Antarctic ascidians under increasing sedimentation: Physiological thresholds and ecosystem hysteresis

Glacier melting sediment inputs affect coastal ecosystems on the Antarctic Peninsula. In Potter Cove (South Shetland Islands, Antarctica), the shift from an “ascidian dominated” to a “mixed” assemblage has been linked to sedimentation. However, in recently described newly ice-free areas ascidians be...

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Bibliographic Details
Published in:Marine environmental research 2021-05, Vol.167, p.105284-105284, Article 105284
Main Authors: Torre, L., Alurralde, G., Lagger, C., Abele, D., Schloss, I.R., Sahade, R.
Format: Article
Language:English
Subjects:
Alternative stable states
Animals
Antarctic Regions
Antarctica
Ascidiacea
Ascidians
Benthos
Coastal ecosystems
Coexistence
Ecosystem
Energy reserves
Glacier retreat
Glaciers
Hysteresis
Ice Cover
Marine invertebrates
Particulate emissions
Particulate matter
Polar environments
Scope for growth
Sedimentation
Sedimentation & deposition
Suspended particulate matter
Suspension feeders
Urochordata
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Summary:Glacier melting sediment inputs affect coastal ecosystems on the Antarctic Peninsula. In Potter Cove (South Shetland Islands, Antarctica), the shift from an “ascidian dominated” to a “mixed” assemblage has been linked to sedimentation. However, in recently described newly ice-free areas ascidians became dominant in spite of total suspended particulate matter (TSPM) concentrations, which are the highest measured in Potter Cove. Here, we compared the gut content and energy reserve of three ascidian species at three stations under different TSPM regimes. All analysed species had a higher gut content with lower %OM at these newly areas. A theoretical relationship between the scope for growth for the targeted ascidians and TSPM explained assemblages' recorded change but failed to explain current ascidians distribution. The results may indicate the existence of a TSPM threshold that allows the spatial coexistence of alternative stable states at benthic Potter Cove system. •Ascidians gut content amount and quality correlates with TSPM gradient and glacier distance.•SFG indicates currently suitable growth conditions in spite of high TSPM.•SFGTSPM allowed us to identify environmental thresholds and explain community changes.
ISSN:0141-1136
1879-0291
DOI:10.1016/j.marenvres.2021.105284