ABSTRACT

Global warming and heavy metals have become the major threat to the growth and reproduction of corals.However, unlikescleractiniancorals, in the context of widespread coral degradation worldwide, there are fewreports on the response ofoctocoralliacorals to high-temperature stress and heavy metals. In the present study,we conducted indoor simulation experiments usingJunceellasquamata. We evaluated the physiological responseof these corals under high-temperature stress at 33 ◦C and cadmium (Cd) stress by comparing the compositionand diversity of their symbiotic bacteria and analyzing differences in their transcriptome. The results show thathigh-temperature stress has more severe adverse effects than cadmium stress. High-temperature stress disruptscoral symbiotic relationships, leading to an increase in alpha diversity associated with disease-causing bacteria,which may increase the risk of infection and potentially contribute to coral mortality. Meanwhile, cadmiumstress increases the instability of the coralholobiont, potentially disrupting DNA stability and RNA transcriptionalregulation. However, an increase in Cd-tolerant bacteria may help corals respond to cadmium stress. Thisstudy reveals the effects of harmful substances on coral and highlights the urgent need for action to protectoctocorals in the face of environmental stress.