Testing ecological and environmental changes during the last 6000 years: A multiproxy approach based on the bivalve Tawera gayi from southern South America

Sandra Gordillo*, Julieta Martinelli, Javiera Cárdenas, M. Sol Bayer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

This paper evaluates if the bivalve Tawera gayi from southern South America represents an opportunity to test ecological variability and environmental changes during the last 6000 years in southern South America. For this purpose, we analyse both modern and fossil (mid-to-late Holocene) T. gayi shells from Tierra del Fuego using different techniques, including taphonomy, stable isotopes, cathodoluminiscence (CL) and linear morphometrics. Taphonomic analysis shows that differences between modern and fossil shells appear best related to local variations of physical factors such as current speed, wave action and freshwater input along the non-uniform Beagle Channel coast. However, slight changes of hydraulic energy regimes throughout the Holocene cannot be ruled out. The analysis of stable isotopes on T. gayi shells indicates a mixing of oceanic waters with freshwater from precipitation, river runoff and glacier meltwater during the mid-to-late Holocene. The high depletion of 18O at ~4400 years before present would be associated with a period of warmer temperatures, the so-called Hypsithermal. Under CL modern and fossil T. gayi shells show a well defined pattern related to the growth dynamics of the shell, which can lead to a better understanding of its biology, adding details to further palaeoenvironmental analysis. Finally, conventional metrics shows that fossil T. gayi shells are smaller and shorter than modern shells. These differences could be related to Holocene environmental changes, but here are best explained on the basis of a predator-prey relationship. This study shows that T. gayi may be a good candidate for looking at evidences of environmental changes in southern South America, and multi-proxy data are necessary to better understand the driving mechanisms of ecological variability and changes over short geological time intervals of few thousands of years.

Original languageEnglish
Pages (from-to)1413-1427
Number of pages15
JournalJournal of the Marine Biological Association of the United Kingdom
Volume91
Issue number7
DOIs
Publication statusPublished - Nov 2011

Keywords

  • Bivalvia
  • drill-holes
  • shell microstructure
  • shell shape
  • South America
  • stable isotopes
  • taphonomy
  • Tawera gayi

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