Caridina multidentata, Stimpson, 1860

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, pp. 104121-104121 : 5-6

3.2. Thermal tolerance and acclimation capacity assessment of Caridina multidentata

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. 1B ). 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. 1B ). 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.

Figures

Fig. 3. Critical thermal maximum of Caridina multidentata acclimated to different temperatures. Data are represented as box plots, with whiskers indicating the minimum and maximum, the box delimiting the first quartile and third quartile, and the median and mean identified by an horizontal line (the value is shown next to the line). Each experiment was conducted on a sample size of n = 10 individuals. Values sharing a common letter are not significantly different (p> 0.05). The summer thermal safety margin (dotted lines) is calculated as the difference between the CTMax (for acclimation at 17 ◦C–26 ◦C since summer water temperatures are between 18 ◦C and 25◦C; Yamada et al., 2024) and the habitat maximum water temperature (25◦C; Yamada et al., 2024). Photo credit: Jacky Yu.

Fig. 1. Temperature data and survival rates of Caridina multidentata in the aquaria. A) temperature was set at 23 ◦C in all aquaria on shrimp arrival and left constant for 2 months (dotted line). The dotted arrows indicate the days when the temperature was increased or decreased by 3 ◦C to reach the final temperatures: on day 61 (aquarium 14, 17, 20, 26, 29, 32), on day 67 (aquarium 14, 17, 29, 32) and on day 70 (aquarium 14 and 32). B) Survival rates under the different acclimation temperatures. Black arrows indicate the days on which CTMax experiments were conducted (n = 10 individuals for each tank).