Seasonal oxygen isotope variations in freshwater bivalve shells as recorders of Amazonian rivers hydrogeochemistry

TitleSeasonal oxygen isotope variations in freshwater bivalve shells as recorders of Amazonian rivers hydrogeochemistry
Publication TypeJournal Article
Year of Publication2019
AuthorsGaillard, B, Lazareth, CE, Lestrelin, H, Dufour, E, Santos, RV, Freitas, CEC, Pouilly, M
JournalIsotopes in Environmental and Health Studies
Pagination1-15
Type of ArticleJournal Article
ISSN1025-6016 1477-2639
KeywordsAmazon basin, freshwater bivalve shells, hydroclimate, isotope ecology, isotope hydrology, oxygen isotopes
Abstract

Freshwater bivalve shell oxygen isotope values (δ18OS) may act as a recorder of river δ18O variations that can then be interpreted in terms of hydrology (e.g. precipitation–evaporation balance, precipitation and river discharge patterns). We investigated the potential of this proxy measured across the hinge of South American unionid shells: Anodontites elongatus collected in Peru and A. trapesialis in Brazil. The isotopic signatures were reproducible between individuals of the same species. A. trapesialis clearly showed a strong δ18OS cyclicity in accordance with its growth patterns while A. elongatus presented less clear δ18OS with lower amplitude. We confirm that the deposition of successive growth lines and increments is annual, with growth line corresponding to the wet season. Also, we suggest that low amplitude of δ18OS in the A. elongatus shells indicates a habitat close to the river while large amplitude of δ18OS cycles observed in A. trapesialis shells would reflect a floodplain lake habitat, seasonally disconnected from the river and thus subjected to higher seasonal fluctuations in water δ18O. Considering these promising first results, future studies could be directed towards the use of fossil shells to reconstruct the past and present hydrological and geochemical conditions of the Amazon.

URLhttps://hal.archives-ouvertes.fr/hal-02314885v1
DOI10.1080/10256016.2019.1666120
Catégorie HCERES
ACL - Peer-reviewed articles
Publication coopération et recherche SUD
Oui