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Fairbanks, AK, United States

Arp C.D.,U.S. Geological Survey | Jones B.M.,U.S. Geological Survey | Schmutz J.A.,U.S. Geological Survey | Urban F.E.,U.S. Geological Survey | Jorgenson M.T.,ABR Inc.
Polar Biology | Year: 2010

Arctic habitats at the interface between land and sea are particularly vulnerable to climate change. The northern Teshekpuk Lake Special Area (N-TLSA), a coastal plain ecosystem along the Beaufort Sea in northern Alaska, provides habitat for migratory waterbirds, caribou, and potentially, denning polar bears. The 60-km coastline of N-TLSA is experiencing increasing rates of coastline erosion and storm surge flooding far inland resulting in lake drainage and conversion of freshwater lakes to estuaries. These physical mechanisms are affecting upland tundra as well. To better understand how these processes are affecting habitat, we analyzed long-term observational records coupled with recent short-term monitoring. Nearly the entire coastline has accelerating rates of erosion ranging from 6 m/year from 1955 to 1979 and most recently peaking at 17 m/year from 2007 to 2009, yet an intensive monitoring site along a higher bluff (3-6 masl) suggested high interannual variability. The frequency and magnitude of storm events appears to be increasing along this coastline and these patterns correspond to a greater number of lake tapping and flooding events since 2000. For the entire N-TLSA, we estimate that 6% of the landscape consists of salt-burned tundra, while 41% is prone to storm surge flooding. This offset may indicate the relative frequency of low-magnitude flood events along the coastal fringe. Monitoring of coastline lakes confirms that moderate westerly storms create extensive flooding, while easterly storms have negligible effects on lakes and low-lying tundra. This study of two interacting physical mechanisms, coastal erosion and storm surge flooding, provides an important example of the complexities and data needs for predicting habitat change and biological responses along Arctic land-ocean interfaces. © 2010 The Author(s). Source

Garshelis D.L.,University of Minnesota | Johnson C.B.,ABR Inc.
Marine Pollution Bulletin | Year: 2013

Sea otters (Enhydra lutris) suffered major mortality after the Exxon Valdez oil spill in Prince William Sound, Alaska, 1989. We evaluate the contention that their recovery spanned over two decades. A model based on the otter age-at-death distribution suggested a large, spill-related population sink, but this has never been found, and other model predictions failed to match empirical data. Studies focused on a previously-oiled area where otter numbers (~80) stagnated post-spill; nevertheless, post-spill abundance exceeded the most recent pre-spill count, and population trends paralleled an adjacent, unoiled-lightly-oiled area. Some investigators posited that otters suffered chronic effects by digging up buried oil residues while foraging, but an ecological risk assessment indicated that exposure levels via this pathway were well below thresholds for toxicological effects. Significant confounding factors, including killer whale predation, subsistence harvests, human disturbances, and environmental regime shifts made it impossible to judge recovery at such a small scale. © 2013 Elsevier Ltd. Source

Harwell M.A.,Harwell Gentile and Associates | Gentile J.H.,Harwell Gentile and Associates | Johnson C.B.,ABR Inc. | Garshelis D.L.,Grand Rapids | Parker K.R.,Data Analysis Group
Human and Ecological Risk Assessment | Year: 2010

A comprehensive, quantitative risk assessment is presented of the toxicological risks from buried Exxon Valdez subsurface oil residues (SSOR) to a subpopulation of sea otters (Enhydra lutris) at Northern Knight Island (NKI) in Prince William Sound, Alaska, as it has been asserted that this subpopulation of sea otters may be experiencing adverse effects from the SSOR. The central questions in this study are: could the risk to NKI sea otters from exposure to polycyclic aromatic hydrocarbons (PAHs) in SSOR, as characterized in 2001-2003, result in individual health effects, and, if so, could that exposure cause subpopulation-level effects? We follow the U.S. Environmental Protection Agency (USEPA) risk paradigm by: (a) identifying potential routes of exposure to PAHs from SSOR; (b) developing a quantitative simulation model of exposures using the best available scientific information; (c) developing scenarios based on calculated probabilities of sea otter exposures to SSOR; (d) simulating exposures for 500,000 modeled sea otters and extracting the 99.9% quantile most highly exposed individuals; and (e) comparing projected exposures to chronic toxicity reference values. Results indicate that, even under conservative assumptions in the model, maximum-exposed sea otters would not receive a dose of PAHs sufficient to cause any health effects; consequently, no plausible toxicological risk exists from SSOR to the sea otter subpopulation at NKI. © Taylor & Francis Group, LLC. Source

Dou F.,University of Alaska Fairbanks | Yu X.,University of Texas at Dallas | Ping C.-L.,University of Alaska Fairbanks | Michaelson G.,University of Alaska Fairbanks | And 2 more authors.
Geoderma | Year: 2010

Coastal erosion plays an important role in the terrestrial-marine-atmosphere carbon cycle. This study was conducted to explore the spatial variation of soil organic carbon (SOC) and other soil properties along the coastline of northern Alaska. A total of 769 soil samples, from 48 sites along over 1800-km of coastline in northern Alaska, were collected during the summers of 2005 and 2006. A geological information system (GIS) and a geostatistical method (ordinary kriging) were coupled to investigate the spatial variation of SOC along the coastline. SOC have a big variation ranging from 0.8 to 187.4 kg C m- 2 with the greatest value observed in the middle and lowest in the northeastern coastline. Compared to the 1-D model or the 1-D model with shortcut distance, the 2-D model was more reasonable to describe SOC along the coastline. The Gaussian correlation structure model had less prediction error than other examined geostatistical models. All mapping results also indicate that soils of the northwestern coastline stored greater SOC than those of the northeastern coastline. The estimation of total SOC along the coastline of northern Alaska was 6.86 * 107 kg m- 1. The prediction errors indicated that greater errors were observed in both ends of the coastline than were observed in other fractions, although the range was from 0.739 to 0.779. Our study suggests that the isotropic 2-D model without a trend, with the nugget effect and the Gaussian correlation structure is a useful tool to investigate SOC in large scale. Results of stable isotope of organic matter indicate that SOC are mainly derived from C3 plant, which ranged from - 30‰ to - 22‰. © 2009 Elsevier B.V. Source

Ping C.-L.,University of Alaska Fairbanks | Michaelson G.J.,University of Alaska Fairbanks | Guo L.,University of Southern Mississippi | Jorgenson M.T.,ABR Inc. | And 4 more authors.
Journal of Geophysical Research: Biogeosciences | Year: 2011

Carbon, nitrogen, and material fluxes were quantified at 48 sampling locations along the 1957 km coastline of the Beaufort Sea, Alaska. Landform characteristics, soil stratigraphy, cryogenic features, and ice contents were determined for each site. Erosion rates for the sites were quantified using satellite images and aerial photos, and the rates averaged across the coastline increased from 0.6 m yr-1 during circa 1950-1980 to 1.2 m yr -1 during circa 1980-2000. Soils were highly cryoturbated, and organic carbon (OC) stores ranged from 13 to 162 kg OC m-2 in banks above sea level and averaged 63 kg OC m-2 over the entire coastline. Long-term (1950-2000) annual lateral fluxes due to erosion were estimated at -153 Gg OC, -7762 Mg total nitrogen, -2106 Tg solids, and -2762 Tg water. Total land area loss along the Alaska Beaufort Sea coastline was estimated at 203 ha yr-1. We found coastal erosion rates, bank heights, soil properties, and material stores and fluxes to be extremely variable among sampling sites. In comparing two classification systems used to classifying coastline types from an oceanographic, coastal morphology perspective and geomorphic units from a terrestrial, soils perspective, we found both systems were effective at differentiating significant differences among classes for most material stores, but the coastline classification did not find significant differences in erosion rates because it lacked differentiation of soil texture. Copyright © 2011 by the American Geophysical Union. Source

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