Heat shock response and metabolic stress in the tropical estuarine copepod Pseudodiaptomus annandalei converge at its upper thermal optimum

Temperature-and sex-specific grazing rate of a tropical copepod Pseudodiaptomus annandalei to food availability: Implications for live feed in aquaculture

“…The increase in PP and SPP when increasing the temperature from 25 to 30°C may be a consequence of an increase in metabolic rate (Angilletta, ; Angilletta, Niewiarowski, & Navas, ; Grote et al, ; Hirche, ). A strong reduction in the pellet production at 35°C may be a result of physiological depression, that has been observed in aquatic taxa in shallow water bodies exposed to extreme temperatures, for example, damselfly (Dinh, Janssens, & Stoks, ), intertidal species (Dong, Yu, Wang, & Dong, ; McArley, Hickey, & Herbert, ) and copepods (Low et al, ).…”

Surviving heatwaves: thermal experience predicts life and death in a Southern Ocean diatom

“…In contrast, we identified that three-day heatwaves sometimes had positive effects on growth rate at either thermal extreme in all three genotypes tested (Figures 2 and 3). An increase in growth rate at upper thermal extremes after heatwave exposure could indicate acclimation (Magozzi & Calosi, 2015, Scharf et al, 2016, Stuhr et al, 2017, in which growth at elevated temperatures cause rapid physiological alterations that limit the negative impact of stress at temperatures above Topt (Low et al, 2018). However, we also saw high variation in growth within genotypes at the upper temperature range, indicating that acclimation at very high temperatures was variable (Figure 4).…”

“…Growth of Fragilariopsis cylindrus under both thermal extremes (-2, +11 o C) revealed similarities in altered gene expression relative to ambient conditions, indicating that generic stress responses were potentially employed in both thermal environments (Mock et al, 2017), and Leptocylindrus aporus cultured at high and low temperatures revealed that the expression of heat shock proteins were upregulated under both thermal regimes (Pargana et al, 2020). The production of HSPs is known to increase during growth above Topt (Leung et al, 2017, Rousch et al, 2004, and has been shown to be maximised as temperatures approach thermal maxima (Tmax) (Low et al, 2018). However, HSPs are also produced during cold shock responses, which is consistent with the observation that heat shocks can enhance tolerance to subsequent cold shocks (Burton et al, 1988, Goto & Kimura, 1998, Scharf et al, 2015, Scharf et al, 2016.…”

“…Furthermore, experimental populations exposed to 0, 3 and 9 day heatwaves were transferred into nutrient-replete media and allowed to grow at a range of temperatures (-2.2, -0.4, +1.5, +2.7, +4.7, +6.2 and +7.6 o C) on a thermal gradient block to produce acute thermal performance curves in the final phase. Heatwave temperatures (7.5 and 9.2 o C) were chosen to simulate thermally stressful environments for A. actinochilus, in which temperatures are either near to or beyond thermal maxima (Low et al, 2018). These temperatures, although not currently experienced in the Ross Sea where the genotypes used in this study were isolated, can occur in other parts of the Southern Ocean during heatwave events (Montie et al, 2020), and as such could be experienced by this species more broadly.…”

“…However, environmental warming that raises temperatures near or above thermal optima induce a number of physiological stress responses (Leung et al, 2017, Low et al, 2018, Madeira et al, 2013, Viant et al, 2003 that depend upon the duration of the thermal extreme, ranging from acute (hours to days) to chronic (days to weeks) (Huey & Bennett, 1990). Energy and resource investment into the expression of acclimation and stress response genes, such as those that produce heat shock proteins, incur fitness costs (Geider et al, 2009, Kingsolver & Woods, 2016, Krebs & Feder, 1997, Viant et al, 2003 and if these are high they can limit responses to future environmental change (Sokolova et al, 2012).…”