Evaluating the Effects of Parentage on the Response of Atlantic silverside (Menidia menidia) to Varying Thermal Regimes

During early development, fish are not only influenced by their external environment but also by parentage. Therefore, it is critical to know whether or not fish that experience changing thermal conditions in the wild will have the capacity to adapt to those changes. We used Atlantic silverside (Menidia menidia) to examine how parentage influences early-life-stage responses under two different constant-temperature thermal regimes. Atlantic silverside is a small, estuarine, forage fish that is an important zooplanktivore and a key prey source for economically important fish species. We utilized a paternal half-sibship mating design, in which each of 14 males was crossed with two females. Each full-sibship egg group (common father and mother) was further assigned to one of two incubation/rearing temperatures (17 and 22°C) and maintained in triplicate containers. Measurements of initial egg size were taken as a possible covariate of offspring performance. For all family-by-temperature replicates, data were collected on survival to hatch, size at hatch, and embryonic period duration (EPD). These response variables have important implications on the fitness of fish during important early-life-stages. Data were analyzed via a nested ANOVA. A significant effect of paternal and maternal identity on survival to hatch was observed (p < 0.001), but no effect of temperature was evident. The paternal influence on survival to hatch suggests that Atlantic silverside will have the capacity to adapt to changing environmental conditions in the future. Temperature and paternal identity had a significant effect on EPD and size of larvae at hatch (p < 0.001). Additionally, the EPD results suggest a male-by-temperature interaction effect which has important implications for preserving genetic diversity within populations. Further analyses and expanded mating designs are warranted, but our results suggest that Atlantic silverside may have the capacity to adapt to changing ocean conditions.