Effects of crude oil on juvenile threespine stickleback somatic and immune development

Aquatic oil spills have resounding effects on surrounding ecosystems, and thus significant resources are committed to oil spill responses to remove the oil from the environment as quickly as possible. Oil has immunotoxic effects and may be particularly harmful to larval and juvenile fish as it can cause a number of developmental defects and stunt growth. In spite of significant efforts to clean oil, it is unclear whether larval and juvenile fish can recover from the effects of oil and no work has been done on the effect crude oil has on developing threespine stickleback (Gasterosteus aculeatus) fish. Threespine stickleback are a ubiquitous sentinel species in the northern hemisphere and are an important food source for many larger, economically valuable fish. As fish with fully marine, anadromous, and freshwater populations, stickleback are exposed to oil in a variety of aquatic environments. We hypothesized that oil exposure would suppress both growth and immunity of developing stickleback, but that fish health could be recovered by removal of the crude oil. Fish were exposed to Alaska North Slope crude oil and then were moved to water without crude oil for two weeks (depuration). Measurements of growth and immunity were taken before and after the depuration. We found that crude oil effected different developmental pathways independently, significantly impacting some but not others. This is the first study to examine the effect crude oil has on early stages of stickleback development, and that stickleback fish are unable to recover from exposure after being transferred to clean water for two-weeks, suggesting larval/juvenile stickleback exposed to crude oil need longer than two-weeks to recover if they are able to recover at all.