Combined Effects of Hypoxia and Crude Oil on the Invasive Comb Jelly Mnemiopsis leidyi

Coastal ecosystems are subject to multiple anthropogenic stressors, including hypoxia and crude oil pollution. This study examines the individual and combined effects of varying oxygen levels (1%, 10%, and 100% O₂ sat.) and crude oil (1 μL L^-1) on the invasive comb jelly Mnemiopsis leidyi, focusing on key life history traits (e.g., reproduction and survival) and functional traits such as prey ingestion. We experimentally found that M. leidyi exhibits remarkable tolerance to both hypoxia and crude oil. Feeding rates remained mostly unaffected across all treatments, while egg production rate increased under both low oxygen and oil exposure, suggesting a stress-induced reproductive response. Hatching success was significantly reduced only under severe hypoxia (<1% O₂ sat.) and in combination with oil exposure, illustrating detrimental effects on embryonic development. Larval survival was reduced by 67% when exposed to both severe hypoxia and crude oil for 4 days, highlighting a synergistic negative impact under extreme conditions. M. leidyi's high tolerance to multiple stressors enhances its invasive potential, exacerbating the species' adverse impact on ecological dynamics in coastal regions experiencing escalating environmental degradation.