Mating behaviour of <Emphasis Type="Italic">Pseudodiaptomus annandalei</Emphasis> (Copepoda,Calanoida) at calm and hydrodynamically disturbed waters

Behavioural observations of male copepods revealed that they commonly follow female footprints to find their mates. Copepods can perceive signals generated by females either hydromechanically or chemically. Signal intensity is affected by hydrodynamic conditions which clear chemical and mechanical cues and modulate copepod’s ability to sense signals of their biotic environment, such as in their search for mates. We studied the patterns and efficiency of the copepod Pseudodiaptomus annandalei to mate in calm and hydrodynamically disturbed waters, in illuminated and dark conditions in experimental containers of different shapes and volumes. Courtship in P. annandalei was a negative function of hydromechanical disturbance, since successful mating events were observed in calm water only. In weakly turbulent conditions (air-bubbling of 100 ml/min), males were not able to pursue females properly; swimming speed decreased about three times in comparison with that in calm water. In calm water conditions, sequential and simultaneous taxis mechanisms were used by P. annandalei males to pursue females. The ability of P. annandalei males to track a three-dimensional trail probably depended on the persistence of fluid-borne signals.