Sr and Sr/Ca in marine and terrestrial foodwebs in the Southwestern Cape, South Africa

Abstract

Strontium and calcium have been measured in a range of plants and animals (both marine and terrestrial) from the southwestern Cape of South Africa as part of an investigation of modern and prehistoric foodwebs in the region. First, the meat of marine molluscs and crustaceans are shown to have Sr and Sr/Ca values comparable to those of terrestrial plants. Thus, the consumption of these marine foods in this region cannot produce the markedly elevated Sr levels seen in archaeological human skeletons from coastal sites; such levels are shown to be a diagenetic phenomenon. Second, reduction in Sr/Ca in higher trophic levels is seen only when predators are compared with their prey. However, individual herbivore or carnivore species cannot be taken to represent other animals in their respective trophic level. These data imply that Sr/Ca is inappropriate for determining meat intake in complex prehistoric human diets in this region. The technique may be more useful in examining specific prey-predator relationships, including those in the early hominid fossil record.