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.

Density of larval and adult forms of the burrowing crustaceansLepidophthalmus siriboia(Callianassidae) andUpogebia vasquezi(Upogebiidae) in an Amazon estuary, northern Brazil

“…Spearman's correlation coefficient (R) for larval density (number of larvae/100 m 3 ) and adult density (number of ind./100 m 2 ) of thalassinidean species in relation to abiotic factors (temperature, pH, salinity and salinity in burrows); * significant results (P,0.05). year, when environmental conditions are favourable (Gonçalves et al, 2003). For example, Paula (1987) encountered two peaks of decapod larval abundance at São Torpes bay, south-western Portugal.…”

Evaluation of estuarine mesozooplankton dynamics at a fine temporal scale: the role of seasonal, lunar and diel cycles

“…However, to examine stresses on a community, the composition, the structure and dynamics should be reasonably understood. Up to this date, only one study addressed the dynamics of decapod crustacean larval under different lunar phases and during nyctemeral cycles in this estuary (Gonçalves et al, 2003). Thus, the present study focuses on short-term temporal and spatial variations in the mesozooplankton community of the Mondego estuary.…”

Zooplankton distribution and dynamics in a temperate shallow estuary

“…In addition, anthropogenic influences may contribute to enhancing natural trends, both directly and indirectly. Although several studies have focused on the zooplankton of the southern branch of the Mondego estuary during the last years (Azeiteiro et al, 1999;Gonçalves et al, 2003;Vieira et al, 2003) a lack of knowledge about the assemblages in the northern branch and a clearly comparative analysis of the communities of both contrasting arms, with different hydrographical conditions, seems to be missing. The aims of the present study, therefore, were: (a) to describe the spatial, temporal and tidal dynamics of the zooplankton communities and (b) to compare the community structure of the zooplankton in the two contrasting branches on tidal, temporal and longitudinal scales.…”