The lesser sandeel (Ammodytes marinus) is a vital forage species in the North Sea, supporting numerous seabird, fish, and marine mammal populations. Its life cycle is characterized by benthic dwelling during juvenile and adult stages and a pelagic larval stage, which makes it especially sensitive to environmental disturbances. This study investigated the sublethal effects of crude oil exposure on early-stage lesser sandeel larvae (2 days post hatch), with a focus on developmental morphology, cardiac function, pigmentation, gene expression, and lipid content. Larvae were exposed to environmentally relevant concentrations of oil (15-99 µg total hydrocarbon (THC)/L) from 2 to 16 days post-hatch. Even at the lowest concentration (15 µg/L), larvae exhibited significant morphological abnormalities in jaw structures. Cardiac assessments revealed bradycardia, atrioventricular block, and silent ventricles in exposed groups, indicating impaired cardiac function. Fatty acid profiling of dissected tissues revealed altered lipid content in the eyes, which may result in visual development impairments. These findings suggest that even minimal oil concentrations can cause functional and developmental impairments in lesser sandeel larvae, potentially reducing survival during this critical life stage. Given the species' ecological importance and population declines, these results underscore the need for species- and stage-specific risk assessments in environmental management and conservation strategies.
Sørhus et al. (Thu,) studied this question.