Promoting the use of low-density fishing nets could enhance corals' chances of survival

Coral reefs are crucial to marine ecosystems. However, as human activities intensify, Abandoned fishing nets (AFNs), a major form of marine debris, pose a significant threat to coral reef ecosystems. This study explored how different AFNs densities affected the growth, physiological characteristics, and microbial communities of Acropora hyacinthus and Acropora microphthalma in coral nurseries. The results demonstrated that both coral species exhibited some adaptability under low-density AFNs. Additionally, A. microphthalma, which can grow upwards, appeared more adaptable to AFNs stress across different densities. High-density AFNs significantly hindered coral growth, primarily due to reduced energy availability, as well as a decrease in photosynthetic physiological indicators resulting from shading and intense competition between algae and corals. Moreover, high-density AFNs stress altered the microbial community structure of the corals. In A. hyacinthus, the dominant microbial group Endozicomonas decreased significantly under net stress, suggesting that high-density AFNs stress may have disrupted the microbial community balance in corals. During recovery monitoring after the removal of AFNs, both coral species in the low-density AFNs group recovered more quickly in terms of physiological status and microbial communities. In contrast, A. hyacinthus in the high-density AFNs group recovered slowly, reflecting the lasting impact of high-density AFNs stress. We believe that promoting the use of low-density fishing nets and regular net removal in coral reef areas is an effective joint management strategy. Additionally, reducing net density to strike a new balance between commercial fisheries and ecological protection is highly feasible, providing preliminary insights for the development of future coral reef conservation and restoration strategies.