Title

Changes in Lake State: Major state changes in an ancient tropical lake through geological time

Standing

Graduate (PhD)

Type of Proposal

Oral Research Presentation

Challenges Theme

Safeguarding Healthy Great Lakes

Faculty Sponsor

Doug Haffner

Abstract/Description of Original Work

Earth has been changing for millions of years, and these changes can even be felt in our freshwater systems, a vital resource influencing all forms of life, from algae to terrestrial mammals. Lake Towuti, Indonesia is one of very few lakes that have the potential to record changes over such long time spans. The pristine nature of this lake, with its low algal biomass and its ability to support a multitude of rare and endemic species, has led this lake to international interest. This study investigates whether the state of Lake Towuti has always been the same by studying the fossil record of deep sediment cores from two sites within Lake Towuti. We hypothesized that the composition of the fossilized algal diatom communities is the same throughout the cores, as it is unlikely that pristine lakes have encountered any major changes. Our methods include identifying diatom species and counting their abundance through microscopy, and measuring the concentrations and of select elements through spectroscopy. Our results to date show: (1) an array of novel endemic diatom species not yet described anywhere else; and (2) major long-term switches in the state of the lake. The complete shift in a lake’s algal community, dominated with species not seen today, shows the potential for lakes to continuously change between different algal states. This study also provides the identification of novel, endemic, and extinct diatom species. And lastly, the disappearance of a more algal lake state highlights the capacity for lakes to recover from extended periods of high productivity, an important finding in a time where we are struggling with harmful algal blooms in our own Great Lakes.

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Changes in Lake State: Major state changes in an ancient tropical lake through geological time

Earth has been changing for millions of years, and these changes can even be felt in our freshwater systems, a vital resource influencing all forms of life, from algae to terrestrial mammals. Lake Towuti, Indonesia is one of very few lakes that have the potential to record changes over such long time spans. The pristine nature of this lake, with its low algal biomass and its ability to support a multitude of rare and endemic species, has led this lake to international interest. This study investigates whether the state of Lake Towuti has always been the same by studying the fossil record of deep sediment cores from two sites within Lake Towuti. We hypothesized that the composition of the fossilized algal diatom communities is the same throughout the cores, as it is unlikely that pristine lakes have encountered any major changes. Our methods include identifying diatom species and counting their abundance through microscopy, and measuring the concentrations and of select elements through spectroscopy. Our results to date show: (1) an array of novel endemic diatom species not yet described anywhere else; and (2) major long-term switches in the state of the lake. The complete shift in a lake’s algal community, dominated with species not seen today, shows the potential for lakes to continuously change between different algal states. This study also provides the identification of novel, endemic, and extinct diatom species. And lastly, the disappearance of a more algal lake state highlights the capacity for lakes to recover from extended periods of high productivity, an important finding in a time where we are struggling with harmful algal blooms in our own Great Lakes.