Scallop shells as geochemical archives of phytoplankton‐related ecological processes in a temperate coastal ecosystem

Abstract Phytoplankton dynamics in coastal ecosystems is increasingly altered by land‐based human activities. Yet, this global vision conceals major disparities, among sites and through time. As conventional monitoring time series are quite sparse relatively short, biological records of environmental variability appear as relevant tools to gain insights into phytoplankton over larger temporal spatial scales. Here, we present results an interdisciplinary project dealing with chemical information archived shells Pecten maximus (Bivalvia; Pectinidae), known form daily growth striae on its shell surface. Several individuals were collected the Bay Brest (France) 2011 2012, analyzed for molybdenum lithium concentrations their soft tissues element‐to‐calcium ratios (Mo : Ca Li Ca) calcitic striae. All revealed high synchrony reproducibility Mo profiles, characterized a peak at end May mid‐June 2011, respectively. Detailed analysis physical, chemical, variables measured seawater during extensive 9‐month survey enabled meticulous description impact geochemistry. Main findings strongly suggest that (1) timing peaks reflects occurrence silicon limitation diatom aggregation periods, (2) height these relates amplitude first spring bloom, (3) serves proxy biovolume biogenic silica recycling sediment–water interface.