Cuttlefish Early Development and Behavior Under Future High CO2 Conditions.

Érica Moura,Maria Rita Pegado,Eduardo Sampaio,Catarina P Santos,Rui Rosa,Vanessa Madeira Lopes,Marta Pimentel

doi:10.3389/fphys.2019.00975

Abstract

The oceanic uptake of carbon dioxide (CO2) is increasing and changing the seawater chemistry, a phenomenon known as ocean acidification (OA). Besides the expected physiological impairments, there is an increasing evidence of detrimental OA effects on the behavioral ecology of certain marine taxa, including cephalopods. Within this context, the main goal of this study was to investigate, for the first time, the OA effects (∼1000 μatm; ΔpH = 0.4) in the development and behavioral ecology (namely shelter-seeking, hunting and response to a visual alarm cue) of the common cuttlefish (Sepia officinalis) early life stages, throughout the entire embryogenesis until 20 days after hatching. There was no evidence that OA conditions compromised the cuttlefish embryogenesis – namely development time, hatching success, survival rate and biometric data (length, weight and Fulton’s condition index) of newly hatched cuttlefish were similar between the normocapnic and hypercapnic treatments. The present findings also suggest a certain behavioral resilience of the cuttlefish hatchlings toward near-future OA conditions. Shelter-seeking, hunting and response to a visual alarm cue did not show significant differences between treatments. Thus, we argue that cuttlefishes’ nekton-benthic (and active) lifestyle, their adaptability to highly dynamic coastal and estuarine zones, and the already harsh conditions (hypoxia and hypercapnia) inside their eggs provide a degree of phenotypic plasticity that may favor the odds of the recruits in a future acidified ocean. Nonetheless, the interacting effects of multiple stressors should be further addressed, to accurately predict the resilience of this ecologically and economically important species in the oceans of tomorrow.

Highlights

Over the past centuries, atmospheric carbon dioxide (CO2) concentration has been increasing, with a current value of ∼ 415 ppm (NOAA, 2019), being the highest registered in the past 800,000 years
Development time was similar in both treatments (∼ 59 ± 9 days), i.e., there was no significant effect under ocean acidification (OA) (Figure 1; p > 0.05; GLM, Poisson family, more details in Supplementary Table 1)
No significant differences were observed regarding to their hunting behavior between control and OA treatments (Figure 4; p > 0.05; GLM, Gamma family, analysis in Supplementary Table 3), as well as for predatory success rate (Figure 4; p > 0.05; GLM, Poisson family, more details in Supplementary Table 1)

Summary

Introduction

Atmospheric carbon dioxide (CO2) concentration has been increasing, with a current value of ∼ 415 ppm (NOAA, 2019), being the highest registered in the past 800,000 years. When a higher amount of CO2 reacts with seawater, it increases the formation of carbonic acid (H2CO3), increases the amount of bicarbonate ions (HCO3−) and reduces the availability of carbonate ions (CO32−) (Rhein et al, 2013) These changes cause an increase in the production of hydrogen ions (H+) and a subsequent reduction of seawater pH. As CO2 levels continue to rise, forecasts indicate that, by the end of this century, the average ocean surface pH will be 0.2–0.4 pH units lower than present values (Rhein et al, 2013). This pH drop may represent a serious threat to the health of the world’s ocean ecosystems (Cubasch et al, 2013)

Objectives

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Results

Conclusion