Physiological observations of Euphausia pacifica sampled in Puget Sound, WA aboard R/V Clifford A. Barnes during cruises CB1073 and CB1078 in 2017.

Data Type: Cruise Results
Version: 1
Version Date: 2021-02-11

» Consequences of hypoxia on food web linkages in a pelagic marine ecosystem (PelagicHypoxia)
Keister, Julie E.University of Washington (UW)Principal Investigator
McLaskey, Anna K.University of British Columbia (UBC-IOF)Contact
Soenen, KarenWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Physiological observations of Euphausia pacifica sampled in Puget Sound, WA aboard R/V Clifford A. Barnes during cruises CB1073 and CB1078 in 2017.


Spatial Extent: N:47.896 E:-122.454 S:47.277 W:-123.133
Temporal Extent: 2017-06-24 - 2017-08-31

Acquisition Description

Krill were collected from surface waters (upper 50 m) at each sampling station during the nighttime using a 60-cm diameter Bongo frame equipped with black 335-μm mesh nets and non-filtering cod ends towed for <10 min at 2-3 kts. Healthy female E. pacifica (obvious ovary) were identified under a microscope, kept chilled (10-14 °C) at all times, and were gently transferred using broad spoons to prevent damage.

Processing Description

Krill were measured for total length (from behind the eye to the end of the telson) at 6X using a calibrated eyepiece reticle then flash frozen individually in liquid nitrogen. Total length was converted to dry weight (DW) using a published length-weight regression (Feinberg et al. 2007).

Protein content was determined according to the bicinchoninic acid (BCA) method (Smith et al. 1985) using a Pierce BCA Protein Assay Kit (Thermo Scientific).

ETS activity was assayed using the method of Owens and King (1975), as modified by Gómez et al. (1996), and adapted for a 96-well plate. Assays and blanks were measured in triplicate at 25 °C, calculated according to Packard and Christensen (2004), and corrected to in situ temperatures (depth integrated) using the Arrhenius equation with an activation energy of 15 kcal mol-1 (Packard et al. 1975) and standardized to protein specific activity, spETS.

AARS was measured following the method of Yebra and Hernadez-León (2004), modified by Yebra et al. (2011), and adapted for a 96-well plate (Yebra et al. 2017). All activities were corrected to in situ temperatures with the Arrhenius equation using an activation energy of 8.57 kcal mol-1 (Yebra et al. 2005) and standardized to protein specific activity, spAARS. spAARS_1 was measured with the NADH Blank and calculated as described by Mclaskey et al. (2020). For each sample, assays and NADH Blanks were measured in triplicate.

Oxygen consumption of individual krill was measured at 12 °C by closed-cell respirometry in 22-mL vials containing optical oxygen sensors (PSt7 PreSens) and a 12-mm magnetic stir bar separated from the animal by 200-μm mesh. Measurements were taken every 15 minutes for 2 hours. Krill were kept in filtered seawater to clear their guts for ~1 hr prior to respirometry.

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Related Publications

Feinberg, L., Shaw, C., & Peterson, W. (2007). Long-term laboratory observations of Euphausia pacifica fecundity: comparison of two geographic regions. Marine Ecology Progress Series, 341, 141–152. doi:10.3354/meps341141
Gómez, M., Torres, S., & Hernández-León, S. (1996). Modification of the electron transport system (ETS) method for routine measurements of respiratory rates of zooplankton. South African Journal of Marine Science, 17(1), 15–20. doi:10.2989/025776196784158446
McLaskey, A. K., Keister, J. E., & Yebra, L. (2020). Individual growth rate (IGR) and aminoacyl-tRNA synthetases (AARS) activity as individual-based indicators of growth rate of North Pacific krill, Euphausia pacifica. Journal of Experimental Marine Biology and Ecology, 527, 151360. doi:10.1016/j.jembe.2020.151360
Owens, T. G., & King, F. D. (1975). The measurement of respiratory electron-transport-system activity in marine zooplankton. Marine Biology, 30(1), 27–36. doi:10.1007/bf00393750
Packard, T. T., & Christensen, J. P. (2004). Respiration and vertical carbon flux in the Gulf of Maine water column. Journal of Marine Research, 62(1), 93–115. doi:10.1357/00222400460744636
Packard, T. T., Devol, A. H., & King, F. D. (1975). The effect of temperature on the respiratory electron transport system in marine plankton. Deep Sea Research and Oceanographic Abstracts, 22(4), 237–249. doi:10.1016/0011-7471(75)90029-7
Smith, P. K., Krohn, R. I., Hermanson, G. T., Mallia, A. K., Gartner, F. H., Provenzano, M. D., … Klenk, D. C. (1985). Measurement of protein using bicinchoninic acid. Analytical Biochemistry, 150(1), 76–85. doi:10.1016/0003-2697(85)90442-7
Yebra, L. (2004). Aminoacyl-tRNA synthetases activity as a growth index in zooplankton. Journal of Plankton Research, 26(3), 351–356. doi:10.1093/plankt/fbh028
Yebra, L., Berdalet, E., Almeda, R., Pérez, V., Calbet, A., & Saiz, E. (2011). Protein and nucleic acid metabolism as proxies for growth and fitness of Oithona davisae (Copepoda, Cyclopoida) early developmental stages. Journal of Experimental Marine Biology and Ecology, 406(1-2), 87–94. doi:10.1016/j.jembe.2011.06.019
Yebra, L., Harris, R. P., & Smith, T. (2005). Comparison of five methods for estimating growth of Calanus helgolandicus later developmental stages (CV–CVI). Marine Biology, 147(6), 1367–1375. doi:10.1007/s00227-005-0039-9
Yebra, L., Kobari, T., Sastri, A. R., Gusmão, F., & Hernández-León, S. (2017). Advances in Biochemical Indices of Zooplankton Production. Advances in Marine Biology, 157–240. doi:10.1016/bs.amb.2016.09.001

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TypeExperiment type: pH or DO experiment unitless
CruiseMonth of cruise unitless
StationStation ID unitless
LatitudeLatitude of krill sampling location, south is negative decimal degrees
LongitudeLongitude of krill sampling location, west is negative decimal degrees
Total_LengthMeasured total length of individual krill millimeters (mm)
Dry_WeightDry weight calculated from total length. milligrams (mg)
ProteinProtein content per individual milligrams (mg)
spETS_activityProtein specific Electron Transport System (ETS) activity umol O2 h-1 mg protein-1
spAARS_activityProtein specific aminoacyl-tRNA synthetase (AARS) activity nmol PPi h-1 mg protein-1
spAARS_1_activityProtein specific aminoacyl-tRNA synthetase (AARS) activity calculated with NADH blank correction described in McLaskey et al. 2020 nmol PPi h-1 mg protein-1
Respiration_rateIndividual oxygen consumption measured by respirometry umol O2 hr-1 ind-1
Start_Sampling_ISO_DateTime_UTCStart DateTime of sampling in ISO format (yyyy-mm-ddThh:mm), UTC timezone unitless

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Dataset-specific Instrument Name
PreSens Microx 4 with PSt7
Generic Instrument Name
Dissolved Oxygen Sensor
Dataset-specific Description
PreSens Microx 4 with PSt7 optical oxygen sensors
Generic Instrument Description
An electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed

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R/V Clifford A. Barnes
Start Date
End Date


R/V Clifford A. Barnes
Start Date
End Date

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Project Information

Consequences of hypoxia on food web linkages in a pelagic marine ecosystem (PelagicHypoxia)

Coverage: Puget Sound, WA (47 N, 123 W)

Description from NSF award abstract:
Low dissolved oxygen (hypoxia) is one of the most pronounced, pervasive, and significant disturbances in marine ecosystems. Yet, our understanding of the ecological impacts of hypoxia on pelagic food webs is incomplete because of our limited knowledge of how organism responses to hypoxia affect critical ecosystem processes. In pelagic food webs, distribution shifts of mesozooplankton and their predators may affect predator-prey overlap and dictate energy flow up food webs. Similarly, hypoxia may induce shifts in zooplankton community composition towards species that impede energy flow to planktivorous fish. However, compensatory responses by species and communities might negate these effects, maintaining trophic coupling and sustaining productivity of upper trophic level species. The PIs propose to answer the question "Does hypoxia affect energy flow from mesozooplankton to pelagic fish?" They approach this question with a nested framework of hypotheses that considers two sets of processes alternatively responsible for either changes or maintenance of pelagic ecosystem energy flows. They will conduct their study in the Hood Canal, WA. Unlike most hypoxia-impacted estuaries, hypoxic regions of Hood Canal are in close proximity to sites that are not affected. This makes it logistically easier to conduct a comparative study and reduces the number of potential confounding factors when comparing areas that are far apart.

Improved understanding of how hypoxia impacts marine ecosystems will benefit the practical application of ecosystem-based management (EBM) in coastal and estuarine ecosystems. Effective application of EBM requires that the impacts of human activities are well understood and that ecological effects can be tracked using indicators. This project will contribute to both of these needs. The PIs will share their findings on local and national levels with Federal, State, Tribal, and County biologists. To increase exposure of science to underrepresented groups, the PIs also will provide Native American youth with opportunities to participate in field collections and laboratory processing through summer internships. The PIs will collaborate with the NSF-funded Pacific Northwest Louis Stokes Alliance for Minority Participation and tribes from the Hood Canal region to recruit and mentor students for potential careers in marine science. This project will support several undergraduate researchers, two Ph.D. students, a post-doc, and two early-career scientists.

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Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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