Cuttlefish Buoyancy in Response to Food Availability and Ocean Acidification

Abstract

<jats:p>Carbon dioxide concentration in the atmosphere is expected to continue rising by 2100, leading to a decrease in ocean pH in a process known as ocean acidification (OA). OA can have a direct impact on calcifying organisms, including on the cuttlebone of the common cuttlefish Sepia officinalis. Moreover, nutritional status has also been shown to affect the cuttlebone structure and potentially affect buoyancy. Here, we aimed to understand the combined effects of OA (980 μatm CO2) and food availability (fed vs. non-fed) on the buoyancy of cuttlefish newborns and respective cuttlebone weight/area ratio (as a proxy for calcification). Our results indicate that while OA elicited negative effects on hatching success, it did not negatively affect the cuttlebone weight/area ratio of the hatchlings—OA led to an increase in cuttlebone weight/area ratio of fed newborns (but not in unfed individuals). The proportion of “floating” (linked to buoyancy control loss) newborns was greatest under starvation, regardless of the CO2 treatment, and was associated with a drop in cuttlebone weight/area ratio. Besides showing that cuttlefish buoyancy is unequivocally affected by starvation, here, we also highlight the importance of nutritional condition to assess calcifying organisms’ responses to ocean acidification.</jats:p>

Camouflage and Exploratory Avoidance of Newborn Cuttlefish under Warming and Acidification

“…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. Thus, on the one hand, A may pose a physiological burden on cuttlefish hatchlings if paired with the downregulation of regulatory and metabolic genes [ 49 ].…”

“…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.…”

Morphological response accompanying size reduction of belemnites during an Early Jurassic hyperthermal event modulated by life history

“…Many experimental studies on modern squid show that several climate-related stressors can change the morphology of squid’s internal skeletons 24 , 78 – 81 . In particular, decreased pH in seawater is associated with abnormal early development of statoliths 81 and cuttlebones in decabrachians as well as hypercalcification 23 , 78 – 80 , 82 . All of these factors would affect buoyancy and locomotion, affecting the ability of young decabrachians to thrive as normal 23 , 24 , 81 .…”

Elasmobranch Responses to Experimental Warming, Acidification, and Oxygen Loss—A Meta-Analysis

“…Indeed, while EW and EA have been observed to influence growth in fishes (Audzijonyte et al, 2020;Sampaio et al, 2021), results appear to be widely context-dependent for both elasmobranchs (e.g., Pistevos et al, 2015) and teleosts (Cattano et al, 2018). Moreover, most studies feature ad libitum feeding, with food availability known to modulate growth under EW and EA (Baumann, 2019;Cominassi et al, 2020;Otjacques et al, 2020). Indeed, feeding and digestion responded positively to EW, with a close trend observed for EAW (Figure 5A; Supplementary Table 3), which aligns with hypothesized increased energetic needs.…”