A changing menu in a changing climate: Using experimental and long‐term data to predict invertebrate prey biomass and availability in lakes of arctic Alaska

• Published in: Freshwater Biology
• Main Authors: Klobucar, Stephen L., Gaeta, Jereme W., Budy, Phaedra
• Other Authors: National Science Foundation, U.S. Geological Survey, Utah State University
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Aquatic Science; Arctic; Arctic Lake; Zooplankton; Alaska
• Online Access: http://dx.doi.org/10.1111/fwb.13162; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Ffwb.13162; https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13162; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/fwb.13162; https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/fwb.13162

Abstract Changes in seasonality associated with climate warming (e.g. temperature, growing season duration) are likely to alter invertebrate prey biomass and availability in aquatic ecosystems through direct and indirect influences on physiology and phenology, particularly in arctic lakes. However, despite warmer thermal regimes, photoperiod will remain unchanged such that potential shifts resulting from longer and warmer growing seasons could be limited by availability of sunlight, especially at lower trophic levels. Thus, a better understanding of warming effects on invertebrate prey throughout the growing season (e.g. early, peak, late) is important to understand arctic lake food‐web dynamics in a changing climate. Here, we use a multifaceted approach to evaluate prey availability to predators in lakes of arctic Alaska. In a laboratory mesocosm experiment, we measured different metrics of abundance for snails ( Lymnaea elodes ) and zooplankton ( Daphnia middendorffiana ) across three time periods (early, mid‐ and late growing season) and across three temperature and photoperiod treatments (control, increased temperature and increased temperature × photoperiod). Additionally, we used generalised additive models and generalised additive mixed‐effects models to relate long‐term empirical observations of zooplankton biomass (1983–2015) to observed temperature regimes in an arctic lake. We then simulated zooplankton biomass for the warmest temperature observations across the growing season to inform likely zooplankton biomass regimes under future change. We observed variable responses by snails and zooplankton across experiments and treatments. Early in the growing season, snail development was accelerated at multiple life stages (e.g. egg and juvenile). In mid‐season, in accordance with warmer temperatures, we observed significantly increased Daphnia abundances. However, in the late season, Daphnia appeared to be limited by photoperiod. Confirming our experimental results, our models of zooplankton biomass showed ...