1,721,133 research outputs found
Biodiversity of benthic macro-and microalgae from Svalbard with special focus on Kongsfjorden
No full textSeveral floristic studies on macroalgae of Svalbard have been published, but as access to the archipelago is difficult, these studies are scattered and often only cover single sites and habitats. Kongsfjorden, Isfjorden and Hornsund are the three most comprehensively investigated areas, and most of the species information comes from these three fjords. Quantitative and structured sublittoral sampling has been undertaken along depth transects and along the fjord only in Kongsfjorden. Clear dif-ferences are found from the outer to the inner parts of the fjord. Macroalgal biodiversity data from Kongsfjorden are presented in detail and compared to data for the whole archipelago. In total 197 species of macroalgae have been recorded for Svalbard; 84 of these occur in Kongsfjorden. The current taxonomic status of some species is discussed. Changes in the macroalgal flora during the last decades for Svalbard in general and in Kongsfjorden in particular, are summarised and possible causes discussed. Information on biodiversity of microphytobenthos is very scarce, and investigations in
Kongsfjorden on benthic diatoms from soft bottom and biotic surfaces provide the first floristic information available. A total of 69 diatoms species have been identified and form a first baseline for a high-latitude fjord system. Biodiversity is relatively low compared to other sandy marine shallow water areas of temperate regions as indicated by the Shannon-Weaver index. Some data on epiphytic diatoms colonising seaweeds are available. Benthic diatoms colonise large parts of Kongsfjorden in high abundances and, in addition to macroalgae, are important as primary producers and therefore also for trophic relationships in the harsh Arctic environment
The Atmosphere above Ny-Ålesund – Climate and global warming, ozone and surface UV radiation
Full text linkThe Arctic region is considered to be most sensitive to climate change, with warming in the Arctic occurring considerably faster than the global average due to several positive feedback mechanisms contributing to the “Arctic amplification”. Also the maritime and mountainous climate of Svalbard has undergone changes during the last decades. Here, the focus is set on the current atmospheric boundary conditions for the marine ecosystem in the Kongsfjorden area, discussed in the frame of long-term climatic observations in the larger regional and hemispheric context.
During the last century, a general warming is found with temperature increases and precipitation changes varying in strength. During the last decades, a strong seasonality of the warming is observed in the Kongsfjorden area, with the strongest temperature increase occurring during the winter season. The winter warming is related to observed changes in the net longwave radiation. Moreover, changes in the net shortwave are observed during the summer period, attributed to the decrease in reflected radiation caused by the retreating snow cover.
Another related aspect of radiation is the intensity of solar ultra-violet radiation that is closely coupled to the abundance of ozone in the column of air overhead. The long term evolution of ozone losses in the Arctic and their connection to climate change are discussed
Ecological Drivers of and Responses by Arctic Benthic Communities, with an Emphasis on Kongsfjorden, Svalbard
No full textKnowledge on the causes and consequences that structure benthic communities is essential to understand and conserve Arctic ecosystems. This review aims to summarize the current knowledge on the effects of abiotic and biotic factors on species interactions and community traits, i.e. diversity, structure, and functioning of Arctic coastal hard- and soft-bottom habitats, with emphasis on Kongsfjorden (Svalbard). Current evidence indicates that descriptive and mensurative studies on the distribution of species prevail and few studies allow inferences on the underlying processes generating observed patterns. Furthermore, Arctic hard- and soft-bottom communities show some fundamental differences in their ecology. The recovery in hard-bottom communities from disturbance, for instance, takes exceptionally long (i.e. > decadal) due to slow growth and/or sporadic recruitment, while it is considerably shorter in soft-bottom communities. Also, Arctic hard-bottom
communities display strong competitive hierarchies that appear negligible in communities populating sedimentary shores. This review concludes with a suggestion to shift the focus in Arctic benthos research from pattern to processes and the identification of major research gaps. These include (i) the apparent demarcation of studies being devoted to either rocky or to sedimentary shores, which hamper studies on habitat connectivity, (ii) the lack of studies addressing the effects of pathogens and diseases on community ecology, and (iii) the incomplete assessment of potentially significant drivers of community ecology, such as trophic interactions, recruitment success, and competition
The underwater ligth climate in Kongsfjorden and its ecological implications
No full textDue to its Arctic location at 79°N, Kongsfjorden in Svalbard experiences strong seasonality in light climate, changing from polar night to midnight sun. Sea ice conditions and the optical properties of seawater further modify the amount and the spectral composition of solar radiation penetrating into the water column, thus defining the underwater light climate in Kongsfjorden. Light represents one of the
major shaping factors for the entire marine ecosystem. A number of studies focusing on implications of the underwater light for marine organisms have beenconducted in Kongsfjorden, generating diverse datasets on seawater optical properties, scattered over time and space. This review synthesizes the fragmentary information available from the literature as well as presenting some unpublished data,
and discusses the underwater light climate and its main controlling factors in Kongsfjorden. Furthermore, we provide a short synopsis about the relevance of light for different components of an Arctic marine ecosystem, exemplified by studies carried out in Kongsfjorden. Due to its year-round accessibility and its high-Arctic location, Kongsfjorden has become a prime fjord for studying how the strong seasonal
changes in light availability, ranging from polar night to midnight sun, affect marine life with respect to primary production, behavioural aspects and synchronization of growth and reproduction
Comparative feeding ecology of the sympatric cod fishes Arctogadus glacialis and Boreogadus saida in North East Greenland evaluated from diet and stable isotope analyses
Full text linkThe fish fauna was investigated in autumn 2003 during the TUNU-I Expedition to NE Greenland fjords. Two gadoids Arctogadus glacialis and Boreogadus saida were abundant in many trawl hauls. In this study, the stomach contents and the stable isotope composition were determined in 60 Arctogadus glacialis and 50 Boreogadus saida from Tyrolerfjord and Dove Bugt. The diets were examined by Stomach Contents Analysis (SCA) and compared with chi-square test and Schoener index. The diets were similar containing the same prey species, mostly crustaceans (copepods, mysids and amphipods). Significant differences were found, mainly in the proportions of two crustaceans, the mysid Mysis oculata and the copepod Metridia longa. Fish was found in the stomachs of large Arctogadus glacialis. The stable isotope composition was analyzed with Stable Isotope Analysis (SIA). Differences were discovered between species and fjords. Arctogadus glacialis had δ13C mean of -20.81 and -21.33‰, δ15N mean of 14.92 and 14.21‰, in Tyrolerfjord and Dove Bugt, respectively. Boreogadus saida had δ13C mean of -21.25 and -21.52‰, δ15N mean of 13.64 and 14.47‰ in the respective fjords. Trophic levels of the species were inferred from mean δ15N-values. The mean δ13C and δ15N values for the predators corresponded well with those of the prey species from the literature, with an enrichment value of 3.8‰ for δ15N. This is the first study that examines the isotope signature and trophical position of Arctogadus glacialis
Spatial and temporal variability of the ice-ocean system in the Marginal Ice Zone of the Barents Sea
Full text linkSpatial and temporal variability of the ice-ocean system in the Marginal Ice Zone of the Barents Sea
No full textEcological processes in the marginal ice-zone of the northern Barents Sea : ICE-BAR 1995, Cruise Report
No full textEcological processes in the marginal ice-zone of the northern Barents Sea : ICE-BAR 1995, Cruise Report
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