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  • 1
    Electronic Resource
    Electronic Resource
    Temporal and spatial variation of dominant pelagic Copepoda (Crustacea) in the Weddell Sea (Southern Ocean) 1929 to 1993 (1997)
    Springer
    Polar biology 18 (1997), S. 280-291 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The abundances of four dominant Antarctic copepod species, Metridia gerlachei, Rhincalanus gigas, Calanoides acutus and Calanus propinquus, were examined in the Southern Ocean in a combination of a literature review, analysis of museum samples and field sampling. The data were analysed for spatial and temporal variations. The data included in the analysis were from the Weddell Sea area in the summertime at periods 1929–1939 and 1989–1993. The results are discussed in the light of environmental changes and their hypothesised and observed consequences in the Southern Ocean: global temperature change, ozone deficiency and cascading trophic interactions. Combining all these hypothetical effects our null hypothesis was that there were no consistent long-term changes in the abundance of dominant pelagic Copepoda. The null hypothesis was rejected, since several taxons did show statistically significant long-term changes in abundance. The changes were not uniform however. The numbers of adults and juveniles of Calanus propinquus increased significantly between the periods studied. Adult stages of Calanoides acutus were the only taxon decreasing in abundance, in concert with the cascading trophic interactions theory. Latitudinally, only Metridia gerlachei showed a significant increase from north to south. Longitudinally, the abundances of Calanus propinquus juveniles and both adults and juveniles of Rhincalanus gigas increased from west to east. There were no significant variations between day and night samples. Interannual changes were statistically significant in juvenile stages of all the species and in adults of Calanus propinquus. We conclude that no uniform and consistent abundance changes could be observed in the pelagic Copepoda of the Weddell Sea that could be connected to major environmental changes, expected to affect the whole planktonic ecosystem of the Southern Ocean. Significant changes in some of the species studied show that the pelagic ecosystem is not in a steady state, but in addition to interannual changes, there are also major fluctuations extending over decades.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050189
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Aquatic biodiversity under anthropogenic stress: an insight from the Archipelago Sea (SW Finland) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 55-70 
    Details
    ISSN: 1572-9710
    Keywords: aquatic biodiversity ; Baltic Sea ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Archipelago Sea in the northern Baltic has been subjected to large-scale cultural, economic and ecological changes, especially during the last three decades. Environmental threats originate from both basin-wide sources, affecting the whole Baltic Sea, and from local sources, such as nutrient loading from nearby river outflows, intense agriculture, fish farming, ships' traffic, boating, and man's physical impacts on the landscape and seascape. Both the Åland archipelago and the Archipelago Sea have been listed as hot-spots by HELCOM, Baltic Marine Environment Protection Commission, eutrophication being the main threat to the aquatic environment. In this study we review how biological communities have reacted to an increase in man-induced multisource stresses. Changes in plankton, benthic animals, macroalgal assemblages and fish communities have been documented in most parts of the Baltic Sea since the 1970s. What remains to be understood is the importance of these structural changes for the functioning of the Archipelago Sea ecosystem under various levels of human impact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008805007339
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    Paper (German National Licenses)
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