Genotypic variation in response to extreme events may facilitate kelp adaptation under future climates

Marine heatwaves (MHWs) have caused declines in many kelp forests globally. Although the ecological effects of these climatic extremes been well examined, studies on role genotypic variation underpinning population responses under pressures are lacking. Understanding how kelps respond to different warming profiles and, particular, intraspecific is necessary confidently anticipate future forests, yet this remains a critical knowledge gap for most species. This study examined early life stages 9 genotypes Australian Ecklonia radiata MHW profiles, where cumulative heat intensity was kept constant: control treatment (constant 19°C), spikes (fluctuating 19-23°C), low (ramp up 23°C) and high 27°C). Overall, we found significant E. gametophyte performance all treatments delays sporophyte recruitment during exposure. We also genotype by environment (G×E) interactions, suggesting tolerance acute thermal stress influenced genetic variation. Our results showed that offspring from within same differently MHWs, indicating some susceptible MHWs while others more resistant. While standing subsequent susceptibility other stressors unknown, our findings suggest addition immediate impacts marine organisms, natural response anomalies may facilitate gradual evolution populations with increased climates.