Marine heatwaves as selective filters on the behaviour of native and non-native invertebrates

Experimental Setup
Animals were acclimated to 18°C for five days before temperature manipulation. The "Heat-wave group" underwent a controlled temperature increase:
Phase 1: Temperature raised to 27°C over 24 hours (using two 300W heaters) and maintained for 3 days.
Phase 2: Further increased to 32°C over 24 hours and held for 3 additional days.
Total experiment duration: 11 days . Behavioral and morphometric data (including mortality) were recorded.

Behavioral Assays
Conducted in duplicate for both Heat-wave and Control groups, with 1-day intervals between replicates to minimize stress. Each replicate included three consecutive tests:
Locomotion Measurement:
Tracked distance moved (m), average speed (m/s), and edge preference (thigmotaxis; risk-aversion proxy) via GoPro Hero 11 cameras. Time-lapse recording (1 frame/5 sec over 60 min) analyzed with Tracker software (calibrated with graph paper).
Spontaneous Behavior:
Undisturbed 5-min observations (24 fps) of: Crawling (exploration/foraging), Folding (U-shaped defensive posture), Rearing (response to stress), Veering (180° direction change)
Response to Disturbance:
Simulated threat (soft plastic stick applied dorsally) followed by 5-min filming.
Measured cerata relaxation time (defensive alertness indicator; BORIS software).

Mortality & Morphometrics
Body length tracked daily (ImageJ); calculated % shortening between phases.
Mortality recorded daily; deceased individuals removed.