributions, I never imagined my research would lead me to seamounts. Lesson of the day: you never know where research will lead you… So here is how it happened.

About twenty years ago when my supervisor, Dr Claire Garrigue, started working on humpback whales in New Caledonia, she was told by fishermen that humpbacks were often observed in prime fishing locations, about 170 km south of the mainland. After a little more investigation into this claim, it was discovered that these fishing spots corresponded with two seafloor topographic features: the Antigonia seamount and Torch Bank (Fig. 1), These features rise from the seafloor to depths of 30 m and 60 m respectively and are surrounded by waters about 1500 m deep. This led Dr. Garrigue to implement an ARGOS-satellite tagging program to follow the movements of humpbacks leaving the South Lagoon (one of the main breeding area in New Caledonia, Fig. 1). Sure enough, most of the tagged whales (61%) visited the Antigonia seamount (Fig. 2; Garrigue et al. 2015)⁠.

Map of New Caledonia and our study areas: the South Lagoon and the Southern Seamounts. Light grey lines represent 200m isobaths. Land is shown in black and reefs in grey.
Figure 1: Map of New Caledonia and our study areas: the South Lagoon and the “Southern Seamounts”. Light grey lines represent 200m isobaths. Land is shown in black and reefs in grey.
Figure 2: ARGOS tracking of 34 humpback whales tagged between 2007 and 2012 in the South Lagoon. The Antigonia seamount and Torch Bank are completely covered by tracklines.
Figure 2: ARGOS tracking of 34 humpback whales tagged between 2007 and 2012 in the South Lagoon. The Antigonia seamount and Torch Bank are completely covered by tracklines.

 

Seamounts are defined as “undersea mountains rising at least 100m from the ocean seafloor” (Staudigel et al. 2010). Most of them have a volcanic origin and the majority of them are located in the Pacific Ocean (Wessel 2001). But what is the link between these structures and marine life? The physical and biological mechanisms by which seamounts attract marine wildlife are diverse (for a review see: Pitcher et al. 2008)⁠. In a nutshell, topography of the ocean floor influences water circulation and isolated seabed features such as seamounts affect vertical mixing and create turbulences, consequently resulting in higher productivity.

For instance, have you ever heard of internal waves? Contrary to the surface waves people play in at the beach, internal waves propagate in three dimensions within the water column and can reach heights superior to a 100m! When these waves encounter steep topography, they break, similar to what a “normal” wave would do when reaching shore. This creates complex turbulence, which in turn may attract megafauna such as cetaceans (see com. by Hans van Haren).

The importance of seamounts for cetaceans is often referenced in the literature, however, few studies have tried to quantify this preference (one of which was recently published by our labmate Courtney Hann, see Hann et al. 2016 for details). So what importance do these seamounts serve for humpback whales in New Caledonia? Are they breeding grounds, do they serve as a navigation cue, a resting area, or even a foraging spot (the latter being the less likely hypothesis given that humpback whales have never been observed feeding in tropical waters)?

To answer this question, an expedition to Antigonia was organized in 2008 and about 40 groups of whales were observed in only 7 days! The density of this aggregation, the high occurrence of groups with calves and the consistent singing of males suggested that this area may be associated with breeding or calving behavior. Several other missions followed, confirming the importance of this offshore habitat for humpbacks.

Looking through all this data I was struck by two things: 1) whales were densely aggregated on top of these seamounts but were rarely found in the surrounding area (Fig. 3), and 2) other seamounts with similar characteristics are only a few kilometers from Antigonia, but seem to be rarely visited by tagged whales.

What is so special about these seamounts? Why would energetically depleted females with calves choose to aggregate in these off-shore, densely occupied and unsheltered waters?

 

Figure 3: 3D surface plot of the seabed in the Southern seamount area. Humpback whale groups observed in-situ during the boat-based surveys conducted between 2001 and 2011 are projected at the surface of the seabed: blue points represent groups without calf and white points represent groups with calf. Antigonia and Torch Bank have a clear flat-top shaped which classifies them in the “guyot” seamount type. Most whale groups aggregated on top of these guyots.
Figure 3: 3D surface plot of the seabed in the Southern Seamounts area. Humpback whale groups observed during the boat-based surveys (2001-2011) are projected at the surface of the seabed: blue points represent groups without calf and white points represent groups with calf. Antigonia and Torch Bank have a clear flat-top shaped and are called “guyots” seamounts. Most whale groups aggregated on top of these guyots. For 3D interactive plot: click here.

I will spend the next two months at the GEMM lab in Newport, OR, trying to answer these questions using ocean models developed by New Caledonian local research teams (at IRD and Ifremer). I will be comparing maps of local currents and topography of several seabed features located south of the New Caledonia main island. The oceanographic model used for this study will allow me to analyze a great number of environmental variables (temperature, salinity, vertical mixing, vorticity etc.) through the water column (one layer every 10m, from 0 to 500m deep) and at a very fine spatio-temporal scale (1km and 1day, even 1 hour at specific discrete locations) to better understand humpback whale habitat preferences.

Figure 4: Modeled Sea Surface Temperature for July 15th 2013 (model in progress, based on MARS3D, development by Romain Legendre). A temperature front occurs in the middle of the study area, along the Norfolk ridge. On this image, a cold eddy is forming right on top of the Antigonia seamount.
Figure 4: Modeled Sea Surface Temperature for July 15th 2013 (model in progress, based on MARS3D, development by Romain Le Gendre). A temperature front occurs in the middle of the study area, along the Norfolk ridge. On this image, a cold eddy is forming right on top of the Antigonia seamount.

 

Looking forward to uncovering the mysteries of seamounts and sharing the results in December!

Literature Cited

Garrigue C, Clapham PJ, Geyer Y, Kennedy AS, Zerbini AN (2015) Satellite tracking reveals novel migratory patterns and the importance of seamounts for endangered South Pacific Humpback Whales. R Soc Open Sci

Hann CH, Smith TD, Torres LG (2016) A sperm whale’s perspective: The importance of seasonality and seamount depth. Mar Mammal Sci:1–12

Pitcher TJ, Morato T, Hart PJ, Clark MR, Haggan N, Santos RS (2008) Seamounts: ecology, fisheries & conservation. Oxford, UK: Blackwell Publishing Ltd.

Wessel P (2001) Global distribution of seamounts inferred from gridded Geosat/ERS-1 altimetry. J Geophys Res 106:19431–19441

Staudigel H, Koppers AP, Lavelle JW, Pitcer TJ, Shank TM (2010) Defining the word ‘seamount’. Oceanography 23,20–21.