There is an ancient Samoan legend that upon entry into a certain bay in Samoa, tuna would sacrifice pieces of their flesh to the community chief1. This was the explanation given for fish with circular shaped wounds where a plug of flesh had been removed. Similar round wounds are also observed on swordfish2, sharks3, and marine mammals including whales4,5, dolphins6, porpoises7, and pinnipeds8,9. In 1971, Everet C. Jones posited that the probable cause of these crater wounds was a small shark only 42-56 cm in length, Isistius brasiliensis1. The species was nicknamed “demon whale-biter” by Stewart Springer, who subsequently popularized the common name for the species, cookie cutter shark.
Figure 1. A yellowfin tuna with a circular bite, characteristic of a cookie cutter shark (Isistius brasiliensis). Photo: John Soward.
I am currently preparing a manuscript on blue whale skin condition. While this is only tangentially related to my doctoral research, it is an exciting side project that has encouraged me to stretch my comfort zone as an ecologist. This analysis of skin condition is part of a broader health assessment of blue whales in New Zealand, where we will be linking skin lesion severity with stress and reproductive hormone levels as well as body condition. Before I continue, I owe a major shout-out to Acacia Pepper, a senior undergraduate student at Oregon State University who has been working with me for nearly the past year through the Fisheries and Wildlife mentorship program. Acacia’s rigor in researching methodologies led us to develop a comprehensive protocol that can be applied widely to any cetacean photo-identification catalog. This method allows us to quantify prevalence and severity of different marking types in a standardized manner. Her passion for marine mammal science and interest in the subject matter is enough to excite this ecologist into fascination with wound morphology and blister concavity. Next thing you know, we are preparing a paper for publication together with P.I. Dr. Leigh Torres on a comprehensive skin condition assessment of blue whales that includes multiple markings and lesion types, but for the purpose of this blog post, I will share just a “bite-sized” piece of the story.
Figure 2. Jaws of a cookie cutter shark. Photo: George Burgess.
Back to the demon whale-biter. What do we know about cookie cutter sharks? Not a whole lot, it turns out. They are elusive, and are thought to live in deep (>1,000 m), offshore waters. They are considered to be both an ectoparasite and an ambush predator. Their distribution is tropical and sub-tropical. Much of what we know and assume about their distribution comes from the bite wounds they leave on their prey2.
In New Zealand where we study a unique population of blue whales10, the southernmost record of cookie cutter sharks is ~ 39⁰S11. We found that in our dataset of 148 photo-identified blue whales, 96% were affected by cookie cutter shark bites. Furthermore, 38% were categorized as having “severe” cookie cutter bite wounds or scars. The latitude of our blue whale sightings ranges from 29-48⁰S and blue whales are highly mobile, so any of the whales in our dataset could theoretically swim in and out of the known range of cookie cutter sharks. In our skin condition assessment, we also categorized cookie cutter bite “freshness” and phase of healing as follows:
We wanted to know if the freshness of cookie cutter shark bites was related in to the latitude at which the whales were photographed. Of the whales photographed north of 39⁰S (n=46), 76% had phase 1 or 2 cookie cutter shark bites present. In contrast, 57.1% of whales photographed south of 39⁰S (n=133) had phase 1 or 2 cookie cutter shark bites. It therefore appears that in New Zealand, the freshness of cookie cutter shark bites on blue whales is related to the latitude at which the whales were sighted, with fresher bites being more common at more northerly latitudes.
Figure 3. A whale with fresh cookie cutter shark bites, photographed in the Bay of Islands, latitude 35.164⁰S. Photo courtesy of Dr. Catherine Peters.Figure 4. A whale with mostly healed cookie cutter shark bites, photographed off of Kaikoura, latitude 42.464⁰S. Photo courtesy of Jody Weir.
In the midst of a PhD on distribution modeling and habitat use of blue whales, I find myself reading about Samoan legends of tuna with missing flesh and descriptions of strange circular lesions from whaling records, and writing a paper about blue whale skin condition. Exciting “side projects” like this one emerge from rich datasets and good collaboration.
References
Jones, E. C. Isistius brasiliensis, a squaloid shark, the probable cause of crater wounds on fishes and cetaceans. Fish. Bull.69, 791–798 (1971).
Papastamatiou, Y. P., Wetherbee, B. M., O’Sullivan, J., Goodmanlowe, G. D. & Lowe, C. G. Foraging ecology of Cookiecutter Sharks (Isistius brasiliensis) on pelagic fishes in Hawaii, inferred from prey bite wounds. Environ. Biol. Fishes88, 361–368 (2010).
Hoyos-Padilla, M., Papastamatiou, Y. P., O’Sullivan, J. & Lowe, C. G. Observation of an Attack by a Cookiecutter Shark ( Isistius brasiliensis ) on a White Shark ( Carcharodon carcharias ) . Pacific Sci.67, 129–134 (2013).
Mackintosh, N. A. & Wheeler, J. F. G. Southern blue and fin whales. Discov. Reports1, 257–540 (1929).
Best, P. B. & Photopoulou, T. Identifying the ‘demon whale-biter’: Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp. PLoS One11, (2016).
Heithaus, M. R. Predator-prey and competitive interactions between sharks (order Selachii) and dolphins (suborder Odontoceti): A review. J. Zool.253, 53–68 (2001).
Van Utrecht, W. L. Wounds And Scars In The Skin Of The Common Porpoise, Phocaena Phocaena (L.). Mammalia23, 100–122 (1959).
Gallo‐Reynoso, J. ‐P & Figueroa‐Carranza, A. ‐L. A COOKIECUTTER SHARK WOUND ON A GUADALUPE FUR SEAL MALE. Mar. Mammal Sci.8, 428–430 (1992).
Le Boeuf, B. J., McCosker, J. E. & Hewitt, J. Crater wounds on northern elephant seals: the cookiecutter shark strikes again. Fish. Bull.85, 387–392 (1987).
Barlow, D. R. et al. Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endanger. Species Res.36, 27–40 (2018).
Dwyer, S. L. & Visser, I. N. Cookie cutter shark (Isistius sp.) bites on cetaceans, with particular reference to killer whales (Orca) (Orcinus orca). Aquat. Mamm.37, 111–138 (2011).
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.
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.
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.
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).
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.
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.
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.
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)
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) 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.
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.
Dawn Barlow scans for marine mammals from the flying bridge of NOAA ship Bell M. Shimada. Photo: Jess O’Loughlin.
Alexa on-effort using binoculars to estimate the distance and bearing of a marine mammal sighted off the starboard bow. Image source: Alexa K.
Common dolphins (Delphinus delphis). Photo: Dawn Barlow.
An image of the NOAA ship Bell M. Shimada transiting between stations. Multiple members of the GEMM Lab conducted surveys from this NOAA vessel in 2018. (Image source: Alexa Kownacki)
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.
Launching the drone. Photo by Alejandro Fernandez Ajo.
The gray whale team aboard R/V Ruby. Photo by Alejandro Fernandez Ajo.
Gray whale photo-identification. Photo by Dawn Barlow.
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.
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’.)
Carere C., & Locurto, C., Interaction between animal personality and animal cognition. Current Zoology, 2015. 57(4): 491-498.
Gosling, S.D., From mice to men: what can we learn about personality from animal research?Psychological Bulletin, 2001. 127(1): 45-86.
Bolnick, D.I., et al., The ecology of individuals: incidence and implications of individual specialisation. The American Naturalist, 2003. 161(1): 1-28.
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.
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.
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.
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.
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.
Peddemors, V.M., & Thompson, G., Beaching behaviour during shallow water feeding by humpback dolphins (Sousa plumbea). Aquatic Mammals, 1994. 20(2): 65-67.
Tyack, P., Population biology, social behavior and communication in whales and dolphins. Trends in Ecology & Evolution, 1986. 1(6): 144-150.
Wiley, D., et al., Underwater components of humpback whale bubble-net feeding behaviour.Behaviour, 2011. 148(5/6): 575-602.
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.
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.
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.
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.
By Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab
It all started with a paper. On Halloween, I sat at my desk, searching for papers that could answer my questions about bottlenose dolphin metabolism and realized I had forgotten to check my email earlier. In my inbox, there was a new message with an attachment from Dr. Leigh Torres to the GEMM Lab members, saying this was a “must-read” article. The suggested paper was Martin A. Schwartz’s 2008 essay, “The importance of stupidity in scientific research”, published in the Journal of Cell Science, highlighted universal themes across science. In a single, powerful page, Schwartz captured my feelings—and those of many scientists: the feeling of being stupid.
For the next few minutes, I stood at the printer and absorbed the article, while commenting out loud, “YES!”, “So true!”, and “This person can see into my soul”. Meanwhile, colleagues entered my office to see me, dressed in my Halloween costume—as “Amazon’s Alexa”, talking aloud to myself. Coincidently, I was feeling pretty stupid at that moment after just returning from a weekly meeting, where everyone asked me questions that I clearly did not have the answers to (all because of my costume). This paper seemed too relevant; the timing was uncanny. In the past few weeks, I have been writing my PhD research proposal —a requirement for our department— and my goodness, have I felt stupid. The proposal outlines my dissertation objectives, puts my work into context, and provides background research on common bottlenose dolphin health. There is so much to know that I don’t know!
Alexa dressed as “Amazon Alexa” on Halloween at her office in San Diego, CA.
When I read Schwartz’s 2008 paper, there were a few takeaway messages that stood out:
People take different paths. One path is not necessarily right nor wrong. Simply, different. I compared that to how I split my time between OSU and San Diego, CA. Spending half of the year away from my lab and my department is incredibly challenging; I constantly feel behind and I miss the support that physically being with other students provides. However, I recognize the opportunities I have in San Diego where I work directly with collaborators who teach and challenge me in new ways that bring new skills and perspective.
Drawing upon experts—albeit intimidating—is beneficial for scientific consulting as well as for our mental health; no one person knows everything. That statement can bring us together because when people work together, everyone benefits. I am also reminded that we are our own harshest critics; sometimes our colleagues are the best champions of our own successes. It is also why historical articles are foundational. In the hunt for the newest technology and the latest and greatest in research, it is important to acknowledge the basis for discoveries. My data begins in 1981, when the first of many researchers began surveying the California coastline for common bottlenose dolphins. Geographic information systems (GIS) were different back then. The data requires conversions and investigative work. I had to learn how the data were collected and how to interpret that information. Therefore, it should be no surprise that I cite literature from the 1970s, such as “Results of attempts to tag Atlantic Bottlenose dolphins, (Tursiops truncatus)” by Irvine and Wells. Although published in 1972, the questions the authors tried to answer are very similar to what I am looking at now: how are site fidelity and home ranges impacted by natural and anthropogenic processes. While Irvine and Wells used large bolt tags to identify individuals, my project utilizes much less invasive techniques (photo-identification and blubber biopsies) to track animals, their health, and their exposures to contaminants.
(Image source: imgflip.com)
Struggling is part of the solution. Science is about discovery and without the feeling of stupidity, discovery would not be possible. Feeling stupid is the first step in the discovery process: the spark that fuels wanting to explore the unknown. Feeling stupid can lead to the feeling of accomplishment when we find answers to those very questions that made us feel stupid. Part of being a student and a scientist is identifying those weaknesses and not letting them stop me. Pausing, reflecting, course correcting, and researching are all productive in the end, but stopping is not. Coursework is the easy part of a PhD. The hard part is constantly diving deeper into the great unknown that is research. The great unknown is simultaneously alluring and frightening. Still, it must be faced head on. Schwartz describes “productive stupidity [as] being ignorant by choice.” I picture this as essentially blindly walking into the future with confidence. Although a bit of an oxymoron, it resonates the importance of perseverance and conviction in the midst of uncertainty.
(Image source: Redbubble)
Now I think back to my childhood when stupid was one of the forbidden “s-words” and I question whether society had it all wrong. Maybe we should teach children to acknowledge ignorance and pursue the unknown. Stupid is a feeling, not a character flaw. Stupidity is important in science and in life. Fascination and emotional desires to discover new things are healthy. Next time you feel stupid, try running with it, because more often than not, you will learn something.
Alexa teaching about marine mammals to students ages 2-6 and learning from educators about new ways to engage young students. San Diego, CA in 2016. (Photo source: Lori Lowder)
By Lisa Hildebrand, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab
Science is truly meaningful because it is shared amongst colleagues and propagated to the wider public. There are many mediums through which information dissemination can occur. A common and most rigorous form is the peer-review scientific publication of papers. The paper approval process is vigorous, can last a long time – sometimes on the scale of several years – and is therefore an excellent way of vetting science that is occurring all over the world in many different disciplines. New studies build upon the results and downfalls of others, and therefore the process of research and communication of knowledge is continuous.
However, scientific journals and the publications within them can be quite exclusive; they are often only accessible to certain members of the scientific community or of an educational institution. For a budding scientist who is not affiliated with an institution, it can be very hard to get your hands on current research. Having said that, this issue is slowly becoming inconsequential since open access and free journals, such as PeerJ, are becoming more prevalent.
How some students feel after reading scientific publications. Source: Know Your Meme.
Something that is perhaps more restrictive is the amount of topic-specific jargon used in publications. While a certain degree of jargon is to be expected, it can sometimes overwhelm a reader to the point where the main findings of the research become lost. This typically tends to be the case for those just at the beginning of their scientific journeys, however I have also known professors to comment on confusing sections of publications due to the heavy use of specific jargon.
Conferences on the other hand offer an opportunity to disseminate meaningful science in a more open and (sometimes) more laid-back setting (this may not always be true depending on the field of science and the calibre of the conference). Researchers of a particular field congregate for a few days to learn about current research efforts, ponder potential collaborations, peruse posters of new studies, and argue over which soccer team is going to win the next World Cup. That is the beauty of conferences – it is very possible to get to know each other on a personal level. These face-to-face opportunities are especially beneficial to students as this relaxed atmosphere lends itself to asking questions and engaging with scientists that are leaders in their fields.
Logo for the Marine Technology Summit. Source: MTS.
Just over a week ago, the GEMM Lab had the opportunity to do all of the above-mentioned things. PI Dr Leigh Torres and I participated in the Marine Technology Summit (MTS) in Newport, OR, a “mini-conference” at which shiny, new technologies for use in marine applications were introduced by leading, and many local, tech companies. While Leigh and I are not technologists, we are ecologists that have greatly benefitted from recent, rapid advances in technology. Both of our gray whale (Eschrichtius robustus) research projects use different technologies to unveil hitherto unknown ecological aspects of these marine mammals.
Leigh presented her research that involves flying drones over gray whales that grace the Oregon coastal waters in the spring and summer. Through these flights, many previously undocumented gray whale behaviours have been captured and quantified1, such as headstands, nursing and jaw snapping (check out the video below). Furthermore, still images from the videos have been used to perform photogrammetry to assess health and body condition of the whales2. These drone flights have added a wealth of valuable data to the life histories of individual whales that previously were assessed mainly through photo-identification and genetics. This still fairly new approach to assess health by using drones can be relatively cost-effective, which has always been one of Leigh’s key aims throughout her research so that methods are accessible to many scientists. These productive drones used by the GEMM Lab are commercially available (yup, just like the ones you see on the shelves at your local Best Buy!).
The use of cost-effective technologies is a common theme in the GEMM Lab and is also central to my research. The estimation of zooplankton density is vital to my project to determine whether gray whales in Port Orford select areas of high prey density over areas with less dense prey. However, the traditional technology used to quantify prey densities in the water column are often bulky or expensive. Instead, we developed a relatively cheap method of measuring relative zooplankton density using a GoPro camera that we reel down through the water column from a downrigger attached to our research kayak. While we are unable to exactly quantify the mass of zooplankton in the water column, we have been successful in assessing changes in relative prey density by scoring screenshots of the footage.
Screenshot of a GoPro video from this summer’s field season in Port Orford, OR revealing a thick layer of zooplankton. Source: GEMM Lab.
While our drones and GoPro technology is not without error, technology rarely is. In truth, we lost our GoPro for several days after it became stuck in a rock crevice and Leigh’s team regrettably lost a drone to the depths of the ocean this summer. This technology reality was part of the reason I presented at the MTS as I wanted to involve technologists to find solutions to some of the problems I have experienced. Needless to say, I got a lot of excellent input from many different people, for which I am very grateful. In addition to developing new opportunities to collaborate, I was very content to sit in the audience and hear about the ground-breaking new marine technologies that are in development. Below are short descriptions of two new technologies I learned about that are revolutionising the marine world.
ASV Unmanned Marine Systems develop autonomous surface vehicles that are powered by renewable energies (solar panels and wind turbines). These vessels are particularly useful for oceanographic monitoring as they are more capable than weather buoys and much more cost effective than manned weather ships or research vessels. Additionally, they can be used for a lot of different marine science applications including active acoustic fisheries monitoring, water quality monitoring, and cetacean tracking. Some models even have integrated drones that are launched and retrieved autonomously.
The Ocean Cleanup is a company that develops technologies to clean garbage out of our oceans. There is presently a large mission underway by The Ocean Cleanup to combat the Great Pacific Garbage Patch (GPGP). The GPGP is essentially a large island in the middle of the North Pacific Ocean comprised of diverse plastic particles – wrappers, polystyrene, fishing line, plastic bags, the list is endless3. A recent study estimates the amount of plastic in the GPGP to be at least 79 thousand tonnes of ocean plastic4. Unfortunately, the GPGP is not the only one of its kind. The Ocean Cleanup hopes to reduce this massive plastic accumulation with the development of a system made up of a 600-m long floater that sits on the ocean’s surface with a 3-m deep skirt attached below it. The skirt will collect debris while the float will prevent plastic from flowing over it, as well as keep the whole system afloat. The system arrived at the GPGP last Wednesday and the team of over 80 engineers, researchers, scientists and computational modellers have successfully installed the system. The team posts frequent updates on their Twitter and I would highly recommend you follow this possibly revolutionary technology.
While attending the MTS, it felt like there are no bounds for the types of marine technology that will be developed in the future. I am excited to see what ecologists working with technicians can develop to keep applying technology to address challenging questions and conservation issues.
References
Torres, L., et al., Drone up! Quantifying whale behaviour from a new perspective improves observational capacity.Frontiers in Marine Science, 2018. 5, DOI:10.3389/fmars.2018.00319.
Burnett, J.D., et al., Estimating morphometric attributes on baleen whales using small UAS photogrammetry: A case study with blue and gray whales, 2018.Marine Mammal Science. DOI:10.1111/mms.12527.
Kaiser, J., The dirt on the ocean garbage patches. Science, 2018. 328(5985): p. 1506.
Lebreton, L., et al., Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. Scientific Reports, 2018. 8(4666).
By Dawn Barlow, PhD student, Geospatial Ecology of Marine Megafauna Lab, Department of Fisheries and Wildlife, Oregon State University
Sun on my face and wind in my hair, scanning the expanse of blue. Forty minutes on, twenty minutes off, from sunrise until sunset, day after day. Hours of seemingly empty blue, punctuated by graceful black-footed albatrosses wheeling and gliding over the swells, by the splashing approach of a curious group of Pacific white-sided dolphins coming to play in the bow of the ship, by whale spouts on the horizon and the occasional breaching humpback. A flurry of data entry—geographic coordinates, bearing and distance from the ship, number of animals, species identification, behavior—and then back to blue.
Scanning for marine mammals from the flying bridge of NOAA ship Bell M. Shimada. Photo: Jess O’Loughlin.
I’ve just returned from the Northern California Current (NCC) ecosystem cruise aboard NOAA ship Bell M. Shimada. My role on board was the marine mammal observer, logging marine mammal sightings during the transits between sampling stations. We surveyed and sampled between Cape Mears, Oregon and Trinidad, California, from right along the coast out to 200 nautical miles offshore. Resources in the marine environment are patchy, and our coastline is highly productive. This diversity in environmental conditions creates niche habitats for many species, which is one reason why surveying and sampling across a broad geographic range can be so informative. We left Newport surrounded by gray whales, feeding in green, chilly waters at temperatures around 12°C. Moving west, the marine mammal and seabird sightings were increasingly sparse, the water increasingly blue, and the surface temperature warmed to a balmy 17°C. We had reached offshore waters, an ocean region sometimes referred to as the “blue desert”. For an entire day I didn’t see a single marine mammal and only just a few seabirds, until a handful of common dolphins—more frequently seen in warm-temperate and tropical waters to the south—joined the ship at sunset. As we transited back inshore over the productive Heceta Bank, the water became cooler and greener. I stayed busy logging sightings of humpback and gray whales, harbor porpoise and Dall’s porpoise, pacific white-sided dolphins and sea lions. These far-ranging marine predators must find a way to make a living in the patchy and dynamic ocean environment, and therefore their distribution is also patchy—aggregated around areas of high productivity and prey availability, and occasionally seen transiting in between.
Here are a few cruise highlights:
Curious groups of common dolphins (Delphinus delphis) came to play in the bow wake of the ship and even checked out the plankton nets when they were deployed. Common dolphins are typically found further south, however we saw several groups of them in the warmer waters far offshore.
Common dolphins (Delphinus delphis). Photo: Dawn Barlow.
Common dolphins (Delphinus delphis). Photo: Dawn Barlow.
Common dolphins (Delphinus delphis). Photo: Dawn Barlow.
Common dolphins (Delphinus delphis). Photo: Dawn Barlow.
Ocean sunfish (Mola mola) will occasionally lay themselves flat at the surface so that seabirds will pick them clean of any parasites. I was delighted to observe this for the first time just off Newport! There were several more sunfish sightings throughout the cruise.
Gull picking parasites off an ocean sunfish (Mola mola). Photo: Dawn Barlow.
A masked booby (Sula dactylatra) hung around the ship for a bit, 16 nautical miles from shore, just south of the Oregon-California border. Considered a tropical species, a sighting this far north is extremely rare. While masked boobies are typically distributed in the Caribbean and tropical Pacific from Mexico to Australia, one found its way to the Columbia River in 2006 (first record in the state of Oregon) and another showed up here to Newport in 2015 – reportedly only the second to be recorded north of Mendocino County, California. Perhaps this sighting is the third?
Masked booby (Sula dactylatra). Photo: Dawn Barlow.
While most of my boat-based fieldwork experiences have been focused on marine mammal research, this was an interdisciplinary cruise aimed at studying multiple aspects of the northern California current ecosystem. There were researchers on board studying oceanography, phytoplankton and harmful algal blooms, zooplankton, and microplastics. When a group of enthusiastic scientists with different areas of expertise come together and spend long days at sea, there is a wonderful opportunity to learn from one another. The hydroacoustic backscatter on the scientific echosounder prompted a group discussion about vertical migration of plankton one evening. Another evening I learned about differences in energetic content between krill species, and together we mused about what that might mean for marine predators. This is how collaborations are born, and I am grateful for the scientific musings with so many insightful people.
Thank you to the Shimada crew and the NCC science team for a wonderful cruise!
Solène Derville, Entropie Lab, French National Institute for Sustainable Development (IRD – UMR Entropie), Nouméa, New Caledonia
Ph.D. student under the co-supervision of Dr. Leigh Torres
Species Distribution Models (SDM), also referred to as ecological niche models, may be defined as “a model that relates species distribution data (occurrence or abundance at known locations) with information on the environmental and/or spatial characteristics of those locations” (Elith & Leathwick, 2009). In the last couple decades, SDMs have become an indispensable part of the ecologists’ and conservationists’ toolbox. What scientist has not dreamed of being able to summarize a species’ environmental requirements and predict where and when it will occur, all in one tiny statistical model? It sounds like magic… but the short acronym “SDM” is the pretty front window of an intricate and gigantic research field that may extend way beyond the skills of a typical ecologist (even so for a graduate student like myself).
As part of my PhD thesis about the spatial ecology of humpback whales in New Caledonia, South Pacific, I was planning on producing a model to predict their distribution in the region and help spatial planning within the Natural Park of the Coral Sea. An innocent and seemingly perfectly feasible plan for a second year PhD student. To conduct this task, I had at my disposal more than 1,000 sightings recorded during dedicated surveys at sea conducted over 14 years. These numbers seem quite sufficient, considering the rarity of cetaceans and the technical challenges of studying them at sea. And there was more! The NGO Opération Cétacés also recorded over 600 sightings reported by the general public in the same time period and deployed more than 40 satellite tracking tags to follow individual whale movements. In a field where it is so hard to acquire data, it felt like I had to use it all, though I was not sure how to combine all these types of data, with their respective biases, scales and assumptions.
One important thing about SDM to remember: it is like a cracker section in a US grocery shop, there is sooooo much choice! As I reviewed the possibilities and tested various modeling approaches on my data I realized that this study might be a good opportunity to contribute to the SDM field, by conducting a comparison of various algorithms using cetacean occurrence data from multiple sources. The results of this work was just published in Diversity and Distributions:
Derville S, Torres LG, Iovan C, Garrigue C. (2018) Finding the right fit: Comparative cetacean distribution models using multiple data sources and statistical approaches. Divers Distrib. 2018;00:1–17. https://doi. org/10.1111/ddi.12782
There are simply too many! Anonymous grocery shops, Corvallis, OR Credit: Dawn Barlow
If you are a new-comer to the SDM world, and specifically its application to the marine environment, I hope you find this interesting. If you are a seasoned SDM user, I would be very grateful to read your thoughts in the comment section! Feel free to disagree!
So what is the take-home message from this work?
There is no such thing as a “best model”; it all depends on what you want your model to be good at (the descriptive vs predictive dichotomy), and what criteria you use to define the quality of your models.
The predictive vs descriptive goal of the model: This is a tricky choice to make, yet it should be clearly identified upfront. Most times, I feel like we want our models to be decently good at both tasks… It is a risky approach to blindly follow the predictions of a complex model without questioning the meaning of the ecological relationships it fitted. On the other hand, conservation applications of models often require the production of predicted maps of species’ probability of presence or habitat suitability.
The criteria for model selection: How could we imagine that the complexity of animal behavior could be summarized in a single metric, such as the famous Akaike Information criterion (AIC) or the Area under the ROC Curve (AUC)? My study, and that of others (e.g. Elith & Graham H., 2009), emphasize the importance of looking at multiple aspects of model outputs: raw performance through various evaluation metrics (e.g. see AUCdiff; (Warren & Seifert, 2010), contribution of the variables to the model, shape of the fitted relationships through Partial Dependence Plots (PDP, Friedman, 2001), and maps of predicted habitat suitability and associated error. Spread all these lines of evidence in front of you, summarize all the metrics, add a touch of critical ecological thinking to decide on the best approach for your modeling question, and Abracadabra! You end up a bit lost in a pile of folders… But at least you assessed the quality of your work from every angle!
Cetacean SDMs often serve a conservation goal. Hence, their capacity to predict to areas / times that were not recorded in the data (which is often scarce) is paramount. This extrapolation performance may be restricted when the model relationships are overfitted, which is when you made your model fit the data so closely that you are unknowingly modeling noise rather than a real trend. Using cross-validation is a good method to prevent overfitting from happening (for a thorough review: Roberts et al., 2017). Also, my study underlines that certain algorithms inherently have a tendency to overfit. We found that Generalized Additive Models and MAXENT provided a valuable complexity trade-off to promote the best predictive performance, while minimizing overfitting. In the case of GAMs, I would like to point out the excellent documentation that exist on their use (Wood, 2017), and specifically their application to cetacean spatial ecology (Mannocci, Roberts, Miller, & Halpin, 2017; Miller, Burt, Rexstad, & Thomas, 2013; Redfern et al., 2017).
Citizen science is a promising tool to describe cetacean habitat. Indeed, we found that models of habitat suitability based on citizen science largely converged with those based on our research surveys. The main issue encountered when modeling this type of data is the absence of “effort”. Basically, we know where people observed whales, but we do not know where they haven’t… or at least not with the accuracy obtained from research survey data. However, with some information about our citizen scientists and a little deduction, there is actually a lot you can infer about opportunistic data. For instance, in New Caledonia most of the sightings were reported by professional whale-watching operators or by the general public during fishing/diving/boating day trips. Hence, citizen scientists rarely stray far from harbors and spend most of their time in the sheltered waters of the New Caledonian lagoon. This reasoning provides the sort of information that we integrated in our modeling approach to account for spatial sampling bias of citizen science data and improve the model’s predictive performance.
Many more technical aspects of SDM are brushed over in this paper (for detailed and annotated R codes of the modeling approaches, see supplementary information of our paper). There are a few that are not central to the paper, but that I think are worth sharing:
Collinearity of predictors: Have you ever found that the significance of your predictors completely changed every time you removed a variable? I have progressively come to discover how unstable a model can be because of predictor collinearity (and the uneasy feeling that comes with it …). My new motto is to ALWAYS check cross-correlation between my predictors, and do it THOROUGHLY. A few aspects that may make a big difference in the estimation of collinearity patterns are to: (1) calculate Pearson vs Spearman coefficients, (2) check correlations between the values recorded at the presence points vs over the whole study area, and (3) assess the correlations between raw environmental variables vs between transformed variables (log-transformed, etc). Though selecting variables with Pearson coefficients < 0.7 is usually a good rule (Dormann et al., 2013), I would worry of anything above 0.5, or at least keep it in mind during model interpretation.
Cross-validation: If removing 10% of my dataset greatly impacts the model results, I feel like cross-validation is critical. The concept is based on a simple assumption, if I had sampled a given population/phenomenon/system slightly differently, would I have come to the same conclusion? Cross-validation comes in many different methods, but the basic concept is to run the same model several times (number of times may depend on the size of your data set, hierarchical structure of your data, computation power of your computer, etc.) over different chunks of your data. Model performance metrics (e.g., AUC) and outputs (e.g., partial dependence plots) are than summarized on the many runs, using mean/median and standard deviation/quantiles. It is up to you how to pick these chunks, but before doing this at random I highly recommend reading Roberts et al. (2017).
The evil of the R2: I am probably not the first student to feel like what I have learned in my statistical classes at school is in practice, at best, not very useful, and at worst, dangerously misleading. Of course, I do understand that we must start somewhere, and that learning the basics of inferential statistics is a necessary step to, one day, be able to answer your one research questions. Yet, I feel like I have been carrying the “weight of the R2” for far too long before actually realizing that this metric of model performance (R2 among others) is simply not enough to trust my results. You might think that your model is robust because among the 1000 alternative models you tested, it is the one with the “best” performance (deviance explained, AIC, you name it), but the model with the best R2 will not always be the most ecologically meaningful one, or the most practical for spatial management perspectives. Overfitting is like a sword of Damocles hanging over you every time you create a statistical model All together, I sometimes trust my supervisor’s expertise and my own judgment more than an R2.
Source: internet
A few good websites/presentations that have helped me through my SDM journey:
Dormann, C. F., Elith, J., Bacher, S., Buchmann, C., Carl, G., Carré, G., … Lautenbach, S. (2013). Collinearity: A review of methods to deal with it and a simulation study evaluating their performance. Ecography, 36(1), 027–046. https://doi.org/10.1111/j.1600-0587.2012.07348.x
Elith, J., & Graham H., C. (2009). Do they? How do they? WHY do they differ? On finding reasons for differing performances of species distribution models . Ecography, 32(Table 1), 66–77. https://doi.org/10.1111/j.1600-0587.2008.05505.x
Elith, J., & Leathwick, J. R. (2009). Species Distribution Models: Ecological Explanation and Prediction Across Space and Time. Annual Review of Ecology, Evolution, and Systematics, 40(1), 677–697. https://doi.org/10.1146/annurev.ecolsys.110308.120159
Friedman, J. H. (2001). Greedy Function Approximation: A gradient boosting machine. The Annals of Statistics, 29(5), 1189–1232. Retrieved from http://www.jstor.org/stable/2699986
Mannocci, L., Roberts, J. J., Miller, D. L., & Halpin, P. N. (2017). Extrapolating cetacean densities to quantitatively assess human impacts on populations in the high seas. Conservation Biology, 31(3), 601–614. https://doi.org/10.1111/cobi.12856.This
Miller, D. L., Burt, M. L., Rexstad, E. A., & Thomas, L. (2013). Spatial models for distance sampling data: Recent developments and future directions. Methods in Ecology and Evolution, 4(11), 1001–1010. https://doi.org/10.1111/2041-210X.12105
Redfern, J. V., Moore, T. J., Fiedler, P. C., de Vos, A., Brownell, R. L., Forney, K. A., … Ballance, L. T. (2017). Predicting cetacean distributions in data-poor marine ecosystems. Diversity and Distributions, 23(4), 394–408. https://doi.org/10.1111/ddi.12537
Roberts, D. R., Bahn, V., Ciuti, S., Boyce, M. S., Elith, J., Guillera-Arroita, G., … Dormann, C. F. (2017). Cross-validation strategies for data with temporal, spatial, hierarchical or phylogenetic structure. Ecography, 0, 1–17. https://doi.org/10.1111/ecog.02881
Warren, D. L., & Seifert, S. N. (2010). Ecological niche modeling in Maxent: the importance of model complexity and the performance of model selection criteria. Ecological Applications, 21(2), 335–342. https://doi.org/10.1890/10-1171.1
Wood, S. N. (2017). Generalized additive models: an introduction with R (second edi). CRC press.
We wanted to know if the freshness of cookie cutter shark bites was related in to the latitude at which the whales were photographed. Of the whales photographed north of 39⁰S (n=46), 76% had phase 1 or 2 cookie cutter shark bites present. In contrast, 57.1% of whales photographed south of 39⁰S (n=133) had phase 1 or 2 cookie cutter shark bites. It therefore appears that in New Zealand, the freshness of cookie cutter shark bites on blue whales is related to the latitude at which the whales were sighted, with fresher bites being more common at more northerly latitudes.
