FIGURE 1: A map of North America with approximate sturgeon locations from the experimental studies used in this review. Only studies that provided data for effect size and acclimation response ratio calculations were included in the figure, and as such, they do not encompass the entire range of each species. River locations are approximate, and for studies where only a hatchery or research facility was listed, those approximate locations were used. Dot size corresponds to the number of studies in that region/river. The Color of the dot corresponds to species. The color on the map highlights the latitudinal temperature gradient across North America.
Angelina M. Dichiera, Madison L. Earhart, William S. Bugg, Colin J. Brauner, Patricia M. Schulte. 2024. Too hot to handle: a meta-analytical review of the thermal tolerance and adaptive capacity of North American sturgeon. Global Change Biology
ABSTRACT
Understanding how ectotherms may fare with rising global temperatures and more frequent heatwaves is especially concerning for species already considered at-risk, such as long-lived, late-maturing sturgeon. There have been concerted efforts to collect data on the movement behavior and thermal physiology of North American sturgeon to enhance conservation efforts; thus, we sought to synthesize these data to understand how sturgeon respond to thermal stress and what capacity they have to acclimate and adapt to warming. Here, we combined a systematic literature review and meta-analysis, integrating field-based observations (distribution and spawning) and laboratory-based experiments (survival, activity, growth, metabolism, and upper thermal limits) for large-scale insights to understand the vulnerability of North American sturgeon to rising global temperatures. We summarized the preferred thermal habitat and thermal limits of sturgeon in their natural environment and using meta-analytical techniques, quantified the effect of prolonged temperature change on sturgeon whole-animal physiology and acute upper thermal limits. While acclimation did not have significant effects on physiological rates or survival overall, there were positive trends of activity and metabolism in young-of-the-year sturgeons, likely offset by negative trends of survival in early life. Notably, North American sturgeon have a greater capacity for thermal tolerance plasticity than other fishes, increasing upper thermal limits by 0.56°C per 1°C change in acclimation temperature. But with limited laboratory-based studies, more research is needed to understand if this is a sturgeon trait, or perhaps that of basal fishes in general. Importantly, with these data gaps, the fate of sturgeon remains uncertain as climate change intensifies, and physiological impacts across life stages likely limit ecological success.