ARCHAEOLOGICAL MIDDEN SCALLOPS AS A KEY TO HOW CLIMATE MAY AFFECT FOOD RESOURCES AT THE PINELAND SITE, SOUTHWESTERN FLORIDA

The Calusa, a group native to southwestern Florida, left extensive shell mounds throughout the region up to and including the 18th century. While oysters and hard clams are known food items for the Calusa, they also ate scallops, but little is known about this food resource. The purpose of our study was to determine if the Bay Scallop, Argopecten irradians, found at the Pineland site in southwestern Florida, provided key insights into Calusa resource use during two major climatic intervals: The Medieval Warm Period (MWP; A.D. 850-1250) and the Little Ice Age (LIA; A.D. 1200-1850). These periods were also compared to modern samples from Tampa Bay. We examined scallop body size, age, and preservational characteristics as a proxy for collection methods, resource quality and environmental productivity. We posit that these scallop characteristics reveal important behavioral and ecological insights concerning the Calusa: 1) whether they individually selected only live scallops or did bulk collections that included dead shells; 2) their resource quality (scallop body size and age at collection); and 3) the marine environmental conditions at the time of collection.

Results indicate that adult scallops (≥ 2 yrs) from the LIA were significantly larger than the warmer MWP and the modern scallops, suggesting that during cooler periods scallops were an advantageous resource for the Calusa. The LIA midden scallops were also represented by a larger diversity of size classes, from small juveniles to adults, indicating that the Calusa were likely using bulk collection methods rather than selecting large individual scallops. About 20% of the LIA scallops had encrusting biota on shell interiors representative of dead shells, further supporting bulk collection methods. Shell surfaces of LIA scallops had a greater diversity of encrusting biota than the other two time periods, suggestive of more productive waters at that time. The Bay Scallop was an important food resource for the Calusa throughout their Pineland residency and are key to understanding not only resource quality and marine environmental conditions but also foraging behavior during major periods of climatic change.