Winter is coming: Interactions of multiple stressors in winter and implications for the natural world

Abstract

Winter is a key driver of ecological processes in freshwater, marine and terrestrial ecosystems, particularly in higher latitudes. Species have evolved various adaptive strategies to cope with food limitations and the cold and dark wintertime. However, human‐induced climate change and other anthropogenic stressors are impacting organisms in winter in unpredictable ways. In this paper, we show that global change experiments investigating multiple stressors have predominantly been conducted during summer months. However, effects of anthropogenic stressors sometimes differ between winter and other seasons, necessitating comprehensive investigations. Here, we outline a framework for understanding the different effects of anthropogenic stressors in winter compared to other seasons and discuss the primary mechanisms that will alter ecological responses of organisms (microbes, animals and plants). For instance, while the magnitude of some anthropogenic stressors can be greater in winter than in other seasons (e.g. some pollutants), others may alleviate natural winter stress (e.g. warmer temperatures). These changes can have immediate, delayed or carry‐over effects on organisms during winter or later seasons. Interactions between stressors may also vary with season. We call for a renewed research direction focusing on multiple stressor effects on winter ecology and evolution to fully understand, and predict, how ecosystems will fare under changing winters. We also argue the importance of incorporating the interactions of anthropogenic stressors with winter into ecological risk assessments, management and conservation efforts.

Studying interactions among anthropogenic stressors in freshwater ecosystems: A systematic review of 2396 multiple‐stressor experiments

“…However, factorial experiments, in which stressors are manipulated individually and in combination, involve trade-offs between ecological realism, replication, temporal scale, and spatial scale (Schindler, 1998;Thomas & Ranjan, 2024), so they are conducted in very different ways, resulting in considerable context-dependency of results (Orr et al, 2020;Simmons et al, 2021). The observed interactive effects of two stressors can be species-or system-specific or can depend on factors including the exposure duration, the stressors' intensities, the response variable being measured, and even the value of other environmental factors that can vary across space and time (Dinh et al, 2023;Jackson et al, 2021;Kefford et al, 2023;Turschwell et al, 2022). The first general synthesis of multiplestressor experiments in freshwater systems was based on 88 publications and was conducted in 2014/15 (Jackson et al, 2016).…”

Temporal patterns in multiple stressors shape the vulnerability of overwintering Arctic zooplankton

“…feed, grow and reproduce (Falk‐Petersen et al., 2009 ). Nonetheless, it is crucial to recognise that significant biological processes also occur during the winter months (Berge et al., 2020 ; Dinh et al., 2023 ). For instance, during the winter season, non‐consumptive mortality (mortality not linked to predation) of Calanus copepods is more pronounced compared to other times of the year due to energy‐demanding investment in moulting and gonad development (Daase et al., 2014 ; Maud et al., 2018 ).…”

Winter, the forgotten season

“…In their paper, Dinh et al. (2023) draw a vivid picture of the manifold, multidimensional effects the anthropogenic stressors may cause on ecological responses in organisms and ecosystems, depending on the season. To guide future global change studies, the authors have listed and categorized different types of interactions between multiple anthropogenic stressors and winter.…”

“…In their closure, Dinh et al. (2023) discuss the urgently needed actions and recommended applications to promote, develop, and increase high‐impact winter research, especially focusing on winter multiple stressor ecology and evolution. They stress the importance of combining different study methods, both in laboratory and in the field, as well as adopting new technologies and networks, such as real‐time remote sensing, machine learning, and citizen science networks.…”

“…In the opinion article presented in Global Change Biology by Dinh et al. (2023), they discuss the causes and effects of the scarcity of winter studies in ecological and evolutionary research and highlight the urgent need for advanced winter research with a focus on understanding the effects of multiple and often simultaneous global change‐induced stressors to wintering organisms and ecosystems. To demonstrate the seasonal bias in experimental studies on multiple stressor effects in freshwater, marine, and terrestrial systems, the authors have synthesized and elaborately reviewed close to 200 articles, of which they then selected 167 most relevant field studies, and categorized them based on the season they were conducted.…”