Effects of UV radiation on hatching, lipid peroxidation, and fatty acid composition in the copepod Paracyclopina nana Eun-Ji Won a , Yeonjung Lee b , Jeonghoon Han a , Un-Ki Hwang c , Kyung-Hoon Shin b , Heum Gi Park d, ⁎, Jae-Seong Lee a, ⁎ a Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea b Department of Marine Sciences and Convergent Technology, College of Science and Technology, Hanyang University, Ansan 426-791, South Korea c Marine Ecological Risk Assessment Center, West Sea Fisheries Research Institute, National Fisheries Research & Development Institute, Incheon 400-420, South Korea d Department of Marine Resource Development, College of Life Sciences, Gangneung-Wonju National University, Gangneung 210-702, South Korea abstract article info Article history: Received 12 March 2014 Received in revised form 26 May 2014 Accepted 10 June 2014 Available online 18 June 2014 Keywords: UV-B Oxidative stress Lipid peroxidation Fatty acid composition Copepod Paracyclopina nana To evaluate the effects of UV radiation on the reproductive physiology and macromolecules in marine zooplank- ton, several doses of UV radiation were used to treat the copepod Paracyclopina nana, and we analyzed in vivo endpoints of their life cycle such as mortality and reproductive parameters with in vitro biochemical biomarkers such as reactive oxygen species (ROS), the modulated enzyme activity of glutathione S-transferase (GST) and su- peroxide dismutase (SOD), and the production of a byproduct of peroxidation (e.g. malonedialdehyde, MDA). After UV radiation, the survival rate of P. nana was significantly reduced. Also, egg sac damage and a reduction in the hatching rate of offspring were observed in UV-irradiated ovigerous females. According to the assessed bio- chemical parameters, we found dose-dependent increases in ROS levels and high levels of the lipid peroxidation decomposition product by 2 kJ m -2 , implying that P. nana was under off-balanced status by oxidative stress- mediated cellular damage. Antioxidant enzyme activities of GST and SOD increased over different doses of UV ra- diation. To measure UV-induced lipid peroxidation, we found a slight reduction in the composition of essential fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These findings indicate that UV radiation can induce oxidative stress-triggered lipid peroxidation with modulation of antioxidant enzyme ac- tivity, leading to a significant effect on mortality and reproductive physiology (e.g. fecundity). These results dem- onstrate the involvement of UV radiation on essential fatty acids and its susceptibility to UV radiation in the copepod P. nana compared to other species. © 2014 Elsevier Inc. All rights reserved. 1. Introduction The UV radiation, reaching the earth's surface, significantly influ- ences aquatic ecosystems and triggers a variety of biological effects. The effects of UV radiation on organisms are a specific concern due to stratospheric ozone depletion (Allen et al., 1998; Häder et al., 2011; Mckenzie et al., 2011). To date, several studies have reported that UV ra- diation significantly affects survival, growth, immune system, and re- production in aquatic organisms including fish, sea urchin, and crab (Gouveia et al., 2005; Bonaventura et al., 2006; Sharma et al., 2010). Par- ticularly, in the Arctic environment, several researchers have provided evidence that UV radiation influences physiological conditions, leading to changes in the community composition and distribution of species (Bothwell et al., 1993; Hessen, 2002; Häder, 1994). However, these ef- fects are not limited to Arctic conditions. For example, Zepp (2003) showed that solar radiation is a significant stressor of coral assemblages in tropical and subtropical marine environments. Also, Dahms and Lee (2010) provided a critical review of the effects of UV radiation on ma- rine ectoderms, emphasizing the molecular alterations and physiologi- cal responses. Radiation-mediated oxidative stress, lipid peroxidation, and DNA strand breakage are important contributors to the harmful ef- fects on the marine ecosystem (Dahms and Lee, 2010). UV radiation has several repercussions on the level of molecular alterations to communi- ty changes (Robinson et al., 2005; MacFadyen et al., 2004; Rastogi et al., 2010). In addition, UV radiation generates reactive oxygen species (ROS) and free radicals via photosensitizing agents (Polle et al., 1993). In marine ecosystems, copepods a dominant group of the mesozooplankton community in aquatic ecosystems (Longhurst, 1985), play a key role in the fundamental food web, as copepod's nauplii, copepodites, and adults are the main prey for larvae of ecologically and economically important fish species (Theilacker and Kimball, 1984). For this reason, they affect the community structure of phytoplankton as predators. For example, copepod grazing impacts phytoplankton com- munities (Båmstedt et al., 1992) and copepods directly affect the growth of phytoplankton by sequestering nutrients from the water column (Johnson and Leucke, 2012). Also, copepods are susceptible to diverse xenobiotic factors and have the potential to be a good indicator species Comparative Biochemistry and Physiology, Part C 165 (2014) 60–66 ⁎ Corresponding authors. Tel.: +82 31 290 7011. E-mail addresses: hgpark@gwnu.ac.kr (H.G. Park), jslee2@skku.edu (J.-S. Lee). http://dx.doi.org/10.1016/j.cbpc.2014.06.001 1532-0456/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Comparative Biochemistry and Physiology, Part C journal homepage: www.elsevier.com/locate/cbpc