Development of Embryonic Market Squid, Doryteuthis opalescens, under Chronic Exposure to Low Environmental pH and [O2]

PLoS One. 2016 Dec 9;11(12):e0167461. doi: 10.1371/journal.pone.0167461. eCollection 2016.

Abstract

The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5-7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.

MeSH terms

  • Acclimatization
  • Algorithms
  • Analysis of Variance
  • Animals
  • California
  • Decapodiformes / embryology*
  • Ecosystem*
  • Embryo, Nonmammalian / embryology*
  • Embryonic Development
  • Hydrogen-Ion Concentration
  • Oceans and Seas
  • Oxygen / metabolism*
  • Seawater / chemistry
  • Stress, Physiological
  • Temperature
  • Time Factors

Substances

  • Oxygen

Grants and funding

This work was funded by National Oceanic and Atmospheric Administration (NOAA:http://www.noaa.gov/) Grant No. NA10OAR4170060, California Sea Grant College Program (https://caseagrant.ucsd.edu/) Project Nos. R/CC-02 and R/CC-04, through NOAA’s National Sea Grant College Program (http://seagrant.noaa.gov/), U.S. Department of Commerce (https://www.commerce.gov/), and by the National Science Foundation-Division of Ocean Sciences (http://www.nsf.gov/div/index.jsp?div=oce) Award Nos. 0903551, 0927445 and 1041062. The statements, findings, conclusions and recommendations are those of the authors and do not necessarily reflect the views of California Sea Grant, state agencies, NOAA, NSF or the U.S. Department of Commerce. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.