Thermal tolerance of juvenile freshwater mussels (Unionidae) under the added stress of copper

Abstract

Freshwater mussels fulfill an essential role in aquatic communities, but are also one of the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change or industrial discharges, can further challenge impaired unionid communities, but thermal stress is almost certainly not the only stressor affecting freshwater mussels. Metals, such as copper (Cu), are a common source of toxicant exposure in aquatic environments. The toxic effects of Cu on the early life stages of freshwater mussels have been well studied, and freshwater mussels are more sensitive to Cu than most aquatic organisms. The purpose of the present study was to determine the effect of a sublethal copper concentration on the upper thermal tolerance of three species, Lampsilis siliquoidea, Potamilus alatus, and Ligumia recta, of juvenile freshwater mussels in 48- and 96-h tests. Thermal tolerance was determined over a range of experimental temperatures (20-42 degrees C) at three acclimation temperatures (17, 22, and 27 degrees C). Median lethal temperatures (LT50s) were calculated in the absence and presence of Cu, and at 48 h ranged from 34.6 to 44.4 degrees C (mean 37.7 degrees C) without Cu, and from 33.8 to 38.9 degrees C (mean 35.8 degrees C) with Cu. The LT50s at 96 h ranged from 32.5 to 35.6 degrees C (mean 34.5 degrees C) without Cu and from 33.0 to 35.4 degrees C (mean 34.2 degrees C) with Cu. Potamilus alatus had a significantly lower 48 h LT50 with Cu than without Cu at the 22 degrees C acclimation temperature; there were no other significant differences in LT50s attributed to Cu. Survival trends showed limited evidence of interactive effects between copper and temperature for all three species, suggesting the combined stress of elevated temperatures and copper exposure to freshwater mussels should be further explored.

Determining Optimum Temperature for Growth and Survival of Laboratory‐Propagated Juvenile Freshwater Mussels

“…Factors that have been found to correlate with mussel growth and survival rates include, but are not limited to, substrate type and size (Hinch et al 1986;Liberty et al 2007), flows and sediment load (Beaty 1997;Zimmerman 2003;Jones et al 2005;Liberty et al 2007;Rypel et al 2008), toxicant exposure (Pandolfo et al 2010a), mussel density (Hanson et al 1988;Beaty 1997;Beaty and Neves 2004;Negishi and Kayaba 2009), food availability (Hanlon 2000), sampling frequency (Beaty 1997;Zimmerman 2003;Liberty et al 2007), maturity of larvae (Jones et al 2005), and temperature (Hanson et al 1988;Buddensiek 1995;Beaty 1997;Hanlon 2000;Zimmerman and Neves 2002;Zimmerman 2003;Liberty 2004;Hanlon and Neves 2006;Pandolfo et al 2010aPandolfo et al , 2010bNegishi and Kayaba 2010). These studies have helped define requirements for mussel propagation and culture by advancing understanding of factors affecting growth and survival and have shown that mussels are useful biological indicators of environmental change.…”

“…Water temperature is one of the most important environmental variables affecting growth and survival of juvenile mussels in captivity (Zimmerman 2003;Jones et al 2005;Pandolfo et al 2010aPandolfo et al , 2010b. Several laboratory experiments have described the effects of temperature on growth and survival of freshwater bivalves during early life stages (i.e., newly transformed juveniles and <1-year-old juveniles ;Buddensiek 1995;Beaty 1997;Hanlon 2000;Zimmerman 2003;Hanlon and Neves 2006;Pandolfo et al 2010aPandolfo et al , 2010b.…”

Plasticity of protective mechanisms only partially explains interactive effects of temperature and UVR on upper thermal limits

“…For example, acclimation to high temperatures can increase upper thermal limits (Schaefer and Ryan, 2006;Ravaux et al, 2012). Exposure to other abiotic/biotic factors, such as environmental contamination or predators (Pandolfo et al, 2010;Sørensen et al, 2011), can also alter physiological capacities to withstand high temperatures (Sørensen et al, 2011;Healy and Schulte, 2012;Jirsa et al, 2013). However it is the interactive effects of multiple factors that will likely determine thermal tolerances.…”

Physiological responses to daily temperature variation and ultraviolet radiation in amphibian larvae

“…Many biotic and abiotic stressors lead to plasticity in thermal tolerance, including diet (Jirsa et al, 2013), presence of predators (Sørensen et al, 2011), environmental contamination (Pandolfo et al, 2010), UVR (Chapter 3 and 4) and precipitation (Clusella-Trullas et al, 2011). If these stressors also interact with temperature to affect thermal tolerances, natural and anthropogenic environmental variation may alter survival.…”

“…For example, acclimation to high temperatures can increase upper thermal limits (Ravaux et al, 2012;Schaefer and Ryan, 2006). Exposure to other abiotic/biotic factors, such as environmental contamination or predators (Sørensen et al, 2011;Pandolfo et al, 2010), can also alter physiological capacities to withstand high temperatures (Jirsa et al, 2013;Healy and Schulte, 2012;Sørensen et al, 2011). However it is the interactive effects of multiple factors that will likely determine thermal tolerances.…”