Reliably estimating the effect of toxicants on fertilization success in marine broadcast spawners

Recently, there has been a dramatic increase in the number of ecotoxicological studies examining the effects of toxicants on fertilization success in marine broadcast spawners and it appears that this life-history stage is one of the most vulnerable to toxicants. Most of the studies examining this issue use single sperm concentrations in their assays. Here, I discuss recent advances in fertilization ecology that suggest this technique has some severe limitations resulting in unreliable estimations of the size and direction of toxicant effects. I present an alternative assay technique and two metrics (Fmax and [Sperm]max) that will reliably estimate the size of a toxicant’s effect on fertilization success. This technique has the added advantage of making comparisons among species and studies easier without an impractical increase in effort.