Short-term temporal fluctuation of very-nearshore larval fish assemblages at the Arrábida Marine Park (Portugal)

Understanding processes affecting fish recruitment and population connectivity is of major importance to the management of Marine Protected Areas. Fluctuations in recruitment of coastal fishes can be affected by processes occurring during the early life stages such as the dispersal and availability of larvae. In nearshore temperate environments, there is a lack of knowledge about the patterns of larval supply or biophysical interactions that may influence recruitment variability in these populations. With the objectives of investigating within season (Spring-Summer period) fluctuations that may affect recruitment, and of understanding patterns of larval retention close to the reefs, we used a plankton net attached to an underwater scooter to investigate weekly variation in the composition of fish larval assemblages, larval density and diversity and ontogenetic patterns of occurrence of fish larvae in the extreme nearshore environment of the Arrábida Marine Park (Portugal). The results from multivariate analysis (PERMANOVA and SIMPER) have showed a lower number of species dominating the assemblage, and significant differences in the abundance between species, when compared to previous studies. The presence of larvae in several developmental stages indicates some degree of retention. These findings are important to the management of the Marine Park