Flooded sinkhole reveals ice age island ecology

Thanks to Janet Franklin for this guest post! A really amazing research program.

A paper published in Proceedings of the National Academy of Sciences, USA reports the richest set of late Pleistocene (ice age) vertebrates found on any Caribbean island to date (Abaco Scientist will post the pdf when it is available, but for now some popular media accounts here and here).

Almost 100 species of fish, reptiles, birds and mammals were identified from fossils found in Sawmill Sink, a flooded sinkhole cave or “blue hole” on Abaco, allowing changes in the animal community to be tracked through time. The warmer, wetter climate and rising sea levels that occurred from 15,000 to 9000 years ago during the Pleistocene (ice age) to Holocene Transition (PHT) coincided with the disappearance on Abaco of at least 17 species of birds. These 17 species are characteristic of the open habitats (pine woodlands and grasslands) found on cooler, drier, larger ice age Bahamian islands (shown by Franklin using geospatial modeling). A diverse group of 22 species of reptiles, birds, and mammals persisted through those environmental changes, however, but did not survive the last 1000 years of human presence. Thus the late Holocene arrival of people probably depleted more animal populations than the dramatic physical and biological changes associated with the PHT. For the species that remain, direct human activity threatens their immediate future more than climate change.

Sawmill Sink is a rich source of well-preserved fossils because of its unique water chemistry. The scientific value of the fossils found in the caves has contributed directly to the recent establishment of a new protected area, South Abaco Blue Holes National Park, protecting the system of flooded caves including Sawmill Sink.

This project was sponsored by the National Science Foundation (1118340).

By | 2017-12-01T14:02:10-05:00 October 20th, 2015|Categories: Blue Holes, Fossils|0 Comments

About the Author:

Craig Layman
My lab’s interdisciplinary pursuits provide for a multi-faceted understanding of environmental change in the coastal realm. We are ecologists, asking questions that span population, community, ecosystem and evolutionary sub-disciplines. We often use a food web based perspective, exploring top-down (e.g., predation) and bottom-up (e.g., nutrient excretion) mechanisms by which animals affect ecosystem processes. All of our efforts are framed within a broader outreach framework, directly integrating science and education, using approaches such as this website.

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