The weakest link: sensitivity to climate extremes across life stages of marine invertebrates

Abstract

Predicting the effects of climate change on Earth's biota becomes even more challenging when acknowledging that most species have life cycles consisting of multiple stages, each of which may respond differently to extreme environmental conditions. There is currently no clear consensus regarding which stages are most susceptible to increasing environmental stress, or ‘climate extremes’. We used a meta‐analytic approach to quantify variation in responses to environmental stress across multiple life stages of marine invertebrates. We identified 287 experiments in 29 papers which examined the lethal thresholds of multiple life stages (embryo, larva, juvenile and adult) of both holoplanktonic and meroplanktonic marine invertebrates subjected to the same experimental conditions of warming, acidification and hypoxia stress. Most studies considered short acute exposure to stressors. We calculated effect sizes (log response ratio) for each life stage (unpaired analysis) and the difference in effect sizes between stages of each species (paired analysis) included in each experiment. In the unpaired analysis, all significant responses were negative, indicating that warming, acidification and hypoxia tended to increase mortality. Furthermore, embryos, larvae and juveniles were more negatively affected by warming than adults. The paired analysis revealed that, when subjected to the same experimental conditions, younger life stages were more negatively affected by warming than older life stages, specifically among pairings of adults versus juveniles and larvae versus embryos. Although responses to warming are well documented, few studies of the effects of acidification and hypoxia met the criteria for inclusion in our analyses. Our results suggest that while most life stages will be negatively affected by climate change, younger stages of marine invertebrates are more sensitive to extreme heating events.

Unmasking intraspecific variation in offspring responses to multiple environmental drivers

“…From that perspective, climate change exposes coastal organisms to conditions not previously experienced for many generations. We focus on larvae because larval stages of marine invertebrates are often the most sensitive stage to multiple drivers (Przeslawski et al 2015, Pandori andSorte 2019) as their tolerance spectrum is often narrower compared to their adults (Pechenik 1987;Charmantier 1998). Larvae determine gene flow and population connectivity (Palumbi 2003;Cowen and Sponaugle 2009).…”

The thermal environment at fertilization mediates adaptive potential in the sea

“…For many organisms, adaptive potential is especially critical at early life stages (e.g., gametes, embryos, and larvae) whose vulnerability to stress makes them weak links in the life cycle (Zinn et al. 2010; Pandori and Sorte 2019). Such stages often sustain high mortality and experience different environmental conditions, allowing selection to modify allele frequencies and plasticity to modify allele expression as development unfolds (Bernasconi et al.…”

Evolutionary Phycology: Toward a Macroalgal Species Conceptual Framework

“…As some species descriptions rely on the heteromorphic or isomorphic alternation of generations, it is critical to assess patterns of gene flow within these life cycles and include both ploidy stages in the gathering of evidence about species delimitation. Understanding these patterns is a necessary component to forecasting how species with complex life cycles will respond to climate change, though macroalgal life cycles are often not included in these assessments (e.g., Pandori and Sorte 2019).…”