Variations saisonnières des appendiculaires de la région nord Adriatique

Appendicularians from 140 hauls made in the north Adriatic area, over a period of 9 months, have been examined. A high population density, with 67 specimens per cubic meter and a low specific diversity with 10 species is described. Three species: Oikopleura dioica, O. longicauda and O. fusiformis represent more than 95% of the specimens collected. The presence of a West-East gradient in the population density is shown, along with a correlation with the influence of the Pô inflow. A study of the seasonal variations of the three main species shows that all the characteristics of the Western region are very favourable to O. dioica. This fact seems to be the clue to the qualitative and quantitative variations of the appendicularian population in this area.