Elevated seawater pCO2 affects reproduction and embryonic development in the pygmy squid, Idiosepius pygmaeus

Blake L Spady; Philip L Munday; Sue-Ann Watson

doi:10.1016/j.marenvres.2019.104812

Elevated seawater pCO₂ affects reproduction and embryonic development in the pygmy squid, Idiosepius pygmaeus

Mar Environ Res. 2020 Jan:153:104812. doi: 10.1016/j.marenvres.2019.104812. Epub 2019 Oct 4.

Authors

Blake L Spady¹, Philip L Munday², Sue-Ann Watson³

Affiliations

¹ ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia; College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia. Electronic address: blake.spady@my.jcu.edu.au.
² ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia.
³ ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia; Biodiversity and Geosciences Program, Museum of Tropical Queensland, Queensland Museum, Townsville, QLD, 4810, Australia.

PMID: 31610954
DOI: 10.1016/j.marenvres.2019.104812

Abstract

The oceans are absorbing additional carbon dioxide (CO₂) from the atmosphere and projected future CO₂ levels and ocean acidification could have negative implications for many marine organisms, especially during early life stages. Cephalopods are ecologically important in marine ecosystems, yet the potential effects of increased partial pressure of CO₂ (pCO₂) in seawater on cephalopod reproduction and embryonic development are little studied. We allowed adult two-toned pygmy squid (Idiosepius pygmaeus) to breed in ambient control (~445 μatm; ~8.05 pH_T) or elevated pCO₂ conditions (~940 μatm; ~7.78 pH_T) and compared reproductive traits in adults and developmental characteristics of their eggs, which remained in control or elevated pCO₂ treatments until hatching. Breeding pairs at elevated pCO₂ produced clutches with 40% fewer eggs, vitelli that were 14% smaller directly after spawning, embryos that were 5% smaller upon hatching, and eggs with an 8% increase in late-stage egg swelling compared with pairs at control conditions. Elevated pCO₂ did not affect fertility, time to hatch, or hatching success. Eggs were laid 40% closer together in elevated pCO₂ compared with control conditions, indicating a possible effect of elevated pCO₂ on reproductive behaviour. These results show that elevated pCO₂ can adversely affect reproduction and embryonic development of the two-toned pygmy squid. As the potential for adaptation is influenced by reproductive success, testing the capacity for squid to adapt to future ocean conditions should be a priority for future research.

Keywords: Animal reproduction; Cephalopod; Climate change; Early embryonic development; Eggs; Ocean acidification.