Thermal tolerances of two stream invertebrates exposed to diumally varying temperature

Abstract

For two key New Zealand freshwater invertebrates (the mayfly Deleatidium autumnale and the snail Potamopyrgus antipodarum) the upper thermal tolerances were measured in the laboratory under both constant and diumally varying temperatures. At constant temperature 50% mortality in 96 h ( const LT 50 ) occurred at 24.2 ± 0.9°C for mayflies and 31.0 ± 0.6°C for snails: values similar to previously published estimates (Quinn et al. 1994). For diurnally varying temperatures (daily amplitude 10°C) 50% mortality occurred when the daily mean temperature was 21.9 ± 0.7°C (mayflies) and 28.6 ± 0.4°C (snails) which is c. 10% (2.5 ± 1.3°C) lower than the const LT 50 . Conversely, 50% mortality occurred when the daily maximum temperature was 26.9 ± 0.7°C (mayflies) and 33.6 ± 0.4°C (snails) which is c. 10% (2.5 ± 1.3°C) higher than the const LT 50 . Many published temperature limits for stream organisms are derived from constant temperature experiments. Our results indicate that such limits should be applied to a temperature midway between the daily average and the daily maximum of a diurnal profile.

Nocturnal river water temperatures: Spatial and temporal variations

“…Extreme Tw can stress or ultimately prove lethal to biota (e.g. Dallas & Rivers-Moore 2012; Martins et al 2011) although some fauna can deploy avoidance strategies and/or acclimate to high temperatures (Breau et al 2011;Cox & Rutherford, 2000;Geist et al 2011). Nonetheless, sub-lethal Tw can still impact on spawning and breeding, hatching, growth, behaviour, distribution and phenology, thereby altering population structure and dynamics (Durance and Ormerod, 2007;Thackeray et al 2010;Ward & Stanford 1982).…”

Trophic basis of production for a mayfly in a North Island, New Zealand, forest stream: Contributions of benthic versus hyporheic habitats and implications for restoration

“…Mayflies are one of the most widespread groups of aquatic invertebrates and are amongst the most sensitive to anthropogenic disturbance (Ward 1992; Hickey 2000; Maxted et al 2000;Collier 2002). Several studies have reported adverse responses among mayfly species to high water temperature (e.g., Quinn et al 1994;Cox & Rutherford 2000;Chadwick & Feminella 2001), low dissolved oxygen (e.g., Nebeker 1972), and increased levels of sediment (e.g., Ciborowski et al 1977).…”

Predicting the effects of time‐varying temperatures on stream invertebrate mortality

“…As discussed below, there is evidence that this assumption may not be valid, especially for Potamopyrgous. Cox & Rutherford (2000) conducted a set of experiments in winter (April-June) 1998 in which animals were collected from two spring-fed streams (daily mean natural temperature 11-13°C) and acclimated for 24-h at 15-16°C. Test animals (30 per experiment) were then transferred to a high temperature bath, temperature was held constant for 96 h, and the number of live animals (A,) was measured after t = 24, 48, 72, and 96 h (all experiments) and 4, 14, 40, and 66 h (some experiments).…”

“…In their winter experiments Cox & Rutherford (2000) also exposed test animals to diurnally varying (±5°C) temperature using the same methods described above. It should be noted that the results of these diurnally varying temperature experiments were not used during model calibration.…”

“…Rutherford et al (1997) advocated the conservative approach of applying such limits to the daily maximum temperature. Cox & Rutherford (2000) conducted laboratory experiments using Deleatidium autumnale and Potamopyrgus antipodarum in which test animals were exposed for 96 h to constant high temperatures and to temperatures that varied diurnally with an amplitude of ±5°C. Mortality was similar when the constant temperature matched a temperature midway between the daily mean and the daily maximum.…”