Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia

Majewski, Wojciech; Szczuciński, Witold; Gooday, Andrew J.

Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia

dc.contributor.author	Majewski, Wojciech
dc.contributor.author	Szczuciński, Witold
dc.contributor.author	Gooday, Andrew J.
dc.date.accessioned	2023-02-03T07:02:39Z
dc.date.available	2023-02-03T07:02:39Z
dc.date.issued	2023-02-02
dc.description.abstract	Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjords of South Georgia, including fjords with and without tidewater glaciers. Their distribution is analyzed in the light of new fjord water and sediment property data, including grain size and sorting, total organic carbon, total sulfur, and δ13C of bulk organic matter. Four well-defined foraminiferal assemblages are recognized. Miliammina earlandi dominates in the most restricted, near-shore and glacier-proximal habitats, Cassidulinoides aff. parkerianus in mid-fjord areas, and Globocassidulina aff. rossensis and an assemblage dominated by Ammobaculites rostratus, Reophax subfusiformis, and Astrononion echolsi are in the outer parts of the fjords. Miliammina earlandi can tolerate strong glacial influence, including high sedimentation rates in fjord heads and sediment anoxia, as inferred from sediment color and total organic carbon sulfur ratios. This versatile species thrives both in the food-poor inner reaches of fjords that receive mainly refractory petrogenic organic matter from glacial meltwater and in shallow-water coves, where it benefits from an abundant supply of fresh, terrestrial, and marine organic matter. A smooth-walled variant of C. aff. parkerianus, apparently endemic to South Georgia, is the calcareous rotaliid best adapted to inner-fjord conditions characterized by moderate glacial influence and sedimentation rates and showing no preference for particular sedimentary redox conditions. The outer parts of fjords with clear, well-oxygenated bottom water are inhabited by G. aff. rossensis. Ammobaculites rostratus, R. subfusiformis, and A. echolsi dominate in the deepest-water settings, with water salinities ≥ 33.9 PSU and temperatures 0.2–1.4 ∘C, characteristic of winter water and Upper Circumpolar Deep Water. The inner- and mid-fjord foraminiferal assemblages seem specific to South Georgia, although with continued warming and deglaciation, they may become more widespread in the Southern Ocean.	pl
dc.description.sponsorship	Polish National Science Centre (grant no. 2018/31/B/ST10/02886)	pl
dc.identifier.citation	Biogeosciences vol. 22, 2023, pp. 523-544.	pl
dc.identifier.doi	https://doi.org/10.5194/bg-20-523-2023
dc.identifier.uri	https://hdl.handle.net/10593/27142
dc.language.iso	eng	pl
dc.publisher	Copernicus Publications	pl
dc.rights	info:eu-repo/semantics/openAccess	pl
dc.rights.uri	http://creativecommons.org/licenses/by-nc-sa/3.0/pl/	*
dc.subject	Sub-Antarctic	pl
dc.subject	South Georgia	pl
dc.subject	fjords	pl
dc.subject	foraminifera	pl
dc.subject	benthic foraminifera	pl
dc.subject	hydrology	pl
dc.subject	sediments	pl
dc.subject	marine sediments	pl
dc.subject	grain size	pl
dc.subject	geochemistry	pl
dc.subject	living foraminifera	pl
dc.subject	fjord environment	pl
dc.subject	benthos	pl
dc.subject	organic matter	pl
dc.subject	foraminiferal assemblage	pl
dc.subject	water masses	pl
dc.subject	tidewater glacier	pl
dc.subject	glacimarine sediments	pl
dc.title	Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia	pl
dc.type	Artykuł	pl