Gaining insights into in situ behaviour of an endangered seahorse using action cameras

Observation bias is an Achilles heel of behavioural research, particularly during underwater in situ assessments. The advent of small, affordable underwater action cameras has helped to overcome this problem and were used to investigate the behaviour of the endangered Knysna seahorse (Hippocampus capensis) within a South African residential marina estate during the austral summer. Four GoPro® cameras were deployed over three time periods, October to December 2015, December 2015 to January 2016 and January to March 2016, and at different times of the day (morning, midday, afternoon) to ascertain whether: (1) cameras can be used to investigate seahorse behaviour, (2) seahorse behaviour changes throughout the day, (3) behaviour can be used to assess the impact of an external stressor (boat noise) on H. capensis. Thirty‐six hours from a total of 161 h (23%) recorded contained seahorse footage. Seahorses were significantly more visible during the morning and spent >80% of their time hunting. Courting behaviour took place exclusively during the morning and aggression was noted between males only. Boat noise increased during the December holiday period and a significant decrease in seahorse visibility, time spent feeding, and courting events were noted during this time. This suggests that noise has an adverse impact on the behaviour of H. capensis. This study confirms the efficacy of using small action cameras in seahorse behavioural research.