Grazing rate of microzooplankton measured experimentally in the North Atlantic during the Maria S. Merian cruise MSM26, spring 2013

DOI

The microzooplankton grazing dilution experiments were conducted at stations 126, 127, 131 and 133-137, following Landry & Hassett (1982). Seawater samples (whole seawater – WSW) were taken via Niskin bottles mounted on to a CTD Rosette out of the chlorophyll maximum at each station. Four different dilution levels were prepared with WSW and GF/F filtered seawater – 100% WSW, 75% WSW, 50% WSW and 25% WSW. The diluted WSW was filled in 2.4 L polycarbonate bottles (two replicates for every dilution level). Three subsamples (250 - 500 mL depending on in situ chlorophyll) of the 100% WSW were filtered on to GF/F filters (25 mm diameter) and chlorophyll was extracted in 5 mL 96% ethanol for 12-24 hours. Afterwards it was measured fluorometrically before and after the addition of HCl with a Turner fluorometer according to Jespersen and Christoffersen (1987) on board of the ship. In addition, one 250 mL subsample of the 100% WSW was fixed in 2% Lugol (final concentration), to determine the microzooplankton community when back at the Institute for Hydrobiology and Fisheries Science in Hamburg. Also, one 50 mL subsample of the 100% WSW was fixed in 1 mL glutaraldehyde, to quantify bacteria abundance. The 2.4 L bottles were put in black mesh-bags, which reduced incoming radiation to approximately 50% (to minimize chlorophyll bleaching). The bottles were incubated for 24 hours in a tank on deck with flow-through water, to maintain in situ temperature. An additional experiment was carried out to test the effect of temperature on microzooplankton grazing in darkness. Therefore, 100% WSW was incubated in the deck tank and in two temperature control rooms of 5 and 15°C in darkness (two bottles each). The same was done with bottles where copepods were added (five copepods of Calanus finmarchicus in each bottle; males and females were randomly picked and divided onto the bottles). In addition, two 100% WSW bottles with five copepods each were incubated at in situ temperature at 100% light level (without mesh-bags). All experiments were incubated for 24 hours and afterwards two subsamples of each bottle were filtered on to GF/F filters (25 mm diameter); 500 - 1000 mL depending on in situ chlorophyll. One 250 mL subsample of one of the two replicates of each dilution level and each additional experiment (temperature and temperature/copepods) was fixed in 5 mL lugol for microzooplankton determination. One 50 mL subsample of one of the two 100% WSW bottles as well as of one of the additional experiments without copepods was fixed in 1 mL glutaraldehyde for bacteria determination later on. Copepods were fixed in 4% formaldehyde for length measurements and sex determination.

Identifier
DOI https://doi.org/10.1594/PANGAEA.819256
Related Identifier IsDocumentedBy https://doi.org/10.1007/BF00397668
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.819256
Provenance
Creator Hänselmann, Kristin; Walter, Bettina
Publisher PANGAEA
Contributor Institut für Hydrobiologie und Fischereiwissenschaften, Universität Hamburg
Publication Year 2013
Funding Reference Seventh Framework Programme https://doi.org/10.13039/100011102 Crossref Funder ID 264933 https://cordis.europa.eu/project/id/264933 Basin Scale Analysis, Synthesis and Integration
Rights Licensing unknown: Please contact principal investigator/authors to gain access and request licensing terms; Data access is restricted (moratorium, sensitive data, license constraints)
OpenAccess false
Representation
Resource Type Dataset
Format text/tab-separated-values
Size 1536 data points
Discipline Earth System Research
Spatial Coverage (-55.977W, 53.358S, -11.000E, 62.857N); North Atlantic Ocean
Temporal Coverage Begin 2013-03-24T19:30:00Z
Temporal Coverage End 2013-04-13T13:49:00Z