Distribution of cephalopod paralarvae in relation to the regional oceanography of the western Iberia

The present study analyses the distribution of cephalopod paralarvaeoff the Portuguese coast. The effects of temporal and physicalvariables on Loligo vulgaris, Octopus vulgaris, sepiolid andommastrephid abundances are analysed with generalized linearmodels. Their distribution patterns are discussed in relationto mesoscale features, including currents, thermal fronts andcoastal upwelling cross-shelf transport, prevailing in the westernIberia upwelling system. Paralarvae of the neritic species occurduring a considerably extended period of the year with two orthree abundance peaks within the highly productive upwellingsystem of the western Portuguese coast and contrasting withthe Gulf of Cadiz area. Temperature and upwelling were shownto be the most important variables in modulating seasonalityand distribution of these paralarvae. The influence of the physicalenvironment is particularly pronounced for the paralarvae ofO. vulgaris, following distinct patterns according to the oceanographyof the western Iberia and the Gulf of Cadiz systems. The paralarvaeof oceanic species, which in many cases have their northernlimit of distribution at these latitudes, were mainly foundin the southern part of the sampling area. The distributionof these species indicates that the prevailing oceanographicfeatures of the Gulf of Cadiz system, especially fronts, togetherwith temperature act as boundaries to geographic dispersal,contributing to an area of high cephalopod biodiversity in thesouthern Portuguese waters.