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

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 δ18O 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.

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Climatic and environmental changes during the middle to late Holocene in southern South America: A sclerochronological approach using the bivalve Retrotapes exalbidus (Dillwyn) from the Beagle Channel

Quaternary International ◽

10.1016/j.quaint.2014.12.036 ◽

2015 ◽

Vol 377 ◽

pp. 83-90 ◽

Cited By ~ 13

Author(s):

Sandra Gordillo ◽

Thomas Brey ◽

Kerstin Beyer ◽

Betina J. Lomovasky

Keyword(s):

South America ◽

Late Holocene ◽

Environmental Changes ◽

Southern South America ◽

Beagle Channel

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Spatial patterns in Late Holocene lithic projectile point technology of Tierra del Fuego (southern South America): assessing size and shape changes

World Archaeology ◽

10.1080/00438243.2014.890914 ◽

2014 ◽

Vol 46 (1) ◽

pp. 78-100 ◽

Cited By ~ 13

Author(s):

Judith Charlin ◽

Marcelo Cardillo ◽

Karen Borrazzo

Keyword(s):

South America ◽

Spatial Patterns ◽

Late Holocene ◽

Tierra Del Fuego ◽

Projectile Point ◽

Southern South America ◽

Size And Shape ◽

Shape Changes

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Future Environments of South America

The Physical Geography of South America ◽

10.1093/oso/9780195313413.003.0030 ◽

2007 ◽

Author(s):

Thomas T. Veblen ◽

Kenneth R. Young

Keyword(s):

South America ◽

Environmental Change ◽

Environmental Changes ◽

Human Impacts ◽

Southern Oscillation ◽

Physical Geography ◽

Tierra Del Fuego ◽

South American ◽

Policy Options ◽

Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

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