Ecological Conditions Experienced During Early Larval Stages Affect Larval Lake Sturgeon Phenotypes and Behavior

Plasticity in expression of phenotypes and behaviors during early ontogenetic stages results from both genetic and environmental effects.  Newly-hatched lake sturgeon  (Acipenser fulvescens) larvae immediately burrow in substrate and exhibit considerable plasticity in timing of emergence.  We quantified the effects of environmental conditions (food, predators, conspecific density), temperature, substrate, phenotype and family on the duration of time from hatch to emergence.  Eggs (n=400) were incubated at 10°C or 18°C, and hatched larvae were placed into cups with substrate and maintained in ambient stream temperature and constant velocity. Time to emergence was recorded in days and cumulative temperature units.  Significant (p<0.01) univariate predictors of emergence time included incubation temperature, growth, loss of yolk-sac, substrate, and degree of temperature deviance. Larvae emerged significantly earlier in treatments of high conspecific density and chemosensory predators cues.  Models of best fit for emergence time included a three-way interaction among incubation temperature, treatment, and degree of temperature deviance, as well as an additive effect of percent loss of yolk-sac. Collectively, data revealed physical and biotic conditions at the time of emergence and prior conditions during incubation affected emergence time.  Plasticity in response to these conditions likely affects survival and recruitment at individual and population levels, respectively.