HIGH-RESOLUTION PALEOTEMPERATURE INFERENCES IN TENERIFE, CANARY ISLANDS FROM ARCHAEOLOGICAL PHORCUS ATRATUS SHELLS

Oxygen isotope analyses (δ¹⁸O) were conducted on shells of Phorcus atratus (Gastropoda; Trochidae) from modern and archaeological sites in Tenerife, Canary Islands, Spain, to examine if and how mean annual sea surface temperatures (SSTs), magnitude of seasonality, and season of shellfish harvest varied over the past ~800 years. Shell carbonate material was collected every ~1 mm from the shell lip to the shell apex of two modern and three selected archaeological shells of known age. The δ¹⁸O values along shell growth direction of live-collected individuals demonstrate that Phorcus atratus is a reliable paleothermometer in the Canary Islands. δ¹⁸O results from archaeological shells throughout the lifespan of the organism suggest that average SSTs were ~1-2 °C cooler ~800 yrs. ago than today. The magnitude of seasonality was also diminished in the archaeological shells, with temperature ranges ~3 °C narrower than the modern range of ~8 °C. Additionally, season of collection is discernable through the analysis of the seasonal temperature profile, and was determined to be late summer/early autumn in all three archaeological shells. This is consistent with prior studies of archaeological deposits on Tenerife that found season of collection of other gastropod species to be in the warm months. This work suggests that marine resource exploitation patterns remained consistent throughout pre-Hispanic times in the Canary Islands.