MEPS 550:111-119 (2016)  -  DOI: https://doi.org/10.3354/meps11737

Extreme low oxygen and decreased pH conditions naturally occur within developing squid egg capsules

Matthew H. Long1,*, T. Aran Mooney2, Casey Zakroff2,3

1Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA
2Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA
3Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography/ Applied OceanScience and Engineering, Cambridge, Massachusetts 02139, USA
*Corresponding author:

ABSTRACT: Young animals are the foundation of future cohorts and populations, but are often particularly susceptible to environmental changes. This raises concerns that future conditions, influenced by anthropogenic changes such as ocean acidification and increasing oxygen minimum zones, will greatly affect ecosystems by impacting developing larvae. Understanding these potential impacts requires addressing present tolerances and current conditions in which animals develop. Here, we examined changes in oxygen and pH adjacent to and within normally-developing squid egg capsules, providing the first observations that the egg capsules, housing hundreds of embryos, have extremely low internal pH (7.34) and oxygen concentrations (1.9 µmol l-1). While early-stage egg capsules had pH and oxygen levels significantly lower than the surrounding seawater, late-stage capsules dropped dramatically to levels considered metabolically stressful even for adults. The structure of squid egg capsules results in a closely packed unit of respiring embryos, which likely contributes to the oxygen-poor and CO2-rich local environment. These conditions rival the extremes found in the squids’ natural environment, suggesting they may already be near their metabolic limit, and that these conditions may induce a hatching cue. While squid may be adapted to these conditions currently, further climate change could place young, keystone squid outside of their physiological limits.


KEY WORDS: Cephalopod · Climate change · Hypoxia · Boundary layer · Eggs · Larva


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Cite this article as: Long MH, Mooney TA, Zakroff C (2016) Extreme low oxygen and decreased pH conditions naturally occur within developing squid egg capsules. Mar Ecol Prog Ser 550:111-119. https://doi.org/10.3354/meps11737

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