Segelken-Voigt, A., Bracher, A., Dorschel, B., Gutt, J., Huneke, W., Link, H. and Piepenburg, Dieter (2016) Spatial distribution patterns of ascidians (Ascidiacea: Tunicata) on the continental shelves off the northern Antarctic Peninsula. Polar Biology, 39 (5). pp. 863-879. DOI 10.1007/s00300-016-1909-y.

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Abstract

Ascidians (Ascidiacea: Tunicata) are sessile suspension feeders that represent dominant epifaunal components of the Southern Ocean shelf benthos and play a significant role in the pelagic-benthic coupling. Here, we report the results of a first study on the relationship between the distribution patterns of eight common and/or abundant (putative) ascidian species, and environmental drivers in the waters off the northern Antarctic Peninsula. During RV Polarstern cruise XXIX/3 (PS81) in January-March 2013, we used seabed imaging surveys along 28 photographic transects of 2 km length each at water depths from 70 to 770 m in three regions (northwestern Weddell Sea, southern Bransfield Strait and southern Drake Passage), differing in their general environmental setting, primarily oceanographic characteristics and sea-ice dynamics, to comparatively analyze the spatial patterns in the abundance of the selected ascidians, reliably to be identified in the photographs, at three nested spatial scales. At a regional (100-km) scale, the ascidian assemblages of the Weddell Sea differed significantly from those of the other two regions, whereas at an intermediate 10-km scale no such differences were detected among habitat types (bank, upper slope, slope, deep/canyon) on the shelf and at the shelf break within each region. These spatial patterns were superimposed by a marked small-scale (10-m) patchiness of ascidian distribution within the 2-km-long transects. Among the environmental variables considered in our study, a combination of water-mass characteristics, sea-ice dynamics (approximated by 5-year averages in sea-ice cover in the region of or surrounding the photographic stations), as well as the seabed ruggedness, was identified as explaining best the distribution patterns of the ascidians.

Document Type:	Article
Additional Information:	Times Cited: 1 Segelken-Voigt, Alexandra Bracher, Astrid Dorschel, Boris Gutt, Julian Huneke, Wilma Link, Heike Piepenburg, Dieter Si
Keywords:	Environmental drivers Spatial scales Photographic survey Bottom topography Macrobenthos Southern Ocean
Research affiliation:	Kiel University Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence
Refereed:	Yes
Open Access Journal?:	No
Publisher:	American Medical Association
Projects:	Future Ocean
Date Deposited:	18 Mar 2017 08:33
Last Modified:	23 Sep 2019 23:58
URI:	https://oceanrep.geomar.de/id/eprint/36315

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