ALBERT

Description: The structure of the zooplankton foodweb and their dominant carbon fluxes were studied in the upwelling system off northern Chile (Mejillones Bay; 23°S) between October 2000 and December 2002. High primary production (PP) rates (18 gC/m**2 d) were mostly due to the net-phytoplankton size fraction (〉23 µm). High PP has been traditionally associated with the wind-driven upwelling fertilizing effect of equatorial subsurface waters, which favour development of a short food chain dominated by a few small clupeiform fish species. The objective of the present work was to study the trophic carbon flow through the first step of this 'classical chain' (from phytoplankton to primary consumers such as copepods and euphausiids) and the carbon flow towards the gelatinous web composed of both filter-feeding and carnivorous zooplankton. To accomplish this objective, feeding experiments with copepods, appendicularians, ctenophores, and chaetognaths were conducted using naturally occurring plankton prey assemblages. Throughout the study, the total carbon ingestion rates showed that the dominant appendicularian species and small copepods consumed an average of 7 and 5 µgC/ind d, respectively. In addition, copepods ingested particles mainly in the size range of nano- and microplankton, whereas appendicularians ingested in the range of pico- and nanoplankton. Small copepods and appendicularians removed a small fraction of total daily PP (range 6-11%). However, when the pico- + nanoplankton fractions were the major contributors to total PP (oligotrophic conditions), grazing by small copepods increased markedly to 86% of total PP. Under these more oligotrophic conditions, the euphausiids grazing increased as well, but only reached values lower than 5% of total PP. During this study, chaetognaths and ctenophores ingested an average of 1 and 14 copepods/ind d, respectively. In terms of biomass consumed, the potential impact of carnivorous gelatinous zooplankton on the small-size copepod community (preferred prey) was important (2-12% of biomass removed daily). However, their impact produced more significant results on copepod abundance (up to 33%), which suggests that carnivorous gelatinous zooplankton may even modulate (control) the abundance of some species as well as the size structure of the copepod community.

Description: The dataset compiles in situ observational data obtained during the R/V Mirai MR16-09 cruise (2017-01-21 to 2017-02-03) off western Patagonia, Chile. The data includes physical oceanographic information of temperature, salinity and depth. Profiles (0 to 〉1000 m depth) of conductivity/salinity, temperature, depth and dissolved oxygen were obtained at each sampling station using a Sea-Bird SBE911plus CTD-O2 equipment. The data was processed using the Sea-Bird software.

Description: The dataset compiles in situ observational data obtained during the R/V Mirai MR16-09 cruise (2017-01-21 to 2017-02-03) off western Patagonia, Chile. The biological data provides information of primary production, total chlorophyll-a, as well as, phytoplankton species composition (abundance of diatoms and dinoflagellates). Water samples for total Chlorophyll-a and phytoplankton cell abundance were collected at the same sampling depths as nutrients. The total Chlorophyll-a was measured by filtering 280 mL of seawater at low vacuum pressure (〈0.02 MPa) onto 25 mm Whatman GF/F filters. After filtration, phytoplankton pigments were immediately extracted in 7 mL of N,N-dimethylformamide and stored at -20°C until fluorometric analysis (Turner Design 10-AU-005). Quantification and taxonomical classification of the main dinoflagellates and diatoms taxa, were done using sub-samples in a 25 mL sedimentation chambers using an inverted microscope (CXK-41 Olympus). Diatoms and dinoflagellates were identified at species or genus level. Primary production rate was calculated using the equation proposed by Hama et al. (1983).

Description: The dataset compiles in situ observational data obtained during the R/V Mirai MR16-09 cruise (2017-01-21 to 2017-02-03) off western Patagonia, Chile. In terms of chemical variables, the dataset includes information of nutrients, nutrient ratios, dissolved oxygen and ammonium concentrations. Water samples for nutrients analysis were collected in duplicate at discrete sampling depths (0, 10, 25, 50 and 100 m depth) from a 36-Niskin bottles (12-liter each) SBE carousel water sampler. The samples were taken into 10 mL polyacrylates vials which were rinsed three times before filling. The closed vials were put into a water bath, set at ambient temperature (22 ± 1°C), for about 30 minutes to stabilize the temperature of the samples, after which were analyzed in an auto-sampler tray within 24 hours after collection. Nitrate, phosphate, silicate and ammonium concentrations were determined using the QuAAtro 2-HR systems (BL-Tech), which the detection limits were 0.02 μmol kg⁻¹, 0.003 μmol kg⁻¹, 0.03 μmol kg⁻¹, and 0.02 μmol kg⁻¹, respectively.

Description: The dataset compiles in situ observational data obtained during the R/V Mirai MR16-09 cruise (2017-01-21 to 2017-02-03) off western Patagonia, Chile. Seawater samples for particulate organic carbon (POC) concentration (one replica) were collected from 0, 25, and 200 m in 1-4.5 L polycarbonate bottles. The samples for POC concentration were filtered immediately onto pre-combusted (450°C for 6h) GF/F filters (Whatman, Kent, UK). Samples collected from surface and 25 m depth were incubated on-deck in an incubator cooling by recirculated sea surface water and samples from the aphotic zone were incubated in a thermostatic incubator under dark condition. The incubations were terminated by gentle vacuum filtration of the samples through a pre-combusted GF/F filter after 24 h. The filters were kept frozen before laboratory analysis. The filters were dried at 50°C overnight, and then exposed to hydrogen chloride (HCl) fumes for 2 h. Total carbon was determined using a mass spectrometer (DELTA V advantage - Thermo Electron, Waltham, Massachusetts, USA) connected to an elemental analyzer (Flash EA - Thermo Electron).

Description: The data-sets comes from three locations representative of three different marine ecosystems: Fjord (Chilean Patagonia), Ny-Ålesund (Arctic) and Mediterranean (Crete). It contains chemical and biological data collected in three mesocosm and four microcosm experiments conducted in the spring - summer period, in which the physico-chemical (pH, Carbon) and biological (grazing) conditions were altered to represent potential future climate change scenarios. The data-sets contains measurements in: carbonate chemistry, macro- and micro-nutrients concentrations, primary production, phytoplankton taxonomy, virus abundance, bacterial production, bacterial abundance, Zoo- and microzoo-plankton abundance, grazing rates for different taxonomic groups.