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Multivariate analyses of the macrozooplankton community and euphausiid larval ecology in the Prydz Bay region, Antarctica


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Hosie, Graham William 1992 , 'Multivariate analyses of the macrozooplankton community and euphausiid larval ecology in the Prydz Bay region, Antarctica', PhD thesis, University of Tasmania.

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Macrozooplankton data from the Prydz Bay region, collected between
1981 and 1991, and representing the months of September to March, were
analysed using duster analysis and non-metric multidimensional scaling to
define the communities within the region, their distribution patterns,
indicator species and species affinities. Four communities were identified.
Three of these communities were dominated respectively by Euphausia
crystallorophias (neritic), copepods-chaetognaths (main oceanic), and salpshyperiids-small
euphausiids (northern oceanic community). The fourth
community was characterized by the high abundance and dominance of the
Antarctic krill, E. superba, and also by the paucity of zooplankton. This
community was mainly located along the outer shelf edge, usually between
the main oceanic and neritic communities. Chlorophyll a abundance and
temperature explained much of the variation in community distribution
patterns. The annual recession of ice, pack-ice cover, and salinity also
explained some of the variation. Water circulation seemed to have only a
clear effect on community distributions at the end of summer in March,
when distributional patterns exhibited a distinct longitudinal zonation
compared to the strong latitudinal pattern seen through most of the summer.
In January 1984, 1985 and March 1987, net sampling surveys were
carried out on the distribution and abundance of euphausiid larvae,
primarily E. superba, in the Prydz Bay region. E. superba occurred in low
abundance in January, probably due to sampling preceding the main
spawning period, but occurred in very high abundance in the east of the
region in March 1987. Thysanoessa macrura occurred throughout the study
area in consistently high abundance. E. crystallorophias was marginally more abundant within its restricted range. Distinct north-south variations in
larval age and developmental stages of T. macrura were observed indicating
regional differences in spawning. Euphausia frigida was mainly confined to the upper 200 m of the Antarctic Circumpolar Current. E. superba larvae
produced north of the shelf break, between 70 to 83° E, moved north-east
into the Antarctic Circumpolar Current. Larvae originating on the shelf
moved rapidly west in the East Wind Drift. E. crystallorophias had the same
westward dispersion, but some larvae appeared to return eastward via the
Prydz Bay Gyre and remain in the region. However, the data indicate that
most E. superba larvae, providing they survive injurious cold temperature
and food deprivation, will leave the area, i.e. Prydz Bay krill may not be a
self maintaining stock.

Item Type: Thesis - PhD
Authors/Creators:Hosie, Graham William
Keywords: Zooplankton, Euphausiidae, Marine ecology
Copyright Holders: The Author
Copyright Information:

Copyright 1992 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1993. Includes bibliographical references. Spine title: Zooplankton and euphausiid larvae of Prydz Bay, Antarctica

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