CLAMS AND CLIMATE IN THE KODIAK ARCHIPELAGO, ALASKA: INSIGHTS FROM OXYGEN ISOTOPE SCLEROCHRONOLOGICAL ANALYSIS OF S. GIGANTEA FROM MIDDLE TO LATE HOLOCENE ARCHAEOLOGICAL DEPOSITS

The paleoenvironmental record reflects fluctuating marine conditions throughout the Gulf of Alaska during the Late Holocene. The effects of changes in regional climate patterns, as well as human responses to such change, however, can exhibit great variability locally. In the Kodiak Archipelago in the Gulf of Alaska, changing environmental conditions, population growth, technological transitions, and contact with other communities likely promoted the transition from needs based maritime hunter-gatherers to surplus based, semi-permanent villages. The precise role of climate in this transition is understudied. Few paleoclimate reconstructions are available for the Kodiak Archipelago and while climate reconstructions for the Gulf of Alaska are not uncommon, regional climate reconstructions are often insufficient for archaeological research. Many climate reconstructions lack sub-annual resolution and cannot produce a detailed understanding of seasonal behaviors in human populations. Sclerochronological and sclerochemical analysis of shellfish remains from archaeological sites in the archipelago may provide additional paleoenvironmental information. The length of shellfish growing season has been found to decrease with increasing latitude and decreasing temperature. Measuring and comparing the length of seasonal shell growth in select species of bivalves may complement stable oxygen isotope analysis, together providing a more precise paleoclimate reconstruction. This research utilizes the growth of Saxidomus gigantea, abundant both on modern and ancient coastlines to provide information about the length of its growing seasons. Archaeological samples were obtained from four sites from the Kodiak Archipelago, Alaska to determine if changes in seasonality, as measured by the number of circalunidian growth increments in one year, is detectable through time. Three samples from the Rice Ridge site (KOD-363), five samples from the Uyak site (KOD-145) represent sequences from Kachemak period, two samples from the Settlement Point site (AFG-105), and two samples from the New Karluk site (KAR-001) were analyzed.