During the summer, the relative influence of resident Atlantic Waters (AW) and new AW largely drives the mesoscale

dynamics around the Balearic Islands (NW Mediterranean). Two principal summer hydrographic scenarios were

identified in the region, differentiated by the relative position of the density front between new and resident AW within

the archipelago and its associated mesoscale activity. In this study, we investigated how those early summer mesoscale

scenarios influence larval fish assemblages, by analyzing data from two cruises representative of these two scenarios

(2004 and 2005). Redundancy analysis was used to assess the variance in the larval fish assemblage that could be sig-

nificantly explained by the most parsimonious combination of available environmental variables in both years. While

depth was the most important variable in explaining the larval fish assemblage structure variability observed under

both scenarios, indicators of mesoscale activity (dynamic height, geostrophic velocity) contributed significantly to

understanding the dynamics of the larval fish community. Mesoscale activity was higher in summer 2004, leading to

higher larval fish abundances and zooplankton biomass and lower larval fish diversity than in the unusually warm

summer 2005, which showed lower mesoscale activity. The larval assemblage dynamics are discussed in terms of ex-