22 research outputs found
The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective
A major aim of this review is to determine
which physiological functions are adopted by adults and
larvae to survive the winter season with low food supply
and their relative importance. A second aim is to clarify the
extent to which seasonal variation in larval and adult krill
physiology is mediated by environmental factors with a
strong seasonality, such as food supply or day light. Experimental
studies on adult krill have demonstrated that speciWc
physiological adaptations during autumn and winter,
such as reduced metabolic rates and feeding activity, are
not caused simply by the scarcity of food, as was previously
assumed. These adaptations appear to be inXuenced
by the local light regime. The physiological functions that
larval krill adopt during winter (reduced metabolism,
delayed development, lipid utilisation, and variable growth
rates) are, in contrast to the adults, under direct control by
the available food supply. During winter, the adults often
seem to have little association with sea ice (at least until
early spring). The larvae, however, feed within sea ice but
mainly on the grazers of the ice algal community rather
than on the algae themselves. In this respect, a miss-match
in timing of the occurrence of the last phytoplankton
blooms in autumn and the start of the sea ice formation, as
has been increasingly observed in the west Antarctic Peninsula
(WAP) region, will impact larval krill development
during winter in terms of food supply and consequently the
krill stock in this region
Comprehensive assessment of a nationwide simulation-based course for artificial life support
10.1371/journal.pone.0257162PLoS ONE1610 October 2021e0257162
Morphological adaptation of a planktonic diatom to growth in Antarctic sea ice.
Chaetoceros dichaeta Ehrenberg is one of the
most important planktonic diatom species in the Southern
Ocean, making a significant contribution to the total biomass
in the region. Our observations on both field and
culture material have revealed the existence of a specialized
form of C. dichaeta adapted to living in sea ice. This
sea ice form differs from the planktonic form by the shape
and orientation of the setae and the aperture length between
sibling cells. Thus, the diameter of the chain is equivalent
to the apical axes of the cells and is accompanied by a two
order of magnitude decrease in minimal space requirement.
Here, we report for the first time on the extraordinary
overwintering strategy of a planktonic diatom in sea ice
facilitated by its rapid morphological adaptation to
changing environmental conditions. This morphological
plasticity enables it to thrive in the confined space of the
sea ice brine matrix and retain its numerical dominance in
recurrent growing seasons and has likely evolved to
optimally exploit the dynamic ecosystem of the seasonally
ice-covered seas of the Southern Ocean