Multiple-stressor effects of ocean warming, acidification and hypoxia on the locomotor behavior of sea cucumber Apostichopus japonicus

Abstract

<p>Driven by human activities, global climate change is causing unprecedented changes in marine ecosystems, such as ocean warming, ocean acidification and hypoxia. These stressors, which often occur simultaneously and interact with each other, have significant negative impacts on marine organisms and ecosystems, and are referred to as the “deadly trio”. Understanding how these environmental stressors affect marine organisms is critical, particularly concerning their behavior and survival. Locomotion behavior, an essential aspect of an organism's ability to find food, evade predators, and reproduce, can be significantly disrupted by environmental changes. The sea cucumber (<em>Apostichopus japonicus</em>), an IUCN-listed endangered species further threatened by climate change, serves as a crucial model organism for studying these effects. This study investigates the impact of combined stressors—ocean warming, acidification and hypoxia on the locomotion behavior of <em>A. japonicus</em> under future ocean scenarios. Cumulative movement distance, cumulative movement time, mean velocity, and maximum velocity of sea cucumbers were measured. The results show that the synergetic interaction of environmental stressors alters locomotor behavior of <em>A. japonicus</em>, increasing movement activity with more erratic patterns. Specifically, compared to the control group (NC), the combined stress group (WAH) showed an increase in cumulative movement time from 79.06 % to 93.40 % (<em>P</em> < 0.05), an increase in cumulative movement distance from 2722.11 cm to 5700.09 cm (<em>P</em> < 0.01), and an increase in mean velocity from 4.63 cm/s to 9.50 cm/s (P < 0.05). These findings indicate that combined stressors significantly affect the locomotion behavior of <em>A. japonicus</em>, providing new insights into its behavioral phenotypic adjustments or responses to environmental stress. This study emphasizes the importance of understanding the impacts of multiple-factor stressors on marine organisms to better predict and mitigate the effects of global climate change.</p>