Corrigendum: A Regional Neural Network Approach to Estimate Water-Column Nutrient Concentrations and Carbonate System Variables in the Mediterranean Sea: CANYON-MED - Fourrier, Marine; Coppola, Laurent; Claustre, Hervé; D'Ortenzio, Fabrizio; Sauzède, Raphaëlle; Gattuso, Jean-Pierre (Frontiers in Marine Science, 2021)