Teratogenic Effects of Larval Low-Salinity Experience in Development of the Juvenile Body in Acanthaster sp

AbstractMetamorphosis appears to be a particularly sensitive stage in marine invertebrate development, with potential carryover effects of larval experience on the postlarval stage. We investigated the impact of salinity exposure history (22‰-34‰) for 2-4 days on the ability of competent crown-of-thorns sea star (Acanthaster sp.; CoTS) brachiolaria larvae to form a normal five-armed juvenile. The decreased salinity levels used were commensurate with levels that these larvae may encounter in their habitat on the Great Barrier Reef (25‰-34‰), and the extreme low level (22‰) was used to assess salinity tolerance. At metamorphosis, low-salinity stress (<34‰) for a few days prior to settlement-as may be experienced by larvae during a runoff pulse-resulted in negative carryover effects, even when the larvae were placed in control salinity during settlement assays. A larval experience of ≤30‰ resulted in smaller juveniles. The low-salinity treatment (22‰) resulted in a large proportion of juveniles deviating from the normal five-armed profile of newly metamorphosed CoTS. Juvenile mortality was high if they were generated from larvae exposed to 22‰ and 25‰ salinity levels. Our findings highlight the importance of ecological developmental biology in understanding potential carryover effects beyond metamorphosis. These insights could help link the exposure of CoTS larvae to terrestrial runoff conditions with juvenile performance and the postmetamorphic processes that influence recruitment into the adult population.