Response of sea-ice microbial communities to environmental disturbance: an in situ transplant experiment in the Antarctic
2011
Sea-ice microbial communities are integral to primary and secondary production in icecovered
regions of the Southern Ocean, but few studies have characterised the heterogeneity of
microbes within the ice or determined whether habitat variability influences community dynamics.
We examined the response of sea-ice microbes to key physicochemical variables by conducting an
18 d reciprocal transplant experiment within Antarctic fast-ice. A series of ice cores were extracted
from 2.6 m annual ice and reinserted upside down to expose resident microbial assemblages to significantly
different light, temperature and salinity regimes. The abundance and community composition
of bacteria, microalgae and protozoa was subsequently determined within 3 sections of each core
(top, middle and bottom) and compared with experimental controls. Results demonstrate that iceassociated
microbes are finely attuned to discrete microhabitats within the sea-ice matrix. Positive
growth and a shift in community composition was observed for microalgae moved from the top to the
bottom of the ice, but significant bleaching of photosynthetic pigments resulted in zero net growth for
bottom-ice communities exposed to the surface. Although bacteria may have been less vulnerable to
initial change in their microenvironment, there was no significant increase in the average abundance
of cells at either end of the flipped cores after 18 d, despite a presumed increase in algal-derived dissolved
organic matter. This suggests a significant lag in the response time of bacteria to available
growth substrates and a temporary ‘malfunction’ of the microbial loop.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
70
References
19
Citations
NaN
KQI