Combined Effects of Hypoxia and Crude Oil on the Invasive Comb Jelly <i>Mnemiopsis leidyi</i>

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 <i>Mnemiopsis leidyi</i>, focusing on key life history traits (e.g., reproduction and survival) and functional traits such as prey ingestion. We experimentally found that <i>M. leidyi</i> 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. <i>M. leidyi</i>'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.