Copepod swimming behaviour: from 3D small-scale patterns to species-specific adaptive traits

Planktonic copepods belong to the zooplankton. They play a key role in the functioning of pelagic ecosystem by linking phytoplankton, on which they graze, to larger consumers by which they are preyed. Their behaviour is affected by physical, chemical and biological forces of their surrounding environment. To survive, copepods need to feed on prey, to escape predators and to find mates. In the present study the swimming behaviour in three-dimensional space was investigated for Centropages typicus, Acartia clausi, Paracalanus parvus, Clausocalanus furcatus and Temora stylifera over two conditions: the presence/absence of natural food particles and the population density. Copepods were collected at the long term ecological research station MareChiara (Gulf of Naples, Italy) during the respective peak of occurrences. Results showed that (i) males and females within a species behave the same; (ii) in almost all the species, food acts as a stimulation of swimming pattern; (iii) three swimming behavioural categories were identified over the five species studied; (iv) copepod species, whose peak of abundance occurs in the same season, did not behave the similarly; (v) population density affect the swimming behaviour of all species; however, genders behave mostly differently. The present study brings into light the behaviour of five most abundant copepod species in the Mediterranean sea. Further experiences have to been conduct to fully understand the copepod behaviour and their interaction with their environment.