RECONSTRUCTING THE EL NIÑO-SOUTHERN OSCILLATION (ENSO) FROM SHORT-LIVED BIVALVES: PERSPECTIVES FROM COASTAL PERU (Invited Presentation)

Over the past ~50 years, bivalve sclerochronology and geochemistry have advanced sufficiently to provide important information about major climatic changes relevant to archaeological questions. In coastal Peru, marine bivalves have become an important archive for reconstructing the El Niño-Southern Oscillation (ENSO). However, most of the bivalves consumed by human populations in the central Andes are short-lived (<5 years). Thus, reconstructions of ENSO and related human-environment dynamics require careful consideration of populations of short-lived bivalves, primarily through the annual range of their geochemistry as it relates to climate signals. Several species have been identified as useful for this method, including the intertidal clam Mesodesma donacium. More recently, the surf clam Donax obesulus has emerged as a complementary archive, with evidence that its geochemistry and morphometric characteristics are useful for reconstructing ENSO in pre-contact coastal Peru.

In this presentation, I discuss recent work calibrating the geochemistry of D. obesulus, evidence of the utility of its morphometrics as a climate proxy, and evidence of changes to ENSO and how human populations responded during the late Holocene in coastal Peru. People living in the north and north-central coast were likely not only well aware of the impacts of ENSO and how to respond but also how it impacted ecological niches and animal populations, including marine bivalves. This work provides evidence of changes to ENSO and human responses and a window into potential future research regarding bivalve sclerochronology in coastal regions.