Metabolic responses of the North Pacific krill, Euphausia pacifica, to short- and long-term pCO2 exposure
While ocean acidification is likely to have major effects on many marine organisms, those species that regularly experience variable pCO2 environments may be more tolerant of future predicted changes in ocean chemistry. Euphausia pacifica is an abundant krill species along the Pacific coast of North America and one that regularly experiences varying pCO2 levels during seasonal upwelling, as well as during daily vertical migrations to depth where pCO2 is higher. Krill were collected from Monterey Bay, California (36.8°N, 121.9°W), and experiments were performed from June to August 2014 and maintained at two pCO2 levels (400 and 1200 µatm). Three metabolic responses (oxygen consumption, ingestion rate, and nutrient excretion rates) of E. pacifica were measured. Oxygen consumption declined by 31 % in the first 24 h following exposure to high pCO2 and remained low after 21 days. Oxygen consumption at low pCO2 was low for the first 12 h, increased by 34 % at 24 h, but returned to initial values by 21 days. After 3 weeks of continuous exposure, oxygen consumption rates were 32 % lower in the high pCO2 group. Ingestion and ammonium excretion rates were both significantly lower in the high pCO2 group after 24-h exposure, but not after 7 or 21 days. There was no effect of pCO2 on phosphate excretion. Taken together, these results indicate that E. pacifica has a lower metabolic rate during both short-term (24 h) and longer-term (21 days) exposure to high pCO2. Such metabolic depression may explain previously reported declines in growth of E. pacifica exposed to high pCO2.
KeywordsPhytoplankton Oxygen Consumption Rate Ocean Acidification Ammonium Excretion High pCO2
The authors would like to thank Luis Hernandez, Honor Weber, and Sarah Dondelinger for laboratory help and assistance with water chemistry analyses; Dave Benet and Steve Clabuesch for assistance in building the pCO2-air mixing system and with krill collections; Betsy Steele for culturing phytoplankton and general laboratory guidance; and Rob Franks for assistance with nutrient and chemical analyses.
This study was funded through awards from the NOAA West Coast and Polar Regions Undersea Research Center (project FP12783A) and NSF (OCE-1040952) to A. Paytan, a UCSC Committee on Research grant and a gift from the Mitsubishi corporation to D. Potts, and awards to H. Cooper from the Friends of Long Marine Laboratory, Meyers Trust, and the UCSC 503 Department of Ecology and Evolutionary Biology.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. This article does not contain any studies with human participants performed by any of the authors.
- Brinton E (1962) The distribution of Pacific euphausiids. Bulletin of the Scripps Institution of Oceanography, University of California 8:41–270Google Scholar
- Brinton E (1976) Population biology of Euphausia pacifica off Southern California. Fish Bull 74(4):733–762Google Scholar
- Caldeira K, Wickett ME (2005) Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean. J Geophys Res 110(C9):C09S04. doi: 10.1029/2004JC002671
- Calosi P, Rastrick SP, Lombardi C, de Guzman HJ, Davidson L, Jahnke M, Giangrande A, Hardege JD, Schulze A, Spicer JI, Gambi MC (2013) Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system. Philos Trans R Soc Lond B Biol Sci 368(1627):20120444. doi: 10.1098/rstb.2012.0444 CrossRefGoogle Scholar
- Cameron JN, Iwama GK (1987) Compensation of progressive hypercapnia in channel catfish and blue crabs. J Exp Biol 133(1):183–197Google Scholar
- Cameron JN, Wood CM (1985) Apparent H+ excretion and CO2 dynamics accompanying carapace mineralization in the blue crab (Callinectes sapidus) following moulting. J Exp Biol 114(1):181–196Google Scholar
- Conover RJ (1978) Transformation of organic matter. Marine ecology. Wiley, Chichester, pp 221–499Google Scholar
- Edenhofer O, Pichs-Madruga R, Sokona Y, Farahani E, Kadner S, Seyboth K (2014) IPCC, 2014: Summary for Policymakers. In: Climate change 2014: Mitigation of climate change. Contribution of working group III to the fifth assessment report of the intergovernmental panel on climate change, Cambridge University Press, Cambridge and New YorkGoogle Scholar
- Harris R, Wiebe P, Lenz J, Skjoldal H-R, Huntley M (2000) ICES zooplankton methodology manual. Academic Press, San DiegoGoogle Scholar
- Heisler N (1986) Acid-base regulation in animals. Elsevier Science, MichiganGoogle Scholar
- Hildebrandt N, Sartoris FJ, Schulz KG, Riebesell U, Niehoff B (2015) Ocean acidification does not alter grazing in the calanoid copepods Calanus finmarchicus and Calanus glacialis. ICES Journal of Marine Science: Journal du Conseil :fsv226. doi: 10.1093/icesjms/fsv226
- Kleypas JA, Feely RA, Fabry VJ, Langdon C, Sabine CL, Robbins LL (2006) Impacts of ocean acidification on coral reefs and other marine calcifiers: a guide for future research. Rep of a workshop sponsored by NSF, NOAA & USGS, St. Petersburg, FL, 18–20 April 2005, p 88Google Scholar
- Langenbuch M, Pörtner H-O (2002) Changes in metabolic rate and N excretion in the marine invertebrate Sipunculus nudus under conditions of environmental hypercapnia: identifying effective acid-base variables. J Exp Biol 205(8):1153–1160Google Scholar
- Marinovic B, Mangel M (1999) Krill can shrink as an ecological adaptation to temporarily unfavorable environments. Ecol Lett 2:338–343Google Scholar
- Melzner F, Gutowska MA, Langenbuch M, Dupont S, Lucassen M, Thorndyke MC, Bleich M, Pörtner HO (2009) Physiological basis for high CO2 tolerance in marine ectothermic animals: pre-adaptation through lifestyle and ontogeny? Biogeosciences 6:2313–2331. doi: 10.5194/bg-6-2313-2009 CrossRefGoogle Scholar
- Pierrot D, Lewis E, Wallace D.W.R. (2006) MS excel program developed for CO2 system calculations [computer file]. ORNL/CDIAC-105a Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy [distributor]Google Scholar
- Pörtner HO, Langenbuch M, Michaelidis B (2005) Synergistic effects of temperature extremes, hypoxia, and increases in CO2 on marine animals: From Earth history to global change. J Geophys Res 110(C9):C09S10. doi: 10.1029/2004JC002561
- Solomon S (2007) Climate Change 2007: the physical science basis: contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge and New YorkGoogle Scholar
- Stocker TF, Qin Q, Plattner G-K, et al. (2013) Summary for Policymakers. In: Climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change, Cambridge University Press, Cambridge and New YorkGoogle Scholar
- Stumpp M, Trübenbach K, Brennecke D, Hu MY, Melzner F (2012) Resource allocation and extracellular acid-base status in the sea urchin Strongylocentrotus droebachiensis in response to CO2 induced seawater acidification. Aquat Toxicol 110–111:194–207. doi: 10.1016/j.aquatox.2011.12.020 CrossRefGoogle Scholar
- Tremblay N (2014) Tolerance mechanisms and responses of krill species of different latitudes to oxygen minimum zones. Dissertation, Universität Bremen, Bremen, GermanyGoogle Scholar
- Whiteley NM, Scott JL, Breeze SJ, McCann L (2001) Effects of water salinity on acid-base balance in decapod crustaceans. J Exp Biol 204(5):1003–1011Google Scholar