Long-term (27-year) data sets on patterns of primary and secondary productivity and nutrient cycling dynamics for Castle Lake and Lake Tahoe, California, will be analyzed to determine the relative importance of biotic recycling of nutrients and the supply of "new" nutrients in controlling lake productivity. In addition, a limited set of measurements at the two lakes will be made to continue the long-term data sets. The major product of this new research will be a conceptual model of factors that control primary and secondary production in the two California lakes. This model will be useful for designing further scientific research. As important, the model will be useful for developing future management strategies for large lake systems that are located in watersheds undergoing land use changes such as resort development. Dr. Goldman and his colleagues have long records of doing high quality science and using this science to help solve societal problems. The institutional support for the research is excellent. The Ecosystem Studies Program recommends award of this grant.
