Effects of polluted seawater on oxidative stress, mortality, and reproductive parameters in the marine rotifer Brachionus koreanus and the marine copepod Tigriopus japonicus

Although many efforts have been made to understand the toxic effects of metals in aquatic invertebrates, there are limited data regarding metal toxicity in natural ecosystems, as most previous studies were conducted under controlled laboratory conditions. To address this data gap, we analyzed toxic effects and molecular responses in the marine rotifer Brachionus koreanus and the marine copepod Tigriopus japonicus following in vivo exposure to a seawater sample collected from a polluted region in South Korea. Inductively coupled plasma-mass spectrometry (ICP-MS) analysis of the field seawater sample found a variety of metals. Exposure to several dilutions of the field seawater sample impacted several endpoints in both species, including mortality and reproduction. Interestingly, the rotifer and copepod test species exhibited different patterns of effects on reactive oxygen species (ROS) and antioxidant enzymatic activities, suggesting that different regulatory mechanisms may be activated in the two species in response to exposure to toxic chemicals. Our study helps to better understand the defense mechanisms activated in aquatic invertebrates in response to metal-induced oxidative stress induced by contaminated seawater.