Tag: Marine Mammals

Marine Mammal Observing: Standardization is key

By: Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

For the past two years, I’ve had the opportunity to be the marine mammal observer aboard the NOAA ship Bell M. Shimada for 10 days in May. Both trips covered transects in the Northern California Current Ecosystem during the same time of year, but things looked very different from my chair on the fly bridge. This trip, in particular, highlighted the importance of standardization, seeing as it was the second replicate of the same area. Other scientists and crew members repeatedly asked me the same questions that made me realize just how important it is to have standards in scientific practices and communicating them.

Northern right whale dolphin porpoising out of the water beside the ship while in transit. May 2019. Image source: Alexa Kownacki

The questions:

  1. What do you actually do here and why are you doing it?
  2. Is this year the same as last year in terms of weather, sightings, and transect locations?
  3. Did you expect to see greater or fewer sightings (number and diversity)?
  4. What is this Beaufort Sea State scale that you keep referring to?

All of these are important scientific questions that influence our hypothesis-testing research, survey methods, expected results, and potential conclusions. Although the entire science party aboard the ship conducted marine science, we all had our own specialties and sometimes only knew the basics, if that, about what the other person was doing. It became a perfect opportunity to share our science and standards across similar, but different fields.

Now, to answer those questions:

  1. a) What do you actually do here and b) why are you doing it?

a) As the only marine mammal observer, I stand watch during favorable weather conditions while the ship is in transit, scanning from 0 to 90 degrees off the starboard side (from the front of the ship to a right angle towards the right side when facing forwards). Meanwhile, an application on an iPad called SeaScribe, records the ship’s exact location every 15 seconds, even when no animal is sighted. This process allows for the collection of absence data, that is, data when no animals are present. The SeaScribe program records the survey lines, along with manual inputs that I add, including weather and observer information. When I spot a marine mammal, I immediately mark an exact location on a hand held GPS, use my binoculars to identify the species, and add information to the sighting on the SeaScribe program, such as species, distance to the sighted animal(s), the degree (angle) to the sighting, number of animals in a group, behavior, and direction if traveling.

b) Marine mammal observing serves many different purposes. In this case, observing collects information about what species are where at what time. By piggy-backing on these large-scale, offshore oceanographic NOAA surveys, we have the unique opportunity to survey along standardized transect lines during different times of the year. From replicate survey data, we can start to form an idea of which species use which areas and what oceanographic conditions may impact species distributions. Currently there is not much consistent marine mammal data collected over these offshore areas between Northern California and Washington State, so our work is aiming to fill this knowledge gap.

Alexa observing on the R/V Shimada in May 2019, all bundled up. Image Source: Alexa Kownacki
  1. What is this Beaufort Sea State scale that you keep referring to?

Great question! It took me a while to realize that this standard measuring tool to estimate wind speeds and sea conditions, is not commonly recognized even among other sea-goers. The Beaufort Sea State, or BSS, uses an empirical scale that ranges from 0-12 with 0 being no wind and calm seas, to 12 being hurricane-force winds with 45+ ft seas. It is frequently referenced by scientists in oceanography, marine science, and climate science as a universally-understood metric. The BSS was created in 1805 by Francis Beaufort, a hydrographer in the Royal Navy, to standardize weather conditions across the fleet of vessels. By the mid-1850s, the BSS was standardized to non-naval use for sailing vessels, and in 1916, expanded to include information specific to the seas and not the sails1. We in the marine mammal observation field constantly collect BSS information while on survey to measure the quality of survey conditions that may impact our observations. BSS data allows us to measure the extent of our survey range, both in the distance that we are likely to sight animals and also the likelihood of sighting anything. Therefore, the BSS scale gives us an important indication of how much absence data we have collected, in addition to presence data.

A description of the Beaufort Sea State Scale. Image source: National Weather Service.

 

  1. Is this year the same as last year in terms of weather, sightings, and transect locations?

The short answer is no. Observed differences in marine mammal sightings in terms of both species diversity and number of animals between years can be normal. There are many potential explanatory variables, from differences in currents, upwelling strength, El Nino index levels, water temperatures, or, what was obvious in this case: sighting conditions. The weather in May 2019 varied greatly from that in May 2018. Last year, I observed for nearly every day because the Beaufort Sea State (BSS) was frequently less than a four. However, this year, more often than not, the BSS greater than or equal to five. A BSS of 5 equates to approximately 17-21 knots of breeze with 6-foot waves and the water appears to have many “white horses” or pronounced white caps with sea spray. Additionally, mechanical issue with winches delayed and altered our transect locations. Therefore, although multiple transects from May 2018 were also surveyed during May 2019, there were a few lines that do not have data for both cruises.

May 2018 with a BSS 1
May 2019 with a BSS 6

 

 

 

 

 

  1. Did you expect to see greater or fewer sightings (number and diversity)?

Knowing that I had less favorable sighting conditions and less amount of effort observing this year, it is not surprising that I observed fewer marine mammals in total count and in species diversity. Even less surprising is that on the day with the best weather, where the BSS was less than a five, I recorded the most sightings with the highest species count. May 2018 felt a bit like a tropical vacation because we had surprisingly sunny days with mild winds, and during May 2019 we had some rough seas with gale force winds. Additionally, as an observer, I need to remove as much bias as possible. So, yes, I had hoped to see beaked whales or orca like I did in May 2018, but I was still pleasantly surprised when I spotted fin whales feeding in May 2019.

Marine Mammal Species Number of Sightings
May 2018 May 2019
Humpback whale 31 6
Northern right whale dolphin 1 2
Pacific white-sided dolphin 3 6
UNID beaked whale 1 0
Cuvier’s beaked whale 1 0
Gray whale 4 1
Minke whale 1 1
Fin whale 4 1
Blue whale 1 0
Transient killer whale 1 0
Dall’s porpoise 2 0
Northern fur seal 1 0
California sea lion 0 1
Pacific white-sided dolphin. Image source: Alexa Kownacki

Standardization is a common theme. Observing between years on standard transects, at set speeds, in different conditions using standardized tools is critical to collecting high quality data that is comparable across different periods. Scientists constantly think about quality control. We look for trends and patterns, similarities and differences, but none of those could be understood without having standard metrics.

The entire science party aboard the R/V Shimada in May 2019, including a marine mammal scientist, phytoplankton scientists, zooplankton scientists, and fisheries scientists, and oceanographers. Image Source: Alexa Kownacki

Literature Cited:

1Oliver, John E. (2005). Encyclopedia of world climatology. Springer.

 

 

Highlights from the 11th Sea Otter Conservation Workshop

By Dominique Kone, Masters Student in Marine Resource Management

I recently attended and presented at the 11th biennial Sea Otter Conservation Workshop (the Workshop), hosted by the Seattle Aquarium. As the largest sea otter-focused meeting in the world, the Workshop brought together dozens of scientists, managers, and conservationists to share important information and research on sea otter conservation issues. Being new to this community, this was my first time attending the Workshop, and I had the privilege of meeting some of the most influential sea otter experts in the world. Here, I recount some of my highlights from the Workshop and discuss the importance of this meeting to the continued conservation and management of global sea otter populations.

Source: The Seattle Aquarium.

Sea otters represent one of the most successful species recovery stories in history. After facing near extinction at the close of the Maritime Fur Trade in 1911 (Kenyon 1969), they have made an impressive comeback due to intense conservation efforts. The species is no longer in such dire conditions, but some distinct populations are still considered at-risk due to their small numbers and persistent threats, such as oil spills or disease. We still have a ways to go until global sea otter populations are recovered, and collaboration across disciplines is needed for continued progress.

The Workshop provided the perfect means for this collaboration and sharing of information. Attendees were a mixture of scientists, managers, advocacy groups, zoos and aquarium staff, and graduate students. Presentations spanned a range of disciplines, including ecology, physiology, genetics, and animal husbandry, to name a few. On the first day of the Workshop, most presentations focused on sea otter ecology and management. The plenary speaker – Dr. Jim Estes (retired ecologist and University of California, Santa Cruz professor) – noted that one of the reasons we’ve had such success in sea otter recovery is due to our vast knowledge of their natural history and behavior. Much of this progress can be attributed to seminal work, such as Keyon’s 1969 report, which provides an extensive synthesis of several sea otter ecological and behavioral studies (Kenyon 1969). Beginning in the 1970’s, several other ecologists – such as David Duggins, Jim Bodkin, Tim Tinker, and Jim himself – expanded this understanding to complex trophic cascades, individual diet specialization, and population demographics.

Jim Estes and Tim Tinker. Source: Jim Estes.

These ecological studies have played an integral role in sea otter conservation, but other disciplines were and continue to be just as important. As the Workshop continued into the second and third days, presentations shifted their focus to physiology, veterinary medicine, and animal husbandry. Two of these speakers – who have played pivotal roles in these areas – are Dr. Melissa Miller (veterinarian specialist and pathologist with the California Department of Fish & Wildlife) and Dr. Mike Murray (director of veterinary services at the Monterey Bay Aquarium). Dr. Miller presented her years of work on understanding causes of mortality in wild southern sea otters in California. Her research showed that shark predation is a large source of mortality in the southern stock, but cardiac arrest, which has gained less attention, is also a large contributing factor.

Dr. Murray discussed his practice of caring for and studying the biology of captive sea otters. He provided an overview of some of the routine procedures (i.e. full body exams, oral surgeries, and radio transmitter implantation) his team conducts to assess and treat stranded wild otters, so they can be returned to the wild. Both presenters demonstrated how advances in veterinary medicine have helped us better understand the multitude of threats to sea otters in the wild, and what interventive measures can be taken to recover sick or injured otters so they can contribute to wild population recovery. By understanding how these threats are impacting sea otter health on an individual level, we can be better equipped to prevent population-wide consequences.

Dr. Melissa Miller conducting a sea otter necropsy. Source: California Department of Fish & Game.

Throughout the entire Workshop, experts with decades of experience presented their work. Yet, one of the most encouraging aspects of this meeting was that several graduate students also presented their research, including myself. In a way, listening to presenters both early and late in their careers gave us a glimpse into the past and future of sea otter conservation. Much of the work currently being conducted by graduate students addresses some of the most pressing and emerging issues (e.g. shark predation, plastic pollution, and diseases) in this field, but also builds off the great knowledge base acquired by many of those at the Workshop.

Perhaps even more encouraging was the level of collaboration and mentorship between graduate students and seasoned experts. Included in almost every graduate student’s acknowledgement section of their presentations, were the names of several Workshop attendees who either advised them or provided guidance on their research. These presentations were often followed up with further meetings between students and their mentors. These types of interactions really demonstrated how invested the sea otter community is in fostering the next generation of leaders in this field. This “passing of the mantel” is imperative to maintain knowledge between generations and to continue to make progress in sea otter conservation. As a graduate student, I greatly appreciated getting the opportunity to interact with and gain advice from many of these researchers, whom I’ve only read about in articles.

Source: Bay Nature.

To summarize my experience, it became clear how important this Workshop was to the broader sea otter conservation community. The Workshop provided the perfect venue for collaboration amongst experts, as well as mentorship of upcoming leaders in the field. It’s important to recognize the great progress and strides the community has made already in understanding the complex lives of sea otters. Sea otters have not recovered everywhere. Therefore, we need to continue to acquire knowledge across all disciplines if we are to make progress in the future, especially as new threats and issues emerge. It will take a village.

Literature Cited:

Kenyon, K. W. 1969. The sea otter in the eastern Pacific Ocean. North American Fauna. 68. 352pp.

More data, more questions, more projects: There’s always more to learn

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab 

As you may have read in previous blog posts, my research focuses on the ecology of blue whales in New Zealand. Through my MS research and years of work by a dedicated team, we were able to document and describe a population of around 700 blue whales that are unique to New Zealand, present year-round, and genetically distinct from all other known populations [1]. While this is a very exciting discovery, documenting this population has also unlocked a myriad of further questions about these whales. Can we predict when and where the whales are most likely to be? How does their distribution change seasonally? How often do they overlap with anthropogenic activity? My PhD research will aim to answer these questions through models of blue whale distribution patterns relative to their environment at multiple spatial and temporal scales.

Because time at sea for vessel-based surveys is cost-limited and difficult to come by, it is in any scientist’s best interest to collect as many concurrent streams of data as possible while in the field. When Dr. Leigh Torres designed our blue whale surveys that were conducted in 2014, 2016, and 2017, she really did a miraculous job of maximizing time on the water. With more data, more questions can be asked. These complimentary datasets have led to the pursuit of many “side projects”. I am lucky enough to work on these questions in parallel with what will form the bulk of my PhD, and collaborate with a number of people in the process. In this blog post, I’ll give you some short teasers of these “side projects”!

Surface lunge feeding as a foraging strategy for New Zealand blue whales

Most of what we know about blue whale foraging behavior comes from studies conducted off the coast of Southern California[2,3] using suction cup accelerometer tags. While these studies in the California Current ecosystem have led to insights and breakthroughs in our understanding of these elusive marine predators and their prey, they have also led us to adopt the paradigm that krill patches are denser at depth, and blue whales are most likely to target these deep prey patches when they feed. We have combined our prey data with blue whale behavioral data observed via a drone to investigate blue whale foraging in New Zealand, with a particular emphasis on surface feeding as a strategy. In our recent analyses, we are finding that in New Zealand, lunge feeding at the surface may be more than just “snacking”. Rather, it may be an energetically efficient strategy that blue whales have evolved in the region with unique implications for conservation.

Figure 1. A blue whale lunges on an aggregation of krill. UAS piloted by Todd Chandler.

Combining multiple data streams for a comprehensive health assessment

In the field, we collected photographs, blubber biopsy samples, fecal samples, and conducted unmanned aerial system (UAS, a.k.a. “drone”) flights over blue whales. The blubber and fecal samples can be analyzed for stress and reproductive hormone levels; UAS imagery allows us to quantify a whale’s body condition[4]; and photographs can be used to evaluate skin condition for abnormalities. By pulling together these multiple data streams, this project aims to establish a baseline understanding of the variability in stress and reproductive hormone levels, body condition, and skin condition for the population. Because our study period spans multiple years, we also have the ability to look at temporal patterns and individual changes over time. From our preliminary results, we have evidence for multiple pregnant females from elevated pregnancy and stress hormones, as well as apparent pregnancy from the body condition analysis. Additionally, a large proportion of the population appear to be affected by blistering and cookie cutter shark bites.

Figure 2. An example aerial drone image of a blue whale that will be used to asses body condition, i.e. how healthy or malnourished the whale is. (Drone piloted by Todd Chandler).
Figure 3. Images of blue whale skin condition, affected by A) blistering and B) cookie cutter shark bites.

Comparing body shape and morphology between species

The GEMM Lab uses UAS to quantitatively study behavior[5] and health of large whales. From various projects in different parts of the world we have now assimilated UAS data on blue, gray, and humpback whales. We will measure these images to investigate differences in body shape and morphology among these species. We plan to explore how form follows function across baleen whales, based on their different  life histories, foraging strategies, and ecological roles.

Figure 4 . Aerial images of A) a blue whale in New Zealand’s South Taranaki Bight, B) a gray whale off the coast of Oregon, and C) a humpback whale off the coast of Washington. Drone piloted by Todd Chandler (A and B) and Jason Miranda (C). 

So it goes—my dissertation will contain a series of chapters that build on one another to explore blue whale distribution patterns at increasing scales, as well as a growing number of appendices for these “side projects”. Explorations and collaborations like I’ve described here allow me to broaden my perspectives and diversify my analytical skills, as well as work with many excellent teams of scientists. The more data we collect, the more questions we are able to ask. The more questions we ask, the more we seem to uncover that is yet to be understood. So stay tuned for some exciting forthcoming results from all of these analyses, as well as plenty of new questions, waiting to be posed.

References

  1. Barlow DR et al. 2018 Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endanger. Species Res. 36, 27–40. (doi:https://doi.org/10.3354/esr00891)
  2. Hazen EL, Friedlaender AS, Goldbogen JA. 2015 Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density. Sci. Adv. 1, e1500469–e1500469. (doi:10.1126/sciadv.1500469)
  3. Goldbogen JA, Calambokidis J, Oleson E, Potvin J, Pyenson ND, Schorr G, Shadwick RE. 2011 Mechanics, hydrodynamics and energetics of blue whale lunge feeding: efficiency dependence on krill density. J. Exp. Biol. 214, 131–146. (doi:10.1242/jeb.048157)
  4. Burnett JD, Lemos L, Barlow DR, Wing MG, Chandler TE, Torres LG. 2018 Estimating morphometric attributes on baleen whales using small UAS photogrammetry: A case study with blue and gray whales. Mar. Mammal Sci. (doi:10.1111/mms.12527)
  5. Torres LG, Nieukirk SL, Lemos L, Chandler TE. 2018 Drone Up! Quantifying Whale Behavior From a New Perspective Improves Observational Capacity. Front. Mar. Sci. 5. (doi:10.3389/fmars.2018.00319)

Signs you’re an ecologist – you don’t spend nearly enough time geeking out about your study species…

By Lisa Hildebrand, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

This past week has been very busy for me as I gave three quite important, yet very different, presentations. The first was on Tuesday at the Pacific High School in Port Orford, near my study site. The aim of the game was recruitment – my quest for two eager local high schoolers to be my interns for this 2019 summer field season has begun (read blogs written by our 2017 HS interns Nathan Malamud and Quince Nye)! I was lucky enough to be given an entire class period to talk to the students and so I hope that the picture I painted of kayaks, gray whales and sun will be enough to entice students to apply to the internship.

The second was a short presentation in one of the classes I took this term, GEOG 561: GIScience II Analysis and Applications. The class focuses on developing and conducting geospatial analyses in R and throughout the term each student develops a small independent research project using some of their own data. For my research project, I decided to do a small cluster analysis of the zooplankton community data that we have collected from the kayak net samples.

The third and final presentation of the week happened on Thursday and marked one of the big milestones on my Master’s journey: my research review. The research review is a mandatory (and extremely helpful) process in the Department of Fisheries & Wildlife where the student (in this case me), the committee (Dr Leigh Torres, Dr Rachael Orben, Dr Kim Bernard and Dr Susanne Brander) and a department representative (Dr Brian Sidlauskas) all assemble to discuss the student’s research proposal, which lays out the intended work, chapters, analysis and timeline for the students’ thesis. My proposal (which currently bears the title: “Tonight’s specials include mysids, gammarids and more: An examination of the zooplankton prey of Oregon gray whales and its impact on individual foraging patterns”) proposes a two-chapter thesis where the first examines the quality of zooplankton prey, while the second looks at potential individual foraging specialization of gray whales along the Oregon coast. While my entire committee agreed that what I have set forth to do in the next two or so years is ambitious, they provided me with excellent feedback and confidence that I would be able to achieve what I have planned.

Now that it’s the weekend and I’ve had some time to sit back and think about the week, I realized one major commonality between all three presentations I gave. None of the Powerpoints featured more than one image of a gray whale. How could this be?! It is after all my study species and I spend so much of my summer looking at them – how could it be that so little of what I showed and talked about was the thing that I am most passionate about and is so central to my research?

In the course of doing research, it’s easy to get wound up in the nitty gritty and forget about the big picture. While the nitty gritty is also imperative to conducting the research (and ultimately getting results), I sometimes forget about why I do what I do, which is that gray whales are AWESOME. Looking into the past, it seems that some of my lab mates have had the same realizations about their study species before too: see here and here. So for this blog, I want to bring it back to basics and share some of the things that I think are most fascinating about gray whales.

  1. Gray whales are the only baleen whale that feeds benthically. This behavior is facilitated by the shorter and tougher baleen that gray whales possess in comparison to other baleen whale species (Pivorunas 1979). The majority of the Eastern North Pacific (ENP) gray whale population feeds benthically in the Bering Sea where they eat ampeliscid amphipods, which are a type of benthic invertebrates (Nerini 1984). It is estimated that gray whales must regain 11-29% of critical body mass during the feeding season (Villegas-Amtmann et al. 2015) in order to obtain the energy stores they require for the entire year. Besides the personal benefit of sea floor foraging, by using this feeding tactic gray whales create depressions in the soft sediment that benefit other species besides themselves. The highly disruptive nature of this action can increase the biodiversity of the seafloor and initiate scavenging events by lysiannassid amphipods on other infauna (Oliver & Slattery 1985). Furthermore, Grebmeier & Harrison (1992) documented that a variety of seabirds including northern fulmars, black-legged kittiwakes and thick-billed murres feed on benthic amphipods brought to the surface by this unique foraging behavior performed by gray whales.
  1. Gray whales are essentially acrobats. A preference for benthic prey goes hand in hand with a preference for shallow, coastal waters, as for example Pacific Coast Feeding Group gray whales tend to forage within the 5-15 m depth range (Weller et al. 1999). With female adults ranging between 13-15 m in length (females tend to be slightly larger than adult males) and weighing anywhere between 15-33 tons (Jones et al. 1984), I am continuously fascinated by how gracefully and slowly gray whales can navigate extremely shallow waters.

    However, it is more than just simple navigation – the behaviors and moves that some gray whales display while in the shallows is phenomenal too. Last year Torres et al. (2018) documented this agility through unmanned aerial systems (UAS) footage that provided evidence for some novel foraging tactics including headstands, side-swimming, and jaw snapping and flexing.

  1. They sure are resilient. Commercial whaling of gray whales began in 1846 after two commercial whaling vessels first discovered the winter breeding grounds in Baja California, Mexico (Henderson 1984). Following this discovery, the ENP were targeted for roughly a century before receiving full protection under the International Convention for the Regulation of Whaling in 1946 (Reeves 1984). Through genetic analyses, it has been estimated that the pre-whaling abundance of the ENP population was between 76,000 – 118,000 individuals (Alter et al. 2012), which is roughly three to five times larger than current estimates (24,000 – 26,000; Scordino et al. 2018). While the gray whale populations that once existed in the Atlantic Ocean were not as fortunate as those in the Pacific (Atlantic gray whales were declared extinct in the 18thcentury due to extensive whaling; Bryant 1995), the ENP has definitely made a strong comeback. Additionally, gray whale resilience is not only evident on this long temporal scale but it can also be seen annually when gray whale mothers fight relentlessly to keep their calves alive when under attack from killer whales. A study on predation of gray whales by transient killer whales in Alaska reported that attacks were quickly abandoned if calves were aggressively defended by their mothers or if gray whales succeeded in reaching depths of 3 m or less (Barrett-Lennard et al. 2011).
  1. For some unimaginable reason, gray whales appear to feel a strong connection to us. For many, gray whales might be best known for actively seeking out human contact during their breeding season in the Mexican lagoons. I find this actuality particularly interesting because of the bloody history we share with Pacific gray whales.

Those are just some of the things about gray whales that make them so fascinating to me. I look forward to potentially discovering one or two more things that we don’t know about them yet through my research. Even if that doesn’t turn out to be the case, I feel so lucky that I at least get to spend so much time with them during their feeding season here along the Oregon coast.

 

References

Alter, E.S., et al., Pre-whaling genetic diversity and population ecology in Eastern Pacific gray whales: Insights from ancient DNA and stable isotopes.PLoS ONE, 2012. doi.org/10.1371/journal.pone.0035039.

Barrett-Lennard, L.G., et al., Predation on gray whales and prolonged feeding on submerged carcasses by transient killer whales at Unimak Island, Alaska. Marine Ecology Progress Series, 2011. 421: 229-241.

Bryant, P.J., Dating remains of gray whales from the Eastern North Atlantic. Journal of Mammalogy, 1995. 76(3): 857-861.

Grebmeier, J.M., & Harrison, N.M., Seabird feeding on benthic amphipods facilitated by gray whale feeding activity in the northern Bering Sea. Marine Ecology Progress Series, 1992. 80: 125-133.

Henderson, D.A., Nineteenth century gray whaling: Grounds, catches and kills, practices and depletion of the whale population.Pages 159-186 inJones, M.L. et al., eds. The gray whale: Eschrichtius robustus, 1984. Academic Press, Orlando.

Jones, M.L., et al., The gray whale: Eschrichtius robustus. 1984. Academic Press, Orlando.

Nerini, M., A review of the gray whale feeding ecology. Pages 423-448 inJones, M.L. et al., eds. The gray whale: Eschrichtius robustus, 1984. Academic Press, Orlando.

Oliver, J.S., & Slattery, P.N., Destruction and obstruction on the sea floor: effects of gray whale feeding.Ecology, 1985. 66: 1965-1975.

Pivorunas, A., The feeding mechanisms of baleen whales.American Scientist, 1979. 67(4): 432-440.

Reeves, R.R., Modern commercial pelagic whaling for gray whales. Pages 187-200 inJones, M.L. et al., eds. The gray whale: Eschrichtius robustus, 1984. Academic Press, Orlando.

Scordino, J., et al., Report of gray whale implementation review coordination call on 5 December 2018.

Torres, L.G., et al., Drone up! Quantifying whale behavior from a new perspective improves observational capacity.Frontiers in Marine Science, 2018. 5: doi:10.3389/fmars.2018.00319.

Villegas-Amtmann, S., et al., A bioenergetics model to evaluate demographic consequences of disturbance in marine mammals applied to gray whales. Ecosphere, 2015. 6(10): 1-19.

Weller, D.W., et al., Gray whale (Eschrichtius robustus) off Sakhalin Island, Russia: Seasonal and annual patterns of occurrence. Marine Mammal Science, 1999. 15(4): 1208-1227.

Understanding sea otter effects through complexity

By Dominique Kone, Masters Student in Marine Resource Management

Species reintroductions are a management strategy to augment the reestablishment or recovery of a locally-extinct or extirpated species into once native habitat. The potential for reestablishment success often depends on the species’ ecological characteristics, habitat requirements, and relationship and effects to other species in the environment[1]. While the science behind species reintroductions is continuously evolving and improving, reintroductions are still inherently risky and uncertain in nature. Therefore, every effort should be made to fully assess ecological factors before a reintroduction takes place. As Oregon considers a potential sea otter reintroduction, understanding these ecological factors is an important piece of my own graduate research.

Sea otters are oftentimes referred to as keystone species because they can have wide-reaching effects on the community structure and function of nearshore marine environments. Furthermore, relative to other marine mammals or top predators, several papers have documented these effects – partially due to the ease in observing their foraging and social behaviors, which typically take place close to shore. In many of these studies, a classic paradigm repeatedly appears: when sea otters are present, prey densities (e.g., sea urchins) are significantly reduced, while macroalgae (e.g., kelp, seagrass) densities are high.

Source: Belleza.

While this paradigm is widely-accepted amongst researchers, a few key studies have also demonstrated that the effects of sea otters may be more variable than we once thought. The paradigm does not necessarily hold true everywhere sea otters exist, or at least not to the same degree. For example, after observing benthic communities along islands with varying sea otter densities in the Aleutian archipelago, Alaska, researchers found that islands with abundant otter populations consistently supported low sea urchin densities and high, yet variable, kelp densities. In contrast, islands without otters consistently had low kelp densities and high, yet variable, urchin densities[2]. This study demonstrates that while the classic paradigm generally held true, the degree to which the ecosystem belonged to one of two dominant states (sea otters, low urchins, and high kelp or no sea otters, high urchins, and low kelp) was less obvious.

This example demonstrates the danger in applying this one-size-fits-all paradigm to sea otter effects. Hence, we want to achieve a better understanding of potential sea otter effects so that managers may anticipate how Oregon’s nearshore environments may be affected if sea otters were to be reintroduced. Yet, how can we accurately anticipate these effects given these potential variations and deviations from the paradigm? Interestingly, if we look to other fields outside ecology, we find a possible solution and tool for tackling these uncertainties: a systematic review of available literature.

Two ecosystem states as predicted by the classic paradigm (left: kelp-dominated; right: urchin-dominated). Source: SeaOtters.com.

For decades, medical researchers have been conducting systematic reviews to assess the efficacy of treatments and drugs by combining several studies to find common findings[3]. These findings can then be used to determine any potential variation between studies (i.e. instances where the results may conflict or differ from one another) and even test the influence and importance of key factors that may be driving that variation[4]. While systematic reviews are quite popular within the medical research field, they have not been applied regularly in ecology, but recognition of their application to ecological questions is growing[5]. In our case of achieving a better understanding of the drivers of ecological impacts of sea otter, a systematic literature review is an ideal tool to assess variable effects. This review will be the focus of my second thesis chapter.

In conducting my review, there will be three distinct phases: (1) review design and study collection, (2) meta-analysis, and (3) factor testing. In the first phase (review design and study collection), I will search the existing literature to collect studies that explicitly compare the availability of key ecosystem components (i.e. prey species, non-prey species, and macroalgae species) when sea otters are absent and present in the environment. By only including studies that make this comparison, I will define effects as the proportional change in each species’ or organism group’s availability (e.g. abundance, biomass, density, etc.) with and without sea otters. In determining these effects, it’s important to recognize that sea otters alter ecosystems via both direct and indirect pathways. Direct effects can be thought of as any change to prey availability via sea otter predation directly, while indirect effects can be thought of an any alteration to the broader ecosystem (i.e. non-prey species, macroalgae, habitat features) as an indirect result from sea otter predation on prey species. I will record both types of effects.

General schematic of a meta-analysis in a systematic review. A meta-analysis is the process of taking multiple datasets (i.e. Data 1, Data 2 etc.) from literature sources, calculating summary statistics or effects (i.e. Summary 1, Summary 2, etc.) for each dataset, running statistical procedures (e.g. SMA = sequential meta-analysis) to relate summary effects and investigate between study variation, and identifying important features driving variation. Source: MediCeption.

In phase two, I will use meta-analytical procedures (i.e. statistical analyses specific to systematic reviews) to calculate one standardized metric to represent sea otter effects. These effects will be calculated and averaged across all collected studies. As previously discussed, there may be key factors – such as sea otter density – that influence these effects. Therefore, in phase three (factor testing), effects will also be calculated separately for each a priori factor to test their influence on the effects. Such factors may include habitat type (i.e. hard or soft sediment), prey species (i.e. sea urchins, crabs, clams, etc.), otter density, depth, or time after otter recolonization.

In statistical terms, the goal of testing factors is to see if the variation between studies is impacted by calculating sea otter effects separately for each factor versus across all studies. In other words, if we find high variation in effects between studies, there may be important factors driving that variation. Therefore, in systematic reviews, we recalculate effects separately for each factor to try to explain that variation. If, however, after testing these factors, variation remains high, there may be other factors that we didn’t test that could be driving that remaining variation. Yet, without a priori knowledge on what those factors could be, such variation should be reported as a major source of uncertainty.

Source: Giancarlo Thomae.

Predicting or anticipating the effects of reintroduced species is no easy feat. In instances where the ecological role of a species is well known – and there is adequate data – researchers can develop and use ecosystem models to predict with some certainty what these effects may be. Yet, in other cases where the species’ role is less studied, has less data, or is more variable, researchers must look to other tools – such as systematic reviews – to gain a better understanding of these potential effects. In this case, a systematic review on sea otter effects may prove particularly useful in helping managers understand what types of ecological effects of sea otters in Oregon are most likely, what the important factors are, and, after such review, what we still don’t know about these effects.

References:

[1] Seddon, P. J., Armstrong, D. P., and R. F. Maloney. 2007. Developing the science of reintroduction biology. Conservation Biology. 21(2): 303-312.

[2] Estes, J. A., Tinker, M. T., and J. L. Bodkin. 2009. Using ecological function to develop recovery criteria for depleted species: sea otters and kelp forests in the Aleutian Archipelago. Conservation Biology. 24(3): 852-860.

[3] Sutton, A. J., and J. P. T. Higgins. 2008. Recent developments in meta-analysis. Statistics in Medicine. 27: 625-650.

[4] Arnqvist, G., and D. Wooster. 1995. Meta-analysis: synthesizing research findings in ecology and evolution. TREE. 10(6): 236-240.

[5] Vetter, D., Rucker, G., and I. Storch. 2013. Meta-analysis: a need for well-defined usage in ecology and conservation biology. Ecosphere. 4(6): 1-13.

Plastics truly are ubiquitous in the marine environment

By Lisa Hildebrand, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

As I enter my second term at OSU as a Master’s student, the ideas and structure of my thesis are slowly coming together. As of right now, my plan is to have two data chapters: The first chapter will assess the quality of zooplankton prey gray whales have access to along the Oregon coast, by looking at energetic value and microplastic content. I will contemplate about how my results potentially affect gray whale health. The second chapter will investigate fine-scale foraging and space use of gray whales in the Port Orford area to determine whether individual specialisation exists.

Fig 1. What it feels like when you start a literature review. Source: Harvard Blogs.

When I first started digging into the scientific literature to prepare for writing my thesis proposal (which is still underway but I’m getting close to the end of a first draft…), one sentence that I seemed to stumble across more often than not was “Marine plastics are ubiquitous” or “Plastics have become ubiquitous in the marine environment” or some other, very similar, iteration of that statement (e.g. Machovsky-Capuska et al. 2019; Eriksen et al. 2014; Fendall & Sewell 2009).

Many of the papers I first read were review papers on microplastics that mostly discussed general concepts like dispersal mechanisms, trophic transfer, or how microplastics become degraded. While I often think of review papers as treasure chests, since they neatly and succinctly summarise an often complicated and busy area of research into just a few pages, sometimes the fine-scale detail can go missing. Therefore, when reading these review papers, I wasn’t learning the in depth details about specific studies where microplastics had been detected in a group of individuals, population or species. So I felt the statement “Plastics are ubiquitous” was just a good (and pretty dramatic) opening line for a paper. However, once I delved into the studies on single species, I was overwhelmed by the amount of results that GoogleScholar spit out at me. If you type “microplastics marine” into the search bar, you’ll get about 7,650 results. This amount might not sound like a lot, especially if you compare it to say “gray whale”, which generates 96,600 results. Yet, the microplastic extraction method typically used was only developed in 2004 (Thompson et al. 2004). Hence, in a span of just 15 years, over 7,000 studies have detected microplastics in over 660 marine organisms (Secretariat of the Convention on Biological Diversity 2012) – a fact I find extremely troubling.

Fig 2. Graphic explaining how plastics don’t go away. Source: Biotecnika.

Microplastics are most commonly viewed as particles <5 mm in size (though there is some contention on this size classification, e.g. Claessens et al. 2013). Microplastics arise from several sources, including fragmentation of larger plastics by UV photo-degradation, wave action and physical abrasion, loss of pre-production pellets (nurdles) and polystyrene beads from shipping vessels, waste water discharge containing microbeads used in cosmetics and microfibers released during the washing of textiles and run-off from land (Nelms et al. 2018). Their small size makes these persistent particles bioavailable to ingestion by a variety of marine taxa, ranging from small prey organisms such as zooplankton, to large megafauna such as whales.

Zooplankton are at the base of marine food webs and are therefore consumed in large quantities by a large number of consumers. The propensity of zooplankton to feed in surface waters makes them highly susceptible to encountering and ingesting microplastics as this is where these synthetic particles are highly abundant (Botterell et al. 2018). Microplastics have been detected in zooplankton from the Northeast Pacific Ocean (Desforges et al. 2015), northern South China Sea (Sun et al. 2017), and Portuguese coast (Frias et al. 2014). Additionally, there is documented overlap between microplastic and zooplankton occurrence at many more locations (e.g. North Western Mediterranean Sea, Collignon et al. 2012; Baltic Sea, Gorokhova 2015; Arctic Ocean, Lusher et al. 2015a). As microplastics research is still in its relative infancy, the extent to which microplastics are ingested by zooplankton and the consequences of this behaviour are uncertain. Nevertheless, exposure to microplastics could lead to entanglement of particles within feeding appendages and/or block internal organs, which may result in reduced feeding, poor overall health, injury and death (Desforges et al. 2015). Though a lab study has found that microplastics are expelled by zooplankton after ingestion, the gut-retention times varied between species, and there is the potential risk of exposure to toxins that leech off of particles while in the body (Cole et al. 2013; the below video is from the afore-mentioned study showing how plankton eat plastics, which are illuminated in fluorescent green).

The large knowledge gap regarding the health implications indicates a strong need for more laboratory studies that investigate the long-term effects of persistent exposure to microplastics on lower trophic organisms, as well as continued short-term experiments that examine whether different zooplankton species are affected differently, since morphologies and life-histories vary widely.

Let’s take a step back and re-focus our lens onto a marine taxa that is much, much bigger in size than a zooplankton: cetaceans. Plastic debris has been documented in the stomachs of stranded individuals of several cetacean species (See Baulch & Perry 2014 for a review), however findings of microplastics in cetaceans are less common. Since cetaceans consume large amounts of prey a day, up to several tons daily for some baleen whales, the likelihood that they are ingesting microplastics through their prey is relatively high (Nelms et al. 2018). Therefore the low number of reported cases is again likely due to the relative novelty of microplastic detection methods. Despite the paucity of studies, microplastics have been found in a True’s beaked whale (Mesoplodon mirus, Lusher et al. 2015b), a humpback whale (Megaptera novaeangliae, Besseling et al. 2015) and an Indo-Pacific humpback dolphin (Sousa chinensis, Zhu et al. 2018), showing that microplastic ingestion by cetaceans does occur. Whether these individuals actively (i.e. active feeding) or passively (i.e. uptake through prey consumption) consumed the microplastics, or inhaled them at the water-air interface, is unknown. As with zooplankton, the short- and long-term impacts of ingesting microplastics by marine mammals is also unknown, though impacts on survival, feeding and uptake of toxins are all possibilities.

Fig 3. Example of a light trap sample collected off the Newport coast. Source: L. Torres.

The data collection and analysis I am doing for my thesis will hopefully fill small pockets in these large knowledge gaps. I hope to be able to quantify the extent of microplastic pollution among zooplankton species in nearshore Oregon waters. By comparing samples from several years, months and locations, I will determine whether microplastic loads vary spatially and temporally. Since their abundance and presence have been described as being patchy due to the influence of oceanographic and weather conditions (GESAMP 2016), it would seem reasonable to assume that there will be variation. But, results are a ways away as we have not even started our microplastic extraction techniques, which involves digesting samples in potassium hydroxide solution, incubating them at 50ºC for 48-72 hours, sorting through the dissolved material to identify potential plastics and sending them away for analysis. We first have to work our way through jars upon jars of unopened zooplankton light trap samplesthat need to be sorted by species. I am thankfully joined by undergraduate Robyn Norman who has already assisted this project immensely over the last two years with her zooplankton sorting prowess. So in case anyone wants to come looking for us over the next few weeks, you’ll find both Robyn and me sitting in front of a laminar flow hood in the lab of ecotoxicologist Dr. Susanne Brander, with whom we are collaborating on the microplastics portion of my thesis.

 

References

Baulch, S., & Perry, C., Evaluating the impacts of marine debris on cetaceans. Marine Pollution Bulletin, 2014. 80(1-2): 210-221.

Besseling, E., et al., Microplastic in a macro filter feeder: humpback whale Megaptera novaeangliae. Marine Pollution Bulletin, 2015. 95: 248-252.

Botterell, Z.L.R., et al., Bioavailability and effects of microplastics on marine zooplankton: a review. Environmental Pollution, 2018. 245: 98-110.

Claessens, M., et al., New techniques for the detection of microplastics in sediments and field collected organisms. Marine Pollution Bulletin, 2013. 70(1-2): 227-233.

Cole, M., et al., Microplastic ingestion by zooplankton. Environmental Science & Technology, 2013. 47(12): 6646-6655.

Collignon, A., et al., Neustonic microplastic and zooplankton in the North Western Mediterranean Sea. Marine Pollution Bulletin, 2012. 64(4): 861-864.

Desforges, JP.W., et al., Ingestion of microplastics by zooplankton in the Northeast Pacific Ocean. Archives of Environmental Contamination and Toxicology, 2015. 69(3): 320-330.

Eriksen, M., et al., Plastic pollution in the world’s oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLoS ONE, 2014. doi.org/10.1371/journal.pone.0111913.

Fendall, L.S., & Sewell, M.A., Contributing to marine pollution by washing your face: microplastics in facial cleansers. Marine Pollution Bulletin, 2009. 58(8): 1225-1228.

Frias, J.P.G.L., et al., Evidence of microplastics in samples of zooplankton from Portuguese coastal waters. Marine Environmental Research, 2014. 95: 89-95.

GESAMP, Sources, fates and effects of microplastics in the marine environment: part 2 of a global assessment. Second United Nations Environment Assembly, 2016. http://www.gesamp.org/site/assets/files/1720/rs93e.pdf

Gorokhova, E., Screening for microplastic particles in plankton samples: how to integrate marine litter assessment into existing monitoring programs? Marine Pollution Bulletin, 2015. 99(1-2): 271-275.

Lusher, A.L., et al., Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples. Scientific Reports, 2015a. 5: 14947.

Lusher, A.L., et al., Microplastic and macroplastic ingestion by a deep diving, oceanic cetacean: the True’s beaked whales Mesoplodon mirus. Environmental Pollution, 2015b. 199: 185-191.

Machovsky-Capuska, G.E., et al., A nutritional perspective on plastic ingestion in wildlife. Science of the Total Environment, 2019. 656: 789-796.

Nelms, S.E., et al., Investigating microplastic trophic transfer in marine top predators. Environmental Pollution, 2018. 238: 999-1007.

Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel – GEF (2012), Impacts of marine debris on biodiversity: current status and potential solutions. Montreal, Technical Series. 67: 1-61.

Sun, X., et al., Ingestion of microplastics by natural zooplankton groups in the northern South China Sea. Marine Pollution Bulletin, 2017. 115(1-2): 217-224.

Thompson, R.C., et al., Lost at sea: where is all the plastic? Science, 2004. 304(5672): 838.

Zhu, J., et al., Cetaceans and microplastics: First report of microplastic ingestion by a coastal delphinid, Sousa chinensis. Science of the Total Environment, 2018. 659: 649-654.

Science (or the lack thereof) in the Midst of a Government Shutdown

By Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

In what is the longest government shutdown in the history of the United States, many people are impacted. Speaking from a scientist’s point of view, I acknowledge the scientific community is one of many groups that is being majorly obstructed. Here at the GEMM Laboratory, all of us are feeling the frustrations of the federal government grinding to a halt in different ways. Although our research spans great distances—from Dawn’s work on New Zealand blue whales that utilizes environmental data managed by our federal government, to new projects that cannot get federal permit approvals to state data collection, to many of Leigh’s projects on the Oregon coast of the USA that are funded and collaborate with federal agencies—we all recognize that our science is affected by the shutdown. My research on common bottlenose dolphins is no exception; my academic funding is through the US Department of Defense, my collaborators are NOAA employees who contribute NOAA data; I use publicly-available data for additional variables that are government-maintained; and I am part of a federally-funded public university. Ironically, my previous blog post about the intersection of science and politics seems to have become even more relevant in the past few weeks.

Many graduate students like me are feeling the crunch as federal agencies close their doors and operations. Most people have seen the headlines that allude to such funding-related issues. However, it’s important to understand what the funding in question is actually doing. Whether we see it or not, the daily operations of the United States Federal government helps science progress on a multitude of levels.

Federal research in the United States is critical. Most governmental branches support research with the most well-known agencies for doing so being the National Science Foundation (NSF), the US Department of Agriculture (USDA), the National Oceanic and Atmospheric Administration (NOAA), and the National Aeronautics and Space Administration. There are 137 executive agencies in the USA (cei.org). On a finer scale, NSF alone receives approximately 40,000 scientific proposals each year (nsf.gov).

If I play a word association game and I am given the word “science”, my response would be “data”. Data—even absence data—informs science. The largest aggregate of metadata with open resources lives in the centralized website, data.gov, which is maintained by the federal government and is no longer accessible and directs you to this message:Here are a few more examples of science that has stopped in its track from lesser-known research entities operated by the federal government:

Currently, the National Weather Service (NWS) is unable to maintain or improve its advanced weather models. Therefore, in addition to those of us who include weather or climate aspects into our research, forecasters are having less and less information on which to base their weather predictions. Prior to the shutdown, scientists were changing the data format of the Global Forecast System (GFS)—the most advanced mathematical, computer-based weather modeling prediction system in the USA. Unfortunately, the GFS currently does not recognize much of the input data it is receiving. A model is only as good as its input data (as I am sure Dawn can tell you), and currently that means the GFS is very limited. Many NWS models are upgraded January-June to prepare for storm season later in the year. Therefore, there are long-term ramifications for the lack of weather research advancement in terms of global health and safety. (https://www.washingtonpost.com/weather/2019/01/07/national-weather-service-is-open-your-forecast-is-worse-because-shutdown/?noredirect=on&utm_term=.5d4c4c3c1f59)

An example of one output from the GFS model. (Source: weather.gov)

The Food and Drug Administration (FDA)—a federal agency of the Department of Health and Human Services—that is responsible for food safety, has reduced inspections. Because domestic meat and poultry are at the highest risk of contamination, their inspections continue, but by staff who are going without pay, according to the agency’s commissioner, Dr. Scott Gottlieb. Produce, dry foods, and other lower-risk consumables are being minimally-inspected, if at all.  Active research projects investigating food-borne illness that receive federal funding are at a standstill.  Is your stomach doing flips yet? (https://www.nytimes.com/2019/01/09/health/shutdown-fda-food-inspections.html?rref=collection%2Ftimestopic%2FFood%20and%20Drug%20Administration&action=click&contentCollection=timestopics&region=stream&module=stream_unit&version=latest&contentPlacement=2&pgtype=collection)

An FDA field inspector examines imported gingko nuts–a process that is likely not happening during the shutdown. (Source: FDA.gov)

The National Parks Service (NPS) recently made headlines with the post-shutdown acts of vandalism in the iconic Joshua Tree National Park. What you might not know is that the shutdown has also stopped a 40-year study that monitors how streams are recovering from acid rain. Scientists are barred from entering the park and conducting sampling efforts in remote streams of Shenandoah National Park, Virginia. (http://www.sciencemag.org/news/2019/01/us-government-shutdown-starts-take-bite-out-science)

A map of the sampling sites that have been monitored since the 1980s for the Shenandoah Watershed Study and Virginia Trout Stream Sensitivity Study that cannot be accessed because of the shutdown. (Source: swas.evsc.virginia.edu)

NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), better known as the “flying telescope” has halted operations, which will require over a week to bring back online upon funding restoration. SOFIA usually soars into the stratosphere as a tool to study the solar system and collect data that ground-based telescopes cannot. (http://theconversation.com/science-gets-shut-down-right-along-with-the-federal-government-109690)

NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) flies over the snowy Sierra Nevada mountains while the telescope gathers information. (Source: NASA/ Jim Ross).

It is important to remember that science happens outside of laboratories and field sites; it happens at meetings and conferences where collaborations with other great minds brainstorm and discover the best solutions to challenging questions. The shutdown has stopped most federal travel. The annual American Meteorological Society Meeting and American Astronomical Society meeting were two of the scientific conferences in the USA that attract federal employees and took place during the shutdown. Conferences like these are crucial opportunities with lasting impacts on science. Think of all the impressive science that could have sparked at those meetings. Instead, many sessions were cancelled, and most major agencies had zero representation (https://spacenews.com/ams-2019-overview/). Topics like lidar data applications—which are used in geospatial research, such as what the GEMM Laboratory uses in some its projects, could not be discussed. The cascade effects of the shutdown prove that science is interconnected and without advancement, everyone’s research suffers.

It should be noted, that early-career scientists are thought to be the most negatively impacted by this shutdown because of financial instability and job security—as well as casting a dark cloud on their futures in science: largely unknown if they can support themselves, their families, and their research. (https://eos.org/articles/federal-government-shutdown-stings-scientists-and-science). Graduate students, young professors, and new professionals are all in feeling the pressure. Our lives are based on our research. When the funds that cover our basic research requirements and human needs do not come through as promised, we naturally become stressed.

An adult and a juvenile common bottlenose dolphin, forage along the San Diego coastline in November 2018. (Source: Alexa Kownacki)

So, yes, funding—or the lack thereof—is hurting many of us. Federally-funded individuals are selling possessions to pay for rent, research projects are at a standstill, and people are at greater health and safety risks. But, also, science, with the hope for bettering the world and answering questions and using higher thinking, is going backwards. Every day without progress puts us two days behind. At first glance, you may not think that my research on bottlenose dolphins is imperative to you or that the implications of the shutdown on this project are important. But, consider this: my study aims to quantify contaminants in common bottlenose dolphins that either live in nearshore or offshore waters. Furthermore, I study the short-term and long-term impacts of contaminants and other health markers on dolphin hormone levels. The nearshore common bottlenose dolphin stocks inhabit the highly-populated coastlines that many of us utilize for fishing and recreation. Dolphins are mammals, that respond to stress and environmental hazards, in similar ways to humans. So, those blubber hormone levels and contamination results, might be more connected to your health and livelihood than at first glance. The fact that I cannot download data from ERDDAP, reach my collaborators, or even access my data (that starts in the early 1980s), does impact you. Nearly everyone’s research is connected to each other’s at some level, and that, in turn has lasting impacts on all people—scientists or not. As the shutdown persists, I continue to question how to work through these research hurdles. If anything, it has been a learning experience that I hope will end soon for many reasons—one being: for science.

GEMM Lab 2018: A Year in the Life

By Dawn Barlow, PhD student, Department of Fisheries & Wildlife, Geospatial Ecology of Marine Megafauna Lab

As 2018 draws to a close, it is gratifying to step back and appreciate the accomplishments of the past year. For all members of the GEMM Lab, 2018 has certainly been one for the books! Here are some of our highlights for your holiday enjoyment.

We conducted fieldwork to collect new data in multiple seasons, multiple hemispheres, and across oceans. For the first time, GEMM Lab members joined the Northern California Current Ecosystem cruises aboard NOAA ship Bell M. Shimada as marine mammal observers—Florence in February, Alexa in May, and me in September.

Summertime in the Pacific Northwest brings the gray whales to the Oregon Coast. The drone-flying, poop-scooping, plankton-trapping team of Leigh, Todd, Leila, Joe, and Sharon took to the water for the third year to investigate the health of this gray whale population. It was a successful field season, ending with 72 fecal samples collected! Visiting students joined our experienced members to shadow the gray whale fieldwork—Julia Stepanuk and Alejandro Fernandez Ajo came from across the country to hop on board with us for a bit. Friendship and collaboration were built quickly in a little boat chasing after whale poop, bonding over peanut butter and jelly sandwiches.

Another GEMM Lab team tracked the gray whales from the cliff in Port Orford. Lisa Hildebrand joined us as the GEMM Lab’s newest graduate student, and immediately led a team of interns on Oregon’s southern coast to track gray whale movements and sample their prey from a trusty research kayak.

The summer 2018 gray whale foraging ecology team, affectionately known as “team whale storm”, at the Port Orford Field Station.

Rachael observed seabirds from Yaquina Head in May and June, where the colony of common murres had the highest reproductive success in 10 years! Then she left the summertime in July to travel to the other end of the world, braving winter in the remote South Atlantic to study South American fur seals in the Falkland Islands.

Dr. Rachael Orben and Dr. Alistair Bayliss looking out towards the fur seals. Photo: Kayleigh Jones

In New Caledonia, Solene and a research team ventured to Antigonia Seamount and Orne Bank to study the use of these offshore areas by breeding humpback whales. They collected numerous biopsy samples and successfully deployed satellite tags. Solene was also selected to receive the Louis Herman research scholarship to continue studying humpback whale movement and diving behavior around seamounts.

Sorting biopsy samples during a successful expedition to study humpback whales around remote seamounts in the South Pacific.

Beyond fieldwork, our members have been busily disseminating our findings. In July, Leigh and I traveled to Wellington to present our latest findings on New Zealand blue whales to scientists, managers, politicians, industry representatives, and advocacy groups. Because of our documentation of a unique New Zealand blue whale population, which was published earlier this year, the New Zealand government has proposed to create a Marine Mammal Sanctuary for the protection of blue whales. This is quite a feat, considering blue whales were classified as only “migrant” in New Zealand waters prior to our work. Fueled by flat whites in wintery Wellington, we navigated government buildings, discussing blue whale distribution patterns, overlap with the oil and gas industry, what we now know based on our latest analyses, and what we consider to be the most pressing gaps in our knowledge.

Dr. Leigh Torres and Dawn Barlow in front of Parliament in Wellington, New Zealand following the presentation of their recent findings.

Alexa spent the summer and fall in San Diego, where she collaborated with researchers at NOAA Southwest Fisheries Science Center on her study of about the health of bottlenose dolphins off the California coast. Her time down south has been productive and we look forward to having her back in Oregon with us to round out the second year of her PhD program.

In the fall, Dom and Leigh participated in the first ever Oregon Sea Otter Status of Knowledge Symposium. With growing interest in a potential sea otter reintroduction, the symposium brought together a range of experts – including scientists, managers, and tribes – to discuss what we currently know about sea otters in other regions and how this knowledge could be applied to an Oregon reintroduction effort. Dom was one of many speakers at this event, and gave a well-received talk on Oregon’s previous sea otter reintroduction attempt and brief discussion on his thesis research. Over the next year, Dom not only plans to finish his thesis, but also to join an interdisciplinary research team to further investigate other social, genetic, and ecological implications of a potential sea otter reintroduction.

Sea otter mom and pup. Source: Hakai Magazine.
2018-19 OSU NRT Cohort. Source: Oregon State University.

Several GEMM Lab members reached academic milestones this year. Rachael was promoted to Assistant Professor in the spring! She now leads the Seabird Oceanography Lab, and remains involved in multiple projects studying seabirds and pinnipeds all over the world. Leila passed her PhD qualifying exams and advanced to candidacy in the spring, a major accomplishment toward completing her doctoral degree. I successfully defended my MS degree in June, and my photo was added to our wall gallery of GEMM Lab graduates. I won’t be leaving the GEMM Lab anytime soon, however, as I will be continuing my research on New Zealand blue whales as a PhD student. The GEMM Lab welcomed a new MS student in the summer—Lisa Hildebrand will be studying gray whale foraging ecology on the Oregon Coast. Welcome, Lisa! In early December, Solene successfully defended her PhD, officially becoming Dr. Derville. Congratulations to all on these milestones, and congratulations to Leigh for continuing to grow such a successful lab and guiding us all toward these accomplishments.

Dawn Barlow answers questions during her M.Sc. defense seminar.
Dr. Solene Derville and co-supervisors Dr. Claire Garrigue and Dr. Leigh Torres after a successful PhD Defense!

Perhaps you’re looking to do some reading over the holidays? The GEMM Lab has been publishing up a storm this year! The bulletin board outside our lab is overflowing with new papers. Summarizing our work and sharing our findings with the scientific community is a critical piece of what we do. The 21 new publications this year in 14 scientific journals include contributions from Leigh (13), Rachael (3), Solene (3), Leila (6), Florence (1), Amanda (1), Erin (1), Courtney (1), Theresa (1), and myself (3). Scroll down to the end of this post to see the complete list!

If you are reading this, thank you for your support of our lab, our members, and our work. Our successes come not only from our individual determination, but more importantly from our support of one another and the support of our communities. We look forward to what’s ahead in 2019. Happy holidays from the GEMM Lab!

The whole GEMM Lab (lab dogs included) gathered for an evening playing “Evolution” at Leigh’s house.

Barlow, D. R., Torres, L. G., Hodge, K. B., Steel, D., Baker, C. S., Chandler, T. E., Bott, N., Constantine, R., Double, M. C., Gill, P., Glasgow, D., Hamner, R. M., Lilley, C., Ogle, M., Olson, P. A., Peters, C., Stockin, K. A., Tessaglia-Hymes, C. T., & Klinck, H. (2018). Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endangered Species Research, 36, 27-40.

Barlow, D. R., Fournet, M., & Sharpe, F. (2018). Incorporating tides into the acoustic ecology of humpback whales. Marine Mammal Science.

Baylis, A. M., Tierney, M., Orben, R. A., Staniland, I. J., & Brickle, P. (2018). Geographic variation in the foraging behaviour of South American fur seals. Marine Ecology Progress Series, 596, 233-245.

Bishop, A., Brown, C., Rehberg, M., Torres, L., & Horning, M. (2018). Juvenile Steller sea lion (Eumetopias jubatus) utilization distributions in the Gulf of Alaska. Movement ecology, 6(1), 6.

Burnett, J. D., Lemos, L., Barlow, D., Wing, M. G., Chandler, T., & Torres, L. G. (2018). Estimating morphometric attributes of baleen whales with photogrammetry from small UASs: A case study with blue and gray whales. Marine Mammal Science.

Cardoso, M. D., Lemos, L. S., Roges, E. M., de Moura, J. F., Tavares, D. C., Matias, C. A. R., … & Siciliano, S. (2018). A comprehensive survey of Aeromonas sp. and Vibrio sp. in seabirds from southeastern Brazil: outcomes for public health. Journal of applied microbiology, 124(5), 1283-1293.

Derville, S., Torres, L. G., Iovan, C., & Garrigue, C. (2018). Finding the right fit: Comparative cetacean distribution models using multiple data sources and statistical approaches. Diversity and Distributions, 24(11), 1657-1673.

Derville, S., Torres, L. G., & Garrigue, C. (2018). Social segregation of humpback whales in contrasted coastal and oceanic breeding habitats. Journal of Mammalogy, 99(1), 41-54.

Hann, C. H., Stelle, L. L., Szabo, A., & Torres, L. G. (2018). Obstacles and Opportunities of Using a Mobile App for Marine Mammal Research. ISPRS International Journal of Geo-Information, 7(5), 169.

Holdman, A. K., Haxel, J. H., Klinck, H., & Torres, L. G. (2018). Acoustic monitoring reveals the times and tides of harbor porpoise (Phocoena phocoena) distribution off central Oregon, USA. Marine Mammal Science.

Kirchner, T., Wiley, D. N., Hazen, E. L., Parks, S. E., Torres, L. G., & Friedlaender, A. S. (2018). Hierarchical foraging movement of humpback whales relative to the structure of their prey. Marine Ecology Progress Series, 607, 237-250.

Moura, J. F., Tavares, D. C., Lemos, L. S., Acevedo-Trejos, E., Saint’Pierre, T. D., Siciliano, S., & Merico, A. (2018). Interspecific variation of essential and non-essential trace elements in sympatric seabirds. Environmental pollution, 242, 470-479.

Moura, J. F., Tavares, D. C., Lemos, L. S., Silveira, V. V. B., Siciliano, S., & Hauser-Davis, R. A. (2018). Variation in mercury concentration in juvenile Magellanic penguins during their migration path along the Southwest Atlantic Ocean. Environmental Pollution, 238, 397-403.

Orben, R. A., Kokubun, N., Fleishman, A. B., Will, A. P., Yamamoto, T., Shaffer, S. A., Takahashi, A., & Kitaysky, A. S. (2018). Persistent annual migration patterns of a specialist seabird. Marine Ecology Progress Series, 593, 231-245.

Orben, R. A., Connor, A. J., Suryan, R. M., Ozaki, K., Sato, F., & Deguchi, T. (2018). Ontogenetic changes in at-sea distributions of immature short-tailed albatrosses Phoebastria albatrus. Endangered Species Research, 35, 23-37.

Pickett, E. P., Fraser, W. R., Patterson‐Fraser, D. L., Cimino, M. A., Torres, L. G., & Friedlaender, A. S. (2018). Spatial niche partitioning may promote coexistence of Pygoscelis penguins as climate‐induced sympatry occurs. Ecology and Evolution, 8(19), 9764-9778.

Siciliano, S., Moura, J. F., Tavares, D. C., Kehrig, H. A., Hauser-Davis, R. A., Moreira, I., Lavandier, R., Lemos, L. S., & Quinete, N. S. (2018). Legacy Contamination in Estuarine Dolphin Species From the South American Coast. In Marine Mammal Ecotoxicology (pp. 95-116). Academic Press.

Sullivan, F. A., & Torres, L. G. (2018). Assessment of vessel disturbance to gray whales to inform sustainable ecotourism. The Journal of Wildlife Management, 82(5), 896-905.

Sztukowski, L. A., Cotton, P. A., Weimerskirch, H., Thompson, D. R., Torres, L. G., Sagar, P. M., Knights, A. M., Fayet, A. L., & Votier, S. C. (2018). Sex differences in individual foraging site fidelity of Campbell albatross. Marine Ecology Progress Series, 601, 227-238.

Torres, L. G., Nieukirk, S. L., Lemos, L., & Chandler, T. E. (2018). Drone up! Quantifying whale behavior from a new perspective improves observational capacity. Frontiers in Marine Science, 5.

Yates, K. L., Bouchet, P. J., Caley, M. J., Mengersen, K., Randin, C. F., Parnell, S., … & Sequeira, A. M. M. (2018). Outstanding challenges in the transferability of ecological models. Trends in ecology & evolution.

 

Inter- and Transdisciplinary Sea Otter Research

By Dominique Kone, Masters Student, Marine Resource Management

As the human population continues to grow, so does our impact on marine environments. In many cases, these problems – such as microplastics, vessel noise, or depleted fisheries – are far too grand for any one person to tackle on their own and it takes a team effort to find adequate solutions. Experts within a single field (e.g. ecology, economics, genetics) have been collaborating to tackle these issues for decades, but there is an increasing interest and recognition of the importance in working with others outside one’s own discipline.

It’s not surprising that most collaborative efforts are between experts from the same field. It’s easier to converse with those with similar vocabulary, we often enjoy learning from our peers, and our thought-processes and problem-solving skills are typically very similar. However, as issues become more complex and stretch across disciplines, the need for interdisciplinary collaboration becomes more and more imperative. As a graduate student studying marine resource management, I’ve learned the great value in conducting interdisciplinary work. Yet, I still have much to learn if I want to continue to help find solutions to the many complex marine issues. Therefore, over the next year, I’ve committed to joining a interdisciplinary team of graduate students, as part of an NSF-funded fellowship program at Oregon State University (OSU), to further investigate a potential sea otter reintroduction to Oregon. Here, I provide a brief overview of the program and my team’s goals for the coming year.

Source: Hakai Magazine.

The fellowship program emphasizes both interdisciplinary and transdisciplinary approaches, so before I explain the program, it’s important to first understand these terms. In short, interdisciplinarity typically relates to experts from different fields analyzing, synthesizing, and coordinating their work as a whole (Choi & Pak 2006). Another way to think about this, in more practical terms, is if two or more experts share information and learn from one another; each expert can then individually apply that information or lessons-learned to their own line of work. In contrast, transdisciplinary work is slightly more collaborative, where experts work more hand-in-hand to develop a product or solution that transcends their disciplines’ traditional boundaries. The experts essentially create a product that would not have been possible working in isolation. In practice, the product(s) that stems from inter- and transdisciplinary work – if they truly are inter- or transdisciplinary by definition – is potentially very different.

Source: Dr. Shoshanah Jacobs.

With an increasing interest in interdisciplinary work, the National Science Foundation (NSF) developed the National Research Traineeship (NRT) program to encourage select universities to develop and implement innovative and transformative models for training graduate students in STEM disciplines. After soliciting proposals, the NSF awarded OSU one of these NRT projects to support OSU’s Risk and Uncertainty Quantification in Marine Science NRT Program. OSU’s NRT program was born out of the recognition that much of the complexity of marine issues is largely due to the uncertainty of natural and human systems. Therefore, the primary purpose of this program is to train the next generation of natural resource scientists and managers to be better equipped to study and manage complex marine systems, especially under extreme uncertainty and potential risk.

Source: Oregon State University.

This NRT program trains graduate students in three core concept areas: coupled natural human systems, big data, and risk and uncertainty analyses and communications. To learn these core concepts, students fulfil a minor that includes coursework in statistical inference, uncertainty quantification, risk analyses, earth system science, and social systems. In addition to the minor, students also conduct collaborative research in small (3-5 students) cross-disciplinary teams to address specific issues in marine resource management. Within each team, students come from different disciplines and fields, and must learn to work together to produce a transdisciplinary research product. Throughout the year, each team will develop a set of research questions to address their issue at hand, conduct research which links all their fields, and produce a transdisciplinary report summarizing the process they undertook and the end product. Most students who are accepted into the NRT program are awarded one-year fellowships, funded by the NSF.

At the start of this academic year, I was awarded one of these NRT fellowships to address the many issues and implications of a potential sea otter reintroduction to Oregon. Over the next year, I will be working with two other OSU graduate students with backgrounds in genetics and social sciences. Our task is to not only investigate the ecological implications – which I am currently doing for my own thesis – but we are to expand this investigation to also address many of the genetic, political, and social factors, as well. While each of us is capable of addressing one of these factors individually, the real test will be in finding linkages between each of our disciplines to make this project truly transdisciplinary.

Structure and vision of OSU’s NRT program. Source: Oregon State University.

Since our project started, we have worked to better understand each another’s expertise, interests, and the general need for a transdisciplinary project of this sort. After acquiring this base understanding, we spent a considerable amount of time developing research questions and potential methods for addressing our issue. Throughout this process, it’s already become apparent that each of us is starting to learn important teamwork and collaboration skills, including effective communication and explanation of complicated concepts, active listening, critical thinking, and constructive feedback.  While these skills are imperative for our research over the next year, they are also life-long skills that we’ll continue to use in our careers beyond graduate school.

As I’ve stated previously, learning to be an effective collaborator is extremely important to me. Getting the opportunity to work interdisciplinarily is what attracted me to my thesis, the marine resource management program, and the NRT program. By choosing to take my graduate education down this path, I’ve been fortunate to obtain important skills in collaboration, as well as work on a project that allows me to tackle real-world issues and creatively develop scientifically-based solutions. I have high hopes for this NRT project, and I’m excited to continue to conduct meaningful and targeted research over the next year with my new team.

2018-19 OSU NRT Cohort. Source: Oregon State University.

References:

Choi, B. C., and A. W. Pak. Multidisciplinarity, interdisciplinarity and transdisciplinarity in health research, service, education and policy: 1. Definitions, objectives, and evidence of effectiveness. Clinical and Investigative Medicine. 29(6): 351-64.

Who Am I? Exploring the theory of individualisation among marine mammals

By Lisa Hildebrand, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

“Just be yourself!” is a phrase that everyone has probably heard at least once in their lives. The idea of being an individual who is distinctly different from other individuals is a concept that is focal to the society we live in today. While historically it may have been frowned upon to be the “black sheep in the crowd”, nowadays that seems to be the goal.

Source: Go Comics.

This quest for uniqueness has resulted in different styles of fashion, speech, profession, interest in art, music, literature, automobile types – the list is endless. The American Psychological Association defines personality as the “individual differences in characteristic patterns of thinking, feeling and behaving”1. So, all of the choices we make on a daily basis shape our behaviour, and our behaviour in turn shapes our personality.

Since personality is something that is so engrained within human society, it isn’t surprising that ecologists have explored this concept among non-humans. Decades of research have resulted in an abundance of literature detailing personality in many different taxa and species, ranging from chimpanzees to mice to ants2. Naturally, the definition of personality for animals differs from that for humans since the assessment of animal thoughts and feelings is still somewhat of a locked box to us. Nevertheless, the behavioural aspect of the two definitions remains consistent whereby animal personality is broadly defined as “consistent variation in behavioural traits between individuals”3.

Although I am an early career marine mammal ecologist finding my footing in this rapidly expanding field, I have a keen interest in teasing apart possible cases of individual specialisation within marine mammal populations. So, before getting straight into the nitty gritty of individual specialisation, it is important for me to take a small step back and consider the concept of specialisation as applied to small subgroups or populations of marine mammals.

Specialisations are mostly related to foraging or feeding behaviour whereby a subgroup of individuals will develop a novel method to locate and capture prey. These behaviours have been reported for several marine mammal species, and are strongly coupled to intra and inter-specific competition with other predators for prey and habitat characteristics. Furthermore, it is posited that factors such as resource benefits (e.g. energy content of prey), prey escape rates, and handling times can be minimised if specialisation for a particular prey type or habitat occurs4.

In Florida Bay, Torres & Read5 documented two distinct foraging strategies employed by two bottlenose dolphin ecotypes. One dolphin ecotype was found to forage using deep diving with erratic surfacings, whereas the second ecotype chose to forage through mud ring feeding and were mostly seen in shallow habitats. The latter ecotype is in fact so adapted to shallow depths that dolphins were typically observed foraging in waters <2 m deep. In this example, the foraging tactics of the two ecotypes are strongly driven by habitat conditions, specifically depth. The video below is aerial footage of bottlenose dolphins performing mud ring feeding.

Such group specialisations have been identified not only in several other bottlenose dolphin populations around the world6,7, but also in other cetacean species, including killer whales (distinct differences in target prey between transients and residents8), Guiana dolphins (mud-plume feeding9), humpback dolphins (strand feeding10), and several others. Noticeable here is that these records concern Odontocete species, which is not surprising since these toothed whales are vastly different to baleen whales in that they often live in structured groups with bonds between individuals sometimes lasting for decades11. Long-term relationships are conducive to developing specialised group hunting strategies as individuals will spend considerable time with one another and the success of obtaining prey depends on the cooperation and coordination of the group.

For baleen whales and other marine mammals, such as pinnipeds, where life history and social organisation is more geared toward a solitary life, examples of group specialisations are relatively rare (with the exception of the well-documented bubble-net feeding exhibited by humpback whales12). While group specialisation may not be as prevalent in Mysticetes, the same problems of inter and intra-specific competition persists among these more solitary species too, which would suggest that individuals should develop their own unique foraging tactics and preferences. Evidence for individualisation is hard to obtain since it requires repeated observations of the same individuals over time with good knowledge of the prey type being consumed and/or the habitat being used to forage in.

Nevertheless, examples do exist. Perhaps the most well-documented case of individualisation within a population for marine mammals is of the sea otter. Estes et al. (2003) describe 10 female sea otters in Monterey Bay that had high inter-individual variation in diet, which they investigated over a scale of 8 years13. Most females specialised on 1-4 types of prey, with marked differences between the diets chosen by each female, despite habitat overlap. This individualisation of diet was not attributable to variation in prey availability; hence, authors concluded that this extreme specialisation occurred to reduce intra-population competition for prey.

Ecologists have historically (and probably still to this day) disagreed on whether individualisation actually matters in the grand scheme of things. There are generally three schools of thought on the matter: (1) individual specialisation is rare and/or weakly influences population dynamics and so is not very important; (2) while individual specialisation does occur and may in fact be commonplace, it does not affect ecological processes at the large population scale; and (3) individual specialisation is widespread and can significantly impact population dynamics and/or ecosystem function.

As you might have guessed by this point, I find myself in the third school of thought. There are many arguments supporting this theory, and what I believe to be very good arguments against statements 1 and 2. While I have only provided one specific named example for individual specialisation in a marine mammal, there are several documented cases of such occurrences among other marine taxa (e.g., pinnipeds14, sharks15, fish16) and a much larger number of studies for terrestrial species4. Thus, the claim that it is rare or weak, seems implausible to me.

Statement 2 is a little more complicated to tackle as it involves understanding how actions on a relatively small scale affect a whole population or even an ecosystem. For instance, consider two female sea otters living in a small coastal area where one sea otter prefers to eat turban snails and the other exclusively feeds on abalone. The sudden decline in abundance of either of these prey could lead to serious health and reproductive issues for those females. Should the low prey abundance persist, then poor health and reproduction of several females in a population that specialise on that prey item can rapidly lead to genetic loss and an overall population decline. Particularly if an individual’s or species’ home range is rather restricted or small. In the case of the sea otter, which are often touted as a keystone species due to its presence preventing sea urchin barren formation that is known to wreak havoc on kelp forests, knock-on effects of such a population decline could result in poor overall ecosystem health.

It may be easy to assume that one individual dolphin, otter, seal or whale cannot possibly make a difference to a whole population or ecosystem. This assumption strikes me as a little odd since humans are always told to ‘be the change they wish to see in the world’ and that ‘every person can make a difference’. Why then should these sentiments not be applicable to non-humans? While a gray whale may not hold a sign at a protest or run for president (actions commonly considered to cause change in the human world), perhaps the choice that a gray whale makes every day to only consume one species of zooplankton, can influence other gray whales in the area, predators from other taxa, habitat structure, other prey availability, and/or cause trophic cascades.

Through my research, I aim to elucidate whether the gray whales display some level of foraging individualisation while feeding in Port Orford, Oregon. I will use data from four years to compare tracks of individual whales with zooplankton samples collected in the area to correlate each individual’s movement patterns with prey availability. I will assess the quality of prey through bomb calorimetry and microplastic analysis of the zooplankton samples to determine energetic content and pollutant levels, respectively. This prey assessment will describe the potential effects of prey specialization on whales, which is fundamental to assessing overall population health. Individualisation can strongly affect fitness of individuals, either positively or negatively depending on several factors, which will undoubtedly have an impact at the population level.

(The videos below are examples of two different tactics we see the gray whales display while foraging along the Oregon coast in the summer months. The first video shows a whale foraging among kelp with some very acrobatic moves, while the second is of a whale employing the ‘sharking’ method where the whale is feeding benthically in such shallow depths that both the pectoral fin and the fluke stick out of the water, making the whale look like a ‘shark’.)

References

  1. American Psychological Association, Personality. Retrieved from: https://www.apa.org/topics/personality/.
  2. Carere C., & Locurto, C., Interaction between animal personality and animal cognition. Current Zoology, 2015. 57(4): 491-498.
  3. Gosling, S.D., From mice to men: what can we learn about personality from animal research?Psychological Bulletin, 2001. 127(1): 45-86.
  4. Bolnick, D.I., et al., The ecology of individuals: incidence and implications of individual specialisation. The American Naturalist, 2003. 161(1): 1-28.
  5. Torres, L.G., & Read, A. J., Where to catch a fish? The influence of foraging tactics on the ecology of bottlenose dolphins (Tursiops truncatus) in Florida Bay, Florida. Marine Mammal Science, 2009. 25(4): 797-815.
  6. Gisburne, T.J., & Connor, R.C., Group size and feeding success in strand-feeding bottlenose dolphins (Tursiops truncatus) in Bull Creek, South Carolina. Marine Mammal Science, 2015. 31(3): 1252-1257.
  7. Gazda, S.K., et al., A division of labour with role specialization in group-hunting bottlenose dolphins (Tursiops truncatus) off Cedar Keys, Florida.Proceedings of the Royal Society: Biological Sciences, 2005. 272(1559): 135-140.
  8. Ford, J.K.B., et al., Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology, 1998. 76(8): 1456-1471.
  9. Rossi-Santos, M.R., & Wedekin, L.L., Evidence of bottom contact behaviour by estuarine dolphins (Sotalia guianensis) on the Eastern Coast of Brazil.Aquatic Mammals, 2006. 32(2): 140-144.
  10. Peddemors, V.M., & Thompson, G., Beaching behaviour during shallow water feeding by humpback dolphins (Sousa plumbea). Aquatic Mammals, 1994. 20(2): 65-67.
  11. Tyack, P., Population biology, social behavior and communication in whales and dolphins. Trends in Ecology & Evolution, 1986. 1(6): 144-150.
  12. Wiley, D., et al., Underwater components of humpback whale bubble-net feeding behaviour.Behaviour, 2011. 148(5/6): 575-602.
  13. Estes, J.A., et al., Individual variation in prey selection by sea otters: patterns, causes and implications. Journal of Animal Ecology, 2003. 72(1): 144-155.
  14. Cherel, Y., et al., Stable isotopes document seasonal changes in trophic niches and winter foraging individual specialization in diving predators from the Southern Ocean. Journal of Animal Ecology, 2007. 76(4): 826-836.
  15. Matich, P., et al., Contrasting patterns of individual specialization and trophic coupling in two marine apex predators. Journal of Animal Ecology, 2010. 80(1): 294-305.
  16. Svanbäck, R., & Persson, L., Individual diet specialization, niche width and population dynamics: implications for trophic polymorphisms. Journal of Animal Ecology, 2004. 73(5): 973-982.