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  • 1990-1994  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Sampling biological characteristics of krill: Effect of heterogeneous nature of swarms (1990)
    Springer
    Marine biology 107 (1990), S. 409-415 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An effect of the very patchy distribution of Antarctic krill (Euphausia superba Dana) in various forms of aggregation is that a single swarm may not provide an unbiased estimate of population parameters such as mean length of krill in the local area. Here, we analyse the number of samples required to estimate the characteristics of a local population as precisely as if there were no differences between krill swarms in terms of their biological composition. Krill were intensively sampled over different spatial and temporal scales around South Georgia in 1981 and 1982, and in the Bransfield Strait in 1985. These varied from replicate hauls at a single station over 24 h and repeat sampling in restricted areas over periods of 6 to 14 d to regional surveys around South Georgia and in the Bransfield Strait. Various biological characteristics were measured such as length, maturity, moult stage and feeding state. Depending upon the biological characteristic examined and the area covered by the sampling programme, the number of samples needed to obtain the same degree of precision as would be found in the absence of heterogeneity varied from 3 to 〉 80 samples. This has important implications for the design of net-sampling programme for monitoring krill populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313422
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cephalopod prey of the grey-headed albatrossDiomedea chrysostoma (1990)
    Springer
    Marine biology 104 (1990), S. 353-362 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cephalopod remains were collected, at regular intervals throughout the fledging period, from the stomach contents of chicks of the grey-headed albatrossDiomedea chrysostoma at Bird Island, South Georgia, in 1984 and 1986 and from regurgitations of adults at the nest in 1986. The 1984 sample was taken during a season characterised by abnormal local oceanographic conditions in which the breeding success was very low; in 1986 conditions were normal and breeding success was high. Cephalopod beaks (289 from adults; 5 651 from chicks) were identified, and allometric equations were used to estimate the biomass represented. Five cephalopod species belonging to five families (Gonatidae, Onychoteuthidae, Psychroteuthidae, Ommastrephidae and Cranchiidae) contributed 98% by number and 97% of the biomass fed to chicks. The most important species was the ommastrephidMartialia hyadesi, contributing 68.9 to 77.4% by number and 72.5 to 79.3% of the total biomass fed to chicks. The relative proportions of cephalopod species in the chicks' diet were similar between 1984 and 1986, but the total number and biomass was significantly less in 1984. There is evidence of growth ofM. hyadesi between January and June.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01314337
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  • 3
    Electronic Resource
    Electronic Resource
    Antarctic krill aggregation characteristics from acoustic observations in the Southwest Atlantic Ocean (1993)
    Springer
    Marine biology 117 (1993), S. 171-183 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distributional features and physical characteristics of 4830 krill (Euphausia superba Dana) aggregations detected acoustically in the Southwest Atlantic between 26 January and 21 February 1981 are described. Results are compared with aggregations detected in the Indian Ocean. Aggregations in the Atlantic were larger, closer to the surface and to each other than in the Indian Ocean. Similar patterns in the distribution of aggregation spacing along survey transects were found in the two areas, although the pattern of spacings in the Atlantic indicates differences in the scale of aggregation. Serial interdependence of aggregation variables was minimal in the Atlantic, with aggregation thickness, length and spacing showing weak inter-relationships. Weak functional association, between water depth and aggregation thickness was evident. Investigation of variability in aggregation structure in relation to prevailing environmental conditions gave equivocal results and no clear association between any aggregation variable and prevailing hydrography was observed. The implications of these results for future studies on krill aggregation are discussed in relation to a conceptual framework which was developed from the present results and aimed at linking krill aggregation characteristics to environmental features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346440
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  • 4
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    Antarctic krill aggregation characteristics from acoustic observations in the Southwest Atlantic Ocean (1993)
    Springer
    Details
    Publication Date: 1993-09-01
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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  • 5
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    Sampling biological characteristics of krill: Effect of heterogeneous nature of swarms (1990)
    Springer
    Details
    Publication Date: 1990-10-01
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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  • 6
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    Unknown
    Cephalopod prey of the grey-headed albatrossDiomedea chrysostoma (1990)
    Springer
    Details
    Publication Date: 1990-10-01
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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  • 7
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    Abundance and diurnal vertical distribution of fish larvae in early spring and summer in a fjord at South Georgia (1992)
    Cambridge University Press
    Details
    Publication Date: 1992-12-01
    Description: The diurnal vertical distribution and abundance of fish larvae was studied by net samples in the 265 m deep fjord of Cumberland East Bay, South Georgia. In early spring the six most abundant species of fish larvae in the upper 200 m of the water column were Champsocephalus gunnari, Lepidonotothen nudifrons, Pseudochaenichthys georgianus, Chaenocephalus aceratus, Parachaenichthys' georgianus and Electrona antarctica. In summer, the larvae of C. gunnari, Gobionotothen gibberifrons, Lepidonotothen larseni and Trematomus hansoni were most abundant, and the majority were found in the upper 140 m of the water column, with greatest densities in the top 2m. During both seasons most species showed some evidence of diurnal vertical migration. A distinct pattern was found for C. gunnari in summer; they were at 0–20 m during the day and 60–100 m at midnight. Net avoidance by the larvae of most species was greater before sunset in early spring, and during all periods of daylight in summer, than at other times of day.
    Print ISSN: 0954-1020
    Electronic ISSN: 1365-2079
    Topics: Biology , Geography , Geosciences
    Published by Cambridge University Press
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  • 8
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    Unknown
    Cephalopod prey of the southern elephant seal, Mirounga leonina L. (1992)
    Canadian Science Publishing
    In:  Canadian Journal of Zoology, 70 (5). pp. 1007-1015.
    Details
    Publication Date: 2020-07-24
    Description: In the austral summers of 1986 and 1988–1989, 51 southern elephant seals (Mirounga leonina) at Husvik, South Georgia (54°10′S; 36°43′W), were stomach lavaged after chemical immobilization. Only cephalopod remains were retrieved, including 1070 lower beaks that were identified and measured. In total these were estimated to represent a wet weight of 187.8 kg. Fourteen species of squid from 11 families and 2 species of octopod from 1 family were present. The most important species overall were the squids Psychroteuthis glacialis in terms of numerical abundance (33.7%) and Moroteuthis knipovitchi in terms of estimated biomass (31.2%). The remaining biomass was mainly comprised of the five large muscular squids, Kondakovia longimana (24.0%), P. glacialis (15.4%), Martialia hyadesi (11.2%), Alluroteuthis antarcticus (10.8%), and Gonatus antarcticus (3.6%). Larger seals of both sexes fed on a wider variety of cephalopod species than smaller seals, with large males taking the greatest diversity. Between the two summers of the study there were some changes in the relative importance of the various cephalopod species consumed; in particular, in 1988–1989 M. knipovitchi and M. hyadesi were less important and P. glacialis was more important. The taxa and size of cephalopods taken by southern elephant seals at South Georgia are almost identical to those taken by the grey-headed albatross (Diomedea chrysostoma), but the relative proportions are quite different. The biogeography of the cephalopods eaten suggests that southern elephant seals sampled at South Georgia do not forage to the north of the Antarctic Polar Front but probably travel southwards towards the Antarctic continent or Peninsula.
    Type: Article , PeerReviewed
    Format: text
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  • 9
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    Cephalopod prey of the grey-headed albatross Diomedea chrysostoma (1990)
    Springer
    In:  Marine Biology, 104 (3). pp. 353-362.
    Details
    Publication Date: 2020-07-14
    Description: Cephalopod remains were collected, at regular intervals throughout the fledging period, from the stomach contents of chicks of the grey-headed albatrossDiomedea chrysostoma at Bird Island, South Georgia, in 1984 and 1986 and from regurgitations of adults at the nest in 1986. The 1984 sample was taken during a season characterised by abnormal local oceanographic conditions in which the breeding success was very low; in 1986 conditions were normal and breeding success was high. Cephalopod beaks (289 from adults; 5 651 from chicks) were identified, and allometric equations were used to estimate the biomass represented. Five cephalopod species belonging to five families (Gonatidae, Onychoteuthidae, Psychroteuthidae, Ommastrephidae and Cranchiidae) contributed 98% by number and 97% of the biomass fed to chicks. The most important species was the ommastrephid Martialia hyadesi, contributing 68.9 to 77.4% by number and 72.5 to 79.3% of the total biomass fed to chicks. The relative proportions of cephalopod species in the chicks' diet were similar between 1984 and 1986, but the total number and biomass was significantly less in 1984. There is evidence of growth ofM. hyadesi between January and June.
    Type: Article , PeerReviewed
    Format: text
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