Integrating laboratory experiments and biogeographic modelling approaches to understand sensitivity to ocean warming in rare and common marine annelids

Abstract

Among ectotherms, rare species are expected to have a narrower thermal niche breadth and reduced acclimation capacity and thus be more vulnerable to global warming than their common relatives. To assess these hypotheses, we experimentally quanti ed the thermal sensitivity of seven common, uncommon, and rare species of temperate marine annelids of the genus Ophryotrocha to assess those species' vulnerability to ocean warming. We measured the upper and lower limits of physiological thermal tolerance, survival, and reproductive performance of each species along a temperature gradient (18, 24, and 30°C). We then combined this information to produce curves of each species' fundamental thermal niche by including trait plasticity. Each thermal curve was then expressed as a habitat suitability index (HSI) and projected for the Mediterranean Sea and temperate Atlantic Ocean under a present day , mid-(2050-2059) and late-(2090-2099) 21st Century scenario for two climate change scenarios (RCP2.6 and RCP8.5). Rare and uncommon species showed a reduced upper thermal tolerance compared to common species, and the niche breadth and acclimation capacity were comparable among groups. The simulations predicted an overall increase in the HSI for all species and identi ed potential hotspots of HSI decline for uncommon and rare species along the warm boundaries of their potential distribution, though they failed to project the higher sensitivity of these species into a greater vulnerability to ocean warming. In the discussion, we provide elements and caveats on the implications of our results for conservation efforts.

Biological traits, geographic distributions, and species conservation in aquatic ecosystems

“…Physiological traits (e.g. critical thermal limits, metabolic index, and cardiac performance) have emerged as having high predictive capacity under various warming and cooling scenarios and have been widely applied to the thermal sensitivity of marine species (Cheung et al, 2015; Deutsch et al, 2008; Liao et al, 2021; Massamba‐N'Siala et al, 2022; Sunday et al, 2011, 2014). Community‐level thermal deviations from local temperatures have also been applied to assess the sensitivity of marine species to warming and predict the warming‐related loss of species from present‐day communities in the future (Stuart‐Smith et al, 2015).…”