Evidence for the Combined Impacts of Climate and Landscape Change on Freshwater Biodiversity in Real-World Environments: State of Knowledge, Research Gaps and Field Study Design Recommendations

Purpose of Review Multiple stressor studies conducted in real-world environments play an important role in discovering how stressor pathways may vary relative to ecological complexity and study scale. We reviewed the evidence for climate and landscape change impacts on freshwater biodiversity in real-world ecosystems at the global scale. Using our compiled database of 150 studies, we asked (1) what are the study characteristics within the available evidence base and (2) what are the main knowledge gaps and recommendations for future research? Recent Findings Most studies employed an observational design and examined climatic and landscape change trends over a broad regional spatial scale (median = 97 sites/study). Ecological complexity was well represented in studies with a median of 11 predictor variables that characterized the relevant climate, landscape condition, and many other environmental attributes. Community-level metrics were common response types across all biota including larger, more mobile organisms such as fish that are challenging to examine in an ecologically-relevant context within controlled laboratory settings. Summary We identified several knowledge gaps including the need for more published time-series data, particularly with respect to understanding climate change impacts. Other opportunities for improved future research included incorporating more stressor and biological interactions, examining potential climate stressors over multiple seasons and streamlining methods for dealing with the pervasive challenges of multicollinearity in real-world systems. We emphasize the unique role of ‘natural experiments’ in validating experimental findings and provide a suite of recommendations for creating more strategic field studies to inform conservation efforts.