The effect of maternal exposure to contaminated sediment on the growth and condition of larval Fundulus heteroclitus

We employed a factorial laboratory experiment to determine the single and combined effect of maternal and larval exposure to contaminated sediment from Elizabeth River, Virginia, a site contaminated with high concentrations of multiple pollutants. Females were exposed to either reference or contaminated sediment and the larvae from both groups of mothers were in turn transferred to either reference or contaminated sediment. We found a strong maternal influence on yolk area, length and RNA:DNA ratio at hatch. Further, the maternal exposure significantly influenced growth rate and RNA:DNA ratios of larvae 14 days after hatch and was a more important factor in determining these endpoints than larval exposure. We found that after 14 days larvae were larger and had higher survivorship when the maternal and larval exposures were the same. There also was no statistical difference with respect to growth and condition between larvae that had hatched from exposed mothers and remained in contaminated water and larvae that had hatched from reference mothers and were placed in either reference or contaminated sediment. However, larvae that hatched from exposed mothers and then were switched to reference sediment had significantly lower growth, lower RNA:DNA ratios, and were smaller despite being large at hatch size, indicating that there are fitness trade-offs in exchange for apparent resistance to contaminants which are provided by the mother. Maternal effects add complexity to ecotoxicological research and should be incorporated into studies to predict population level responses more realistically.