Visible spectroscopy reliably tracks trends in paleo-production

We review the use of visible range spectroscopy (VRS) to measure concentrations of chlorophyll a and its degradation products (collectively classified as chlorins) from lake sediments. This method for reconstructing aquatic production offers a rapid and non-destructive alternative to wet-chemical techniques, which has led to VRS measurements of aquatic production to become a routine analysis in paleolimnological studies. Over the last decade, VRS has been used to measure paleo-production in a variety of lake types exposed to numerous stressors, including climate change, natural and anthropogenic eutrophication, and whole-lake manipulations. Here, we summarize some of these studies with the intent of demonstrating the utility and the consistency of VRS to track past trends in aquatic production. In all cases, VRS-derived measurements matched a priori predictions of production changes based on historical data of trophic status, or as inferred by multiple, independent proxies of primary production.