Browsing by Subject "NORTH"

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  • Luostarinen, Tiia; Ribeiro, Sofia; Weckstrom, Kaarina; Sejr, Mikael; Meire, Lorenz; Tallberg, Petra; Heikkila, Maija (2020)
    We recorded diatom species succession over one full year (May 2017-May 2018) using automated sediment traps installed in two contrasting Greenlandic fjords: the seasonally ice-covered Young Sound in high-arctic Northeast Greenland and the nearly sea-ice free Godthabsfjord in subarctic Southwest Greenland. The traps were positioned at differing water depths (37m in Young Sound vs. 300m in Godthabsfjord). Distinct differences between the study sites were observed in both sediment and diatom fluxes. In Young Sound, total diatom flux was extremely seasonal and as high as 880 x 10(6) valves m(-2) d(-1) in the spring. In Godthabsfjord, total diatom flux was more stable throughout the year, with a maximum of 320 x 10(6) valves m(-2) d(-1) in the summer. The diatom assemblage in Young Sound was dominated by the sea-ice species Fragilariopsis oceanica, Fragilariopsis reginae-jahniae and Fossula arctica, which exhibited pulse-like deposition in the trap during and after the ice melt. In Godthabsfjord, the fluxes were dominated by Chaetoceros (resting spores), while the remaining assemblage was characterised by the cold-water indicator species Detonula confervacea (resting spores) and Thalassiosira antarctica var. borealis (resting spores) together with Fragilariopsis cylindrus. Our data show that, F. oceanica, F. reginae-jahniae and F. arctica exhibit similar seasonal behaviour and a clear link to sea ice. Fragilariopsis cylindrus seems to have a more flexible niche, and based on our study, cannot be considered an unequivocal ice indicator. Taking into account these ecological and seasonal preferences of individual diatom species is crucial when reconstructing past sea-ice conditions both qualitatively and quantitatively.
  • Virkkala, Raimo; Lehikoinen, Aleksi; Rajasärkkä, Ari (2020)
    Protected areas (PAs) should maintain populations of focal species, but their ability to achieve this target is affected both by land use outside PAs and by climate warming. To study effects of land use on species and ability of PAs to maintain populations of species, we compared trends in abundance of 15 resident bird species between two periods of relatively stable and increasing logging volume in boreal forests in Finland, in 2006-2011 and 2012-2018, respectively. We studied trends in abundance of forest birds in unprotected areas and in PAs, where logging is not allowed. In general, patterns of population changes did not differ between PAs and unprotected areas. Abundances of ten of the 15 species were, however, concentrated in southern Finland, where PAs have low coverage, and where trends in abundance merely reflect changes in unprotected areas. Five species declined, and they all probably suffered from the effects of increased logging. Four of them had a southern distribution in Finland, so they should even benefit from the rapid climate warming occurring in these regions. In northern Finland, PAs cover a much higher proportion of land than in southern Finland, and thus PA network may better maintain populations, which was also reflected in more stable populations of species therein. For populations to persist in PAs and for PAs to buffer against environmental changes, a PA network should have a high level of coverage as in northernmost Finland thus supporting Aichi Target 11.
  • Hoekman, David; LeVan, Katherine E.; Ball, George E.; Browne, Robert A.; Davidson, Robert L.; Erwin, Terry L.; Knisley, C. Barry; LaBonte, James R.; Lundgren, Jonathan; Maddison, David R.; Moore, Wendy; Niemelä, Jari; Ober, Karen A.; Pearson, David L.; Spence, John R.; Will, Kipling; Work, Timothy (2017)
    The National Ecological Observatory Network (NEON) will monitor ground beetle populations across a network of broadly distributed sites because beetles are prevalent in food webs, are sensitive to abiotic factors, and have an established role as indicator species of habitat and climatic shifts. We describe the design of ground beetle population sampling in the context of NEON's long-term, continentalscale monitoring program, emphasizing the sampling design, priorities, and collection methods. Freely available NEON ground beetle data and associated field and laboratory samples will increase scientific understanding of how biological communities are responding to land-use and climate change.
  • Unger Moreno, Katharina A.; Thal, Janis; Bach, Wolfgang; Beier, Christoph; Haase, Karsten M. (2021)
    The formation of isolated seamounts distant from active plate boundaries and mantle plumes remains unsolved. The solitary intraplate volcano Vesteris Seamount is located in the Central Greenland Basin and rises ∼3,000 m above the seafloor with a total eruptive volume of ∼800 km3. Here, we present a new high-resolution bathymetry of Vesteris Seamount and a detailed raster terrain analysis, distinguishing cones, irregular volcanic ridges, volcanic debris fans, U-shaped channels and lava flows. The slope angles, ruggedness index and slope direction were combined with backscatter images to aid geologic interpretation. The new data show that the entire structure is a northeast to southwest elongated stellar-shaped seamount with an elongated, narrow summit surrounded by irregular volcanic ridges, separated by volcanic debris fans. Whole-rock geochemical data of 78 lava samples form tight liquid lines of descent with MgO concentrations ranging from 12.6 to 0.1 wt%, implying that all lavas evolved from a similar parental magma composition. Video footage from Remotely Operated Vehicle (ROV) dives shows abundant pyroclastic and hyaloclastite deposits on the summit and on the upper flanks, whereas lavas are restricted to flank cones. The seamount likely formed above a weak zone of the lithosphere possibly related to initial rifting parallel to the nearby Mohns Ridge, but the local stress field increasingly affected the structure of the volcano as it grew larger. Thus, we conclude that the evolution of Vesteris Seamount reflects the transition from deep, regional lithospheric stresses in the older structures to shallower, local stresses within the younger volcanic structures similar to other oceanic intraplate volcanoes. Our study shows how the combination of bathymetric, visual and geochemical data can be used to decipher the geological evolution of oceanic intraplate volcanoes.