• Long-term shifts in community structure, growth, and relative abundance of nearshore Arctic fishes: a response to changing environmental conditions

      Priest, Justin T.; Sutton, Trent M.; Mueter, Franz J.; Raborn, Scott W. (2020-08)
      Environmental conditions influence the presence, species composition, abundance, and growth of fish species in the nearshore Arctic ecosystem. With ongoing shifts in Arctic conditions due to climate change, how fish communities and individual species respond to such changes to environmental variability more broadly is unknown. This study analyzed catch and length data from a long-term fish monitoring project near Prudhoe Bay, Alaska, 2001-2018, to quantify the effects of environmental variables on the overall fish community and on the juveniles of two important whitefishes, Arctic Cisco Coregonus autumnalis and Broad Whitefish Coregonus nasus. Abundance data (n = 1.78 million fish) from daily sampling (July-August) at four stationary sampling locations showed distinct shifts in fish community metrics. Since 2001, annual species richness has significantly increased by one species per decade while water temperature warmed by over 1.4°C. The species composition based on biweekly catch data has significantly changed across years, with distinct variations among sample locations and throughout the season. Species composition was significantly affected by both salinity and water temperature. The effects of environmental conditions on growth showed that water temperature was positively and linearly associated with increases in growth for juvenile whitefish, while salinity negatively affected growth of age-0 Arctic Cisco. Changes in the abundance of juvenile whitefishes were related to both water temperature and salinity. Results from all analyses suggest that species positively associated with observed warming in the aquatic environment are generalist species such as Broad Whitefish. This study concluded that continued climate change, and especially Arctic warming, will likely increase growth, change the species composition, and alter abundance in the Arctic nearshore ecosystem. These changes will have impacts on subsistence harvests and on upper trophic level species that prey on nearshore fishes.
    • Shallow surface thermogenic hydrocarbon migration over western Prudhoe Bay Region, Alaska

      Sarkar, Sudipta (2008-12)
      "Hydrocarbons leak from petroleum reservoirs to the surface. In continuous permafrost regions like the Alaska North Slope, surface migration of thermogenic hydrocarbons may be hindered by the presence of ground ice. However, suitable permeable migration pathways in the permafrost can exist. Unfrozen sediments at the bottom of the lakes, or open faults can facilitate thermogenic hydrocarbon migration. I studied the nature and distribution of gaseous alkanes (C1 to C6) and helium in the shallow permafrost cores (2 m depth); depth profiles of alkanes (C1 to C7) in the two wells (1500 m deep); and stable isotopes of CH₄ trapped in lake gas bubbles, to trace the presence of thermogenic hydrocarbons and their migration pathways. Geostatistical analysis of the alkane and helium distributions shows that most anomalies occur along northwest-southeast oriented lineaments, roughly corresponding to the trend of the Eileen fault mapped at 2675 m depth, high fault density zones of the Kuparuk Formation, and northwest-southeast trending Sagavanirktok faults mapped at 457 m depth. The anomalies above the Eileen fault can be explained by a fluid-flow model in a dilational jog along a wrench fault. This model agrees with the movements along the Eileen fault"--Leaf iii
    • Winter movements of Arctic foxes in Northern Alaska measured by satellite telemetry

      Pamperin, Nathan J.; Follman, Erich H.; Lindberg, Mark S.; Huettmann, Falk; Person, Brian (2008-12)
      We studied winter movements of 37 arctic foxes (Alopex lagopus) collared within a petroleum development area at Prudhoe Bay, Alaska (n = 20), and an undeveloped area in the National Petroleum Reserve-Alaska (NPR-A, n = 17) during the winters of 2004, 2005, and 2006 using satellite telemetry. Comparing Prudhoe Bay and NPR-A, differences in mean movement rates of juveniles was 23.9 ± 2.7 km per duty cycle and 10.6 ± 2.8 km per duty cycle for adults, and mean difference in maximum distance from capture site for juveniles was 265.2 ± 63.2 km and 205.5 ± 128.9 km for adults. Juveniles and adults collared in NPR-A were highly mobile and made long distance movements (up to 782 km) while foxes from Prudhoe Bay remained in or near the oil field throughout winter. Extensive use of sea-ice by three juvenile foxes from NPR-A was documented during the winter of 2005-2006. Three juvenile foxes traveled long distances (904, 1096, and 2757 km) during the winter and remained on the sea-ice for extended periods of time (76, 120, and 156 days). These findings verify the use of sea-ice by arctic foxes and raise concerns that the diminishing ice cover may negatively impact populations by limiting access to marine food sources. We conclude that the oilfields are having a strong effect on the winter movements of arctic fox and suggest differences in movements are likely attributable to the availability of anthropogenic foods at Prudhoe Bay.