Dataset: Particles and Zooplankton Amino Acid Compound Specific Isotope Analyses (AA-CSIA) and zooplankton biomass at Station ALOHA and the Equatorial Pacific from R/V Kilo Moana cruises KM1407, KM1418, & KM1515 from 2014-2015

ValidatedFinal no updates expectedDOI: 10.26008/1912/bco-dmo.806502.1Version 1 (2020-03-19)Dataset Type:Cruise Results

Principal Investigator: Brian N. Popp (University of Hawaiʻi at Mānoa)

Co-Principal Investigator: Jeffrey C. Drazen (University of Hawaiʻi at Mānoa)

BCO-DMO Data Manager: Shannon Rauch (Woods Hole Oceanographic Institution)


Project: Evaluating the relative importance of suspended and sinking particles to the meso and bathypelagic food web in the central North Pacific (SuspendSinkPart)

Project: Collaborative Research: Isotopic insights to mercury in marine food webs and how it varies with ocean biogeochemistry (Hg_Biogeochemistry)


Abstract

Particles and Zooplankton Amino Acid Compound Specific Isotope Analyses (AA-CSIA) and zooplankton biomass at Station ALOHA and the Equatorial Pacific from R/V Kilo Moana cruises KM1407, KM1418, & KM1515 from 2014-2015.

Particles were collected using in situ McLane pumps equipped with mini-MULVFS (Bishop et al. 2012) 2-tiered filter holders. Particle collection captured sequentially large (>53 µm) particulates on acid-cleaned Nitex mesh filters and small particles (<53 µm) on pre-combusted GFF or QMA filters at discrete depths for amino acid compound-specific isotope analysis (AA CSIA) and for particulate carbon and nitrogen. This method is designed to exclude motile metazoans but include all other ambient, non-swimming particulate matter (see Bishop et al. 2012). Immediately after collection, large particles were rinsed off of the Nitex screens and onto pre-combusted 25-mm QMA filters using 0.2 µm filtered seawater. All filters were frozen at -20°C or -80°C as soon as possible after collection.

Zooplankton were collected using a 1-m² MOCNESS net during the day (~09:00-15:00) and at night (~20:00-03:00). Night and day tows were repeated to obtain replicate samples for biomass and isotopic analyses. Upon collection, each sample was size-fractionated using 0.2, 0.5, 1.0, 2.0 and 5.0 mm mesh sieves, filtered onto pre-weighed 47 mm filters of 0.2 mm Nitex mesh and stored frozen at -80ºC.

For nitrogen isotope composition of the amino acids, particles and zooplankton samples were freeze dried and analyzed following the methods Hannides et al. (2013). δ¹⁵N values of source amino acids ( δ¹⁵NSrc₋AA ) for both particles and zooplankton were calculated as the average δ¹⁵N of: serine, phenylalanine, lysine and glycine. Freeze-dried zooplankton filters for all size fractions were weighed to calculate zooplankton biomass (mg in dry weight/m³) at each depth during the day and at nighttime.


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Methods

Bishop, J. K. B., Lam, P. J., & Wood, T. J. (2012). Getting good particles: Accurate sampling of particles by large volume in-situ filtration. Limnology and Oceanography: Methods, 10(9), 681–710. doi:10.4319/lom.2012.10.681
Methods

Hannides, C. C. S., Popp, B. N., Choy, C. A., & Drazen, J. C. (2013). Midwater zooplankton and suspended particle dynamics in the North Pacific Subtropical Gyre: A stable isotope perspective. Limnology and Oceanography, 58(6), 1931–1946. doi:10.4319/lo.2013.58.6.1931
Methods

Hannides, C. C. S., Popp, B. N., Close, H. G., Benitez-Nelson, C. R., Ka’apu-Lyons, C. A., Gloeckler, K., … Drazen, J. C. (2020). Seasonal dynamics of midwater zooplankton and relation to particle cycling in the North Pacific Subtropical Gyre. Progress in Oceanography, 182, 102266. doi:10.1016/j.pocean.2020.102266
Methods

Wiebe, P. H., K.H. Burt, S. H. Boyd, A. W. Morton (1976). A multiple opening/closing net and environment sensing system for sampling zooplankton. J. Mar. Res., 34, 313-326.