Senior Lecturer in Marine Ecology
Centre for Ecology and Conservation
Hi Luis. Where are you at the moment?
I’m in Punta Arenas right now. Tomorrow we're heading down to Antarctica actually.
That’s exciting. I’m glad I caught you to talk about your work. Your research investigates the role of large marine animals. In particular, you focus on areas susceptible to climate change. At what point did you become interested in oceanography in general?
Marine ecology was my passion. I always wanted to be a marine ecologist and I always wanted to work with top predators. Particularly pinnipeds, cetaceans, and maybe a little bit of seabirds. But I did my undergrad and my masters in Chile and there were very few opportunities to study these animals, except for getting involved with oceanography. I did my undergrad, masters in Chile, and PhD later on in the US based on oceanography. So, I gained a really good background on how the entire system works that I can now take advantage of and apply to my studies on top predators in particular.
When did you broaden that research to focus specifically on the Antarctic?
That was in my PhD. In 2005 I moved to the United States to do my PhD at UC Santa Cruz with Dan Costa. My original idea when I was there was trying to work with South American sea lions, which is what I had been doing up to that point in Chile. For one reason or another we weren't able to find funding for that, but my advisor had an ongoing project on southern elephant seals and crabeater seals in the Peninsula. So, he offered for me to take the lead on that project--which I did. That’s how I slowly got involved in field work in Antarctica and then focused my dissertation in Antarctica. My PhD was on those two seal species around the Peninsula, the same area where we are going right now. Later on, as a PhD student and then as a postdoc, I had more opportunities to work in different areas.
You’ve been to Antarctica over ten times now. Your first opportunity was during your PhD. What were your initial impressions the first time you went?
I was mesmerized by the environment, the beauty of Antarctica, the biodiversity, the life that you see here in these waters. It just catches you and doesn’t let you go.
It was incredible. I was a little bit intimidated because I hadn’t had any previous training to work with live animals. I was also the youngest grad student there. There were only two grad students and four PIs with huge names – not only my advisor Dan Costa but other collaborators of his that are huge names in environmental science including Mike Fedak at the University of St Andrews, Dan Crocker from Sonoma State University, and Mike Goebel from The Southwest Fisheries Science Center at NOAA; it was intimidating from that sense. From the sense of working with the animals, it was sort of a realization that this was exactly my call in life. Automatically I loved fieldwork and working with animals. That’s one of the reasons why I never stopped; I kept getting involved with different opportunities to work with these species all over the planet just because the impression Antarctica gave me was so positive. I was mesmerized by the environment, the beauty of Antarctica, the biodiversity, the life that you see here in these waters. It just catches you and doesn’t let you go.
Of all your experiences in Antarctica, could you point to one being your most memorable field experience?
That was an impressive opportunity because not only was it my first time leading a field crew of people who had no experience – I had to train them and guide them – but also it was incredible working with the largest species of seal on the planet.
There's a couple of them; one of them during my PhD. I was able to lead the first field season on my own in 2009 working with southern elephant seals. That was an impressive opportunity because not only was it my first time leading a field crew of people who had no experience – I had to train them and guide them – but also it was incredible working with the largest species of seal on the planet. We were working in an environment where there’s such a high diversity of predators with fur seals, Weddell seals, and different species of penguins and seabirds in general.
The second experience must be in McMurdo in the Ross Sea where we get there during the breeding season of Weddell seals, sometimes even before the season starts and the animals have really started arriving in big numbers and it’s one of those weird days with no wind, if you walk on the sea ice you don’t hear absolutely anything. Complete silence. That’s what I define as the true Antarctic sound, because there is a couple of times where you can go to certain areas where the seals are just about to haul out and there's no sound. There’s nothing, you cannot hear anything else. It’s such a dramatic silence; it basically takes your breath away.
That sounds incredible. Your work involved tagging and placing different instruments on seals. Could you walk me through that process of tagging an animal, how you attach it, and how far and deep do the seals typically travel?
I’m interested in trying to understand how animals are capable of finding food in such a big, massive environment like the open ocean. Unlike land predators where you can observe them, track them, and follow them, it’s impossible for us to do these things with marine animals that are diving constantly and traveling thousands of kilometers away from the coast. To our advantage in the last couple of decades there’s been a huge development of the instrumentation that we can put on these animals. These instruments have allowed us to follow them in real-time throughout their entire trips over thousands of kilometers. The equipment that we put on these animals has achieved such a level of technology and specialization, that the amount of data that we can collect from these animals is not limited anymore to just diving location; you can get things like the diving behavior where you can actually measure how deep they go and for how long.
For the first time we are actually understanding things like energetics, how many times the animal strokes their flippers, how many times the animal moves, and how they move through a three-dimensional environment. Are they swimming upside down, or right side up? You can add instrumentation that allows you to measure the environment that they are going through. So, if you think about it, how do you know if they prefer colder or warmer waters, where now we put instruments that can actually measure the temperature and salinity of the water. They can even measure the amount of chlorophyll, a proxy for the amount of phytoplankton biomass, the primary producers that you have in the water. So, it's an incredible opportunity to learn a lot about not only the animals but also the environment that they are using. We have developed a lot of research in this area, and the good thing is that we can work with these animals because they’re big and we’re seeing them enough that we can put these instruments on them for seven weeks to months, and we can get a lot of information. Once we deploy the instruments, they transmit the data through satellite, so all we have to do is literally download the data through our computers at home, and we can just get all this amazing data. And the procedure sounds relatively easy, but of course when I say easy, I have to make the clarification that this is work with wild animals that can bite, some of them can particularly hurt you really bad. So, we have lots of experience with that, we sedate the animals so that we can work safely with them. We literally glue the instrument to the fur of the animal. If you think about it, just like your dog at home, seals and sea lions shed their fur once a year. So, we wait until they’re done with the shedding part and with that molt, and we glue the instrument using a marine epoxy to the fur on their back or on their head. That way the instrument stays with the animal for about a year, sometimes less than a year, until the next year when they molt it off.
You’ve mentioned all of the different datasets you can now get with these different types of tags. One of the projects you’ve worked on was aimed at determining the feasibility of using existing data sets collected by diving predators. How did that come about? Are you using data that have already been collected by other people, or is it data that you collected and are now using for a different purpose?
It’s data that has been collected by a series of different researchers from all over the planet. It interested me because the tag that had been collecting that data doesn't have the capability to transmit over satellite. These are data like temperature and light penetration in the water column. These two variables are important to understand, particularly in coastal ecosystems. The data that we work with for this project comes from tags that archive the information in their internal memory, which means that we have to recover them to get the data and, in most cases, the environmental data that they’ve collected has not been shared. We decided to first identify these datasets with the intention that these data would actually be used in oceanography. We are doing a pilot experiment where we contacted a series of collaborators and asked them for their data. We were trying to prove that those data have a lot of value. Then we can use them to learn something about how particularly the coastal environments in the Southern Ocean are changing. These data sets span for decades. We have probably hundreds, if not thousands, of data sets that are just basically gathering dust in people’s computers. So, we prove that these are an important source of oceanographic data. Our idea is to streamline the distribution of these data to the right people so they can actually be used on oceanographic models in order to understand how climate change is impacting the environment and how the coastal ocean is changing.
This is particularly important because the coastal ocean is so dynamic. If you think about all the waves and all the energy that you see in these environments, that basically means that trying to sample those environments is very difficult. Animals naturally occur and occupy these environments; they’re a perfect opportunity for us to sample those environments that would otherwise be really hard, if not impossible, to sample.
Thanks for that clarification. How far are you into that project?
We are sort of just past the half point; we hope to get everything done by winter 2024. We contacted collaborators that had been working with Antarctic fur seals and seal species on some south Antarctic islands. We are now finalizing the process where we are seeing how valuable those data sets are, basically validating those sets and comparing those data sets with other sources of oceanographic data.
Another project you’re working on is looking at the impact of climate change on crabeater seals. I've always had this question: why were they named crabeater seals in the first place?
We don’t know exactly. The urban myth about it is it was a mistranslation from the German word for crustacean that was translated into crabs. I think that the word they use in German should be crustacean-eater seal, and that was mistranslated into crabeater seal. The reason for that is because their diet is almost 100% exclusively Antarctic krill, which is a crustacean.
What sort of population changes have you observed with crabeater seals?
We haven't, that’s the thing. Research in Antarctica for seals in particular has been sort of spotty. We have a few species that are very well known, the Weddell seal, particularly the population that lives in McMurdo Sound where the United States has McMurdo Station. That population of Weddell seals is really well known. But other than that, there are few species that have been studied at the level that Weddell seals have and one of those is the crabeater seal. There are few data. In the late 1990s there was a multi-nation effort to estimate the population size of pack ice seals in certain specific sectors from ships and planes, the Antarctic Pack Ice Seals program (APIS). But other than that, we have no data, so it’s really impossible to talk about changes in the populations. There were a couple of attempts in the 1990s and early 2000s to start putting tags on them by the Americans, Australians, Germans and Norwegians, maybe I’m missing a few. There was an effort in 2001 and 2002 led by my PhD advisor, Dan Costa, and then he again got another grant in 2007. That was what I analyzed for my PhD, but that’s it. We never had anything else. There are very few studies in terms of crabeater population density and what the effects of climate change are. So that’s the reason why I’m talking to you from a research vessel in Punta Arenas. We’re going down to Antarctica to study the crabeater seal and for the first time understand what kind of changes that species is facing or has gone through during the last couple of decades since the first studies in 2001 and 2002. I can’t really answer your question effectively. I can’t really tell you what kind of changes the populations of crabeater seals have gone through, because we haven’t been able to document that. That’s one of the objectives of this cruise, we’re going to hopefully for the first time understand how things are changing. The reason why we’re able to do that is because we have that baseline data from twenty years ago. We are lucky those data exist because there are a lot of other species that have no baseline data. Talking about changes for Antarctic seals or polar seals in general is very complicated because we did not collect data before the changes occurred.
Interesting, well I’m excited to follow your work in the future and see what you find. Are you also studying their foraging habits in order to infer where Antarctic krill are?
Yes exactly. This is the idea. Studying prey in the ocean is very hard. Following the fish or the krill is particularly hard. So, one of the things that we can potentially do is understand the movements of the predators. If you think about it, the predators are going to occur where the food is. They’re not going to go places where they don’t find food. The ones that do die. What we’re thinking is that we can basically use the distribution of crabeater seals to tell us about the distribution of krill. That’s what we’ve done in the past, where we have seen the predictions that we get from the model about crabeater seals match really well to the distribution of krill. The idea is that by studying predators like crabeater seals we are able to learn more about not only the species but also the entire ecosystem. This is an idea we talk a lot about in our community – that marine mammals are what we call sentinel species, which means they can tell us something not only about themselves but also about the status of the entire marine ecosystem.
For the particular project that you’re heading south down for now, what particular instruments are you using this time and what data are you hoping to get from them?
We’re using satellite tags that are measuring temperature at a higher spatial resolution. We are hoping to get high resolution behavioral data. We’re going to be getting diving data as well, but for the first time we are expanding our research and including a lot of the diving physiology. Basically, we are going to see how animals are operating in the environment. How much does it cost to be a crabeater seal? We are going to be comparing crabeater seals from the northern part of the Antarctic Peninsula to those from the southern part of the Antarctic Peninsula and see whether the different environmental conditions are affecting how these animals are doing. Our prediction is that the animals in the north are swimming longer distances to reach their prey. Because they have to spend more energy swimming, they probably are not doing as well as the animals in the south which we hope are a little bit fatter and a little bit better in terms of population and the number of pups they are having. We are going to incorporate not only the movement and preying behavior, but we are also incorporating the factor of latitude to see whether the animals in the north and south are different. We are also studying their diets. We’re going to be using biogeochemical tracers to understand what kind of prey they are eating and also what food webs they are affecting or are a part of. Are they part of a more coastal food web, or perhaps they’re impacting more of an open ocean traffic web too. So, it’s a multidisciplinary study that works with several collaborators from the United States and the United Kingdom. We are also using drone technology for the first time to hopefully be able to tell how seals are doing from the skies. We’ll be taking pictures of the animals to see whether we can detect body condition as well as counting the number of seals and trying to understand the relation between the distribution of the animals and the ice conditions that we see on the Peninsula.
Can you elaborate more on how you’re determining their diet, how that process works?
Yes, we’re using stable isotopes which are natural markers. Everything is made of isotopes which are different forms of the same element. So, by using this principle you can actually track down the fluxes of energy and matter through entire trophic webs, all the way from the base of the trophic web – the primary producers – to the pinnipeds that we are working with. By using this technique, we’re able to estimate the contribution of different prey items to the diet of particular consumers. Along with tagging animals we’re going to be collecting samples of their prey. We’ll be collecting samples of krill and fish in Antarctica, measure the values of those stable isotopes for the prey, measure the stable isotopes for the predator, and hopefully estimate the contribution of each one of those prey items to the diet of the crabeater seal. On top of that, we’ll also have the stable isotopes measured from the primary producers to the top predators; we’re going to be able to tell what food web they’re impacting. What I mean by that is if you think about coastal Antarctica, there’s a trophic web that’s relying on phytoplankton associated with sea ice. There’s also another trophic web based on phytoplankton associated with open water. So, we’re sure one of those two trophic webs is the one that is supporting the population of crabeater seals and, hopefully, we’re going to be able to figure it out.
How long will your field season be this time?
Five weeks, that sounds like a great project. I just wanted to step back and talk a little bit about your involvement with SCAR. You’ve been a member of the SCAR Expert Group on Birds and Marine Mammals and you’re now involved with the SCAR Scientific Research Program on Integrated Science to Inform Antarctic and Southern Ocean Conservation (Ant-ICON). How did you first get involved with SCAR and these groups and what has your role been in each?
I started going to SCAR meetings as a grad student when I got involved with the project, I was telling you about with my advisor. Back in the day, SCAR was going through a transition. There weren't expert groups yet but there was something called the Birds Group, and another was called the Marine Mammals Group. For the first time these two groups merged together as I was about to finish my dissertation. I started going to those meetings and started talking to the different scientists from different nations that were working with the same species that I was working with. So that’s how I slowly started going to these meetings or workshops before the larger open science meetings that happen every couple of years and slowly started having a more active role in these initiatives. That is how I ended up being a part of the core group that conducted the retrospective analysis of Antarctic tracking data. A group of close to twelve of us were meeting a couple times a year and analyzing tracking data for every single species of Antarctic predator. This resulted in a paper that was published a couple of years ago where we used tracking data from a bunch of predators to identify areas of importance for conservation within the Southern Ocean (https://www.nature.com/articles/s41586-020-2126-y). Once you go to these meetings you realize there are several groups that are forming and others that are closing down that are of interest to your science. You can also make a contribution and that’s how I got involved into one of the newer groups. However, due to the pandemic we haven't been able to meet yet, but we are slowly trying to get started with the kind of research and the tasks that we have ahead.
Is your group still trying to collaborate virtually?
Because of the spirit of SCAR in general and the EG-BAMM group in particular is such a collaborative effort, everyone just automatically comes to share data, to start new collaborations, and to start new projects.
Yes. The Expert Group on Birds and Marine Mammals (EG-BAMM) group is one of my favorite meetings to go to. Because of the spirit of SCAR in general and the EG-BAMM group in particular is such a collaborative effort, everyone just automatically comes to share data, to start new collaborations, and to start new projects. It is one of the most fascinating professional experiences that I ever had. As I mentioned, the Retrospective Analysis of Antarctic Tracking Data (RAATD) project started in 2012 and resulted in this paper that I mentioned, but we’re still meeting, we’re still analyzing, we’re still working together as a group because we still want to keep working on Antarctic conservation.
Awesome, I haven’t been to an Open Science Conference with SCAR yet, but hopefully in the future. Getting back to in-person meetings will be huge for collaboration. I only have one more question, and this is one I tend to ask everyone. If you think back to how you got into your Antarctic research at the beginning, what advice would you give to early career scientists wanting to get involved with Antarctic research?
I guess my advice would be to not be afraid to ask for help within the community, because it’s such an amazing, supportive community that you’re going to be in very good company.
Don’t be afraid to ask for help. One of the things that I personally went through: I’m quite shy. I don’t like talking to people and I’m not very outgoing. I think if I would have done something different it would have been asking for help at these meetings and asking for help from the community. Because it’s such a receptive community you won't be turned down. If your aspiration is to have a role in Antarctic science, volunteer. I’m not talking about volunteering as a grad student, everyone is going to be doing an active role. You’re not going to be taken advantage of, you’re going to be given proper credit and you’re going to have an opportunity to learn from the best people involved with Antarctic science and also develop your own professional skills. I guess my advice would be to not be afraid to ask for help within the community, because it’s such an amazing, supportive community that you’re going to be in very good company.
That’s great advice. I think I was pretty lucky to have people kind of introduce me into the community.
Yes, exactly. It’s an amazing place to just talk about science, discuss priorities, and discuss what we should be working on. People will take into consideration your opinion. Even though you may just be a grad student and you think you don’t have anything to say, you actually do, and you’re going to be listened to.
I really appreciate you making the time to join me on a call from the other end of the world. I hope that your field season goes really well, you have good weather, and you don’t have too many delays getting to Antarctica.