Concurrent changes in spatial distribution of the demersal community in response to climate variations in the southern Iberian coastal Large Marine Ecosystem

摘要

Species inhabiting transitional areas in large marine ecosystems are highly sensitive to climate variations and thus of paramount importance as indicators of ecosystem changes. The spatiotemporal distribution of representative species of the demersal community in the southern Iberian coastal Large Marine Ecosystem was investigated using time series data from trawl surveys conducted in the Gulf of Cadiz. The geographic and bathymetric variability in the population distribution was analyzed. We investigated the influence of hydroclimatic (chlorophyll a concentration, sea surface temperature, precipitation, runoff, oceanic wind and meso- and large-scale climate indices) and population drivers (density) on species depth and location. Distribution shifts were more evident over the longitudinal gradient with species approaching and moving away from the Strait of Gibraltar. This contrasting behavior was segregated by depth and the hydro-graphical boundary of the Guadalquivir River runoff plume. On the shallow shelf (100 m), a southeastward movement towards the Strait of Gibraltar was clear. This geographical shift was also observed in species from the deeper strata, occasionally coupled with depth changes. These movements were mainly associated with climate variability, in particular the North Atlantic Oscillation, whose effects were clearly species specific. Additionally, longitudinal variations of the community at a regional scale were related to a local climatic index that captured a pattern of covariation in local surface wind, temperature and precipitation. This study focuses on responses of several species with contrasting life histories (from Sparidae to Elasmobranchs) to hydroclimatic variability in the southern Iberian coastal Large Marine Ecosystem.