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The role of the Mar Chiquita lagoon and its adjacent coastal area as nursery ground for fish larvae and juveniles and the factors which regulate their recruitment process, was evaluated. To do so, we analyzed the fish early life stages composition and spatio-temporal variation over the marine-estuarine gradient of the lagoon and its relationship with environmental factors; the diel variation of these stages in the immediate area at the mouth of the lagoon; and the source of the organic carbon which feed them on the mouth of the lagoon and adjacent coastal area, by using stable isotope analysis. The richness and mean density of larvae were higher at the offshore area than at the lagoon. Inside the lagoon the dominant species in larval stage was Brevoortia aurea, while in the offshore zone Gobiosoma parri and the Engraulidae Family were dominant. The composition of juvenile stages showed a temporal variation, being Platanichthys platana, Ramnogaster arcuata and Odontesthes argentinensis the first to colonize the lagoon. Although possibly the first two species are represented by both juveniles and adults stages. The low values of abundance and diversity collected at the surf zone suggest that this environment is only used as a transient route between the sea and the lagoon. The highest abundances of both stages were associated with onshore winds, whilst there was no clear pattern in relation to tides. Variations in the composition of fish between light and dark periods were evident, with higher abundances during the first hours of the night, coinciding with the decline of the seabreeze phenomenon. According to isotopic labels, the main source of organic matter that supports larval and juvenile fish outside the lagoon is the macro-detritus derived from terrestrial and marsh plants present in the lagoon. Similar ~d15N values between larval and juvenile fishes suggest that both stages share the resource of food. Finally, we propose a conceptual framework to the lagoon recruitment mediated by environmental factors which rule the entry and exit of water and also discussed the role of small lagoons in the life histories of coastal fishes. Tesis (Doctorado) Laboratorio de Biotaxonomía Morfológica y Molecular de Peces (BIMOPE)- Instituto de Investigaciones Marinas y Costeras (IIMyC), CONICET. (Mar del Plata) Unpublished peces salobres medioambiente salobre lagunas costeras ciclo de vida juveniles larvas de peces reclutamiento abundancia Brevoortia aurea Gobiosoma parri Engraulidae Platanichthys platana sardina Odontesthes argentinensis pejerrey saraca lacha engrulidos |
