A predictive model for water clarity following dreissenid invasion

Abstract

Optical transparency, or water clarity, is a fundamental property of lake ecosystems which influences a wide range of physical, chemical and biological variables and processes. The establishment of non-native dreissenid mussels in lake and river ecosystems across North America and Europe has been associated with often dramatic, but highly variable, increases in water clarity. The objective of this study was to develop a predictive model for water clarity (Secchi depth, m) in lakes following the establishment of dreissenids. We compiled water clarity data before and after dreissenid invasion from North American lakes that varied in size and nutrient status. An AIC model averaging approach was used to generate post-invasion water clarity predictions based on pre-invasion water clarity and lake morphometric characteristics from a 53 lake dataset. The accuracy of the model was verified using cross-validation. We then extended this model to existing empirical models of lake mixing depth and Walleye (Sander vitreus) yield, to demonstrate that increased water clarity associated with dreissenid invasion may have far-reaching physical and ecological consequences in lakes, including deeper thermoclines and context-dependent changes in fish yields.