| Summary: | Tese de mestrado, Biologia da Conservação, Universidade de Lisboa, Faculdade de Ciências, 2019 Atmospheric CO 2 levels are rising since the beginning of the Industrial Era, and concomitantly, the uptake of CO 2 by the oceans is increasing and changing the seawater chemistry, a phenomenon known as ocean acidification (OA). These changes can compromise key biological traits of many marine organisms, with potential cascading effects to population and ecosystem levels. Besides the significant neurological/physiological impairments, there is increasing evidence of detrimental OA effects on the behavioural ecology of certain marine taxa, including in cephalopods. Yet, the previous behavioural studies performed in these highly developed invertebrates were only focused on squids and the potential impacts in cuttlefish behaviour are still unknown. Within this context, the main objectives of this dissertation were to investigate OA effects in the development and behaviour of the common cuttlefish ( Sepia officinalis ) early-life stages – from early embryogenesis until 20 days after hatching, namely by exposing them to either present day ( ~ 400 μatm) and to the near-future levels of p CO 2 ( ~ 1000 μatm; ΔpH = 0.4). A comprehensive assessment of OA effects on cuttlefish development was performed by gauging embryogenesis duration, hatching success, early survival rate and body size measures (e.g. weight and length). Furthermore, different aspects of the cuttlefish behavioural ecology, including shelter-seeking, hunting behaviour and response to a visual alarm cue, were analysed to achieve a holistic overview of the OA impacts in cuttlefish early development. The present work did not find any evidence that OA future conditions compromise the cuttlefish embryonic development. The development time, hatching success, survival rate, and the length and weight of newly-hatched cuttlefish were similar between normocapnia and hypercapnia treatments. The Fulton’s Index was the only parameter that showed significant differences, ...
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