Spatial competition in a global disturbance minimum; the seabed under an Antarctic ice shelf

Frinault, B.A.V.; Barnes, D.K.A. ORCID: https://orcid.org/0000-0002-9076-7867; Biskaborn, B.K.; Gromig, R.; Hillenbrand, C.-D. ORCID: https://orcid.org/0000-0003-0240-7317; Klages, J.P.; Koglin, N.; Kuhn, G.. 2023 Spatial competition in a global disturbance minimum; the seabed under an Antarctic ice shelf. Science of the Total Environment, 903, 166157. 10, pp. 10.1016/j.scitotenv.2023.166157

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Text (Open Access) © 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CCBY license (http://creativecommons.org/licenses/by/4.0/). 1-s2.0-S0048969723047824-main.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (6MB) | Preview

Abstract/Summary

The marine habitat beneath Antarctica's ice shelves spans ∼1.6 million km2, and life in this vast and extreme environment is among Earth's least accessible, least disturbed and least known, yet likely to be impacted by climate-forced warming and environmental change. Although competition among biota is a fundamental structuring force of ecological communities, hence ecosystem functions and services, nothing was known of competition for resources under ice shelves, until this study. Boreholes drilled through a ∼ 200 m thick ice shelf enabled collections of novel sub-ice-shelf seabed sediment which contained fragments of biogenic substrata rich in encrusting (lithophilic) macrobenthos, principally bryozoans – a globally-ubiquitous phylum sensitive to environmental change. Analysis of sub-glacial biogenic substrata, by stereo microscopy, provided first evidence of spatial contest competition, enabling generation of a new range of competition measures for the sub-ice-shelf benthic space. Measures were compared with those of global open-water datasets traversing polar, temperate and tropical latitudes (and encompassing both hemispheres). Spatial competition in sub-ice-shelf samples was found to be higher in intensity and severity than all other global means. The likelihood of sub-ice-shelf competition being intraspecific was three times lower than for open-sea polar continental shelf areas, and competition complexity, in terms of the number of different types of competitor pairings, was two-fold higher. As posited for an enduring disturbance minimum, a specific bryozoan clade was especially competitively dominant in sub-ice-shelf samples compared with both contemporary and fossil assemblage records. Overall, spatial competition under an Antarctic ice shelf, as characterised by bryozoan interactions, was strikingly different from that of open-sea polar continental shelf sites, and more closely resembled tropical and temperate latitudes. This study represents the first analysis of sub-ice-shelf macrobenthic spatial competition and provides a new ecological baseline for exploring, monitoring and comparing ecosystem response to environmental change in a warming world.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.scitotenv.2023.166157
ISSN:	0048-9697
Additional Keywords:	Global climate change, Weddell Sea, Boreholes through ice shelves, Stereo microscopy, Macrobenthos interactions, Bryozoa
Date made live:	22 Aug 2023 11:29 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/535656

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