taxonID	type	description	language	source
6261E66DFFD07D3C0501F9247F51F8D9.taxon	description	The CTMax values for C. multidentata acclimated at temperatures ranging from 14 ◦ C to 32 ◦ C gradually increased from 31.5 ◦ C to 40.1 ◦ C, corresponding to an increase of around 2.4 ◦ C in CTMax for each 5 ◦ C increase in acclimation temperature (Fig. 3). The calculated thermal safety margin ranges from 17 ◦ C (14 ◦ C-acclimated specimens) to 8 ◦ C (32 ◦ C-acclimated specimens). 3.3. Survival of Caridina multidentata at different acclimation temperatures Survival of C. multidentata was 96 – 100 % after 1 month of acclimation at temperatures ranging from 14 ◦ C to 32 ◦ C (Fig. 1 B). After this one-month period, the CTMax experiments were carried out. Among the specimens subjected to CTM experiments, 3 out of 10 died the day after testing for the acclimation temperatures of 29 ◦ C and 32 ◦ C (this mortality is included in the monitoring of survival shown in Fig. 1 B). Survival subsequently decreased in the following weeks to 74 % for the batch acclimated at 32 ◦ C, and 83 % for the batches acclimated at 14 ◦ C and 29 ◦ C. Survival rates for the other batches (17 ◦ C – 26 ◦ C) remained between 92 % and 100 % during the 3 months of monitoring at the final acclimation temperature.	en	Ravaux, Juliette, Bosc, Olivia, Fusari, Charles-Edouard, Gricourt, Sara-Mae, Itin, Maria, Lestin, Michel, de Mazancourt, Valentin (2025): Thermal tolerance and vulnerability to climate warming in the freshwater shrimp Atyaephyra desmarestii and Caridina multidentata. Journal of Thermal Biology 129: 104121, DOI: 10.1016/j.jtherbio.2025.104121, URL: https://doi.org/10.1016/j.jtherbio.2025.104121
6261E66DFFD07D3D0501FAB078C9F90F.taxon	description	The CTMax values for A. desmarestii originating from Spain were 33.2 ◦ C (acclimation at 18 ◦ C), 35.0 ◦ C (acclimation at 23 ◦ C), and 37.3 ◦ C (acclimation at 28 ◦ C), corresponding to a 2 ◦ C increase in CTMax for each 5 ◦ C increase in acclimation temperature (Fig. 2). The calculated thermal safety margin is 15 ◦ C (acclimation at 18 ◦ C), 12 ◦ C (acclimation at 23 ◦ C), and 9 ◦ C (acclimation at 28 ◦ C). The CTMax value for A. desmarestii originating from France was 34.7 ◦ C (acclimation at 23 ◦ C), giving a summer thermal safety margin of 12 ◦ C (Fig. 2).	en	Ravaux, Juliette, Bosc, Olivia, Fusari, Charles-Edouard, Gricourt, Sara-Mae, Itin, Maria, Lestin, Michel, de Mazancourt, Valentin (2025): Thermal tolerance and vulnerability to climate warming in the freshwater shrimp Atyaephyra desmarestii and Caridina multidentata. Journal of Thermal Biology 129: 104121, DOI: 10.1016/j.jtherbio.2025.104121, URL: https://doi.org/10.1016/j.jtherbio.2025.104121
6261E66DFFD07D3D0501FAB078C9F90F.taxon	discussion	Here we compare the CTMax of two populations of A. desmarestii more than 900 km apart, corresponding to 6 ◦ on a latitudinal axis: the southern population of Spain and the northern population of the Paris region (Fig. 2). The expected variation in CTMax should be around 1 ◦ C for these populations (about 0.17 ◦ C per degree of latitude; Sunday et al., 2019), yet the CTMax values obtained were equivalent, all other things being equal: acclimation at the same temperature, identical maintenance and experimental conditions. These data suggest that this species’ upper thermal limit would not shift as a function of the geographic zone, meaning that the thermal tolerance would not adjust to the thermal conditions of its habitat at the scale of its geographical distribution. And yet, the populations from Spain and from France are subject to clearly different thermal conditions in their environment, particularly with regard to extreme summer temperatures. A broad correspondence has been shown between thermal limits and extreme environmental temperatures, suggesting that latitudinal patterns of thermal tolerance can be largely explained by the extreme temperatures encountered in each environment (Sunday et al., 2019). Temperature recorded in summer ranged from 19 to 31 ◦ C on the Spanish site (Arbat-Bofill, 2015), and from 19 to 23 ◦ C on the French site (measurement in the Seine over 26 years for the 20 th century; Rivi`ere et al., 2021). The data of the Seine do, however, show a warming of the water temperature, which sometimes reaches 27 ◦ C and more rarely exceeds 27 ◦ C. High summer temperatures for the French population therefore remain several degrees below those of the Spanish population. Moreover, the French population has settled in the Seine since at least 1843 (No ¨ el, 2017), so it’ s a long-established colonization that has given this population ample time to adapt to the climatic conditions of this habitat. These preliminary results pave the way for further study of this species to determine the seasonal thermal limits of populations over its geographical range, in order to test the relationship between geographical distribution and thermal tolerance. This would involve comparing populations at the north-south limits of the species’ range, where differences in habitat temperature are most marked, to confirm whether the latitudinal migration leads to a shift in the thermal tolerance. Experimental translocations of shrimp populations could also provide information on the kinetics and range of species’ acclimation and ultimately adaptation to a new thermal environment.	en	Ravaux, Juliette, Bosc, Olivia, Fusari, Charles-Edouard, Gricourt, Sara-Mae, Itin, Maria, Lestin, Michel, de Mazancourt, Valentin (2025): Thermal tolerance and vulnerability to climate warming in the freshwater shrimp Atyaephyra desmarestii and Caridina multidentata. Journal of Thermal Biology 129: 104121, DOI: 10.1016/j.jtherbio.2025.104121, URL: https://doi.org/10.1016/j.jtherbio.2025.104121
