Upper Temperature Tolerance of Loach Minnow under Acute, Chronic, and Fluctuating Thermal Regimes

We used four methods to estimate the upper lethal temperature of loach minnow Rhinichthys cobitis: The lethal thermal method (LTM), chronic lethal method (CLM), acclimated chronic exposure (ACE) method with static temperatures, and ACE method with diel temperature fluctuations. The upper lethal temperature of this species ranged between 32°C and 38°C, depending on the method and exposure time; however, temperatures as low as 28°C resulted in slowed growth compared with the control groups. In LTM trials, we increased temperatures 0.3°C/min and death occurred at 36.8 ± 0.2°C (mean ± SE) for fish (37–49 mm total length) acclimated to 30°C and at 36.4 ± 0.07°C for fish acclimated to 25°C. In CLM trials, temperatures were increased more slowly (1°C/d), allowing fish to acclimate. Mean temperature at death was 33.4 ± 0.1°C for fish 25–35 mm and 32.9 ± 0.4°C for fish 45–50 mm. In the ACE experiment with static temperatures, we exposed fish for 30 d to four constant temperatures. No fish (20–40 mm) survi...