Impacts of rapid environmental change on the reproduction and fertilisation dynamics of marine invertebrates, using an urchin model

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Human driven environmental forcing is producing broad-scale change in marine ecosystems. The Polar-Regions, which have experienced rapid regional change, house relict faunas adapted to constant temperatures over millennia. These regions provide early warning systems against climate change, and therefore unique opportunities to evaluate the effects of environmental variability on species persistence. Although climate change affects marine organism physiology and behaviour, the impacts of environmental variation on fundamental functions, e.g. reproduction, remain poorly understood. Reproductive success is an evolutionary mechanism that determines species persistence and survival. It is therefore important to understand how reproductive processes respond to environmental change. In broadcast spawners (gametes released and fertilised in the water column, i.e. eggs and sperm), processes determining gamete function and fertilisation-success determine reproductive efficiency. Studies show variation in population and environmental parameters (sperm-dilution, sperm-egg ratio, gamete age and contact time; seawater temperature, salinity and pH) alters gamete function. However, mechanistic knowledge of how these changes impact the resilience of broadcast spawners is lacking. Time-series samples of urchin reproduction collected since 2012 will be used to elucidate how environmental change: (1) has impacted long-term reproductive cycles of the Antarctic sea urchin Sterechinus neumayeri; (2) affects fertilisation-success and population persistence of this circumpolar species.