Preface The expedition ARK XIX/3 with the German icebreaking RV ...

ITS2 genes. These genes have proven to be useful for different phylogenetic levels and
to give complementary information.
Feeding eco-ethology
Traps results (Tab. C13-1) indicated 12 lysianassoid amphipod species being regular
scavengers. Checking of the mouthparts morphology and of the degree of extension of
the “storing” gut showed typical adaptations to necrophagy: mandibles with strong
incisor, bowl-shaped mandibular body, and molar process with different degrees of
reduction, long extended foregut or midgut (Eurythenes) for storing food.
About 200 specimens of Eurythenes gryllus (mostly juvenile, of a size of 12 to 65 mm)
were kept in aquarium for a maximum of 10 days. After having been taken on the bottom
at about 2500 m deep, at a temperature of -0.8 °C, they transited through the 6 °C
surface waters for about 30 minutes and were out of the water for about 10 minutes
before being put in aquarium at 0 °C (± 1 °C). Most of them (90 %) recovered from the
decompression and the thermal shocks, and after maximum 24 h could be seen moving
and swimming around. No Saduria cf. sabini put in aquaria survived the capture.
Most of Eurythenes had their mid-gut dilated and entirely filled with easily distinguishable
pieces of bait (herring). After 8 days in aquarium, the gut content did not show any
apparent transformation or reduction (15 specimens checked).
Several tens of amphipod specimens of selected species were deep-frozen alive at -30
°C for further stomach content analyses and for the stable isotopes (carbon and
nitrogen) analyses.
C. 14 Experimental approaches to study causes and effects of environmental gradients
at the deep seafloor
Soltwedel, T., Schewe, I., Sauter, E., Hasemann, C., Klages, M.
To identify factors controlling the high biodiversity in the deep sea, we carried out a
number of biological long-term experiments at stations “Hausgarten”-Central and
“Hausgarten”-South (Fig. C1). During the expedition ARK XIX/3c, the ROV “Victor 6000”
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