Carbon biogeochemistry of the eastern Bering Sea shelf

Thesis (Ph.D.) University of Alaska Fairbanks, 2013The uptake of anthropogenic carbon dioxide (CO₂) has caused perturbations to marine biogeochemistry in recent years, including decreasing ocean pH and carbonate mineral saturation states (Ω). Collectively termed ocean acidification (OA), these conditions hinder the growth of calcium carbonate shells and effectively reduce habitat for some marine calcifiers. Given that the Bering Sea is one of the world's most productive marine ecosystems and supports both commercial fishing industries and subsistence communities, it is integral to understand its susceptibility to OA. Here, new observations of the organic and inorganic carbon systems are used to identify mechanisms leading to CO₂ accumulation and sub-regional enhancement of vulnerability to OA processes. Chapter 1 describes the state of knowledge of OA in this area, highlighting two regions where low Ω conditions are consistently observed: near the coast, and over the northern shelf. Chapter 2 describes net heterotrophic processes near the coast, in conjunction with low bottom water Ω. Chapter 3 examines this heterotrophy in more detail, showing that focused deposition of organic matter and its subsequent respiration. Chapters 4 and 5 focus on very low Ω values observed over the northern shelf. In combination with natural respiration processes, anthropogenic CO₂ was shown to cause low Ω and seasonal dissolution of carbonate minerals in Chapter 4. Chapter 5 illustrates how sea ice cover inhibits the flux of CO₂ from the surface ocean to the atmosphere, which raises the inventory of CO₂ in the water column. These results are synthesized in Chapter 6. Low-Ω conditions and areas of carbonate mineral dissolution will continue to expand as anthropogenic CO₂ accumulates in shelf waters in the coming decades, further reducing viable habitat for key calcifiers. Model projections of future surface water conditions indicate that average Ω over the Bering Sea shelf will drop below the observed natural variability by 2100, with average conditions favoring carbonate mineral dissolution in surface waters by 2150. Presently, episodic events will cause regions of the Bering Sea to be undersaturated in Ω, which could have significant and cascading impacts throughout the Pacific-Arctic region

Linked Open Data: What We Learned at the Society of American Archivists Conference

Are you curious what Linked Open Data can do for our libraries and our patrons? Do you wonder if it’s the next best thing or just a fad? Come join us (and bring your lunch!) for a presentation and discussion about Linked Open Data. Jim Cross and Jessica Serrao will share what they learned at the Society of American Archivists conference, including a crash course on what Linked Open Data is and use cases from other institutions. Following will be an open discussion on what this means for Clemson Libraries and the future of discovery and reuse of library and special collections data

Relationship of Athletic Injuries to the Sport's Season (Poster)

There are many factors that contribute to a college athlete's risk for injury.  Previous studies have shown that life stress can be a predictor for injury.  The current study investigated if academic stress plays a role in athletic injury rate.  Data collected from the university athletic trainer between 2012 and 2015 on athletic injuries was analyzed.  Results indicate that season start and end dates play a role in when injuries occur.  No evidence was found for academic events such as mid-terms and finals influencing the rate of injury. These findings suggest that the rate of injury for a given sport may be classified as being predominantly early-season, predominantly late-season, or predominately mid-season. Further research is needed to determine the individual factors for each sport that may explain the changes in rate of injury

Sagittal Subtalar and Talocrural Joint Assessment During Ambulation With Controlled Ankle Movement (CAM) Boots

Background: The purpose of the current study was to determine sagittal plane talocrural and subtalar kinematic differences between barefoot and controlled ankle movement (CAM) boot walking. This study used fluoroscopic images to determine talar motion relative to tibia and calcaneal motion relative to talus. Methods: Fourteen male subjects (mean age 24.1 ± 3.5 years) screened for normal gait were tested. A fluoroscopy unit was used to collect images at 200 Hz during stance. Sagittal motion of the talocrural and subtalar joints were analyzed barefoot and within short and tall CAM boots. Results: Barefoot talocrural mean maximum plantar and dorsiflexion were 9.2 ± 5.4 degrees and −7.5 ± 7.4 degrees, respectively; short CAM boot mean maximum plantar and dorsiflexion were 3.2 ± 4.0 degrees and −4.8 ± 10.2 degrees, respectively; and tall CAM boot mean maximum plantar and dorsiflexion were −0.2 ± 3.5 degrees and −2.4 ± 5.1 degrees, respectively. Talocrural mean range of motion (ROM) decreased from barefoot (16.7 ± 5.1 degrees) to short CAM boot (8.0 ± 4.9 degrees) to tall CAM boot (2.2 ± 2.5 degrees). Subtalar mean maximum plantarflexion angles were 5.3 ± 5.6 degrees for barefoot walking, 4.1 ± 5.9 degrees for short CAM boot walking, and 3.0 ± 4.7 degrees for tall CAM boot walking. Mean minimum subtalar plantarflexion angles were 0.7 ± 3.2 degrees for barefoot walking, 0.7 ± 2.9 degrees for short CAM boot walking, and 0.1 ± 4.8 degrees for tall CAM boot walking. Subtalar mean ROM decreased from barefoot (4.6 ± 3.9 degrees) to short CAM boot (3.4 ± 3.8 degrees) to tall CAM boot (2.9 ± 2.6 degrees). Conclusion: Tall and short CAM boot intervention was shown to limit both talocrural and subtalar motion in the sagittal plane during ambulation. The greatest reductions were seen with the tall CAM boot, which limited talocrural motion by 86.8% and subtalar motion by 37.0% compared to barefoot. Short CAM boot intervention reduced talocrural motion by 52.1% and subtalar motion by 26.1% compared to barefoot. Clinical Relevance: Both short and tall CAM boots reduced talocrural and subtalar motion during gait. The short CAM boot was more convenient to use, whereas the tall CAM boot more effectively reduced motion. In treatments requiring greater immobilization of the talocrural and subtalar joints, the tall CAM boot should be considered

Kinesin-1 captures RNA cargo in its adaptable coils

The prototypic and ubiquitous microtubule motor, kinesin-1, uses a variety of adaptor proteins to facilitate the selective transport of diverse cargo within the cell. These cargo adaptors bind to the motor complex through interactions with the kinesin light or heavy chains (KLCs or KHCs). In this issue of Genes & Development, Dimitrova-Paternoga et al. (pp. 976–991) present the first structural characterization of a KHC–cargo adaptor interface. They describe an antiparallel heterotrimeric coiled-coil complex between the carboxy tail of KHC and Tm1-I/C (aTm1), the atypical tropomyosin that is important for oskar mRNA transport in Drosophila oocytes. This interaction enhances direct binding between KHC and RNA. Their findings demonstrate the structural plasticity of the KHC tail as a platform for protein–protein interactions and reveal how a cargo adaptor protein can modify a motor–RNA interface to promote transport

Ocean acidification in the surface waters of the Pacific-Arctic boundary regions

Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 2 (2015): 122-135, doi:10.5670/oceanog.2015.36.The continental shelves of the Pacific-Arctic Region (PAR) are especially vulnerable to the effects of ocean acidification (OA) because the intrusion of anthropogenic CO2 is not the only process that can reduce pH and carbonate mineral saturation states for aragonite (Ωarag). Enhanced sea ice melt, respiration of organic matter, upwelling, and riverine inputs have been shown to exacerbate CO2 -driven ocean acidification in high-latitude regions. Additionally, the indirect effect of changing sea ice coverage is providing a positive feedback to OA as more open water will allow for greater uptake of atmospheric CO2 . Here, we compare model-based outputs from the Community Earth System Model with a subset of recent ship-based observations, and take an initial look at future model projections of surface water Ωarag in the Bering, Chukchi, and Beaufort Seas. We then use the model outputs to define benchmark years when biological impacts are likely to result from reduced Ωarag. Each of the three continental shelf seas in the PAR will become undersaturated with respect to aragonite at approximately 30-year intervals, indicating that aragonite undersaturations gradually progress upstream along the flow path of the waters as they move north from the Pacific Ocean. However, naturally high variability in Ωarag may indicate higher resilience of the Bering Sea ecosystem to these low-Ωarag conditions than the ecosystems of the Chukchi and the Beaufort Seas. Based on our initial results, we have determined that the annual mean for Ωarag will pass below the current range of natural variability in 2025 for the Beaufort Sea and 2027 for the Chukchi Sea. Because of the higher range of natural variability, the annual mean for Ωarag for the Bering Sea does not pass out of the natural variability range until 2044. As Ωarag in these shelf seas slips below the present-day range of large seasonal variability by mid-century, the diverse ecosystems that support some of the largest commercial and subsistence fisheries in the world may be under tremendous pressure.This project was funded by the National Science Foundation (PLR- 1041102 and AGS-1048827)

Formation and transport of corrosive water in the Pacific Arctic region

This paper is not subject to U.S. copyright. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 152 (2018): 67-81, doi:10.1016/j.dsr2.2018.05.020.Ocean acidification (OA), driven by rising anthropogenic carbon dioxide (CO2), is rapidly advancing in the Pacific Arctic Region (PAR), producing conditions newly corrosive to biologically important carbonate minerals like aragonite. Naturally short linkages across the PAR food web mean that species-specific acidification stress can be rapidly transmitted across multiple trophic levels, resulting in widespread impacts. Therefore, it is critical to understand the formation, transport, and persistence of acidified conditions in the PAR in order to better understand and project potential impacts to this delicately balanced ecosystem. Here, we synthesize data from process studies across the PAR to show the formation of corrosive conditions in colder, denser winter-modified Pacific waters over shallow shelves, resulting from the combination of seasonal terrestrial and marine organic matter respiration with anthropogenic CO2. When these waters are subsequently transported off the shelf, they acidify the Pacific halocline. We estimate that Barrow Canyon outflow delivers ~2.24 Tg C yr-1 to the Arctic Ocean through corrosive winter water transport. This synthesis also allows the combination of spatial data with temporal data to show the persistence of these conditions in halocline waters. For example, one study in this synthesis indicated that 0.5–1.7 Tg C yr-1 may be returned to the atmosphere via air-sea gas exchange of CO2 during upwelling events along the Beaufort Sea shelf that bring Pacific halocline waters to the ocean surface. The loss of CO2 during these events is more than sufficient to eliminate corrosive conditions in the upwelled Pacific halocline waters. However, corresponding moored and discrete data records indicate that potentially corrosive Pacific waters are present in the Beaufort shelfbreak jet during 80% of the year, indicating that the persistence of acidified waters in the Pacific halocline far outweighs any seasonal mitigation from upwelling. Across the datasets in this large-scale synthesis, we estimate that the persistent corrosivity of the Pacific halocline is a recent phenomenon that appeared between 1975 and 1985. Over that short time, these potentially corrosive waters originating over the continental shelves have been observed as far as the entrances to Amundsen Gulf and M’Clure Strait in the Canadian Arctic Archipelago. The formation and transport of corrosive waters on the Pacific Arctic shelves may have widespread impact on the Arctic biogeochemical system and food web reaching all the way to the North Atlantic.National Science Foundation Grant PLR-1303617