Comparison between two lunar situations on emission and larval transport of decapod larvae in the Mondego estuary (Portugal)

Abstract

This study compares the rhythms of larval release of the most abundant decapod crustaceans between the New Moon and the First Quarter. Eurelian field surveys were conducted at a small estuary (Mondego river) on the Atlantic coast of Portugal. All taxa showed tidal and lunar rhythm changes in abundance. The larval emission was very strong during nocturnal ebb neap tides at the First Quarter. Export of zoea did not occur to Rhithropanopeus harrisii. Despite the extensive literature on seasonal abundance, dispersal patterns, larval emission and recruitment of estuarine crabs, little is known about patterns of emission and larval transport in estuaries of Atlantic coast of Portugal, with crepuscular high tides around the quarter moons. The aim of the present study was to compare the larval emission of decapods in the Mondego river estuary, at different lunar situations and during nyctemeral cycles.