Aquatic Environment and Biodiversity Annual Review 2012

AEBAR 2012: Marine Biodiversity
taxa were orders of magnitude higher on the continental shelf than on the slope or abyss plain, and
shelf, slope, and abyssal samples were distinct from each other in multivariate analyses. Diversity,
however, was comparable between shelf and abyssal sites and lowest on the slope. Bacterial
diversity was highest in abyssal and slope samples, but abundance, biomass, production, and
activity of all enzymes except proteinase, which was highest in the abyss, were significantly higher
in shelf samples. Benthic mega-epifaunal community composition was more strongly correlated
with depth and seabed current speed than either water column productivity or seasonal ice cover,
indicating that local hydrodynamics and their influence on advection of primary production are
more important in determining distributions across the shelf than are local variations in production.
Fauna on the seamounts were distinct from all other samples and were comprised of both Antarctic
and Southern Ocean species, including remarkable populations of a new hyocrinid species on
Admiralty seamount (Bowden et al. 2011, Eléaume et al. 2011).
Published research to date has provided new insights into the distributions of several taxonomic
groups (Lörz et al. 2009) , raised questions about the history of the northern seamount fauna over
evolutionary time (Bowden et al. 2011), and contributed to a meta-analysis of the relationship
between productivity and diversity in the deep sea (Leduc et al. 2012). In combination with
molecular phylogenies and existing data from around Antarctica, results from this project represent
a major contribution to knowledge of the Antarctic marine ecosystem.
Specific Objective 10: To describe trophic/ecosystem relationships in the Ross Sea ecosystem
(pelagic and benthic, fish and invertebrates).
Progress has been made on obtaining data from which to elucidate trophic relationships between
organisms in the Ross Sector of Antarctica collected on the IPY-CAML survey in February–March
2008. Two methods have been used. First, 1081 stomachs from 22 species of Antarctic fish were
examined and the contents of the full or partially-full stomachs (comprising 776 fish) were
identified to 68 prey codes. Index of Relative Importance (IRI) has been calculated from these data
and diet overlap between fish species is presented. Second, stable isotope and elemental
composition analysis of samples were carried out for carbon and nitrogen. In total, nearly 2000
samples were analysed. Samples include:
• Fish (N=662 muscle, N=377 liver samples, 22 species);
• Cephalopods (N=193);
• Pelagic invertebrates (N=407);
• Benthic sediments (N=36);
• Phytoplankton (N=92);
• Benthic invertebrates (N=200 completed, 95 pending analysis);
Results have already been used to assist in parameterising and validating the quantitative model of
the food web of the Ross Sea (paper accepted by CCAMLR Science). Research on the shrinkage of
Antarctic silverfish carried out as part of this objective has contributed to a paper presented to the
Ministry of Fisheries Antarctic Fisheries Working Group and accepted for submission to the
CCAMLR working group on fisheries assessment in September 2010 (Pinkerton et al. 2007,
2009a, 2009b).
Specific Objective 11: Assess molecular taxonomy and population genetics of selected Antarctic
fauna and flora to estimate evolutionary divergence within and among ocean basins in circumpolar
species. Provide DNA barcoding for all fish and multi-cellular invertebrate species by sequencing
reference specimens in conjunction with Canadian Barcoding Centre, for specimen identification
in gut content, plankton, and in taxonomic and population genetic projects.
DNA data sets generated for selected Ross Sea taxa were combined with parallel data sets
generated by other Institutes in order to estimate divergence within and among regions in the
Southern Ocean. High levels of divergence, indicative of cryptic speciation, were found in all
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