Upper thermal tolerances of early life stages of freshwater mussels

Abstract

Freshwater mussels (order Unioniformes) fulfill an essential role in benthic aquatic communities, but also are among the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change, industrial discharges, drought, or land development, could further challenge imperiled unionid communities. The aim of our study was to determine the upper thermal tolerances of the larval (glochidia) and juvenile life stages of freshwater mussels. Glochidia of 8 species of mussels were tested: Lampsilis siliquoidea, Potamilus alatus, Ligumia recta, Ellipsaria lineolata, Lasmigona complanata, Megalonaias nervosa, Alasmidonta varicosa, and Villosa delumbis. Seven of these species also were tested as juveniles. Survival trends were monitored while mussels held at 3 acclimation temperatures (17, 22, and 27uC) were exposed to a range of common and extreme water temperatures (20-42uC) in standard acute laboratory tests. The average median lethal temperature (LT50) among species in 24-h tests with glochidia was 31.6uC and ranged from 21.4 to 42.7uC. The mean LT50 in 96-h juvenile tests was 34.7uC and ranged from 32.5 to 38.8uC. Based on comparisons of LT50s, thermal tolerances differed among species for glochidia, but not for juveniles. Acclimation temperature did not affect thermal tolerance for either life stage. Our results indicate that freshwater mussels already might be living close to their upper thermal tolerances in some systems and, thus, might be at risk from rising environmental temperatures.

Comparative physiological, biochemical, and molecular thermal stress response profiles for two Unionid freshwater mussel species

“…Although rather common in marine bivalves, there has been very little comparative research on thermal stress for freshwater mussels. Furthermore, what is available has focused on acute, laboratorycontrolled thermal challenges at extreme temperatures Luo et al, 2014;Buschini et al, 2003;Pandolfo et al, 2010). Therefore, the main objective of this study was to compare the response of a hypothesized thermally tolerant species (V. lienosa) with a thermally sensitive species (V. nebulosa) of unionid freshwater mussel to both an acute, laboratory-controlled thermal challenge and a field chronic warming simulation at environmentally relevant temperatures.…”

“…In the southeastern USA, summer freshwater temperatures can average 35°C and exceed 40°C during extreme heat waves, which is near or above the upper thermal tolerance limits of many freshwater species (Archambault et al, 2014;Pandolfo et al, 2010;Ganser et al, 2015; also reviewed by Ficke et al, 2007). Such significant temperature changes have the potential to disrupt ecosystem stability, resulting in species-specific differences in susceptibility, with factors such as physiological tolerance range, potential for adaptation to abiotic stressors, and life history characteristics (Hofmann and Somero, 1995;Somero, 2002Somero, , 2012 all playing important roles in determining a 'winners' versus 'losers' status (Somero, 2010).…”

Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus

“…The survival of released glochidia followed drop offs observed for other mussel species (Zimmerman & Neves, 2002;Cope et al, 2008). Elevated temperatures may possibly affect metabolic rates and result in short-lived glochidia, as seen in the HIGH temperature scenario (Teutsch, 1997;Jansen et al, 2001;Pandolfo et al, 2010). This is supported by a prolonged glochidia survival at LOW temperatures.…”

Latitudinal comparison of thermotolerance and HSP70 production in F2 larvae of the Greenshell mussel (Perna canaliculus)

“…The use of whole-system bioassays, such as assessing mortality in response to acute thermal challenges, has also proven a robust comparative tool and provided excellent insights into inter-and intraspecific responses of invertebrates to heat stress (Kuo and Sanford, 2009;Pandolfo et al, 2010). By pairing these whole-organism assays with the HSR, an integrative understanding of the impact of thermal stress upon the organism is afforded.…”

“…Furthermore, pronounced sub-lethal effects are evident in mussels exposed to temperature stress, with both northern (M. edulis) and southern hemisphere (P. canaliculus) mussel species exhibiting reduced growth and reproductive output in response to acute temperature challenges (Petes et al, 2007;Petes et al, 2008). Additionally, short-term responses are also evident, with freshwater mussel species increasing heart beat frequency when experiencing thermal stress (Pandolfo et al, 2010).…”