Climate warming amplifies the frequency of fish mass mortality events across north temperate lakes

Abstract

Recent increases of animal mass mortality events have coincided with substantial changes in global climate. Yet, tractable approaches that predict how climate change will accentuate occurrences of these ecological catastrophes remain nascent. We compiled one of the most comprehensive datasets of lentic fish mortality events, thermal tolerances of affected families, and 1.2 million air and water temperature profiles across 8891 north temperate lakes in North America. Temperature extremes within and across lakes were strongly associated with the three most frequent cause types (infectious agents, summerkills, winterkills). Thermal tolerances mediated the lethality of direct thermal stress, but mortalities of warm‐ and cold‐water fishes occurred at similar temperature deviations. Water and air temperature‐based models accurately predicted contemporary summerkills and suggested ~ 6‐ to 34‐fold increases, respectively, in their frequency by 2100. These models forecast and contextualize impending ecosystem changes in an increasingly volatile world.

Persistence of fish populations to longer, more intense, and more frequent mass mortality events

“…duration, intensity, and frequency of events, early life, fish, marine heatwaves, mass mortality events, population level freshwater fishes (Fey et al, 2015;Raymond et al, 2022;Tye et al, 2022). In the marine environment, mass mortality events are associated with a range of causes, including thermal and oxygen stress, biotoxicity, disease, and contaminants (Fey et al, 2015), that often can be directly or indirectly related to climate change.…”

“…For example, the increasing prevalence and severity of diseases with climate change are affecting aquatic populations (Hoegh-Guldberg & Bruno, 2010), including fish (Genin et al, 2020;Tye et al, 2022). Harmful algal blooms (HABs) have increased in frequency over the last decades, partially linked to climate change (Gobler, 2020).…”

“…Such extreme climatic events often cause extreme ecological events such as mass mortality events that rapidly remove a large proportion of individuals from many demographic classes over a relatively short period. An increased occurrence of mass mortality events has been reported globally and across taxa, including marine invertebrates and marine and freshwater fishes (Fey et al., 2015; Raymond et al., 2022; Tye et al., 2022). In the marine environment, mass mortality events are associated with a range of causes, including thermal and oxygen stress, biotoxicity, disease, and contaminants (Fey et al., 2015), that often can be directly or indirectly related to climate change.…”

Cisco population characteristics in Wisconsin lakes in relation to lake‐ and landscape‐level factors

“…Given these relatively strict oxythermal habitat requirements, the presence of Cisco is often associated with high water quality, and Cisco population declines or extirpations are often interpreted as indicators of environmental change (Jacobson et al 2008;Sharma et al 2011). Summer mortality of Cisco related to depletion of suitable oxythermal habitat has increased in prevalence (Jacobson et al 2008;Kumar et al 2013;Tye et al 2022), and their sensitivity to environmental change has manifested in drastic declines in Cisco populations over the past century, especially at the southern edge of their range in the Upper Midwest of the United States (Sharma et al 2011;Honsey et al 2016). For example, the number of Indiana lakes containing Cisco declined from 45 in the early 1900s to 24 in 1975, and only seven Indiana lakes contained Cisco during recent surveys in 2012-2015 (Honsey 2014;Honsey et al 2016).…”

“…2013; Tye et al. 2022), and their sensitivity to environmental change has manifested in drastic declines in Cisco populations over the past century, especially at the southern edge of their range in the Upper Midwest of the United States (Sharma et al. 2011; Honsey et al.…”