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The Expedition ANTARKTIS XI1113 (EASIZ I) of "Polarstern" to the Eastern Weddell Sea in 1996

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The Expedition ANTARKTIS XI1113 (EASIZ I) of The Expedition ANTARKTIS XI1113 (EASIZ I) of "Polarstern" to the eastern Weddell Sea in 1996 Edited by Wolf Arntz and Julian Gutt with contributions of the participants Ber. Polarforsch. 249 (1997) ISSN 0176 - 5027 Contents: Page Introduction ...............................................................................1 Objectives of the Cruise ....................................................................1 Summary Review of Results ..............................................................5 Itinerary ......................................................................................5 Weather Conditions ...................................................................... 6 Bathymetry ................................................................................9 Seafloor Mapping and Side Looking Sonar Studies with Hydrosweep ...........................................................................9 Pelagobenthic Coupling ..............................................................14 Feeding Ecology of Antarctic Cnidarian Suspension Feeders (Hydrozoa. Gorgonacea. Pennatulacea) .................................................14 Presence of Fluff in an Antarctic Shelf trough. at 600 m Depth ......................16 Benthos: Community Related Research ........................................17 Meiobenthos ................................................................................17 Taxonomic Biodiversity of Bottom Invertebrates in the Easte~nWeddell Sea ................................................................25 Small/Medium Scale Distribution Patterns of Macrobenthic Invertebrates in Relation to Environmental and Biotic Parameters ...................31 The Impact of Icebergs On Benthic Assen~blages...................................... 35 The Trophic Structure of the Benthic Community On the Weddell Sea Shelf ..................................................................41 Population Dynarnics of Echinodenns ...................................................43 Benthos: Individual Taxonomic Groups .......................................44 The Sponge Fauna of the Weddell Sea and its Integration in Benthic Processes .......................................................................44 Composition and Distribution of the Eastern Weddell Sea Scleractinian Coral Fauna .................................................................53 Bryozoans of the Weddell Sea ............................................................55 Ecology and Taxonomy of Molluscs in the Eastem Weddell Sea ....................62 Aerobic Metabolism and Antioxidant Defence in Antarctic Sipunculids .............65 Autecology of Aphroditidae and Polynoidae (Polychaeta) On the Continental Shelf and Slope of the Eastem Weddell Sea ..............................66 Genetic Isolation of Benthic Isopoda (Cmstacea) and Speciation Mechanisms in the Southem Ocean ......................................................73 Trophodynamics, Biodiversity and Gigantism of the Amphipod Crustacea Taxocoenosis ...................................................................76 Nekton: Cephalopods ................................................................-79 Cephalopod Ecology and Physiology ...................................................79 Ecological Physiology of Antarctic Cephalopods ......................................81 Nekton: Fish and Fish Parasites ..................................................82 Weddell Sea Fish ecology .................................................................82 Ecophysiology of Antarctic Fish .........................................................97 2.6.3 Antifreeze Proteins from Antarctic Fish .................................................99 2.6.4 A Contribution to the Parasitic Fauna of the Weddell Sea ........................... 100 2.6.5 Faunistic Analysis of Fish Parasites ...................................................101 2.7 Seabird Observations Between South Africa and the Eastern Weddell Sea .....................................................104 ANNEXES................................................................................ 108 Abbrevations of gears ...................................................................108 Station list .................................................................................109 AGT 1 GSN check aboard ...............................................................116 Prelirninary list of amphipod species ..................................................124 Qualitative meiofauna sampling ........................................................128 Bryozoa. additional information........................................................ 129 Participants ................................................................................143 Ship's Crew ..............................................................................145 Participating Institutions .................................................................146 1. Introduction 1.1 Objectives of the Cruise (W. Arntz) 'Polarstern" cruise ANT XIIU3, as the first cruise of the EASIZ (Ecology of the Sea Ice Zone) programme adopted by the Scientific Council of Antarctic Research (SCAR) during its XXIII meeting in Rome, was planned to make a contribution to the ecological study of the high Antarctic shelf of the Weddell Sea. This area best reflects typical polar conditions such as distinct seasonality, a short primary production phase, extremely low water temperatures and the impact of ice in its different ways. It also houses some of the most interesting benthic assemblages in the Southern Ocean with an overwhelming dominance of suspension-feeding epifauna, a three- dimensional structure, and great faunal richness (biodiversity). Due to former work in the area culrninating in the European "Polarstern" Study (EPOS), many of the faunal components and large-scale structures are fairly well known, and in a first trophic interaction model an attempt has been made to account for the energy fluxes among the major faunal groups. In contrast to former expeditions, this first EASIZ cruise aimed at a higher resolution of factors and processes, both abiotic and biotic, that shape the faunal structures and dynamics under high Antarctic conditions. For this purpose the investigations were planned to concentrate on a few localities ("box concept") rather than applying large-scale measuring and sampling. However, the combination of different gears and methodological approaches, which had turned out useful in former expeditions, was to be continued including, for the first time, the use of hydrosweep- parasound techniques for ecological purposes. Also, international cooperation was to be strengthened both as a consequence of positive German experience in the past and as one of the colurnns of the EASIZ Programme. Cape Town Fig. 1: Cruise track of RV "Polarstern" during the EASIZ cruise ANT XIIU3. The cruise schedule (Fig. 1) was to concentrate work with a broad variety of gears in the Kapp Norvegia area (ca. 72OS, 12OW, Fig. 2) and to visit an additional area south-west of Vestkapp 1 (73% lgOW, Fig 3) mainly for fishing purposes, as fisheries biologists had experienced difficulties in using trawled gear in the former region due to its huge biomasses of sporiges. From the proposals of the participants several focal research themes emerged, all of them within the EASIZ framework: Resilience of Antarctic benthic communities following disturbance by iceberg scouring. This involves studies of iceberg impact as well as the identification of successional Stages, and ageing of those organisms that dominate them. * Pelago-benthic coupling and the role of suspension feeders. Of interest in this context are the size, quantity and quality of particles from the pelagial arriving at the seafloor and those available by resuspension or in the sediment (all of them together representing the food offer for suspension feeders), the size, quality and quantity of food ingested by, and the biology of the suspension feeders (condition, reproductive Stage, etc.). Population dynamics, reproduciive biology and ecophysiology of benthic and fish key species, including special conservation techniques for the application of new methods (isotopes, molecular genetics, etc.). Biodiversity within high Antarctic benthic communities from ROV sequences and trawl samples. Occurrence and characteristics of meiobenthic drift fauna. * Food availability and characteristics of pelagic food offer for Weddell seals and Emperor penguins in the Drescher Inlet area. Fusthermore, the cruise offered the oppoitunity io complement the species inventory for various groups and to collect material for other purposes, taking care, however, that "collecting" did not become a primary objective for station planning Fig. 2: The Kapp Norvegia working area with approximate location of stations (for exact coordinates consult the table in annex 3.2). Source: AWI, Bathymetric Chart of the Weddell Sea, Antarctica, Sheet 553, and helicopter measurements of the shelf ice edge during the cruise. Fig. 3: The working area SW of Vestkapp including the Drescher inlet, with approximate location of stations (for exact coordinates consult the table in annex 3.2). 1.2 Summary Review of Results (W. Arntz) Despite rather unfavourable ice and wind conditions during most of the cruise, ANT XI1113 has yielded a large number of highly interesting results. Of Course, many of them require further analysis; so this attempt of a Summary must be considered preliminaq.
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