University of Tasmania

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Eukaryote plankton assemblages in the southern Kerguelen Axis region: ecological drivers differ between size fractions

journal contribution
posted on 2023-05-20, 01:03 authored by Laurence ClarkeLaurence Clarke, Deagle, BE
Southern Ocean plankton communities are extremely important for global biogeochemical processes. However,recent efforts to survey marine eukaryote diversity focussed on tropical and temperate plankton communities,with limited sampling of the Southern Ocean. We used high-throughput sequencing of 18S ribosomal DNA to characterise eukaryotic diversity in 284 size-fractionated plankton samples from across the southern Kerguelen Axis, one of the most productive regions in the Indian Sector of the Southern Ocean. Based on three size fractions, combined eukaryote communities in the K-Axis region form three distinct groups, corresponding to a southern seasonal ice zone (SIZ), northern SIZ and open ocean zone. Generalised dissimilarity modelling showed that days since sea-ice melt was the key driver of community composition for the two larger size fractions (nano-and microplankton). In contrast, chlorophyll a and nitrate concentrations were better predictors for eukaryotic communities smaller than 5 μm (piconanoplankton). Other predictors varied in importance between taxonomic groups and depths, providing insights into drivers of community structure for different groups. Our results suggest that Southern Ocean eukaryotes will respond differently to environmental change depending on their taxonomy and size. Predicted changes in sea-ice extent and other environmental factors will not simply cause a shift in community location, but change the overall community composition and the suite of possible ecological interactions, with implications for trophodynamics, biogeochemistry, and carbon export.


Publication title

Deep-Sea Research Part II



Article number









Institute for Marine and Antarctic Studies


Pergamon-Elsevier Science Ltd

Place of publication

The Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb

Rights statement

© 2018 Elsevier Ltd. All rights reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Biodiversity in Antarctic and Southern Ocean environments; Marine biodiversity; Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)