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    Stefanie KaiserStefanie Kaiser

Report Stefanie Kaiser

Taxonomic study on abyssal isopod crustaceans from the Ross Sea
Report on a CeDAMar Taxonomic Exchange to the National Institute of Water & Atmospheric Research (NIWA) in Wellington (NZ), April 2009.

The aim of the visit was the identification of isopod crustaceans sampled during the NIWA IPY cruise (TAN0802) with RV Tangaroa to the Ross Sea. In Austral summer 2007/08 benthic material was collected at 16 stations using an epibenthic sledge (EBS, cf. Brenke 2005) at shelf, slope and abyssal depths.
    In the Antarctic (as elsewhere), the EBS has been successfully deployed on soft bottom from shallow shelf to hadal depths (see Brandt et al 2004, 2007; Linse et al. 2002; Kaiser et al 2009 etc.). Briefly, it consists of two nets, an upper supra (i.e. top) - and a lower epi-net (for detailed description see Brenke 2005). Onboard RV Tangaroa these nets have been elutriated to facilitate subsequent sorting. In total, the so called ´top net elutriates´ yielded about 1,200 isopod specimens, and here selected families (Desmosomatidae, Nannoniscidae and Macrostylidae) could be assigned to generic (17) and some to species level. Most of these species appear to be new to science, though some have been previously recorded from elsewhere in the Antarctic (e.g. East Antarctic, Amundsen, Weddell and Scotia seas). Further morphological and molecular (if possible) analyses on this material will help to elucidate cryptic speciation and evaluation of ´true´ range sizes.
    During my visit a single abyssal sample could be completely sorted and all metazoans combined comprised more than 2,300 specimens. These were separated into 12 phyla and more than 21 classes. Here, isopods represented the most dominant group (31%), which have been identified to 15 families and more than 70 species. Certainly, further work/sorting will reveal both high isopod abundance and richness in the Ross Sea, and thus invaluable material for the Pacific sector of the Southern Ocean.
    Completely sorted the Ross Sea material could be compared with existing data sets from the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III and BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1&2 cruises (i.e. CeDAMar and CAML core projects respectively) using complementary sampling protocols.  Combined, these samples provide an unparalleled and comparable data set for the Southern Ocean spanning shelf to abyssal depths and five major regions (i.e. Scotia, Weddell, Bellingshausen, Amundsen and Ross seas). Further identifications and comparison of the isopod material (including future cooperation and synthesis of research projects) will help to evaluate the assessment of geographic and bathymetric ranges in SO abyssal species as well as the structure of SO biodiversity and distributions across different spatial scales.

Many thanks to CeDAMar for supporting this work, it has been greatly appreciated!

Stefanie Kaiser
Zoological Museum, University of Hamburg, Germany


References

Brandt A, Brökeland W, Brix S, Malyutina M (2004) Diversity of Antarctic deep-sea Isopoda (Crustacea, Malacostraca) – a comparison with shelf data. Deep-Sea Research II 51 (14-16), 1753–1769.

Brandt A, Brix S, Brökeland W, Choudhury, M, Kaiser S, Malyutina M (2007b) Deep-sea isopod biodiversity, abundance and endemism in the Atlantic sector of the Southern Ocean – results from the ANDEEP I - III expeditions. Deep-Sea Research II 54, 1760–1775.

Brenke N (2005) An epibenthic sledge for operations on marine soft bottom and bedrock. Marine Technology Society Journal, 39(2), 10–19.

Kaiser S, Barnes DKA, Sands CJ, Brandt A (2009) Biodiversity of an unknown Antarctic sea; spatial patterns of richness and abundance on the most (Scotia) and least (Amundsen) sampled shelves. Marine Biodiversity, Doi: 10.1007/s12526-009-0004-9.

Linse K, Brandt A, Hilbig B, Wegener G (2002) Composition and distribution of suprabenthic fauna in the southeastern Weddell Sea and off King George Island. Antarctic Science 14(1), 3–10.

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