Climate vulnerability of South American freshwater fish: Thermal tolerance and acclimation

Abstract

Freshwater fish are restricted by their physiology to rivers and lakes, and are generally limited in their capacity to disperse across basins. As a result, there is often a close match between the evolutionary history of river basins and their natural history. Thus, the regional landscape and ecological features, such as temperature, have shaped the evolution and adaptation of local fish assemblages. Climate change is expected to affect fish diversity and increase extinction, especially in low latitudes, and it has been suggested that species that inhabit low latitude species are more susceptible since they live close to their maximum thermal limits and have low capacity for acclimation. To understand the mechanisms of variation in thermal tolerance across a broad‐scale of South American fishes is fundamental to be able to assess the vulnerability of species and habitat to global warming. Herein, we present the first attempt to analyze the vulnerability of South American freshwater fish species, based on the review of upper thermal limits of 106 species from a broad range of latitudinal habitats. Our findings show that upper thermal limits decrease with latitude, while the thermal safety margin (TSM) increase. Furthermore, the latitude has little effects on the acclimation response ratio, and the TSM decreased with rising temperatures. These data suggest that thermal phenotypic acclimation has low potential for mitigating global warming. These results indicate that South American fish species living in tropical areas are more susceptible to global warming since they are already living close to their maximum habitat temperature.

Take time to look at the fish: Behavioral response to acute thermal challenge in two Amazonian cichlids

“…CT max measured at the average maximum temperature encountered in the natural habitat of the six species ranged from ~39.2°C for L. victorianus to ~42.2°C for C. macropomum . In a recent review of thermal tolerance in South American fish Campos et al (2021) summarized data for CT max in 106 species; for those species from the Amazon acclimated to their average habitat temperature, CT max averaged 38.6°C and ranged from 30.9 to 42.8°C (data extracted from aggregated data set). Nyboer and Chapman quantified the CT max of Nile perch ( Lates niloticus ) held for 3 weeks to the average maximum water temperature of the home environment (Lake Victoria) and reported a CT max of ~39.1°C.…”

“…Applying this projection to the 5160 described species of freshwater fishes in the region (Reis et al, 2016), over 1100 species of South American fishes may be at risk of extinction due to climate change. A recent review of thermal tolerance and acclimation capacity for 106 species of South American freshwater fishes by Campos et al (2021) supports a higher susceptibility of fish species living at the tropical areas of South America as they are living close to their thermal limits and have low acclimation capacity. These studies highlight the potential vulnerability of tropical South America fish species to climate change and the importance of increasing our understanding of thermal limits for fishes of this region.…”

“…For example, Åsheim et al (2020) found that upper thermal tolerance to rapid warming (CT max ) was correlated with upper thermal tolerance measured under slow warming conditions in zebrafish acclimated to 22°C and weakly correlated in fish acclimated to 34°C. Data on CT max are available for many freshwater ectotherms providing a strong comparative framework for evaluating relative tolerance, plasticity in thermal tolerance, and for predicting shifts in geographic distributions (Campos et al, 2021; Morley et al, 2019; Sunday et al, 2012). However, recent studies have shown that some fish species exhibit avoidance behavior well before the CT max is reached (McDonnell et al, 2019; McDonnell & Chapman, 2015; Turko et al, 2020; Wells et al, 2016), suggesting that behavioral metrics may provide additional, ecologically relevant information on thermal tolerance.…”

Catfish 2020, A Clear Vision of the Future

“…Recent research suggests that many warmwater fish species exist in habitats near their upper thermal tolerance limits and are particularly vulnerable to warming temperatures (Barbarossa et al. 2021; Campos et al., in press). Thus, catfishes may be vulnerable to climate warming, especially those that face other ecological and biological stressors, such as madtom species.…”

Upper thermal tolerances and vulnerability to global warming in a Brazilian Caatinga fishAstyanax bimaculatus (Linnaeus, 1758) population

“…2012; Campos et al. 2021). Within the tropical and subtropical areas, some special biomes and particular microhabitats such as open forest and semi‐arid biomes are currently suffering high temperatures and their biological communities may be candidates to suffer increased heat impacts (Duarte et al.…”