Dataset Information

Restructuring of nutrient flows in island ecosystems following human colonization evidenced by isotopic analysis of commensal rats.

ABSTRACT: The role of humans in shaping local ecosystems is an increasing focus of archaeological research, yet researchers often lack an appropriate means of measuring past anthropogenic effects on local food webs and nutrient cycling. Stable isotope analysis of commensal animals provides an effective proxy for local human environments because these species are closely associated with human activities without being under direct human management. Such species are thus central to nutrient flows across a range of socionatural environments and can provide insight into how they intersected and transformed over time. Here we measure and compare stable carbon and nitrogen isotope data from Pacific rat (Rattus exulans) skeletal remains across three Polynesian island systems [Mangareva, Ua Huka (Marquesas), and the Polynesian Outlier of Tikopia] during one of the most significant cases of human migration and commensal introduction in prehistory. The results demonstrate widespread ?15N declines across these islands that are associated with human land use, intensification, and faunal community restructuring. Local comparison of rat stable isotope data also tracks human activities and resource availability at the level of the settlement. Our results highlight the large-scale restructuring of nutrient flows in island ecosystems that resulted from human colonization and ecosystem engineering activities on Pacific islands. They also demonstrate that stable isotope analysis of often-ignored commensal taxa can provide a tool for tracking human land use and environmental effects.

SUBMITTER: Swift JA

PROVIDER: S-EPMC6016769 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Restructuring of nutrient flows in island ecosystems following human colonization evidenced by isotopic analysis of commensal rats.

Swift Jillian A JA Roberts Patrick P Boivin Nicole N Kirch Patrick V PV

Proceedings of the National Academy of Sciences of the United States of America 20180604 25

The role of humans in shaping local ecosystems is an increasing focus of archaeological research, yet researchers often lack an appropriate means of measuring past anthropogenic effects on local food webs and nutrient cycling. Stable isotope analysis of commensal animals provides an effective proxy for local human environments because these species are closely associated with human activities without being under direct human management. Such species are thus central to nutrient flows across a ra ...[more]

PMID: 29866832

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Project description:Isotopic and hydrochemical data from lakes provide direct information on catchment response to changing rainfall, evaporation, nutrient cycling, and the health of ecosystems. These techniques have not been widely applied to lakes in the Southern Hemisphere high latitudes, including Southern Ocean Islands (SOIs) experiencing rapid, significant shifts in climate. Historical work has highlighted the localised nature of geochemical drivers in controlling the hydrochemical evolution of lakes, such as geology, sea spray contribution, vegetation, geographical location, and ice cover extent. The role of groundwater in lake hydrology and hydrochemistry has not been identified until now, and its omission will have major implications for interpreting soil-water-air processes affecting lakes. Here we present the first comprehensive, island-wide hydrochemical and isotopic survey of lakes on a SOI. Forty lakes were examined across Macquarie Island, using comparable methods to identify key environmental processes and their geochemical drivers. Methods include stable carbon (δ13CDOC: dissolved organic carbon and δ13CDIC: dissolved inorganic carbon), oxygen (δ18O), hydrogen (δ2H) and strontium isotopic ratios (87Sr/86Sr) in water. These provide essential baseline data for hydrological, biological, and geochemical lake processes. Lakes on the western side of the island are influenced by sea spray aerosols. In general, it was found that lakes at higher elevations are dilute and those located in lower elevation catchments have experienced more water-rock interactions. The hydrochemical and isotopic tracers suggest that lakes in lower elevations contain more terrestrial sourced ions that may be contributed from groundwater. Increasing temperatures and changing rainfall patterns predicted for the region will lead to shifts in nutrient cycles, and impact the island's unique ecosystems. Future research will focus on long-term monitoring to understand seasonal, annual, and long-term variability to test fundamental hypotheses concerning ecosystem function and the consequences of environmental change on SOIs.

Dataset Information

Restructuring of nutrient flows in island ecosystems following human colonization evidenced by isotopic analysis of commensal rats.

Publications

Restructuring of nutrient flows in island ecosystems following human colonization evidenced by isotopic analysis of commensal rats.

Similar Datasets

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