Multibiomarker Responses to Polycyclic Aromatic Hydrocarbons and Microplastics in Thumbprint Emperor Lethrinus Harak from a South Pacific Locally Managed Marine Area

Abstract

To determine the baseline threat of microplastics and polycyclic aromatic hydrocarbons (PAHs) in an important seafood fish from Vueti Navakavu LMMA, a multibiomarker risk assessment was conducted on the thumbprint emperor fish. K-factor was significantly lower in samples from the wet season compared to the dry season but no significant differences were observed for HSI between seasonal groups. PAHs levels of four metabolites in emperor fish from Fiji waters is reported here for the first time; seasonal groups showed no significant differences, but all samples presented levels of biliary PAHs. The specimens also contained at least one microplastic in its gastrointestinal system; fibres were the predominant form-type and ingestion levels showed that more than 80 % of fragment sizes were below 1.0 mm. Biochemical responses were observed for EROD and GST biotransformation activity, oxidative stress (GPX and GR activity; LPO concentration) and genotoxicity (micronuclei assay). Though there were no statistically significant differences found, there were biological significances that were important to note; relatively low levels of pollutant exposure showed low levels of biochemical responses as well, and enzymes response were as expected to their roles in the body. This reflects that a multibiomarker approach can be helpful to monitor future trends of pollution levels, and help improve or strengthen the efforts of existing conservation mechanisms such as LMMAs. Coastal communities consume 0.55 kgs more seafood fishes annually in the world, so their livelihood security and health safety should be paramount in our efforts to curb the issue. We recommend adopting new techniques, like biomonitoring, to improve the conservation mechanisms and systems in place.