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1. Krill availability in adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Antarctica

   https://doi.org/10.1002/lno.11750  

   Nardelli, Schuyler C.; Cimino, Megan A.; Conroy, John A.; Fraser, William R.; Steinberg, Deborah K.; Schofield, Oscar (May 2021, Limnology and Oceanography)

   Abstract The Palmer Deep canyon along the West Antarctic Peninsula is a biological hotspot with abundant phytoplankton and krill supporting Adélie and gentoo penguin rookeries at the canyon head. Nearshore studies have focused on physical mechanisms driving primary production and penguin foraging, but less is known about finer‐scale krill distribution and density. We designed two acoustic survey grids paired with conductivity–temperature–depth profiles within adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Antarctica. The grids were sampled from January to March 2019 to assess variability in krill availability and associations with oceanographic properties. Krill density was similar in the two regions, but krill swarms were longer and larger in the gentoo foraging region, which was also less stratified and had lower chlorophyll concentrations. In the inshore zone near penguin colonies, depth‐integrated krill density increased from summer to autumn (January–March) independent of chlorophyll concentration, suggesting a life history‐driven adult krill migration rather than a resource‐driven biomass increase. The daytime depth of krill biomass deepened through the summer and became decoupled from the chlorophyll maximum in March as diel vertical migration magnitude likely increased. Penguins near Palmer Station did not appear to be limited by krill availability during our study, and regional differences in krill depth match the foraging behaviors of the two penguin species. Understanding fine‐scale physical forcing and ecological interactions in coastal Antarctic hotspots is critical for predicting how environmental change will impact these ecosystems. 

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2. Use and prevalence of novel bubble-net foraging strategy in Western Antarctic humpback whales

   https://doi.org/10.3354/meps14654  

   Allen, JA; Nichols, RC; Pallin, LJ; Johnston, DW; Friedlaender, AS (August 2024, Marine Ecology Progress Series)

   The innovation of new foraging strategies allows species to optimize their foraging in response to changing conditions. Humpback whales provide a good study species for this concept, as they utilize multiple novel foraging tactics across populations in diverse environments. Bubble-net feeding (BNF), commonly seen in the Northern Hemisphere, has emerged as a foraging innovation in the past 20 yr within the Western Antarctic Peninsula. Using sightings data from 2015-2023, we found that BNF was present in every study year, with an annual average of 30% of foraging sightings. This data was supplemented with 26 animal-born tags deployed over the same study period. Of these tags, 12 detected instances of BNF, with BNF making up an average of 19% of the foraging lunges detected. There were seasonal trends in BNF sightings, as it was observed significantly more often at the beginning of the feeding season (January) before declining. BNF group sizes (mean: 3.41) were significantly larger than non-BNF surface feeding groups (mean: 2.21). This observation is consistent with BNF in the Northern Hemisphere, which also appears to primarily be a group foraging strategy. The seasonal pattern and relatively recent emergence of BNF suggests that its use is likely tied to specific environmental conditions, which should be investigated by comparing BNF with variables such as prey density and light availability. The social transmission of novel foraging strategies across other populations further suggests that the prevalence of this strategy likely occurs through social learning. 

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3. Evolved increases in hemoglobin-oxygen affinity and the Bohr effect coincided with the aquatic specialization of penguins

   https://doi.org/https://doi.org/10.1073/pnas.2023936118  

   Signore, Anthony V; Tift, Michael S; Hoffman, Federico G; Schmitt, Todd L; Moriyama, Hideaki; Storz, Jay F. (March 2021, Proceedings of the National Academy of Sciences of the United States of America)

   Somero, George N. (Ed.)

   Dive capacities of air-breathing vertebrates are dictated by onboard O2 stores, suggesting that physiologic specialization of diving birds such as penguins may have involved adaptive changes in convective O2 transport. It has been hypothesized that increased hemoglobin (Hb)-O2 affinity improves pulmonary O2 extraction and enhances the capacity for breath-hold diving. To investigate evolved changes in Hb function associated with the aquatic specialization of penguins, we integrated comparative measurements of whole-blood and purified native Hb with protein engineering experiments based on site-directed mutagenesis. We reconstructed and resurrected ancestral Hb representing the common ancestor of penguins and the more ancient ancestor shared by penguins and their closest nondiving relatives (order Procellariiformes, which includes albatrosses, shearwaters, petrels, and storm petrels). These two ancestors bracket the phylogenetic interval in which penguin-specific changes in Hb function would have evolved. The experiments revealed that penguins evolved a derived increase in Hb-O2 affinity and a greatly augmented Bohr effect (i.e., reduced Hb-O2 affinity at low pH). Although an increased Hb-O2 affinity reduces the gradient for O2 diffusion from systemic capillaries to metabolizing cells, this can be compensated by a concomitant enhancement of the Bohr effect, thereby promoting O2 unloading in acidified tissues. We suggest that the evolved increase in Hb-O2 affinity in combination with the augmented Bohr effect maximizes both O2 extraction from the lungs and O2 unloading from the blood, allowing penguins to fully utilize their onboard O2 stores and maximize underwater foraging time. 

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4. Evaluating the performance of Deep learning methods for hurricane-related image classification.

   Johnson, M.; Murthy, D.; Robertson, B. W.; Smith, W. R.; & Stephens, K. K. (January 2019, Proceedings of the ... International ISCRAM Conference)

   Global social media use during natural disasters has been well documented (Murthy et al., 2017). In the U.S., public social media platforms are often a primary venue for those affected by disasters . Some disaster victims believe first responders will see their public posts and that the 9-1-1 telephone system becomes overloaded during crises. Moreover, some feel that the accuracy and utility of information on social media is likely higher than traditional media sources . However, sifting through content during a disaster is often difficult due to the high volume of ‘non-relevant’ content. In addition, text is studied more than images posted on Twitter, leaving a potential gap in understanding disaster experiences. Images posted on social media during disasters have a high level of complexity (Murthy et al., 2016). Our study responds to O’Neal et al.’s (2017) call-to-action that social media images posted during disasters should be studied using machine learning. 

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5. Age and tectonic setting of the Paleocene Glacier Island volcanic sequence of the Orca Group in Prince William Sound, Alaska.

   https://doi.org/10.1130/abs/2019CD-329372  

   Noseworthy, C. (April 2019, Proceedings of the Keck Geology Consortium.)

   Southern Alaska has a long history of subduction, accretion, and coastwise transport of terranes (Coney et al., 1980; Monger et al., 1982; Plafker et al., 1994). The Chugach-Prince William (CPW) terrane is about 2200 km long and extends through much of southern Alaska (Plafker et al., 1994) (Fig. 1A). The inboard Chugach terrane can be divided into two parts, a mélange and sedimentary units that are Permian to Early Cretaceous in age and a turbidite sequence that is from the Upper Cretaceous (Plafker et al., 1994). In the Prince William Sound area, the outboard Prince William terrane is comprised of Paleocene to Eocene turbidites and associated basaltic rocks of the Orca Group (Davidson and Garver, 2017), and the turbidites of the inboard Chugach terrane are known as the Valdez Group. The turbidites are intruded by the Sanak-Baranof Belt (SBB), a group of 63-47 Ma plutons that are progressively younger to the east. The Border Ranges fault system marks the northern boundary of the CPW terrane, separating the Chugach terrane from the Wrangellia composite terrane and the Contact fault separates the Chugach and Prince William terrane (Fig. 1; Plafker et al., 1994). There are three ophiolite sequences in the Orca Group: Knight Island (KI), Resurrection Peninsula (RP), and Glacier Island (GI) (Fig. 1B). The KI ophiolite contains a sequence of massive pillow basalts, sheeted dikes, and a minor amount of ultramafic rocks (Tysdal et al, 1977; Nelson and Nelson, 1992; Crowe et al., 1992). The RP ophiolite is a typical ophiolite sequence and has interbedded Paleocene turbidites (Davidson and Garver, 2017). Paleomagnetic data gathered from the RP ophiolite indicated a mean depositional paleolatitude of 54° ± 7° which implies 13° ± 9° of poleward displacement (Bol et al., 1992). These data suggest that the RP ophiolite was translated northward to its current position after being formed in the Pacific Northwest, and thus the CPW terrane may have been originally located at 48-49° north and at 50 Ma was transferred 1100 km to the north by strike-slip faulting (Cowan, 2003). However, an opposing hypothesis suggests that the terrane has not experienced significant displacement and formed in Alaska due to a now-subducted Resurrection plate (Haeussler et al., 2003). KI and RP ophiolites have traditionally been assumed to be oceanic crust that was tectonically emplaced into the CPW terrane (Bol et al., 1992; Lytwyn et al., 1997). However, a more recent study suggests a hypothesis that the ophiolites originated in an upper plate setting and formed due to transtension (Davidson and Garver, 2017). Previous workers have used discriminant diagrams to identify the volcanic rocks of KI ophiolite and RP ophiolite as mid-ocean ridge basalts (Lytwyn et al., 1997; Miner, 2012). This project presents new geochemical and geochronological data from the GI ophiolite to determine its age and tectonic setting. The purpose of this study is to compare the data from GI with the data from KI and RP, and the comparison of the geochemical data will allow for a greater understanding of the tectonic setting of southern Alaska. 

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