Wave climate impact on massive mortality events of wild clam beds in the Ría de Vigo

• Main Authors: Villacieros-Robineau, Nicolás, Darriba, Susana, López, Carmen, Iglesias, David, Febrero, Fernando, Rodríguez, Luis, Montero, Pedro, Babarro, José M. F., Gilcoto, Miguel
• Other Authors: Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), Xunta de Galicia
• Format: Still Image
• Language: English
• Published: 2023
• Subjects: Wave climate; clam mortality events; intracellular prokaryotic infections; climate variability; population collapse; http://metadata.un.org/sdg/14; Conserve and sustainably use the oceans; seas and marine resources for sustainable development; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10261/286985; https://doi.org/10.13039/501100003329; https://doi.org/10.13039/501100010801; https://doi.org/10.13039/501100004837

Poster.-- Clivar 2023, Towards an integrated view of climate, 24-26 January, Madrid Several massive mortality events and drops in catches of wild clam beds (Polititapes rhomboides) have been reported during the last decades in the Galician rias (NW Iberia coastal upwelling system). In June 2010, one of these mortality events was detected and monitored in the Ría de Vigo until 2021 (Acción CIMA 19/04, Darriba et al., 2019). The histopathological analysis showed an abnormal high-intensity infection of intracellular prokaryotic colonies (Rickettsiales-like) in the gills of the affected clams that was suggested as the cause of mortality. We hypothesized that an atypical long period (7 months, autumn 2009 to spring 2010) of continuous and strong wave storms could be the precursor of these infections. Strong waves entailed high bottom boundary layer dynamics with intense sediment mobilization and resuspension inside the ria, which could have weakened the clams' ecophysiology inhibiting an efficient immune response. On top of that, warm water conditions (17ºC) near the seabed prevailed immediately after this energetic period, and could have promoted the prokaryote colonies proliferation. The synergetic effect of stress produced by the continuous wave impact on the seabed and the expansion and infection of Rickettsial colonies would have led to the clams' mortality. The variability of mean winter wave conditions inside the ria was recently associated with the combination of NAO (North Atlantic Oscillation) and WEPA (West Europe Pressure Anomaly) climate indices (Villacieros-Robineau et al., 2021). Winters with the highest waves occur during negative NAO and/or positive WEPA phases. Warmer temperatures and low salinity conditions (downwelling scenarios) are more frequent during these severe winters. Considering these previous results and following our main hypothesis, we investigated the link between the interannual variability of mean wave height, the infection intensity, and the evolution of the clams’ population. ...