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

Frinault, B.A.V.; Barnes, D.K.A. ORCID:; Biskaborn, B.K.; Gromig, R.; Hillenbrand, C-D. ORCID:; 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.

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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):
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)

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