Immune responses of sea cucumber (Apostichopus japonicus) to combined environmental stress from high temperature and oil pollution

Abstract

Context High temperature and oil pollution are typical examples of environmental stress to sea cucumber (Apostichopus japonicus) in northern China. Aims Evaluate the combined effects of high temperature and oil pollution on the immune responses of sea cucumbers. Methods In this study, we investigated the immune responses in the respiratory tree of sea cucumber subjected to the optimal temperature (16°C), high temperature (26°C), Oman crude oil (OCO) water-accommodated fractions (WAF) at 16°C (WAF + 16°C) and OCO WAF at 26°C (WAF + 26°C) for 48 h. Key results All three treatments significantly up-regulated total antioxidant capacity and disturbed active oxygen species homeostasis in sea cucumbers. Moreover, all three treatments caused immune-enzyme activity disorders, manifested by a significant increase in acid–alkaline phosphatase and nitric oxide synthase activities and a noticeable decline in lysozyme activity. Conclusions Combining the integrated biomarker-response index (WAF + 26°C > 26°C > WAF + 16°C), the combined stress could result in a more adverse effect on the immune responses of sea cucumbers than do high temperature or oil pollution alone, which might further exacerbate the health challenges for sea cucumbers in response to environmental stress. Implications This study has provided an insight into the immune impacts in benthic organisms caused by high temperature and oil pollution.