Sea urchin reproductive performance in a changing ocean: poor males improve while good males worsen in response to ocean acidification.

Ocean acidification (OA) is predicted to be a major driver of ocean biodiversity change. At projected rates of change, sensitive marine taxa may not have time to adapt. Their persistence may depend on pre-existing inter-individual variability. We investigated individual male reproductive performance under present-day and OA conditions using two representative broadcast spawners, the sea urchins Lytechinus pictus and Heliocidaris erythrogramma. Under the non-competitive individual ejaculate scenario, we examined sperm functional parameters (e.g. swimming speed, motility) and their relationship with fertilization success under current and near-future OA conditions. Significant inter-individual differences in almost every parameter measured were identified. Importantly, we observed strong inverse relationships between individual fertilization success rate under current conditions and change in fertilization success under OA. Individuals with a high fertilization success under current conditions had reduced fertilization under OA, while individuals with a low fertilization success under current conditions improved. Change in fertilization success ranged from -67% to +114% across individuals. Our results demonstrate that while average population fertilization rates remain similar under OA and present-day conditions, the contribution by different males to the population significantly shifts, with implications for how selection will operate in a future ocean.

Fluoxetine Exhibits Pharmacological Effects and Trait-Based Sensitivity in a Marine Worm.

Global production of pharmacologically active compounds exceeds 100 000 tons annually, a proportion of which enters aquatic environments through patient use, improper medicine disposal, and production. These compounds are designed to have mode-of-action (MoA) effects on specific biological pathways, with potential to impact nontarget species. Here, we used MoA and trait-based approaches to quantify uptake and biological effects of fluoxetine, a selective serotonin reuptake inhibitor, in filter and deposit feeding marine worms (Hediste diversicolor). Worms exposed to 10 µg L(-1), accumulated fluoxetine with a body burden over 270 times greater than exposure concentrations, resulting in ∼10% increased coelomic fluid serotonin, a pharmacological effect. Observed effects included weight loss (up to 2% at 500 µg L(-1)), decreased feeding rate (68% at 500 µg L(-1)), and altered metabolism (oxygen consumption, ammonia excretion, and O/N from 10 µg L(-1)). Bioconcentration of fluoxetine was dependent on route of uptake, with filter feeding worms experiencing up to 130 times greater body burden ratios and increased magnitudes of effects than deposit feeders, a trait-based sensitivity likely as a consequence of fluoxetine partitioning to sediment. This study highlights how novel approaches such as MoA and trait-based methods can supplement environmental risk assessments of pharmaceuticals.