Cuttlefish Early Development and Behavior Under Future High CO2 Conditions

Abstract

The oceanic uptake of carbon dioxide (CO 2 ) 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.

Cuttlefish Buoyancy in Response to Food Availability and Ocean Acidification

“…OA is known to differently affect calcification processes [ 20 ]. Contrarily to previous studies [ 36 , 49 ], here, we observed that cuttlefish hatching success was significantly lower under high CO 2 according to the exposure time. More specifically, hatching success was lower when the cuttlefish spent a longer time of their embryonic development under high CO 2 , with a delay of three days regarding the hatching time (here, defined as the time when 50% of cuttlefish hatched) when compared to control treatment.…”

Camouflage and Exploratory Avoidance of Newborn Cuttlefish under Warming and Acidification

“…As previously reported [ 25 , 26 , 28 ] for lower pH (Δ pH 0.4, 0.5, and 0.4, respectively), acidification of Δ pH ~0.3 had no relevant effect on hatching success. CO 2 partial pressures can be three times higher within the egg than surrounding seawater p CO 2 [ 25 , 28 ], making them uniquely prepared for projected levels of OA.…”

“…Moreover, cuttlefish are active swimmers and consequently need an efficient ion transport system to maintain a stable blood pH during exercise in order to cope with their respiratory CO 2 [ 47 ]. Indeed, contrarily to most marine invertebrates, ectotherms with high metabolic rates, such as teleosts and cephalopods, are able to garner soft tissue mass and calcify under hypercapnia [ 26 ]. Additionally, as observed by Moura et al [ 26 ], exposure to A during embryogenesis was found to not affect the size of newly-hatched cuttlefish.…”

“…Indeed, contrarily to most marine invertebrates, ectotherms with high metabolic rates, such as teleosts and cephalopods, are able to garner soft tissue mass and calcify under hypercapnia [ 26 ]. Additionally, as observed by Moura et al [ 26 ], exposure to A during embryogenesis was found to not affect the size of newly-hatched cuttlefish. Similarly to squid under Δ pH 0.4 [ 48 ] and cuttlefish under 980 µatm p CO 2 [ 27 ], our findings indicate that acidification prolongs embryogenesis.…”

“…Further, pre-hatching eggs display lower hypoxic thresholds when exposed to both stressors simultaneously ( S. officinalis ) [ 25 ]. However, acidification per se was found to have no impacts on cuttlefish hatchlings’ fitness, i.e., ability to reproduce [ 25 , 26 ], except for increased rates of calcification in the cuttlebone at 980 μatm (assuming cuttlefish are fed) [ 27 ], or starting from a decrease of 0.25 pH units [ 28 ] relative to current pH levels. Concerning behavior, Moura et al [ 26 ] observed no effects of acidification on shelter-seeking, hunting, or detection of conspecifics in cuttlefish hatchlings.…”