Temperature is the main environmental factor moderating different physiological processes of marine ectotherms, as well as their distribution, survival, growth and reproduction. Climate change generated by high atmospheric CO2 emissions is causing increases in ocean temperatures. Using integrative approaches to ecophysiological information, complemented by satellite temperature data, could help to more accurately determine the effects of ocean warming. Therefore, the aim of this study was to determine the effect of ocean warming on the distribution of two species of tubeworms from the temperate northern Pacific (Spirobranchus spinosus ) and tropical eastern Pacific (S. cf. corniculatus). Adult worms of both species were collected and acclimated for 30 days at different temperatures to determine thermal tolerance, thermal window, optimal temperature, and thermal safety margins. All this information was complemented with satellite temperature data, which allowed the generation of potential distribution models for a present (2010-2020) and future (2090-2100) scenario of high CO2 concentrations (SSP5-8.5).
The thermal tolerance of both species was significantly affected by acclimation temperatures (S. spinosus : CTmax : 13.7-22.7°C, CTmin : 8.3-15.6°C; S. cf. corniculatus : CTmax : 31.3-35.1°C, CTmin: 17.9-27.8°C) and had narrow thermal windows (S. spinosus: 37°C2 ; S. cf. corniculatus: 71°C2 ), characteristic of stenothermic species. The optimal temperatures for S. spinosus and S. cf. corniculatus were 14 and 30°C, respectively. By the end of this century, thermal safety margins will likely decrease, which will generate retractions and expansions in the distribution of both species. Therefore, it is important that countries worldwide join efforts to reduce CO2 emissions and declare protected areas for the care and conservation of marine species.