Foraging behaviour of the epaulette shark Hemiscyllium ocellatum is not affected by elevated CO2

Increased oceanic uptake of atmospheric carbon dioxide (CO2) is a threat to marine organisms and ecosystems. Among the most dramatic consequences predicted to date are behavioural impairments in marine fish which appear to be caused by the interference of elevated CO2 with a key neurotransmitter receptor in the brain. In this study, we tested the effects of elevated CO2 on the foraging and shelter-seeking behaviours of the reef-dwelling epaulette shark, Hemiscyllium ocellatum. Juvenile sharks were exposed for 30 d to control CO2 (400 µatm) and two elevated CO2 treatments (615 and 910 µatm), consistent with medium- and high-end projections for ocean pCO2 by 2100. Contrary to the effects observed in teleosts and in some other sharks, behaviour of the epaulette shark was unaffected by elevated CO2. A potential explanation is the remarkable adaptation of H. ocellatum to low environmental oxygen conditions (hypoxia) and diel fluctuations in CO2 encountered in their shallow reef habitat. This ability translates into behavioural tolerance of near-future ocean acidification, suggesting that behavioural tolerance and subsequent adaptation to projected future CO2 levels might be possible in some other fish, if adaptation can keep pace with the rate of rising CO2 levels.

Nutrients and oxygen concentrations measured in water samples from the North Atlantic during the James Cook cruise JC087 in March 2013

Analysis for micro-molar concentrations of nitrate and nitrite, nitrite, phosphate, silicate and ammonia was undertaken on a SEAL Analytical UK Ltd, AA3 segmented flow autoanalyser following methods described by Kirkwood (1996). Samples were drawn from Niskin bottles on the CTD into 15ml polycarbonate centrifuge tubes and kept refrigerated at approximately 4oC until analysis, which generally commenced within 30 minutes. Overall 23 runs with 597 samples were analysed. This is a total of 502 CTD samples, 69 underway samples and 26 from other sources. An artificial seawater matrix (ASW) of 40g/litre sodium chloride was used as the inter-sample wash and standard matrix. The nutrient free status of this solution was checked by running Ocean Scientific International (OSI) low nutrient seawater (LNS) on every run. A single set of mixed standards were made up by diluting 5mM solutions made from weighed dried salts in 1litre of ASW into plastic 250ml volumetric flasks that had been cleaned by washing in MilliQ water (MQ). Data processing was undertaken using SEAL Analytical UK Ltd proprietary software (AACE 6.07) and was performed within a few hours of the run being finished. The sample time was 60 seconds and the wash time was 30 seconds. The lines were washed daily with wash solutions specific for each chemistry, but comprised of MQ, MQ and SDS, MQ and Triton-X, or MQ and Brij-35. Three times during the cruise the phosphate and silicate channels were washed with a weak sodium hypochlorite solution.

(Table 1) Indices of feeding of natural populations of Infusoria in antarctic and subantarctic waters

Ration of mass species of infusoria and their consumption of phytoplankton in the 0-200 m layer of antarctic and subantarctic waters of the Pacific Ocean are evaluated from microscopic study of digestive vacuoles and counts of algae present in them. In antarctic waters tintinnids, which make up 63-75% of total biomass of infusoria, consumed 19-27% of biomass of nannophytoplankton or 0.1-0.3% of biomass of all phytoplankton. In Subantarctic the main infusorial consumers of phytoplankton were large strombidia, which were dominant in infusorial biomass and in their areas of maximum development consumed 14% of biomass of nannophytoplankton, equivalent to about 10% of total biomass of phytoplankton in the 0-200 m layer.

Tab. 6+7: Altitudes and variations of altitudes in the area of the Filchner and Neumayer Stations

The determination of the strain and velocity behaviour of the ice surface near the two German Antarctic Stations on Filchner/Ronne and Ekström ice shelves was performed by the use of various geodetic measuring techniques. The relative positions and heights of control points valid for reference data were deduced from terrestrial observations (horizontal and vertical angle selectro optical distances). After a second sampling of data, these values served as the basis for the deformation analyses. Doppler-Satellite-observations (Navy Navigation Satellite System) made absolute positioning (latitude, longitude, height) of special points possible. These Doppler observations, supported by azimuth measurements (gyro-theodolite and sun observations) provided the datum of control networks (translations and orientation). After the repetition of these observations, the drift rates and azimuths of the control points as wenas the rotanon rates of the surface elements could be given. From vertical angles and horizontal distances differences in height end refraction coefficients were calculated. On days without clouds the refraction coefflcients increased by arnounts of up to 3.0 (in extreme cases up to 5.0). Distances over 1 km have to be subdivided to reach a standard deviation level of an heigh: difference better than 0.05 m. In order to determine the heterögeneity of refraction, some height differences should be measured with higher accuracy end-by subdivision of distances.