Temperature affects transition timing and phenotype between key developmental stages in white sturgeon Acipenser transmontanus yolk-sac larvae.

Temperature differentially influences developmental trajectories of traits during early life stages that can affect survival and recruitment. Experiments were conducted to quantify temperature-induced developmental responses of White Sturgeon (Acipenser transmontanus) yolk-sac larvae (YSL) reared at temperatures encountered across the species' range (12.5, 14.0, 15.5, and 17.0 °C). We quantified effects of temperature on timing of transitions between sequential developmental stages from hatch to initiation of exogenous feeding. Rate of development significantly increased at warmer compared to cooler temperatures; no significant difference was observed between 15.5 and 17.0 °C or 12.5 and 14.0 °C. When standardized by relative timing of development (RT_i), developmental rate was not significantly different among treatments. Morphological traits (total length; body area; yolk-sac area; head area; gill filament area; mouth area; pectoral fin area) were measured daily, though only data for YSL reared at 12.5 and 17.0 °C was used to quantify phenotypic variation. Morphological traits (excluding yolk-sac area) were generally larger 48+ hours post hatch for YSL reared at 17. 0 °C compared to 12.5 °C. In contrast, these same traits, with the exception of gill filament area, were larger in 12.5 °C reared YSL when considered as a function of developmental stage. These opposing results suggest trade-offs associated with allocating resources to a particular trait depended on rearing temperature. Our results provide the ability to estimate timing of critical early life stages (i.e., hatch, emergence) as a function of temperature which is an important management tool to understand how early life development contributes to recruitment processes and adaptability in thermally altered systems. [ABSTRACT FROM AUTHOR]