Lofoten Vesteralen Research Articles

New ecological knowledge of the bubblegum coral Paragorgia arborea (L. 1758) using computer vision

IntroductionModern stationary observatories, equipped with cameras and other sensors, make it possible to observe and study cold-water corals in situ over increasingly long periods of time. In this study we investigate data collected for a bubblegum coral (Paragorgia arborea) with the LoVe (Lofoten Vesteralen) observatory for a period of 117 days, including time series of images, current, water depth and temperature. This kind of multimodal time series data represent a new methodological challenge for marine technology and bioinformatics.MethodsIn this work, we continue on the path to computer-aided ocean data analysis and show how, in addition to polyp activity, morphological parameters can be extracted from image data with a new deep learning-based approach. Using customized visualizations we show how this image-derived data together with the environmental data can be analysed and new interpretations are supported.ResultsOur results indicate that the polyp activity and branch diameter variation followed a semi-cyclic pattern, with the polyps changing from fully retracted to fully expanded faster than the image sampling rate, resulting in an almost binary time series that showed positive correlation with the current strength, which may be related to food supply. The periods of full polyp expansion ranged from 1 to 4 h, with the majority around 1 h. The variation in branch diameter and volume of intra-skeletal channels probably relates to the intra-colonial transport of nutrients and waste products. During a 16 day period in March 2019, the polyps remained retracted for an extended period accompanied by little variation in branch diameter. This behaviour was not related to any of the measured environmental conditions. Further studies are required to determine if this could be linked to biological processes, such as reproduction.

Canyons and slope instability on the Lofoten–Vesterålen continental margin, North Norway

Canyons are relatively unusual features of the 2500 km long Norwegian–Svalbard continental slope, where ice sheets have delivered large volumes of sediment to the upper slope a number of times during the Quaternary (Ottesen et al. 2005). The 250 km long, steep and topographically complex slope off Lofoten and Vesteralen in North Norway (Taylor et al. 2000; Laberg et al. 2007) has recently been mapped in detail using high-resolution multibeam methods (Fig. 1a–g) (www.mareano.no). The slope is dissected by 15 well-defined canyon systems and numerous slide scars (Rise et al. 2013), with the largest and deepest of these canyons incised by nearly 1100 m (Laberg et al. 2007). Fig. 1. Canyons and mass movements on the Lofoten–Vesteralen margin, North Norway. Acquisition system Kongsberg EM 120. Frequency 12 kHz. Grid-cell size 25 m. ( a ) Shaded-relief image. Blue dashed lines mark axes of cross-shelf troughs. Fifteen canyons are numbered. A, Andoya. ( b ) Elongate slide scars on the upper slope of canyon 3. L, debris lobe. ( c ) Upper part of canyons 8 and 9. Note amphitheatre-shaped head- and side-walls indicating retrogressive slide activity. White dashed lines mark ridges (R) between adjacent slide branches. ( d ) Slope gradient image combined with …

The Andøya Canyon, Norwegian Sea

The relatively steep continental slope offshore north Norway (3–7°) is dissected by several valleys (e.g. Taylor et al. 2000; Rise et al. 2013), none of which is related to coastal rivers opening into the fjords dominating the coast (Corner 2005). Two end-member valley forms have been identified: (1) classical submarine canyons characterized by a V-shaped cross-section, which can be followed from the shelf edge to the base of the continental slope where they continue as deep-sea channels; and (2) steep-sided, flat-floored valleys, some of uniform width, others widening upslope, some of which can be followed upslope to the shelf break while others have their headwalls located further downslope; debris-flow lobes occur beyond their downslope terminations (Rise et al. 2013). The Andoya Canyon (Fig. 1) exemplifies the morphology of the classical submarine canyons on the Lofoten–Vesteralen margin (Laberg et al. 2007). The canyon is about 40 km long (from the headwall to 2100 m water depth), about 9 km wide between the canyon shoulders and the maximum incision is …

Structural geomorphology and morphological development in the Lofoten–Vesterålen area, Norway

Peulvast, J. P. 1986. Structural geomorphology and morphological development in the Lofoten–Vesteralen area, Norway. Norsk geogr. Tidsskr. Vol. 40, 135–161. Oslo. ISSN 0029–1951. The Lofoten–Vesteralen area is mainly developed in a system of horsts of weakly caledonized Precambrian rocks, north of the Polar Circle. The respective influences of lithology and Mesozoic and Tertiary tectonics on the differentiation of the three main morphostructural types (jagged migmatitic or mangeritic mountains, heavy monzonitic or gabbroic plateaus, systems of ridges and corridors developed in gneisses and intrusive rocks more or less modified by the Sveconorwegian metamorphism) are analysed. Differential erosion appears to have been a prevalent process in the morphological development. Through the main types of landscapes, the meaning of the minor features is discussed respectively in bare rock areas, in areas covered with saprolites and in strandflat areas. This is the basis for a tentative reconstruction of the morphot...

Geochemistry of Precambrian basal gneisses in Lofoten—Vesterålen, northern Norway

Abstract The basal gneiss complex of Lofoten—Vesteralen consists of an older (ca. 2.7 Ga) migmatite complex, believed to be largely supracrustal in origin, and a younger (ca. 1.8 Ga) cover complex of clearly supracrustal origin. The major-element geochemistry of both groups is that of an igneous suite of generally calc-alkaline character. Similarities with the volcanic rocks of modern continental-margin environments extend to trace-element contents and REE patterns. A complex multistage evolution is inferred. An orthopyroxene isograd bisects the area. Element fractionation between amphibolitefacies and granulite-facies rocks appears to be limited to some trace elements; REE patterns are not affected by the metamorphism.

Continental Margin off Norway: A Geophysical Study

Geophysical investigations consisting of gravity, magnetic, depth sounding, seismic reflection and refraction measurements were made aboard R/V Vema on the continental margin off Norway. Utilizing these and earlier data in the area, maps showing bathymetry, free-air gravity, magnetic residual total intensity, seismic refraction results, total sediment thickness and thickness of Cenozoic sediments have been constructed. The data are also presented as profiles across the margin. The Voring Plateau is underlain by a buried escarpment; the basement is shallow on the seaward side and deep on the landward side. A similar marginal escarpment, the Faroe–Shetland, exists farther south. These escarpments mark the site of the Tertiary opening of the Norwegian Sea. Seaward, Tertiary sediments overlie a basement generated by sea-floor spreading. Landward, a thick sequence of sediments that may be as old as Paleozoic overlies a continental basement. The magnetic quiet zone on the landward side of the escarpment is attributed to the continental nature of the basement. A nearly continuous belt of positive gravity and magnetic anomalies that exists just landward of the edge of the shelf is attributed primarily to intrabasement density contrasts in rocks that are probably Precambrian in age. It extends from northwest Scotland to the Lofoten–Vesteralen islands. The continental margin off Norway formed an epicontinental sea continuous with the North Sea in which a large amount of sedimentation kept pace with subsidence—a phenomenon which perhaps started in the late Paleozoic. The thickness of pre-Cenozoic sediments exceeds 6 km in some areas, but has a relative minimum over the belt of high density rocks of Precambrian age, which presumably underwent the least relative subsidence. We suggest that the opening of the Norwegian Sea at the marginal escarpments is associated with subsidence of the continental crust between the escarpments and the shelf where the high-density belt acts as a hinge line and accounts for the existence of the shelf break. The subsided area is characterized by a regional free-air gravity low. The marginal Voring Plateau Escarpment formed at the opening of the Norwegian Sea served to dam the Tertiary sediments and develop the V0ring Plateau. The Norwegian Channel is shown not to be of tectonic origin. The Tertiary basin of the North Sea continues northward under the continental margin off Norway.