Water temperature influences holothurian bioturbation and benthic habitat with special reference to the impact of ocean warming.

Sea cucumbers, as ecosystem engineers, effectively clear nutrient accumulation in sediments, thus alleviating ecological pressure imposed on marine environments by the large-scale aquaculture industry. However, water temperature continues to increase because of increased carbon dioxide emissions, affecting the physiological and behavior state of sea cucumbers. Moreover, limited research exists on sea cucumber at varying temperatures. In this study, we evaluated the temperature-dependent effects of the temperate sea cucumber Apostichopus japonicus (Selenka) on sedimentary physicochemical characteristics across the temperature gradients (10-30 °C). Results indicated that A. japonicus exhibited optimal growth and bioturbation activity at 10-15 °C, significantly reducing bacterial abundance, chlorophyll a, and nutrient concentrations (OM, TOC, TC, TN) in sediments, while improving sediment oxidation-reduction potential. In contrast, higher temperatures (25-30 °C) suppressed sea cucumber performance and weakened their impact on sediment quality. These findings underscore the importance of maintaining optimal temperature regimes for the effective use of A. japonicus in sustainable management of aquaculture systems. Given that ocean temperatures are projected to increase in intensity and duration, sea cucumbers may help to mitigate nutrient accumulation and promote redox states in sediments, and potentially improving the stability of sedimentary environments against the backdrop of ocean warming.