Marine environmental variability in Northern Patagonia (Southwestern Atlantic Ocean) as recorded in Glycymeris longior shells

Abstract

Certain marine regions in the world lack long instrumental records of environmental variables or such recordsare incomplete. This deficiency particularly applies to Argentine Patagonia, where existing instrumental recordsspan only the last few decades. In the present study it was explored whether such data can be reconstructed froma natural archive, specifically shells of the bivalve mollusk Glycymeris longior from the San Matías Gulf, northPatagonia. For this purpose, a multidecade-long time-series was constructed using variations in the annual shellgrowth. The time-series spans from 1890 to 2020 and is based on shells from museum collections (live-collectedfrom 1918, 1933 and 1945) and from scientific surveys conducted between 1989 and 2021. An analysis of thelinks between environmental variables and shell growth was performed between 1976 and 2020 (expressedpopulation signal >0.85). The common signal among the growth curves of individual specimens of G. longiorsuggests that the growth is influenced by environmental parameters. However, the growth of G. longior did notshow significant correlations with the low- nor with the high-frequency components of SST and food supply(chlorophyll-a concentration and POC), suggesting that these parameters do not limit shell growth at the studiedsite or were undetected with our analyses. The chronology also seems to be insensitive to regional climatepatterns such as the Southern Annular Mode. The chronology has the potential for being expanded spatially andtemporally.