Contrasting spatial and temporal patterns of zooplankton diversity to test space-for-time substitution in lakes

Understanding of how biological communities respond to environmental change is of critical import to predicting future biodiversity scenarios and prioritizing management efforts. However, our understanding of how communities contend with stressors under realistic conditions is challenged by a lack of long-term data capturing biological responses to changing conditions. Given this limitation, researchers frequently rely on spatial patterns (i.e., environmental and biotic differences between sites) to infer potential consequences of environmental changes over time. But despite the ubiquity of space-for-time substitution, the underlying assumption that communities will respond to changes over time in the same way as they respond to comparable spatial gradients has rarely been tested. Addressing this knowledge gap, we leverage long-term zooplankton and water quality data from over 120 lakes sampled for nearly 25 years as part of the Iowa Ambient Lake Monitoring Program. Relationships between zooplankton biodiversity and several water quality variables (including temperature and nutrient concentrations) were assessed, using a series of mixed-effect models to contrast spatial and temporal responses to environmental gradients. This unique, long-term data resource provided a valuable opportunity to test key assumptions of the space-for-time substitution approach and develop empirical insights to support its broader use.

Primary Presenter: Daniel Edwards, Iowa State University (dje@iastate.edu)

Authors:

Daniel Edwards, Iowa State University  (dje@iastate.edu)

Charlie Loewen, Iowa State University  (cloewen@IASTATE.EDU)