Relative influences of microhabitat incubation conditions and genetic parentage effects on lake sturgeon (Acipenser fulvescens) offspring traits during early ontogeny

Abstract

Knowledge on factors influencing traits during critical early growth periods is essential for predicting population persistence. Genetic effects and microhabitat stream conditions at female selected oviposition sites influence larval phenotypes. However, limited work has examined contributions of both factors across sequential ontogenetic stages for larvae of wild origin. Using a wild population of lake sturgeon (Acipenser fulvescens) from Black Lake, Michigan (USA), fertilized eggs were collected from stream substrate just prior to hatch at one-meter intervals along seven transect lines at an adult-selected spawning area. Microhabitat variables (depth, discharge, substrate size) were recorded at egg collection points. Body length, body area, and yolk-sac area were quantified for yolk-sac larvae (N = 359) at the time of hatch. Following the onset of exogenous feeding, larval growth was measured weekly for four weeks. Parentage was assigned using genetic-based analysis. Inter-individual variation in phenotypic traits quantified at hatch were attributed to stream microhabitat variables; mean depth had the largest influence. No additive genetic effects were detected at hatch. Post-emergence larval growth significantly varied within and among half-sibling groups with the greatest range in body size observed at 33 days post-hatch. Additive genetic variance and heritability increased with age. Results demonstrate that female-selected incubation habitats influenced traits at hatch for wild-origin fish, but effects do not persist to a sequential ontogenetic stage. Alternatively, growth after the onset of exogenous feeding was largely influenced by intrinsic (genetic) factors which must be considered when designing and implementing rehabilitation strategies for lake sturgeon and potentially other threatened riverine fishes.