Data from: Ocean warming and acidification alter the behavioural response to flow of the sea urchin Paracentrotus lividus

Ocean warming (OW) and acidification (OA) are intensively investigated as
they pose major threats to marine organism. However, little effort is
dedicated to another collateral climate change stressor, the increased
frequency and intensity of storm events, here referred to as intensified
hydrodynamics. A 2-month experiment was performed to identify how OW and
OA (temperature: 21°C; pHT: 7.7, 7.4; control: 17°C-pHT7.9) affect the
resistance to hydrodynamics in the sea urchin Paracentrotus lividus using
an integrative approach that includes physiology, biomechanics and
behaviour. Biomechanics was studied under both no-flow condition at the
tube foot (TF) scale and flow condition at the individual scale. For the
former, TF disk adhesive properties (attachment strength, tenacity) and TF
stem mechanical properties (breaking force, extensibility, tensile
strength, stiffness, toughness) were evaluated. For the latter, resistance
to flow was addressed as the flow velocity at which individuals detached.
Under near- and far-future OW and OA, individuals fully balanced their
acid-base status, but skeletal growth was halved. TF adhesive properties
were not affected by treatments. Compared to the control, mechanical
properties were in general improved under pHT7.7 while in the extreme
treatment (21°C-pHT7.4) breaking force was diminished. Three behavioural
strategies were implemented by sea urchins and acted together to cope with
flow: improving TF attachment, streamlining and escaping. Behavioural
responses varied according to treatment and flow velocity. For instance,
individuals at 21°C-pHT7.4 increased the density of attached TF at slow
flows or, controlled TF detachment at fast flow to compensate for weakened
TF mechanical properties. They also showed an absence of streamlining
favouring an escaping behaviour as they ventured in a riskier faster
movement at slow flows. At faster flows, the effects of OW and OA were
detrimental causing earlier dislodgment. These plastic behaviours reflect
a potential scope for acclimation in the field, where this species already
experiences diel temperature and pH fluctuations.