By Rachel Kaplan, PhD candidate, Oregon State University College of Earth, Ocean, and Atmospheric Sciences and Department of Fisheries, Wildlife, and Conservation Sciences, Geospatial Ecology of Marine Megafauna Lab
I moved to Corvallis exactly four years ago, in the deep, dark midst of the Covid pandemic, and during the added chaos of the 2020 Labor Day Fires, some of the worst in Oregon’s history. I vividly remember attending our virtual lab meeting sitting on the floor surrounded by boxes, while my labmates told me their own stories (many, surprisingly!) of moving during natural disasters. At the time, beginning graduate school represented so many big changes in my life: I had quit my job, sold my furniture, and moved across the country, hoping to explore an area of research that had been calling to me for years, and to gain a new skillset and confidence.
Highlight: A very pandemic cruise. My first day of marine mammal fieldwork in 2021, at sea with (now Dr.) Dawn Barlow.
Now, I’m starting the fifth year of my PhD, thinking about all that has happened and all that is to come. Graduate school is full of milestones to mark time and progress: I’ve taken the courses required for my program, sat for a written exam to test my broad knowledge of oceanography, and written a dissertation proposal. Earlier this year, I spent two months buried in the literature on oceanography, krill, and whale ecology in preparation for my oral qualifying exam. I’ve stared at the water for dozens of hours watching for whales off the Oregon coast, and experienced polar night studying winter krill in Antarctica. I’ve conquered my fear of learning to code, and felt constant, profound gratitude for the amazing people I get to work with.
The last four years have been incredibly busy and active, but now more than ever, it feels like the time to really do. I can see the analytical steps ahead for my final two dissertation chapters more clearly than I’ve been able to see either of the other two chapters that have come before. One of my favorite parts of the process of research is discussing analytical decisions with my labmates and supervisors, and experiencing how their brains work. Much of our work hinges on modeling relationships between animals and their environment. A model, most fundamentally, is a reduced-scale representation of a system. As I’ve learned to use statistical models to understand relationships between krill and whales, I have simultaneously been building a mental model of the Northern California Current (NCC) ecosystem and the ecological relationships within it. Just as I have long admired in my supervisors and labmates, I can now feel my own mind becoming more playful as I think about this ocean environment, the whales and krill that make a living in the NCC, and the best way to approach studying them analytically.
Highlight: Working on my dissertation proposal during a friend’s 2022 wedding celebration in Utah.
Graduate school demands that you learn and work to constantly exceed your own bounds, and pushing to that extent for years is often stressful and even existentially threatening. However, this process is also beautiful. I have spent the last four years growing in the ways that I’ve long wanted to, and reveled in feeling my mind learn to play. I wouldn’t give up a moment of the time I’ve spent in the field, the relationships I’ve built with my labmates, or the confidence I’ve developed along the way.
As I look ahead to this next, final, year of graduate school, I hope to use what I’ve learned every day – and not just about how to conduct research, but about myself. I want to always remember that krill, whales, and the ocean ecosystem are incredible, and that it is a privilege to study them. I hope to work calmly and intentionally, and to continue appreciating this process of research and growth.
Highlight: My first in-person oral presentation, at the 2024 ICES-PICES International Zooplankton Production Symposium in Hobart, Tasmania.
By Nina Mahalingam, University of California Davis, OSU CEOAS REU program
Hello! I’m Nina Mahalingam, a rising junior at the University of California, Davis studying biochemistry and molecular biology. Growing up in New Hampshire and Massachusetts, the Boston Aquarium was practically in my backyard – and with just one feel of a touch tank, a lifelong affinity for marine sciences began. CEOAS has provided me with a grand opportunity to pursue this passion, and I can’t wait to dip my toes into the salt water!
Here at OSU, I’m researching how our tiny friends, the krill, can provide a krill-uminating perspective on trophic ecology and the vitality of marine ecosystems by investigating the caloric content of an understudied species of krill off the coast of New Zealand. Nyctiphanes australis serves as a key prey species to numerous higher trophic levels. Limited knowledge exists regarding the distribution of N. australis in the South Taranaki Bight (STB), with only a handful of studies focused exclusively on the species. The majority of recent information available on the species in the STB came out of research on blue whales and their foraging behaviors (e.g., Barlow et al., 2020). However, given that the spatial distribution of N. australis directly influences the distribution of predator species that depend on them for sustenance (Barlow et. al. 2020), studying the krill may yield a more comprehensive understanding of blue whale behavior as well as ecosystem resilience.
Seawater temperatures around New Zealand have been increasing since 1981 (Sutton & Bowen, 2019), and there is a growing concern about the implications to marine life. In particular, increasing ocean temperatures have had significant impacts on local aquaculture and fisheries (Sutton et al. 2005; Bowen et al. 2017). Although warming trends along the North Island, north of East Cape, have been more severe (around 0.4℃ increase per decade), warming has also been observed in the central and western areas of the STB, averaging around 0.15-0.20℃ increase per decade (Sutton & Bowen, 2019). During Marine Heat Waves (MHWs) (data collected between 2002 and 2018), warming anomalies were observed to decrease phytoplankton presence (Chiswell & Sutton, 2020). Being krill’s primary food source, this suggests a consequent decrease in krill health and reproduction. A recent study on blue whale reproductive patterns in the STB found that whale feeding activity decreased during MHWs, leading to a decline in their reproductive activity during the following breeding season (Barlow et al., 2020). Concurrently, the study observed that there were less krill aggregations and that they were less dense on average (Barlow et al., 2020). This is presumed to be a result of less upwelling nutrients, and therefore poor conditions for krill feeding and reproduction. These findings indicate that the absence of their primary food source, krill, during MHWs can lead to severely negative consequences for the blue whale populations (Barlow et al., 2023).
Anthropogenic activity in the STB, including high vessel traffic, as well as petroleum and mineral exploration and extraction activities, has also been identified as a threat to the local blue whale population (Torres et. al., 2013). Given the cultural significance of the blue whales in this region, there is an urgent need for improved, dynamic management practices in the STB that can be achieved using predictive models to forecast blue whale spatial distribution. Using environmental factors to inform predictive spatial distribution models (SDMs) of blue whales (Redfern et al. 2006, Elith & Leathwick 2009), Barlow et al. (2021) designed a blue whale forecasting tool for managers and decision-makers in New Zealand.
Given the ecological and cultural significance of blue whales and their krill prey in the STB, a Project SAPPHIRE (Synthesis of Acoustics, Physiology, Prey, and Habitat in a Rapidly changing Environment) was developed to examine the impacts of climate change on the health of these crucial species. The overarching goal of Project SAPPHIRE is to measure prey (krill) and predator (blue whales) response to environmental change off the coast of New Zealand. Despite forecasts of high probability of occurrence of blue whales in the STB during the first field season conducted in January-February 2024, both the blue whales and their krill prey were scarce, and it is currently unclear why. My research will focus on examining the calorie content of N. australis in order to advance understanding of how they fulfill the energetic needs of blue whales. Thus, this data can inform future SDMs to forecast impacts of climate change on New Zealand’s marine ecosystem.
This project has already proven tricky – but I’m ready to embrace the challenge. I would like to thank the CEOAS REU program as well as my mentors Kim Bernard, Rachel Kaplan, and Abby Tomita for their continued support. I can’t wait to see what this summer brings!
References
Barlow DR, Klinck H, Ponirakis D, Branch TA, Torres LG. 2023. Environmental conditions and marine heatwaves influence blue whale foraging and reproductive effort. Ecol Evol. 2023;13:e9770.
Barlow D, Kim S. Bernard, Pablo Escobar-Flores, Daniel M. Palacios, Leigh G. 2020. Torres Links in the trophic chain: modeling functional relationships between in situ oceanography, krill, and blue whale distribution under different oceanographic regimes. Marine Ecology Progress Series.
Sutton, P.J.H., & Bowen, M. 2019. Ocean temperature change around New Zealand over the last 36 years. New Zealand Journal of Marine and Freshwater Research, 53(3), 305–326.
Sutton P.J.H., Bowen M, Roemmich D. 2005. Decadal temperature changes in the Tasman Sea. New Zealand Journal of Marine and Freshwater Research. 39:1321–1329.
Bowen M, Markham J, Sutton P, Zhang X, Wu Q, Shears N, Fernandez D. 2017. Interannual variability of sea surface temperatures in the Southwest Pacific and the role of ocean dynamics. Journal of Climate.
Stephen M. Chiswell & Philip J. H. Sutton. 2020. Relationships between long-term ocean warming, marine heat waves and primary production in the New Zealand region. New Zealand Journal of Marine and Freshwater Research.
By Matoska Silva, OSU Department of Integrative Biology, CEOAS REU Program
My name is Matoska Silva, and I just finished my first year at Oregon State University studying biology with a focus in ecology. This summer will be my first experience with marine ecology, and I’m eager to dive right in. I’m super excited for the opportunity to research krill due to the huge impacts these tiny organisms have on their surrounding ecosystems. The two weeks I’ve spent in the CEOAS REU so far have been among the most fun and informative of my life, and I can’t wait to see what else the summer has in store for me.
Figure 1. Matoska presents his proposed research to the CEOAS REU program.
I’ve spent most of my life in Oregon, so I was thrilled to learn that my project would focus on krill distribution along the Oregon Coast that I know and love. More specifically, my project focuses on the Northern California Current (NCC, the current found along the Oregon Coast) and the ways that geographic distribution of krill corresponds to climatic conditions in the region. Here is a synopsis of the project:
The NCC system, which spans the west coast of North America from Cape Mendocino, California to southern British Columbia, is notable for seasonal upwelling, a process that brings cool, nutrient-rich water from the ocean depths to the surface. This process provides nutrients for a complex marine food web containing phytoplankton, zooplankton, fish, birds, and mammals (Checkley & Barth, 2009). Euphausiids, commonly known as krill, are among the most ecologically important zooplankton groups in the NCC, playing a vital role in the flow of nutrients through the food web (Evans et al., 2022). Euphausia pacifica and Thysanoessa spinifera are the predominant krill species in the NCC, with T. spinifera mainly inhabiting coastal waters and E. pacifica inhabiting a wider range offshore (Brinton, 1962). T. spinifera individuals are typically physically larger than E. pacifica and are generally a higher-energy food source for predators (Fisher et al., 2020).
Temperature has been previously established as a major factor impacting krill abundance and distribution in the NCC (Phillips et al., 2022). Massive, ecosystem-wide changes in the NCC have been linked to extreme warming brought on by the 2014-2016 marine heatwave (Brodeur et al., 2019). Both dominant krill species have been shown to respond negatively to warming events in the NCC, with anomalous warm temperatures in 2014-2016 being linked to severe declines in E. pacifica biomass and with T. spinifera nearly disappearing from the Oregon Coast (Peterson et al., 2017). Changes in normal seasonal size variation and trends toward smaller size distributions in multiple age groups have been observed in E. pacifica in response to warming in northern California coastal waters (Robertson & Bjorkstedt, 2020).
The El Niño-Southern Oscillation (ENSO) is a worldwide climatic pattern that has been linked to warming events and ecosystem disturbances in the California Current System (McGowan et al., 1998). El Niño events of both strong and weak intensity can result in changes in the NCC ecosystem (Fisher et al., 2015). Alterations in the typical zooplankton community accompanying warm water conditions and a decline in phytoplankton have been recorded in the NCC during weak and strong El Niño occurrences (Fisher et al., 2015). A strong El Niño event occurred in 2023 and 2024, with three-month Oceanic Niño Index means reaching above 1.90 from October 2023 to January 2024 (NOAA Climate Prediction Center, https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt).
Figure 2. A graph of the ONI showing variability across two decades. Retrieved from NOAA at https://www.climate.gov/news-features/understanding-climate/climate-variability-oceanic-nino-index
While patterns in krill responses to warming have been described from previous years, the effects of the 2023-2024 El Niño on the spatial distribution of krill off the Oregon coast have not yet been established. As climate models have predicted that strong El Niño events may become more common due to greenhouse warming effects (Cai et al., 2014), continuing efforts to document zooplankton responses to El Niño conditions are vital for understanding how the NCC ecosystem responds to a changing climate. By investigating krill spatial distributions in April 2023, during a period of neutral ENSO conditions following a year of La Niña conditions, and April 2024, during the 2023-2024 El Niño event, we can assess how recent ENSO activity has impacted krill distributions in the NCC. In addition to broader measures of ENSO, we will examine records of localized sea surface temperatures (SST) and measurements of upwelling activity during April 2023 and 2024.
Understanding spatial distribution of krill aggregations is both ecologically and economically relevant, with implications for both marine conservation and management of commercial fisheries. Modeling patterns in the distribution of krill species and their predators has potential to inform marine management decisions to mitigate human impacts on marine mammals like whales (Rockwood et al., 2020). The data used to identify krill distribution were originally collected as part of the Marine Offshore Species Assessments to Inform Clean Energy (MOSAIC) project. The larger MOSAIC initiative centers around monitoring marine mammals and birds in areas identified for possible future development of offshore wind energy infrastructure. The findings of this study could aid in the conservation of krill consumers during the implementation of wind energy expansion projects. Changes in krill spatial distribution are also important for monitoring species that support commercial fisheries. Temperature has been shown to play a role in the overlap in distribution of NCC krill and Pacific hake (Merluccius productus), a commercially valuable fish species in Oregon waters (Phillips et al., 2023). The findings of my project could supplement existing commercial fish abundance surveys by providing ecological insights into factors driving changes in economically important fisheries.
Figure 3. The study area and transect design of the MOSAIC project, during which active acoustic data was collected (MOSAIC Project, https://mmi.oregonstate.edu/marine-mammals-offshore-wind).
I’m very grateful for the chance to work on a project with such important implications for the future of our Oregon coast ecosystems. My project has a lot of room for additional investigation of climate variables, with limited time being the main constraint on which processes I can explore. There are also unique methodological challenges to address during the project, and I’m ready to do some experimentation to work out solutions. Wherever my project takes me, I know that I will have developed a diverse range of skills and knowledge of krill by the end of the summer.
References
Brinton, E. (1962). The distribution of Pacific euphausiids. Bulletin of the Scripps Institution of Oceanography, 8(2), 51-270. https://escholarship.org/uc/item/6db5n157
Brodeur, R. D., Auth, T. D., & Phillips, A. J. (2019). Major shifts in pelagic micronekton and macrozooplankton community structure in an upwelling ecosystem related to an unprecedented marine heatwave. Frontiers in Marine Science, 6. https://doi.org/10.3389/fmars.2019.00212
Cai, W., Borlace, S., Lengaigne, M., van Rensch, P., Collins, M., Vecchi, G., Timmermann, A., Santoso, A., McPhaden, M. J., Wu, L., England, M. H., Wang, G., Guilyardi, E., & Jin, F. F. (2014). Increasing frequency of extreme El Niño events due to greenhouse warming. Nature Climate Change, 4, 111–116. https://doi.org/10.1038/nclimate2100
Checkley, D. M., & Barth, J. A. (2009). Patterns and processes in the California Current System. Progress in Oceanography, 83, 49–64. https://doi.org/10.1016/j.pocean.2009.07.028
Evans, R., Gauthier, S., & Robinson, C. L. K. (2022). Ecological considerations for species distribution modelling of euphausiids in the Northeast Pacific Ocean. Canadian Journal of Fisheries and Aquatic Sciences, 79, 518–532. https://doi.org/10.1139/cjfas-2020-0481
Fisher, J. L., Peterson, W. T., & Rykaczewski, R. R. (2015). The impact of El Niño events on the pelagic food chain in the northern California Current. Global Change Biology, 21, 4401–4414. https://doi.org/10.1111/gcb.13054
Fisher, J. L., Menkel, J., Copeman, L., Shaw, C. T., Feinberg, L. R., & Peterson, W. T. (2020). Comparison of condition metrics and lipid content between Euphausia pacifica and Thysanoessa spinifera in the Northern California Current, USA. Progress in Oceanography, 188, 102417. https://doi.org/10.1016/j.pocean.2020.102417
McGowan, J. A., Cayan, D. R., & Dorman, L. M. (1998). Climate-ocean variability and ecosystem response in the Northeast Pacific. Science, 281, 210–217. https://doi.org/10.1126/science.281.5374.210
Phillips, E. M., Chu, D., Gauthier, S., Parker-Stetter, S. L., Shelton, A. O., & Thomas, R. E. (2022). Spatiotemporal variability of Euphausiids in the California Current Ecosystem: Insights from a recently developed time series. ICES Journal of Marine Science, 79, 1312–1326. https://doi.org/10.1093/icesjms/fsac055
Phillips, E. M., Malick, M. J., Gauthier, S., Haltuch, M. A., Hunsicker, M. E., Parker‐Stetter, S. L., & Thomas, R. E. (2023). The influence of temperature on Pacific hake co‐occurrence with euphausiids in the California Current Ecosystem. Fisheries Oceanography, 32, 267–279. https://doi.org/10.1111/fog.12628
Peterson, W. T., Fisher, J. L., Strub, P. T., Du, X., Risien, C., Peterson, J., & Shaw, C. T. (2017). The pelagic ecosystem in the Northern California Current off Oregon during the 2014–2016 warm anomalies within the context of the past 20 years. Journal of Geophysical Research: Oceans, 122(9), 7267–7290. https://doi.org/10.1002/2017jc012952
Robertson, R. R., & Bjorkstedt, E. P. (2020). Climate-driven variability in Euphausia pacificasize distributions off Northern California. Progress in Oceanography, 188, 102412.https://doi.org/10.1016/j.pocean.2020.102412
The Northern California Current region feeds a taxonomically diverse suite of top predators, including numerous species of seabirds, fish, and marine mammals. Baleen whales such as blue, fin, and humpback whales make this productive area a long stop on their seasonal migration, drawn in large part by abundant krill, a shrimp-like zooplankton that serves as an important prey item.
Aspects of both quality and quantity determine whether a prey resource is advantageous for a predator. In the case of whales, sheer biomass is key. It takes a lot of tiny krill to sustain a large whale – literally tons for a blue whale’s daily diet (Goldbogen et al., 2015). Baleen whales are such big eaters that they actually reshape the ocean ecosystem around them (Savoca et al., 2021).
Figure 1. A blue whale lunge feeds on a shallow krill swarm.Read more here.
But the quality of prey, in addition to its quantity, is crucial to energetic profitability, and baleen whales must weigh both elements in their foraging decisions. The outcome of those calculations manifest in the diverse feeding strategies that whales employ across ecosystems. In the California Current region, blue whales preferentially target the larger, more lipid-rich krill Thysanoessa spinifera (Fiedler et al., 1998). In Antarctica, humpback whales target larger and reproductive krill with higher energetic value, if these extra-juicy varieties are available (Cade et al., 2022). Prey-switching, a strategy in which animals target prey based on relative availability, allows fin whales to have a more broad diet than blue whales, which are obligate krill predators.
So, what makes krill of high enough quality for a whale to pursue – or low enough quality to ignore? Krill are widely distributed across the NCC region, so why do foraging whales target one krill patch over another?
That whale of a question combines behavior, foraging theory, biochemistry, physics, climate, and more. One key aspect is the composition of a given prey item. Just as for human diet, nutrients, proteins, and calories are where the rubber hits the road in an animal’s energetic budget. The energy density of prey items sets the cost of living for cetaceans, and shapes the foraging strategies they use (Goldbogen et al., 2015; Spitz et al., 2012). In the NCC, T. spinifera krill are more lipid-rich than Euphausia pacifica (Fisher et al., 2020). Pursuing more energy dense prey increases the profitability of a given mouthful and helps a whale offset the energy expended to earn it, including the costly hunt for prey on the foraging grounds (Videsen et al., 2023).
Krill are amazingly dynamic animals in their own right, and they have evolved life history strategies to accommodate a broad range of ocean conditions. They can even exhibit “negative growth,” shrinking their body length in response to challenging conditions or poor food quality. This plasticity in body size can allow krill to survive lean times – but from the perspective of a hungry whale, this strategy also shrinks the available biomass into smaller packages (Robertson & Bjorkstedt, 2020).
One reason why krill are such advantageous prey type for baleen whales is their tendency to aggregate into dense swarms that may contain hundreds of thousands of individuals. The large body size of baleen whales requires them to feed on such profitable patches (Benoit-Bird, 2024). The packing density of krill within aggregations determines how many a whale can capture in one mouthful, and drives patch selection, such as for blue whales in Antarctica (Miller 2019).
Figure 2. The dense swarms formed by krill make them a prime target for many predators, including these juvenile Pacific sardines. (Photo: Richard Herrmann)
However, even the juiciest, densest krill won’t benefit a foraging whale if the energy required to consume it outweighs the gains. The depth of krill in the water column shapes the acrobatic foraging maneuvers blue whales use to feed (Goldbogen et al., 2015), and is a key driver of patch selection (Miller et al., 2019). The horizontal distance between the whale and a new krill patch is important too. Foraging humpback whales adapt their movements to the hierarchical structure of the preyfield, and feeding on neighboring prey schools can reduce the energy and time expended during interpatch travel, increasing net foraging gain (Kirchner et al., 2018).
Prey quality is dynamic, shaped by environmental conditions, extreme events, and climate change processes (Gomes et al., 2024). We can’t yet fully predict how change will alter prey and predator relationships in the NCC region (Muhling et al., 2020), making every step toward understanding prey dynamics relative to environmental variability key to anticipating how whales will fare in an unknown future (Hildebrand et al., 2021). If you are what you eat, then learning more about krill prey quality will give us unique insights into the baleen whales that come from far and wide to the NCC foraging grounds.
References
Benoit-Bird, K. J. (2024). Resource Patchiness as a Resolution to the Food Paradox in the Sea. The American Naturalist, 203(1), 1–13. https://doi.org/10.1086/727473
Cade, D. E., Kahane-Rapport, S. R., Wallis, B., Goldbogen, J. A., & Friedlaender, A. S. (2022). Evidence for Size-Selective Predation by Antarctic Humpback Whales. Frontiers in Marine Science, 9, 747788. https://doi.org/10.3389/fmars.2022.747788
Fiedler, P. C., Reilly, S. B., Hewitt, R. P., Demer, D., Philbrick, V. A., Smith, S., Armstrong, W., Croll, D. A., Tershy, B. R., & Mate, B. R. (1998). Blue whale habitat and prey in the California Channel Islands. Deep Sea Research Part II: Topical Studies in Oceanography, 45(8–9), 1781–1801. https://doi.org/10.1016/S0967-0645(98)80017-9
Fisher, J. L., Menkel, J., Copeman, L., Shaw, C. T., Feinberg, L. R., & Peterson, W. T. (2020). Comparison of condition metrics and lipid content between Euphausia pacifica and Thysanoessa spinifera in the northern California Current, USA. Progress in Oceanography, 188. https://doi.org/10.1016/j.pocean.2020.102417
Goldbogen, J. A., Hazen, E. L., Friedlaender, A. S., Calambokidis, J., DeRuiter, S. L., Stimpert, A. K., & Southall, B. L. (2015). Prey density and distribution drive the three‐dimensional foraging strategies of the largest filter feeder. Functional Ecology, 29(7), 951–961. https://doi.org/10.1111/1365-2435.12395
Gomes, D. G. E., Ruzicka, J. J., Crozier, L. G., Huff, D. D., Brodeur, R. D., & Stewart, J. D. (2024). Marine heatwaves disrupt ecosystem structure and function via altered food webs and energy flux. Nature Communications, 15(1), 1988. https://doi.org/10.1038/s41467-024-46263-2
Hildebrand, L., Bernard, K. S., & Torres, L. G. (2021). Do Gray Whales Count Calories? Comparing Energetic Values of Gray Whale Prey Across Two Different Feeding Grounds in the Eastern North Pacific. Frontiers in Marine Science, 8. https://doi.org/10.3389/fmars.2021.683634
Kirchner, T., Wiley, D., Hazen, E., Parks, S., Torres, L., & Friedlaender, A. (2018). Hierarchical foraging movement of humpback whales relative to the structure of their prey. Marine Ecology Progress Series, 607, 237–250. https://doi.org/10.3354/meps12789
Miller, E. J., Potts, J. M., Cox, M. J., Miller, B. S., Calderan, S., Leaper, R., Olson, P. A., O’Driscoll, R. L., & Double, M. C. (2019). The characteristics of krill swarms in relation to aggregating Antarctic blue whales. Scientific Reports, 9(1), 16487. https://doi.org/10.1038/s41598-019-52792-4
Muhling, B. A., Brodie, S., Smith, J. A., Tommasi, D., Gaitan, C. F., Hazen, E. L., Jacox, M. G., Auth, T. D., & Brodeur, R. D. (2020). Predictability of Species Distributions Deteriorates Under Novel Environmental Conditions in the California Current System. Frontiers in Marine Science, 7. https://doi.org/10.3389/fmars.2020.00589
Robertson, R. R., & Bjorkstedt, E. P. (2020). Climate-driven variability in Euphausia pacifica size distributions off northern California. Progress in Oceanography, 188. https://doi.org/10.1016/j.pocean.2020.102412
Savoca, M. S., Czapanskiy, M. F., Kahane-Rapport, S. R., Gough, W. T., Fahlbusch, J. A., Bierlich, K. C., Segre, P. S., Di Clemente, J., Penry, G. S., Wiley, D. N., Calambokidis, J., Nowacek, D. P., Johnston, D. W., Pyenson, N. D., Friedlaender, A. S., Hazen, E. L., & Goldbogen, J. A. (2021). Baleen whale prey consumption based on high-resolution foraging measurements. Nature, 599(7883), 85–90. https://doi.org/10.1038/s41586-021-03991-5
Spitz, J., Trites, A. W., Becquet, V., Brind’Amour, A., Cherel, Y., Galois, R., & Ridoux, V. (2012). Cost of Living Dictates what Whales, Dolphins and Porpoises Eat: The Importance of Prey Quality on Predator Foraging Strategies. PLoS ONE, 7(11), e50096. https://doi.org/10.1371/journal.pone.0050096
Videsen, S. K. A., Simon, M., Christiansen, F., Friedlaender, A., Goldbogen, J., Malte, H., Segre, P., Wang, T., Johnson, M., & Madsen, P. T. (2023). Cheap gulp foraging of a giga-predator enables efficient exploitation of sparse prey. Science Advances, 9(25), eade3889. https://doi.org/10.1126/sciadv.ade3889
The depths of the productive coastal Oregon ecosystem have long held a mystery – an increasing paucity in the concentration of dissolved oxygen at depth. When dissolved oxygen concentrations dips low enough, the condition “hypoxia” can alter biogeochemical cycling in the ocean environment and threaten marine life. Essentially, organisms can’t get enough oxygen from the water, forcing them to try to escape to more favorable waters, stay and change their behavior, or suffer the consequences and potentially suffocate.
Recent work has illuminated the cause of this mysterious rise in hypoxic waters: an increase in the wind-driven oceanographic process of upwelling (Barth et al., 2024). The seasonal upwelling of cold, nutrient-rich waters underlies the incredible productivity of the Oregon coast, but its dark twin is hypoxia: when organic material in the upper layer of the water column sinks, microbial respiration processes consume dissolved oxygen in the surrounding water. In addition, the deep waters brought to the surface by upwelling are depleted in oxygen compared to the aerated surface waters. These effects combine to form an oxygen-poor water layer over the continental shelf, which typically lasts from May until October in the Northern California Current (NCC) region. The spatial extent of this layer is highly variable – hypoxic bottom waters cover 10% of the shelf in some years and up to 62% in others, presenting challenging conditions for life occupying the Oregon shelf (Peterson et al., 2013).
Figure 1. An article in The Oregonian from 2004 documents research on a hypoxia-driven “dead zone” off the Oregon coast.
While effects of hypoxia on benthic communities and some fish species are well-documented, is unclear how increasing levels of hypoxia off Oregon may impact highly mobile, migratory organisms like whales. A primary pathway is likely through their prey – particularly species that occupy hypoxic regions and depths, like the zooplankton krill. Over the continental shelf and slope, which are important krill habitat, seasonally hypoxic waters tend to extend from about 150 meters depth to the bottom. The vertical center of krill distribution in the NCC region is around 170 meters depth, suggesting that these animals encounter hypoxic conditions regularly.
Interestingly, the two main krill species off the Oregon coast, Euphausia pacifica and Thysanoessa spinifera, use different strategies to deal with hypoxic conditions. Thysanoessa spinifera krill decrease their oxygen consumption rate to better tolerate ambient hypoxia, a behavioral modification strategy called “oxyconformity”. Euphausia pacifica, on the other hand, use “oxyregulation” to maintain the same, quite high, oxygen utilization rate regardless of ambient levels – which may indicate that this species will be less able to tolerate increasingly hypoxic waters (Tremblay et al., 2020).
Figure 2. This figure from Barth et al. 2024 maps the concentration of dissolved oxygen (uM/kg; cooler colors indicate less dissolved oxygen) to show an increase in hypoxic conditions over the continental shelf and slope (green and blue colors) across seven decades in the NCC region.
Over long time scales, such environmental pressures shape species physiology, life history, and evolution. The krill species Euphausia mucronate is endemic to the Humboldt Current System off the coast of South America, which includes a region of year-round upwelling and a persistent Oxygen Minimum Zone (OMZ). Fascinatingly, Humboldt krill can live in the core of the OMZ, using metabolic adaptations that even let them survive in anoxic conditions (i.e., no oxygen in the water). Humboldt krill abundances actually increase with shallower OMZ depths and lower levels of dissolved oxygen, pointing to the huge success of this species in evolving to thrive in conditions that challenge other local krill species (Díaz-Astudillo et al., 2022).
Back home in the NCC region, will Euphausia pacifica and Thysanoessa spinifera be pressured to adapt to continually increasing levels of hypoxia? If so, will they be able to adapt? One of krill’s many superpowers is an ability to tolerate a wide range of environmental conditions, including the dramatic gradients in temperature, water density, and dissolved oxygen that they encounter during their daily vertical migrations through the water column. Both species have strategies to deal with hypoxic conditions, and this capacity has allowed them to thrive in the active upwelling region that is the NCC. Now, the question is whether increasingly hypoxic waters will eventually force a threshold that compromises the capacity of krill to adapt – and then, what will happen to these species, and the foragers dependent on them?
References
Barth, J. A., Pierce, S. D., Carter, B. R., Chan, F., Erofeev, A. Y., Fisher, J. L., Feely, R. A., Jacobson, K. C., Keller, A. A., Morgan, C. A., Pohl, J. E., Rasmuson, L. K., & Simon, V. (2024). Widespread and increasing near-bottom hypoxia in the coastal ocean off the United States Pacific Northwest. Scientific Reports, 14(1), 3798. https://doi.org/10.1038/s41598-024-54476-0
Díaz-Astudillo, M., Riquelme-Bugueño, R., Bernard, K. S., Saldías, G. S., Rivera, R., & Letelier, J. (2022). Disentangling species-specific krill responses to local oceanography and predator’s biomass: The case of the Humboldt krill and the Peruvian anchovy. Frontiers in Marine Science, 9, 979984. https://doi.org/10.3389/fmars.2022.979984
Peterson, J. O., Morgan, C. A., Peterson, W. T., & Lorenzo, E. D. (2013). Seasonal and interannual variation in the extent of hypoxia in the northern California Current from 1998–2012. Limnology and Oceanography, 58(6), 2279–2292. https://doi.org/10.4319/lo.2013.58.6.2279
Tremblay, N., Hünerlage, K., & Werner, T. (2020). Hypoxia Tolerance of 10 Euphausiid Species in Relation to Vertical Temperature and Oxygen Gradients. Frontiers in Physiology, 11, 248. https://doi.org/10.3389/fphys.2020.00248
By Kim Bernard, Associate Professor, Oregon State University College of Earth, Ocean, and Atmospheric Sciences
Euphausiids, commonly known as “krill”, represent a globally distributed family of pelagic crustacean zooplankton, spanning from tropical to polar oceans. These remarkable organisms inhabit a vast range of marine habitats, from nearshore coastal waters to the expansive open ocean, and from the sea surface to abyssal depths. Notably, they claim the title of the largest biomass among non-domestic animal groups on Earth! Beyond their sheer abundance, euphausiids play a pivotal role in shaping global marine food webs, supporting both economically significant fisheries and extensive populations of marine megafauna.
Figure 1: Nyctiphanes australis. Photo credit: A. Slotwinski, CSIRO.
As our planet continues to warm, the ongoing and anticipated shifts in the distribution and biomass of krill populations herald potential disruptions to marine ecosystems and food webs globally. Marine heatwaves, which are expected to increase in frequency, intensity, and duration in the coming decades, have a significant impact on global krill populations, with knock-on effects through food webs. At our home-base off the coast of Oregon, a severe marine heatwave in 2014-2016 resulted in altered krill distributions and reduced biomass, causing a suite of ecological implications ranging from decline in salmon health to increased occurrence of whale entanglements in fishing gear (Daly et al. 2017; Santora et al. 2020).
Figure 2: (A) Simrad EK80 transducers (the larger one is a 38kHz transducer, the smaller is a 120kHz transducer) mounted to a pole that gets lowered into the water during our daily surveys. The transducers emit sound waves that bounce off objects, like krill, in the water and return to the instrument’s transceiver, allowing us to map krill within the water column. (B) The acoustic data collected by the echosounder appears in real-time on our computer screen allowing us to find krill that we can then target with the Bongo net. Photo credits: Kim Bernard.
Here, off the coast of New Zealand, the krill species Nyctiphanes australis (Figure 1) is an important prey item for many marine predators, including slender tuna (Allothunnus fallai), Australian salmon (Kahawai, Arripis trutta), Jack mackerel (Trachurus declivis), short-tailed shearwater (Puffinus tenuirostris) (O’Brien 1988), and of course, the reason we are out here, blue whales (Balaenoptera musculus brevicauda) (Torres et al. 2020). In a precursor study to the SAPPHIRE project, members of our current research team demonstrated the potential negative impacts that marine heatwaves can have off the coast of New Zealand. During that study, our team noted declines in the abundance and changes in the distribution patterns of Nyctiphanes australis during a marine heatwave compared to normal conditions, with subsequent negative impacts on the distribution and behavior of the local New Zealand blue whale population (Barlow et al. 2020). The impetus of the SAPPHIRE project is to improve our understanding of the physiological mechanisms underlying the observed changes in both krill and blue whale populations, with the goal to better predict future changes.
As a zooplankton ecologist and “kriller”, my role on the SAPPHIRE project is to further our knowledge on the prey, Nyctiphanes australis. There are several components to this part of our research: (1) mapping distribution patterns of krill, (2) measuring the quality of krill as prey to whales, and (3) running experiments to test how warming affects krill physiology. To map the krill distribution patterns, we are using active acoustics (Figure 2). To measure the quality of krill, we first need to collect them, and we do that using a Bongo net (Figure 3) that gets towed behind the boat targeting krill we find using the echosounder.
Figure 3: Kim Bernard and Ngatokoa Tikitau empty the contents of one of the Bongo net cod-ends into a bucket to examine the catch. Unfortunately, it was not filled with krill as we had hoped, but rather a gelatinous zooplankton known as Salpa democratica. Photo credit: KC Bierlich.
Once we have the krill, we’ll flash freeze them in liquid nitrogen and take them back to Oregon where we’ll measure the amount of protein, fats (lipids), and calories each one contains. Finally, for the experiments on temperature effects, we will use live krill collected with the Bongo net placed individually into 1L Nalgene bottles, each outfitted with oxygen sensors so that we can measure the respiration rates of krill at a range of temperatures they would experience during normal conditions and marine heatwaves (Figure 4).
Figure 4: Respiration experiment set-up with two circulating waterbaths in the foreground feeding two temperature treatments in coolers (aka “chilly bins”) behind. Once we catch krill (which has yet to happen), we will use this set-up to test the effects of warming on krill respiration rates. Photo credit: Kim Bernard.
References
Barlow DR, Bernard KS, Escobar-Flores P, Palacios DM, Torres LG (2020) Links in the trophic chain: modeling functional relationships between in situ oceanography, krill, and blue whale distribution under different oceanographic regimes. Marine Ecology Progress Series 642:207-225. https://doi.org/10.3354/meps13339
Daly EA, Brodeur RD, Auth TD (2017) Anomalous ocean conditions in 2015: impacts on spring Chinook salmon and their prey field. Marine Ecology Progress Series 566:169-182. https://doi.org/10.3354/meps12021
O’Brien DP (1988) Surface schooling behaviour of the coastal krill Nyctiphanes australis (Crustacea: Euphausiacea) off Tasmania, Australia. Marine Ecology Progress Series 42: 219-233.
Santora JA, Mantua NJ, Schroeder ID, Field JC, Hazen EL, Bograd SJ, Sydeman WJ, Wells BK, Calambokidis J, Saez L, Lawson D, Forney KA (2020) Habitat compression and ecosystem shifts as potential links between marine heatwave and record whale entanglements. Nature Communications 11(1):536. doi: 10.1038/s41467-019-14215-w.
Torres LG, Barlow DR, Chandler TE, Burnett JD. 2020. Insight into the kinematics of blue whale surface foraging through drone observations and prey data. PeerJ 8:e8906 https://doi.org/10.7717/peerj.8906
Here in the GEMM lab, we love the Oregon coast for its amazing animals – the whales we all study, the seabirds we can sometimes spot from the lab, and the critters that come up in net tows when we’re out on the water. Oregonians owe the amazing biological productivity of the Oregon coast to the underlying atmospheric and oceanographic processes, which make our local Northern California Current (NCC) ecosystem one of the most productive places on earth.
While the topographical bumps of the Oregon coastline and vagaries of coastal weather do have a big impact on the physical and biological processes off the coast, the dominant forces shaping the NCC are large-scale, atmospheric heavy hitters. As the northeasterly trade winds blow across the globe, they set up the clockwise-rotating North Pacific Subtropical Gyre, a major feature covering about 20 million square kilometers of the Pacific Ocean. The equatorward-flowing part of the gyre is the California Current. It comprises an Eastern Boundary Upwelling Ecosystem, one of four such global systems that, while occupying only 1% of the global ocean, are responsible for a whopping 11% of its total primary productivity, and 17% of global fish catch.
Figure 1. Important features of the California Current System (Checkley and Barth, 2009).
At its core, this incredible ocean productivity is due to atmospheric pressure gradients. Every spring, an atmospheric system called the North Pacific High strengthens, loosening the hold of the stormy Aleutian Low. As a result, the winds begin to blow from the north, pushing the surface water in the NCC with them towards the equator.
This water is subject to the Coriolis effect – an inertial force that acts upon objects moving across a rotating frame of reference, and the same force that airplane pilots must account for in their flight trajectories. As friction transmits the stress of wind acting upon the ocean’s surface downward through the water column, the Coriolis effect deflects deeper layers of water successively further to the right, before the original wind stress finally peters out due to frictional losses.
This process creates an oceanographic feature called an Ekman spiral, and its net effect in the NCC is the offshore transport of surface water. Deep water flows up to replace it, bringing along nutrients that feed the photosynthesizers at the base of the food web. Upwelling ecosystems like the NCC tend to be dominated by food webs full of large organisms, in which energy flows from single-celled phytoplankton like diatoms, to grazers like copepods and krill, to predators like fish, seabirds, and our favorite, whales. These bountiful food webs keep us busy: GEMM Lab research has explored how upwelling dynamics impact gray whale prey off the Oregon coast, as well as parallel questions far from home about blue whale prey in New Zealand.
Figure 2. The Coriolis effect creates an oceanographic feature called an Ekman Spiral, resulting in water transport perpendicular to the wind direction (Source: NOAA).
Although the process of upwelling lies at the heart of the productive NCC ecosystem, it isn’t enough for it to simply happen – timing matters, too. The seasonality of ecological events, or phenology, can have dramatic consequences for the food web, and individual populations in it. When upwelling is initiated as normal by the “spring transition”, the delivery of freshly upwelled nutrients activates the food web, with reverberations all the way from phytoplankton to predators. When the spring transition is late, however, the surface ocean is warm, nutrients are depleted, primary productivity is low, and the life cycles and abundances of some species can change dramatically. In 2005, for example, the spring transition was delayed by a month, resulting in declines and spatial redistributions of the taxa typically found in the NCC, including hake, rockfish, albacore tuna, and squid. The Cassin’s auklet, which feeds on plankton, suffered its worst year on record, including reproductive failure that may have resulted from a lack of food.
Upwelling is alchemical in its power to transform, modulating physical and atmospheric processes and turning them into ecosystem gold – or trouble. As oceanographers and Oregonians alike wonder how climate change may reshape our coast, changes to upwelling will likely play a big role in determining the outcome. Some expect that upwelling-favorable winds will become more prevalent, potentially increasing primary productivity. Others suspect that the timing of upwelling will shift, and ecological mismatches like those that occurred in 2005 will be increasingly detrimental to the NCC ecosystem. Whatever the outcome, upwelling is inherent to the character of the Oregon coast, and will help shape its future.
Figure 3. The GEMM Lab is grateful that the biological productivity generated by upwelling draws humpback whales like this one to the Oregon coast! (photo: Dawn Barlow)
References
Chavez, Francisco & Messié, Monique. (2009). A comparison of Eastern Boundary Upwelling Ecosystems. Progress In Oceanography. 83. 80-96. 10.1016/j.pocean.2009.07.032.
Chavez, F P., and J R Toggweiler, 1995: Physical estimates of global new production: The upwelling contribution. In Dahlem Workshop on Upwelling in the Ocean: Modern Processes and Ancient Records, Chichester, UK, John Wiley & Sons, 313-320.
Checkley, David & Barth, John. (2009). Patterns and processes in the California Current System. Progress In Oceanography. 83. 49-64. 10.1016/j.pocean.2009.07.028.
Early June marked the onset of El Niño conditions in the Pacific Ocean , which have been strengthening through the fall and winter. For Oregonians, this climate event means unseasonably warm December days, less snow and overall precipitation (it’s sunny as I write this!), and the potential for increased wildfires and marine heatwaves next summer.
This phenomenon occurs about every two to seven years as part of the El Niño Southern Oscillation (ENSO), a cyclical rotation of atmospheric and oceanic conditions in the Pacific Ocean that is initiated by departures from and returns to “normal conditions” at the equator. Typically, the trade winds blow warm water west along the equator, and El Niño occurs when these winds weaken or reverse. As a result, the upwelling of cold water at the equator ceases, and warm water flows towards the west coast of the Americas, rather than its typical pathway towards Asia. When the trade winds resume their normal direction, usually after months or a year, the system returns to “normal” conditions – or, it can enter the cool La Niña part of the cycle, in which the trade winds are stronger than normal. “El Niño de Navidad” was named by South American fisherman in the 1600s because this event tends to peak in December – and El Niño is clearly going to be a guest for Christmas this year.
Figure 1. Maps of sea surface temperature anomalies show Pacific Ocean conditions during a strong La Niña (top) and El Niño (bottom). Source: NOAA climate.gov
These events at the equator trigger changes in global atmospheric circulation patterns, and they can shape weather around the world. Teleconnection, the coherence between meteorological and environmental phenomena occurring far apart, is to me one of the most incredible things about the natural world. This coherence means that the biological community off the Oregon coast is strongly impacted by events initiated at the equator, with consequences that we don’t yet fully understand.
The effects of El Niño are diverse – floods in some places, droughts in others – and their onset can mean wildly different things for Oregon, Peru, Alaska, and beyond. As we tap our fingers waiting to be able to ski and snowboard in Oregon, what does our current El Niño event mean for the life in the waters off our coast?
Figure 2. Anomalous conditions at the equator qualified as an El Niño event in June 2023.
ENSO plays a big role in the variability in our local Northern California Current (NCC) system, and the outcomes of these events can differ based on the strength and how the signal propagates through the ocean and atmosphere (Checkley & Barth, 2009). Large-scale “coastal-trapped” waves flowing alongshore can bring the warm water signal of an El Niño to our ocean backyard in a matter of weeks. One of the first impacts is a deepening of the thermocline, the upper ocean’s steep gradient in temperature, which changes the cycling of important nutrients in the surface ocean. This can result in a decrease in upwelling and primary productivity that sends ramifications through the food web, including consequences for grazers and predators like zooplankton, marine mammals, and seabirds (Checkley & Barth, 2009).
In addition to these ecosystem effects that result from local changes, the ocean community can also receive new visitors from afar, and see others flee . For krill, the shrimp-like whale prey that I spend a lot of my time thinking about, community composition can change as subtropical species typically found off southern and Baja California are displaced by horizontal ocean flow, or as resident species head north (Lilly & Ohman, 2021).
Figure 3. This Euphausia gibboides krill is typically found in offshore subtropical habitats but moves north and inshore during El Niño events, and tends to persist awhile in these new environments, impacting the local zooplankton community. Source: Solvn Zankl
The two main krill species that occur in the NCC, Euphausia pacifica and Thysanoessa spinifera, favor the cool, coastal waters typical off the coast of Oregon. During El Niño events, E. pacifica tends to contract its distribution inshore in order to continue occupying these conditions, increasing its spatial overlap with T. spinifera (Lilly & Ohman, 2021). In addition, both tend to shift their populations north, toward cooler, upwelling waters (Lilly & Ohman, 2021).
These krill species are a favored prey of rorqual whales, and the coast of Oregon is an important foraging ground for humpback, blue, and fin whales. Predators tend to follow their prey, and shifting distributions of these krill species may cause whales to move, too. During the 2014-2015 “Blob” event in the Pacific Ocean, a marine heatwave was exacerbated by El Niño conditions. Humpback whales in central California shifted their distributions inshore in response to sparse offshore krill, increasing their overlap with fishing gear and leading to an increase in entanglement events (Santora et al., 2020). Further north, these conditions even led humpback whales to forage in the Columbia River!
Figure 4. In September 2015, El Niño conditions led humpback whales to follow their prey and forage in the Columbia River.
As El Niño events compound with the impacts of global climate change, we can expect these distributional shifts – and perhaps surprises – to continue. By the year 2100, the west coast habitat of both T. spinifera and E. pacifica will likely be constrained due to ocean warming – and when El Niños occur, this habitat will decrease even further (Lilly & Ohman, 2021). As a result, the abundances of both species are expected to decrease during El Niño events, beyond what is seen today (Lilly & Ohman, 2021). This decline in prey availability will likely present a problem for future foraging whales, which may already be facing increased environmental challenges.
Understanding connections is inherent to the field of ecology, and although these environmental dependencies are part of what makes life so vulnerable, they can also be a source of resilience. Although humans have known about ENSO for over 400 years, the complex interplay between nature, anthropogenic systems, and climate change means that we are still learning the full implications of these events. Just as waiting for Santa Claus always keeps kids guessing, the dynamic ocean keeps surprising us, too.
References
Checkley, D. M., & Barth, J. A. (2009). Patterns and processes in the California Current System. Progress in Oceanography, 83(1–4), 49–64. https://doi.org/10.1016/j.pocean.2009.07.028
Lilly, L. E., & Ohman, M. D. (2021). Euphausiid spatial displacements and habitat shifts in the southern California Current System in response to El Niño variability. Progress in Oceanography, 193, 102544. https://doi.org/10.1016/j.pocean.2021.102544
Santora, J. A., Mantua, N. J., Schroeder, I. D., Field, J. C., Hazen, E. L., Bograd, S. J., Sydeman, W. J., Wells, B. K., Calambokidis, J., Saez, L., Lawson, D., & Forney, K. A. (2020). Habitat compression and ecosystem shifts as potential links between marine heatwave and record whale entanglements. Nat Commun, 11(1), 536. https://doi.org/10.1038/s41467-019-14215-w
Hello from Palmer Station, Antarctica! I’ve spent the last five months here in a kind of parallel universe to that of my normal life in Oregon. It’s spring here at the Western Antarctic Peninsula (WAP), and since May I’ve been part of a team studying Antarctic krill (Euphausia superba) – a big change from the Oregon species I typically study, and one that has already taught me so much.
I am here as part of a project titled “The Omnivore’s Dilemma: The effect of autumn diet on winter physiology and condition of juvenile Antarctic krill”. Through at-sea fieldwork and experiments in the lab, we have spent this field season investigating how climate-driven changes in diet impact juvenile and adult krill health during the long polar night. Winter is a crucial time for krill survival and recruitment, and an understudied season in this remote corner of the world.
Within this field season, we have been part of two great research cruises along the WAP, and spent the rest of the time at Palmer Station, running long-term experiments to learn how diet influences krill winter growth and development. The time has passed incredibly fast, and it’s hard to believe that we’ll be heading home in just a couple weeks.
There have been so many wonderful parts to our time here. While at sea, I was constantly aware that each new bay and fjord we sampled was one of the most beautiful places I would ever have the privilege to visit. I was also surprised and thrilled by the number of whales we saw – I recorded over one hundred sightings, including humpbacks, minke, and killer whales. As consumed as I was by looking for whales during the few hours of daylight, it was also rewarding to broaden my marine mammal focus and learn about another krill predator, the crabeater seal, from a great team researching their ecology and physiology.
In between our other work, I have been processing active acoustic (echosounder) data collected during a winter 2022 cruise that visited many of the same regions of the WAP. Antarctic krill have been much more thoroughly studied than the main krill species that occur off the coast of Oregon, Euphausia pacifica and Thysanoessa spinifera, and it has been amazing to draw upon this large body of literature.
Figure 2. The active acoustic data I’m working with from the Western Antarctic Peninsula, pictured here, was collected along a wiggly cruise track in 2022, giving me the opportunity to learn how to process this type of survey data and appreciate the ways in which a ship’s movements translate to data analysis.
Working with a new flavor of echosounder data has presented me with puzzles that are teaching me to navigate different modes of data collection and their analytical implications, such as for the cruise track data above. I’ll never take data collected along a standardized grid for granted again!
I’ve also learned new techniques that I am excited to apply to my research in the Northern California Current (NCC) region. For example, there are two primary different ways of detecting krill swarms in echosounder data: by comparing the results of two different acoustic frequencies, and by training a computer algorithm to recognize swarms based on their dimensions and other characteristics. After trying a few different approaches with the Antarctic data this season, I developed a way to combine these techniques. In the resulting dataset, two different methods have confirmed that a given area represents krill, which gives me a lot of confidence in it. I’m looking forward to applying this technique to my NCC data, and using it to assess some of my next research questions.
Figure 3. A combination of krill detection techniques selected these long krill aggregations off the coast of the Western Antarctic Peninsula (WAP).
Throughout it all, the highlight of this season has been being part of an amazing field team. I’m here with Kim Bernard (as a co-advised student, I refer to Kim as my “krill advisor” and Leigh as my “whale advisor”), and undergraduate Abby Tomita, who just started her senior year at OSU remotely from Palmer. From nights full of net tows to busy days in the lab, we’ve become a well-oiled machine, and laughed a lot along the way. Working with the two of them makes me sure that we’ll be able to best any difficulties that come up.
Now, our next challenge is wrapping up our last labwork, packing up equipment and samples, and getting ready to say goodbye. Leaving this wild, remote place is always heartbreaking – you never really know if you’ll be back. But there’s a lot to look forward to as we journey north, too: I can’t wait to hug my family and friends, eat a salad, and drive out to Newport to see the GEMM Lab. I’m excited to head back to the world with everything I’ve learned here, and to keep working.
Figure 4. Kim (left), Abby (middle), and I (right) hike on the Marr Ice Piedmont during a gorgeous day off.
By Abby Tomita, undergraduate student, OSU College of Earth, Ocean, and Atmospheric Sciences, research intern in the GEMM and Krill Seeker Labs
This February, during the winter term of my third year at Oregon State, I was presented with a once-in-a-lifetime opportunity. After spending the last year studying the zooplankton krill as part of Project OPAL, I was invited to spend the austral winter season doing research on Antarctic krill (Euphausia superba) under supervision of experts Dr. Kim Bernard and PhD student Rachel Kaplan. Additionally, we were lucky enough to participate in two research cruises along the Western Antarctic Peninsula (WAP).
Figure 1. Sailing into the sunset on the RV Laurence M. Gould.
Unsurprisingly, it is no easy feat getting to the bottom of the world. After an incredibly thorough physical qualification process and two days of air travel from Portland, Oregon, we reached the lovely city of Punta Arenas, Chile. It was such a relief to arrive – but we were only halfway there. The next portion of our trip was the one that I was most anxious about, especially as someone who is prone to seasickness: crossing the Drake Passage. This stretch of the ocean, from the southernmost tip of South America to the Antarctic Peninsula, is notoriously treacherous as water in this area circulates the globe completely unobstructed by land masses. I soon learned the value of scopolamine patches and nausea bracelets, which helped me immensely through this five day journey. From Punta Arenas, we boarded the RV Laurence M. Gould, along with a seal research team from the University of North Carolina Wilmington. They were headed down south to look for crabeater seals to better understand not only their physiology, but also their role in the trophic ecology of the WAP.
The Passage was rough, but not as terrible as I expected. The hype around it made me think I’d be faced with something as menacing as the giant wave from The Perfect Storm, and while the rocking and rolling of the ship was far from pleasant, my nausea aids, as well as the amazing people and vast selection of movies on board made it manageable. Despite being extremely nervous for the Passage, I was also very excited to celebrate my twenty-first birthday during it. It was a memorable, although untraditional birthday experience that was made all the more special by my friends on the ship who took the time to celebrate the day as best as we could.
Figure 2. Taking in the sights of the Neumayer Channel with Kim!
The morning that we reached the Bransfield Strait was something truly unforgettable. Up until that point, I knew our destination was Antarctica, but I couldn’t really wrap my head around it because it was such a distant place and concept to me. I remember walking out onto the starboard side of the second level deck and seeing huge mountains out in the distance. For some reason, I had never considered how massively tall the mountains of the peninsula are, and just the fact that there were mountains down here at all. I joined the others at the bow, where we stood for hours in awe at the first land we had seen in days. Though many of the other scientists and crew members on board had been to this icy continent before, this was my first time, and I was in a state of disbelief. We’d finally made it and it sunk into me that I was in Antarctica, and that I would be here for the next five and half months.
After a day of hiding from strong winds in the Neumayer Channel, we were able to dock at Palmer Station (the smallest of the three US research bases in Antarctica) for our first port call, and seeing Palmer for the first time was just as exciting as seeing the continent. It looked so small at first, especially with the glacier and mountains looming behind it. Once the ship was tied up, orientation began. The station manager came onto the ship to give us an overview of what we could expect on station and the general Palmer etiquette. Next, we were given a tour of the facilities, from the lab spaces and aquarium room, up through the galley/dining area, past the hot tub and sauna, and into the lounge and bar in the GWR (Garage, Warehouse, and Recreation) building. I was surprised at how cozy the station was on the inside. In pictures, the buildings’ exteriors looked similar to the outside of a metal shipping container, but the inside was welcoming and warm. Those of us staying on station then sat through several hours of a more detailed orientation that somehow wore us out despite sitting in comfy recliner sofas the whole time. After sleeping on the rocking ship for about a week, I had some of the best sleep of my life that first night at Palmer Station.
Figure 3. Arriving at the Palmer Station pier in the first morning light.
Our first research cruise started a few days after arriving at Palmer, and just like that, we were off to explore the Southern Ocean. This leg of the trip took us south, down to Marguerite Bay and the region of Alexander Island, for ten days. The views were just spectacular everywhere we went, and it was so humbling to step out onto the deck to see gigantic mountains all around the ship. By day, us “krillers”, as our team is known, camped out on the bridge of the ship with the seal team, where we looked for sea ice floes with lounging crabeater seals. By night we conducted CTD casts, filtered water for chlorophyll, and deployed nets to catch our favorite tiny crustacean critters, along with any other zooplankton in our track. Unfortunately for both our group and the seal team, many areas that we visited were not frequented by krill or crabeater seals, though the seal team did successfully study and tag one seal over the course of the first cruise.
Figure 4. Rachel (right) and I (left) filtering water for chlorophyll on the LMG.
One of the highlights of this leg of the cruise was our Crossing Ceremony, as we’d crossed the Antarctic Circle (approximately 66.5ºS) shortly after leaving Palmer station. Myself and six others were crossing for the first time, so to earn our “Red Noses”, we had to pay tribute to King Neptune and his court. It would not be a Crossing Ceremony without at least some light pranking, so when they brought us out individually to the main deck, I knew something was coming our way.
Figure 5. Taking a celebratory picture with King Neptune’s court…with a surprise after.
The ten days flew by, and when we arrived back on station, we had less than a week to prepare for our next excursion on the LMG, which would be fifteen days. The time back at Palmer went quickly as we organized our lab space and entered data from the first cruise. The ship came back once more and we were off, this time heading north along the Peninsula to the Gerlache Strait. The sights were as breathtaking as ever, and I was excited to be back with my friends from the ship.
Figure 6. Kim (left) and I (right) pour krill we caught into an XACTIC tank.
Our first day of transit was through the Lemaire Channel, one of the most stunning areas that we passed through (check out the photo gallery at the end of this post!). We spent the majority of the day on the bow and the deck of the bridge taking in the beautiful towering mountains on either side of the narrow channel and watching for penguins and humpbacks, of which there were many. This voyage segued into an extremely productive night of science for us where we caught thousands of krill that we were able to keep live in tanks on the ship, in preparation for later use for our experiments on station. Our first productive night of science was auspicious for the rest of the cruise as we caught and processed thousands more krill, and the seal team had a much more fruitful experience finding crabeater seals (they found/worked on 8 seals and named them all after fruits!). The highlight of this second cruise for me was getting to accompany the seal team onto an ice floe in the Lemaire Channel to assist them in their work on the crabeater, a female juvenile who they named Mango!
Figure 7. Watching Mango’s nose to calculate and record her breaths per minute (US NMSF Permit #25770).
Returning to Palmer for the final time on the LMG was just as exciting as arriving the first time, especially with the knowledge that we’d have one last night of celebration with our friends from the ship at the Cross Town Dinner – a night to celebrate the solstice with both the Palmer crew and LMG crew. Although the dinner and subsequent party were a blast, I felt a lingering sadness knowing that the majority of the people I spent almost two months with would be heading north, back to their respective homes while Kim, Rachel, and I stayed at Palmer for the next few months. The next day, after saying our goodbyes, the three of us stood on the Palmer pier with tears streaming down our faces, waving frantically at the ship to our friends on the deck. In spite of my sadness, I knew that the coming months would be a thrilling series of new experiences in one of the most magical and special places that I have ever had the pleasure of being in.
Figure 8. The LMG departs Palmer Station for the last time this winter!
