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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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