The rapid decline of several marine mammal species such as dolphins and whales is a growing problem on a global scale. Losses in abundance have been especially important in the Mediterranean, a biodiversity hotspot which supports a diverse range of marine ecosystems. Marine mammals are threatened by various human activities and their effects, such as marine traffic, habitat degradation, fishing, tourism, and pollution. Behavioural studies of how marine mammals interact with each other and their environment contribute to a more holistic understanding of population and individual health. Changes in behavioural budgets can provide information on the biological significance of an impact, and improve protective measures over habitats that support fundamental biological relations for the species.
From Archipelagos’ research vessels, we monitor marine mammal populations in the Aegean Sea. During sightings, we collect data about the species and any activity at least 50% of the individuals are engaging in. We record video footage, which we then upload to BORIS (Behaviour Observation Research Interactive Software). Using an ethogram (a table of all behaviours observed in an animal), we code the duration of short-term behaviours (events), long-term behaviours (states), and combinations of states and events (categories). Examples of events are inspecting boat, bow riding, and leaping. States include swimming and diving, while categories include feeding, porpoising, resting, sharking, socialising, and travelling. From this data we produce activity budgets which quantify the total duration for all observed behaviours.
Some of the marine mammal species we focus on include the short beaked common dolphin Delphinus delphis (which unlike its name implies is now rare in the Mediterranean Sea), the bottlenose dolphin (Tursiops truncatus), the striped dolphin (Stenella coeruleoalba), the Risso’s dolphin (Grampus griseus), the sperm whale (Physeter macrocephalus) and Cuvier’s beaked whale (Ziphius cavirostris). Current projects in which our research teams are engaged investigate behavioural comparisons between species, seasonal behaviour changes, as well as how behaviour is influenced by the presence of factors such as marine litter, research vessels, and marine traffic.
A large quantity of data is required in order to continue addressing questions about behavioural patterns in relation to a number of environmental variables and biological agents. With increasing climatic extremes, behavioural studies and efficient conservation action are even more necessary to prevent increasing losses of marine mammal populations.
Amelia Macapia, BSc. Biology and Environmental Studies at Tufts University, USA;
Aileen Roncoroni, MSc. Marine Sciences at Utrecht University, Netherlands;
Aina Rossinyol, BSc. Environmental Biology at Universitat Autònoma de Barcelona, Spain