Complexities of Stable Carbon and Nitrogen Isotope Biogeochemistry in Ancient Freshwater Ecosystems: Implications for the Study of Past Subsistence and Environmental Change

Abstract

Stable carbon and nitrogen isotope analyses of human and animal tissues have become an important means of studying both anthropogenic and natural food webs in aquatic ecosystems. Within the rapidly expanding field of human and animal paleodietary analyses, archaeologists routinely incorporate isotopic data from fish, birds, and aquatic mammals into their interpretations of ancient freshwater resources use; however, these studies rarely consider the complex and dynamic nature of the carbon and nitrogen cycles that give structure to nutrient regimes and their isotopic compositions in freshwater ecosystems. This review outlines two thematic areas in which this surge in stable isotope applications to the study of ancient human societies could be enhanced by incorporating concepts from limnology, ecology, and biology. First, building on studies conducted in modern ecosystems, this paper outlines key aspects of the stable isotope ecology of freshwater environments, highlighting the importance of considering physical and biological processes associated with ancient biogeochemical cycles when conducting human paleodietary reconstructions. Second, this paper discusses areas where isotopic analyses of archaeological freshwater animal remains could contribute to broader research fields including climate change and cultural eutrophication research, human impacts on long-term food web dynamics and animal behavior, and by providing novel approaches to reconstructing ancient fish management practices.

WITHDRAWN: A global carbon and nitrogen isotope perspective on modern and ancient human diet

“…Humid environments are separated into the warmer regions that potentially contain C 4 biomass (Humid C 3 /C 4 ) and colder regions that contain only C 3 biomass (Cold C 3 ), based on the modern distribution of C 4 biomass 28 . Across all three categories some ancient populations also had a variable degree of access to marine and/or freshwater aquatic resources with a stable isotope composition often distinct from local terrestrial resources 10,14,37 .…”

“…agriculture and pastoralism), changing technological innovation, and social practices and structures [11][12][13] . Although interpretation can sometimes be straightforward when observed differences are large, smaller differences are complicated by the complexities associated with disentangling the ecosystem processes driving C and N isotope fractionation within the food webs supporting human diet 13,14 .…”

Quality control for modern bone collagen stable carbon and nitrogen isotope measurements

“…In contrast, research investigating earlier ecosystems has been extensively focused on analysing the isotopic composition of proteins extracted from hard tissues, such as bones and teeth, which are more readily available because they are generally the only vertebrate structures that preserve in archaeological and paleontological deposits (Ambrose, 1990). In this context, Type I collagen (hereafter, ‘collagen’), which makes up 90% of bone and tooth protein (Herring, 1972), has been the primary focus of a vast majority of protein‐based isotopic research on ancient environments (Guiry, 2019; Szpak, Metcalfe, & Macdonald, 2017).…”

Storing fish?: a dog’s isotopic biography provides insight into Iron Age food preservation strategies in the Russian Arctic

“…6), suggesting that this dog's diet was also relatively isotopically homogenous (i.e., still fish-focused) over the last several months of its life. Slight, although inconsistent trends appear to occur in these nail keratin isotopic compositions with a minor decrease and increase in δ 13 C and δ 15 N, respectively, which would be consistent with small adjustments in the proportion of diet made up by fish, the species of fish consumed, or spatiotemporal variation in local aquatic baselines (for review, see Guiry 2019).…”