Coral cover remains suppressed three years after derelict net removal in a remote shallow water coral reef ecosystem.

The uninhabited Northwestern Hawaiian Islands (NWHI) contain 70 % of the shallow water coral reefs in the United States. An estimated 52 metric tons of derelict fishing nets accumulate here annually, becoming entangled in the reef structure and reducing coral cover. Here, we investigated the longevity of derelict net impacts on coral reef communities three years after net removal at Pearl and Hermes Atoll. Structure-from-Motion technology was used to resurvey net impact and control sites to determine whether coral cover rebounded at impact sites over time. Our results showed significantly lower coral cover at impact sites. Much of the bare substrate immediately exposed after net removal was also colonized by algae —not reef calcifiers. Continued monitoring of these sites will add clarity to the lasting nature of derelict nets on reefs, and supplementing net removal efforts with active restoration activities may assist in restoring the ecosystem function of impacted sites faster. • Benthic impacts of derelict nets persist on reefs three years after net removal • Coral cover reduced at net impacted sites compared to controls • Bare substrate after removal colonized by algae over time—not by reef calcifiers • Continued monitoring needed to determine lasting nature of derelict nets on reefs • Supplement net removal effort with restoration to restore ecosystem function faster [ABSTRACT FROM AUTHOR]