Effects of temperature, dissolved oxygen, and substrate on the development of metabolic phenotypes in age-0 lake sturgeon (Acipenser fulvescens): implications for overwintering survival

Abstract

The impact of early rearing environment on phenotypic development in teleosts has been reasonably well-documented, but only recently has attention been paid to sturgeon raised for conservation purposes. In the present study, we hypothesized that rearing environment will result in the development of distinct metabolic phenotypes in age-0 lake sturgeon (Acipenser fulvescens) and that these phenotypes will drive differential survival rates during a simulated overwintering event. Lake sturgeon gametes were fertilized and raised in one of three different environments: 16 °C + 100% dissolved oxygen (DO), 14 °C + 100% DO, and 16 °C + 80% DO, each with or without substrate. We measured standard metabolic rate, forced maximum metabolic rate, metabolic scope, energy density, hepatosomatic index, Fulton’s condition factor, and enzyme activities associated with ATP production. Our results suggest that subtle changes in abiotic environments during early life history result in the development of distinct metabolic phenotypes during the first year of life. These have important implications for survival of age-0 lake sturgeon when stocked in the fall of their first year.

Influence of a dynamic rearing environment on development of metabolic phenotypes in age-0 Lake Sturgeon, Acipenser fulvescens

“…A simulated overwintering event was performed with changes in temperature and light intensity similar to what has previously been described (Yoon et al ., 2018) while DO remained constant within each treatment throughout the experimental period (Fig. 1).…”

“…Previous results have indicated that acute exposure to hypoxia down to 80% of air saturation did not affect aerobic metabolism or hypoxia avoidance behaviours in a number of species of fish (Poulsen et al ., 2011; McBryan et al ., 2013; Svendsen et al ., 2014); however, long-term exposure to 80% dissolved oxygen (DO) could result in increased mortality and loss of aerobic capacity following exposure to a stressful environment (i.e. low temperature and food deprivation; Yoon et al ., 2018). Previous studies have predominantly focused on teleost fish (Fernandes et al ., 1995; Hobbs and Mcdonald, 2010), but these relationships remain poorly understood in ancestral fishes such as sturgeons.…”

“…We chose ambient river temperature (ART) and ART+2°C to represent natural temperature profiles that age-0 Lake Sturgeon may experience in Manitoba, Canada, and 80% of air-saturation DO was chosen as mild hypoxia is often observed in aquaculture due to high biomass density, loss of flow or in nature due to eutrophication (Diaz and Breitburg, 2009). Further, we included substrate based on the previous findings regarding its impacts on phenotypic development in sturgeon species (Gessner et al ., 2009; McAdam, 2011; Zubair et al ., 2012; Boucher et al ., 2018; Yoon et al ., 2018). Specifically, we tested the environmental matching hypothesis and predicted that fish raised in ART 100% DO with substrate would show the highest K, ED, MS and survival rate throughout the experiment.…”

To feed or flee: early life-history behavioural strategies of juvenile lake sturgeon (Acipenser fulvescens) during risk-sensitive foraging

“…However, lake sturgeon chronically exposed to AC+PC had significantly lower Fulton's condition factor (p < 0.05) than chronic PC+C and control treatments (Fig. 4), which may impact overwinter survival in juvenile lake sturgeon (Yoon et al 2019).…”

“…After spring spawning, juvenile lake sturgeon have a single season to grow before they endure their first overwinter challenge, which may last for at least 3 months with limited foraging opportunities and temperatures near 0°C (McDougall et al 2014). Such overwintering events have large consequences for survival and subsequent year-class strength as that cohort moves into the following year (Post and Evans 1989;Hurst and Conover 2003;Deslauriers et al 2018;Yoon et al 2019). Recent laboratory studies have demonstrated complex behavioural responses in juvenile lake sturgeon (Wishingrad et al 2014b(Wishingrad et al , 2014cFerrari et al 2015;Sloychuk et al 2016;Bjornson and Anderson 2018), but none have attempted to determine the trade-off between foraging and responding to predation threats in juvenile lake sturgeon.…”