Changes in the Specific and Biogeographic Composition of Coastal Fish Assemblages in Patagonia, Driven by Climate Change, Fishing, and Invasion by Alien Species

Abstract

Climate change, fishing, and invasion by alien species are the drivers of global change that mainly affect Patagonian marine fish assemblages. In this chapter, we reconstructed the coastal fish assemblages and their changes in richness and composition in three areas at northern, central, and southern Patagonia between 1970 and 2020. Overall, there was an increase in fish richness (30 species) driven by an influx of species from warmer waters in northern and central Patagonia and by the invasion of alien species at central and southern Patagonia. Such a trend is consistent with the global pattern of tropicalization in temperate waters described for other regions and recent evidence of change in the sea surface temperature (SST) up to 48°S latitude. We detected only two local extinctions of skates from warm waters that disappeared from the northern area. A large number of fishes (30 species) diminished their frequency of occurrence. A total of 20 species of commercial importance, 7 of which were elasmobranchs, were the most affected by partial losses. Future research is needed to understand the functional role of the species arriving or retracting and the consequences of such changes on ecosystem functioning.