Long-term trends in seasonal plankton dynamics in Lake Mead (Nevada-Arizona, USA) and implications for climate change.
Over the past few decades, Lake Mead (Nevada-Arizona, USA) has experienced multiple ecosystem stressors including drought, increased water demand, and establishment of invasive species (quagga mussels, gizzard shad). Despite these potential stressors, zooplankton and phytoplankton community dynamics in the pelagic regions of Lake Mead have generally followed consistent seasonal patterns. Long-term monitoring results (2007-2015) show that zooplankton and phytoplankton communities remain relatively stable in Lake Mead on an inter-annual basis, but are susceptible to shifts caused by extreme climate fluctuations and alterations in mixing regimes. A warm winter characterized by low snowpack in 2014/2015 preceded a large bloom of toxic cyanobacteria (Microcystis aeruginosa Kützing) in Las Vegas Bay the following summer. Large bloom events are rare in Lake Mead; however, under future climate scenarios, these types of events may become more frequent. Because of the consistency of plankton community dynamics over an extended period of time, Lake Mead offers an ideal system for the study of future climate change impacts. This study aims to characterize the response of plankton communities in Lake Mead to both linear and dynamic environmental changes.