<strong>Oxygen loss compromises the survival and cognition of a coastal cephalopod</strong>

The ocean is undergoing deoxygenation and the spread of hypoxic areas. Ocean deoxygenation and standing levels of hypoxia are shrinking fundamental niches, particularly in coastal areas, yet documented repercussions on species development and behavior are limited. Here, we tackled the impacts of deoxygenation (7 mg O2 L-1), mild hypoxia (nocturnal 5 mg O2 L-1), and severe hypoxia (2 mg O2 L-1) on cuttlefish (<em>Sepia officinalis</em>) development (hatching success, development time, mantle length) and behavior, i.e., ability to learn (iundividual- and socially), to camouflage, and to explore its surroundings spatially. We found that hypoxia yielded lower survival rates, smaller body sizes and inhibited predatory (increased latency to attack the prey) and anti-predator (camouflage) behaviors. Acute and chronic exposure to low oxygen produced similar effects on cognition (inability to socially learn, increased open-field activity levels, no changes in thigmotaxis). It is thus expected that, although cuttlefish can withstand oxygen limitation to a certain degree, expanding hypoxic zones will diminish current habitat suitability.