Upwelling signals in radiocarbon from early 20th-century Peruvian bay scallop (Argopecten purpuratus) shells

We quantified Delta C-14, delta O-18, and delta C-13 Cycles along ontogeny within four bay scallop (Argopecten purpuratus) shells collected from Callao Bay, Salaverry, and Sechura Bay, Peru following the 1907-1908 non-El Nino years and the 1925-1926 El Nino Delta C-14 and delta C-13 generally covary; Delta C-14 and delta O-18 vary inversely. Simultaneous decreases in Delta C-14 and increases in delta O-18 in non-El Nino shells are followed by constant Delta 14C and gradually decreasing delta O-18, which we interpret as evidence for discrete marine upwelling events followed by warming of the initially cold upwelled water Upwelling changes from El Nino events are detectable with difficulty in mollusk shell Delta C-14. Published by Elsevier Inc on behalf of University of Washington.