BiEau-Amaz

In recent years, the use of geochemical markers in geosciences and ecology has considerably increased in order to improve understanding of the functioning of hydrosystems. Within the Amazon basin, the main hydrogeochemical databases are provided by the HYBAM observatory, which has been monitoring different stations for more than 10 years. The size and complexity of the basin make monthly water monitoring logistically and financially complex, especially in the long term.

An innovative way of obtaining hydrogeochemical data would be to rely on a bio-indicator: the bivalve shell. The elementary and isotopic signatures of shells and their variations over time are at least partly related to the chemical characteristics of the water in which they are produced. Since some bivalve species are sessile and their shells grow day by day, often over several years, they may be true witnesses of changes in water chemistry over time.

We propose to test the temporal correlation, on an infra-monthly scale, between the chemical composition of bivalve shells and water in the Amazon basin. We will focus our efforts on the stable isotopes of strontium (87Sr :86Sr), oxygen (∂18O) and carbon (∂13C), markers dependent on the geological and hydrological context of basins, frequently used in geosciences and ecology. We will study two Unionidae species, Anodontitis trapesialis and A. elongatus, which are widely present in rivers and floodplains of the Amazon. Once validated, these natural probes can be used systematically to provide data on the Amazon basin that can be used in hydrological and ecological studies. This project will bring together multidisciplinary teams to combine hydrology, ecology and analytical chemistry.

Funding:
CNRS-INSU-EC2CO – Biohefect

Project coordinator:
Claire E. Lazareth