First paper from Antony’s PhD is now available – Importance of sperm density in assessing the toxicity of metals to the fertilization of broadcast spawners. In the paper Antony shows that the way many ecotoxicology tests are done can lead to underestimation of toxicity – it depends on a) whether the action of the toxicant affects sperm function and/or interactions and fertilisation with eggs and, if so, b) whether the tests are then run at (greater) sperm densities to ensure high fertilisation rates in controls (which is typical in most fertilisation/spermiotoxicity protocols). Using a model broadcast spawning species (the intertidal Serpulid worm Galeolaria caespitosa), Antony showed that for metals such as copper and zinc – which affect sperm/fertilisation (rather than egg or larval viability) – the sperm density used in experiments can make several orders of magnitude difference to derived measures of toxicity such as EC50s. The results have implications for the way many ecotoxicology assays are developed and illustrates why much more complex experiments are really needed to estimate how a toxicant might affect processes such as broadcast spawning and external fertilisation. Moreover, even if more complicated fertilisation assays like the ones in the paper can’t be done routinely, at least some are needed during pilot work in order to be able to set appropriate sperm densities for the experiment. Co-authors on the paper are CAS and Monique Binet from CSIRO.