Penilia avirostris: Regional and global patterns of seasonal cycles

Seasonal cycles of the Penilia abundance were compared, over five coastal regions-the north-western part of the Black Sea (Sevastopol Bay), the northern part of the Adriatic Sea (Gulf of Trieste), the north-eastern Atlantic (Vigo coast), the north-western Mediterranean basin (Barcelona coast), and the north-western part of the Arabian Sea (the Gulf of Oman). Satellite derived monthly data were used, to analyze coupling between the Penilia abundance, sea surface temperature, and chlorophyll a concentration over these regions. Two types of seasonal dynamics were noticed: (1) a unimodal type of population dynamics with one peak lasting 3-4 months in summer to fall (in Vigo, Sevastopol, and Trieste regions) and (2) all year round persisting population in subtropical highly productive waters of the Arabian Sea (Gulf of Oman). A regional link between abundance and temperature was also reflected by the global geography of the Penilia habitats. As far as the global aspect is concerned, a general relationship representing the abundance as the linear function of two environmental variables-sea surface temperature and chlorophyll a concentration was proposed.