Marta Román1,2, María M. Mendez3,4, Juan P. Livore3,4
1Universidade de Vigo - 2 Université de Nantes, France - 3 Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina - 4Universidad Nacional de la Patagonia San Juan Bosco, Argentina
Scorched mussels Perumytilus purpuratus dominate temperate Atlantic Patagonian rocky intertidal shores. As key foundation species, they form dense beds that support over 40 associated species. Historically, mussel cover has been consistently higher than 70% and disturbance-generated bare space throughout the beds has been strikingly rare. However, massive losses of mussels were registered at different sites after the 2019 austral summer, which were related to increases in temperature and the higher frequency of occurrence of heatwaves. Thus, we studied the extent of mussel mortality along the coast of the Valdés Peninsula (42⁰S; 63⁰W), a UNESCO protected area and marine biodiversity hotspot during the following 5 years. We also assessed their recovery and the role that temperature and anthropogenic pressure had on mussel losses. Hence, we estimated mussel cover yearly at 8 sites, we deployed temperature loggers and we determined anthropogenic influence at coastal areas. Our results provided, for the first time, the thermal patterns to which intertidal organisms on Patagonian rocky shores are subjected and detected the presence of heatwaves throughout the study area. We found that mussel losses were concentrated in Nuevo Gulf, where no recovery was registered over the last 5 years. Although this gulf did not record the highest temperatures, it is more affected by anthropogenic pressure, including population density and industrial activities. Our results expose the synergy between local anthropogenic and global stressors which directly affect existing organisms and concurrently suppresses the recovery of intertidal ecosystems. The mechanisms behind these two aspects of impact are likely different and are currently being studied. Thus, our findings evidenced the unforeseen consequences of the interaction of stressors on P. purpuratus populations, which led to the phase shift described here and can result in the decrease in biodiversity on Patagonian rocky shores.
Biography
Marta studies the ecology of intertidal ecosystems and the effects of local and global disturbances. She studied the effect of anthropogenic pressure of coastal watersheds on the nitrogen inputs into estuarine seagrass meadows. She then developed studies on the ecological interactions between intertidal seagrass and commercial bivalves under climatic stressors. More recently, she is focusing on the mapping of intertidal macroalgae and sessile invertebrates through remote sensing.