The position of the Gulf Stream influences waterbird brood numbers in a Mediterranean wetland (Albuferas de Adra, Spain)

Wetlands constitute complex ecosystems where different stable states alternate through catastrophic regime shifts. It is known that the inter-annual variation in the spring weather conditions constitutes a key factor for catastrophic shifts between phytoplankton-dominated turbid states and clear water phases in Albuferas de Adra, a Mediterranean coastal wetland. In previous studies we demonstrated that this alternation of equilibrium states has an effect on waterbirds, which show higher abundance and brood production in years characterised by the occurrence of clear water phases. In this paper we examine the teleconnection between the Gulf Stream position, a large-scale oscillating phenomena influencing weather conditions in West Europe, the weather variability in Albuferas de Adra and waterbird brood numbers in such an ecosystem. Our results suggest that when the Gulf Stream moves towards the south unstable meteorological conditions prevail in the region, favouring the productivity of waterbirds within the wetland through the occurrence of clear water phases. By contrast, northern displacements of the oceanic current are associated with stable weather, turbid water phases and lower numbers of broods. The Gulf Stream position significantly influenced the reproduction of the specialist coots, grebes and diving ducks, while no relation with the generalist and ubiquitous dabbling ducks was found. Potential implications for wetland management and waterfowl conservation are noted.