Lenght measurements and carbon biomass of individual zooplankton from METEOR cruise M87/1 in April 2012

Zooplankton samples were taken in five depth strata using a Multinet type Midi, with 50 µm nets. The samples were taken during the second leg only, three times at station 1, two times at station 2 and once at station 3. Zooplankton were identified to species / genus and life-stage, and at least 300 individuals were counted per sample. 10 individuals of each stage / species were measured and the numbers of eggs counted.

Activity and biomass of small benthic biota in the central Arctic Ocean

Sediment samples collected during the expedition "Arctic Ocean '96" with the Swedish ice-breaker ODEN were investigated to estimate for the first time heterotrophic activity and total microbial biomass (size range from bacteria to small metazoans) from the perennially ice-covered central Arctic Ocean. Benthic activities and biomass were evaluated analysing a series of biogenic sediment compounds (i.e. bacterial exoenzymes, total adenylates, DNA, phospholipids, particulate proteins). In contrast to the very time-consuming sorting, enumeration and weight determination, analyses of biochemical sediment parameters may represent a useful method for obtaining rapid information on the ecological situation in a given benthic system. Bacterial cell numbers and biomass were estimated for comparison with biochemically determined biomass data, to evaluate the contribution of the bacterial biomass to the total microbial biomass. It appeared that bacterial biomass made up only 8-31% (average of all stations = 20%) of the total microbial biomass, suggesting a large fraction of other small infaunal organisms within the sediment samples (most probably fungi, yeasts, protozoans such as flagellates, ciliates or amoebae, as well as a fraction of small metazoans). Activity and biomass values determined within this study were generally extremely low, and often even slightly lower than those given for other deep oceanic regions, thus characterizing the seafloor of the central Arctic Ocean as a "benthic desert". Nevertheless, some clear trends in the data could be found, e.g. generally sharply decreasing values within the sediment column, a vague tendency for declining values with increasing water depth of sampling stations, and also differences between various Arctic deep-sea regions.

(Appendix A) Pigment content, microbial biomass and activity, and grain size characteristics in caged and control sites of the Arctic long-term observatory HAUSGARTEN

Present theories of deep-sea community organization recognize the importance of small-scale biological disturbances, originated partly from the activities of epibenthic megafaunal organisms, in maintaining high benthic biodiversity in the deep sea. However, due to technical difficulties, in situ experimental studies to test hypotheses in the deep sea are lacking. The objective of the present study was to evaluate the potential of cages as tools for studying the importance of epibenthic megafauna for deep-sea benthic communities. Using the deep-diving Remotely Operated Vehicle (ROV) "VICTOR 6000", six experimental cages were deployed at the sea floor at 2500 m water depth and sampled after 2 years (2y) and 4 years (4y) for a variety of sediment parameters in order to test for caging artefacts. Photo and video footage from both experiments showed that the cages were efficient at excluding the targeted fauna. The cage also proved to be appropriate to deep-sea studies considering the fact that there was no fouling on the cages and no evidence of any organism establishing residence on or adjacent to it. Environmental changes inside the cages were dependent on the experimental period analysed. In the 4y experiment, chlorophyll a concentrations were higher in the uppermost centimeter of sediment inside cages whereas in the 2y experiment, it did not differ between inside and outside. Although the cages caused some changes to the sedimentary regime, they are relatively minor compared to similar studies in shallow water. The only parameter that was significantly higher under cages at both experiments was the concentration of phaeopigments. Since the epibenthic megafauna at our study site can potentially affect phytodetritus distribution and availability at the seafloor (e.g. via consumption, disaggregation and burial), we suggest that their exclusion was, at least in part, responsible for the increases in pigment concentrations. Cages might be suitable tools to study the long-term effects of disturbances caused by megafaunal organisms on the diversity and community structure of smaller-sized organisms in the deep sea, although further work employing partial cage controls, greater replication, and evaluating faunal components will be essential to unequivocally establish their utility.

Biomass of seston in the benthic layer of the Southwestern Indian Ocean

At stations to 1530 m depth in the Mozambique Channel and on the Saya-de-Malha and Walters banks seston biomass 2 m above the bottom was lower than at 30 m. Above the Walters shoal this difference was 13.2 mg/m**3 and was not equal to zero for P < 0.001. These results contradict previous ideas of biomass increase in benthic layers. The most likely cause of the observed impoverishment of plankton may be predominant consumption of living zooplankton component of seston by bottom and near-bottom predators. In the area of the Walters shoal this consumption is estimated as being about 300 mg/m**2 per day. Animals inhabiting this area live mainly on plankton brought in by horizontal advection, so that existence of faunal assemblages even on shallow-water submarine elevations is supported not mainly by local photosynthesis, but by primary production of surrounding waters.