Developmental and transcriptomic responses of Hawaiian bobtail squid early stages to ocean warming and acidification.

Cephalopods play a central ecological role across all oceans and depths. However, under the current climate crisis, their physiology and behaviour are impacted, and we are beginning to comprehend the effects of environmental stressors at a molecular level. Here, we study the Hawaiian bobtail squid (Euprymna scolopes), known for its specific binary symbiosis with the bioluminescent bacterium Vibrio fischeri acquired post-hatching. We aim to understand the response (i.e. developmental and molecular) of E. scolopes after embryogenetic exposure to different conditions: (i) standard conditions (control), (ii) increased CO2 (∆pH 0.4 units), (iii) warming (+3°C), or (iv) a combination of the two treatments. We observed a decrease in hatching success across all treatments relative to the control, and elevated temperature shortened the developmental time. Using transcriptomics, we identified modulation in metabolic pathways and energy production, at the expense of development under increased CO2. In addition to finding differentially expressed genes related to RNA editing, we also identified several splicing events linked to phenotypic plasticity in response to increased CO2 and temperature. The data also suggest that the initiation of the symbiosis may be negatively affected by these environmental drivers of change in the biosphere, although the animal may counter these via coping mechanisms.