Impacts of Environmental Variability Related to Climate Change on Biological Resources in the Mediterranean

Abstract

Current estimates of the trend in Sea Surface Temperature (SST) from satellite-based remote sensing represent the main evidence of Mediterranean Climate change. The reported diminution of rainfall reduces the river run-off input of inland nutrients while the observed warming enhances the stratification of surface layers and hinders nutrient pumping from below. All this affects primary production and indirectly impacts biological processes (reproduction, growth, survival, migration etc.) governing the spatial distribution and fluctuations in the abundance of fish stocks and the sustainability of their exploitation. However, the observed warming trends have uneven spatial patterns, and more insights on the current trend in the regional impacts on the primary production are needed, especially in the neritic zone where most of the processes supporting the status of fish populations take place. The main goal of this Research Topic is to relate the available information about Mediterranean warming to a set of indicators of current trends in spatial distribution and productivity of fish populations. Fish species characterized by short life cycles, including forage fish, are strongly affected by changes in environmental conditions at short time scales. Overall, the biomass of many species targeted by fisheries relies on the success of annual recruitment processes. In turn, recruitment is affected by favorable feeding conditions in retention areas of early life stages, able to impact their growth and survival, and in the spawning areas of the adult fraction of fish populations, as far as food availability can impact fecundity and mitigate natural mortality. More insight about the climate-driven impacts on key processes such as primary production or the advection of early life stages from spawning to nursery areas is therefore considered highly relevant for understanding their role in determining current patterns and trends in the abundance of fish populations, also at the community level. Potential contributors to this collection of articles are expected to address different aspects of the topic. In particular, they should investigate: - the current relationship between the interannual fluctuations in SST and Chl-a concentration (to be used as a proxy for primary production), at the basin and regional scales, with special emphasis on coastal upwelling areas. - the impact of Mediterranean warming on the interannual variability of the mesoscale patterns able to affect productivity and retention processes. - the impact of environmental stressors on the spatial distribution and reproductive ecology of fish populations. - trends in fish population abundances in relation to environmental changes at different life stages. - the effect of climate-driven changes in Mediterranean waters on fish communities and biodiversity.