Enhancing Recovery
The following recommended actions contain direct management interventions that may be controversial in some cases, because they require manipulation of natural systems. Managers should use their own judgment in deciding what they can and cannot do, as guided by their organizational policies.
Bleaching damage can severely alter the ecosystem balance; an overabundance of predators and competitors can impair recruitment. Therefore, physical removal or relocation of predators and competitors may be needed in some situations.
To counteract these impacts:
- Conduct regular surveys for coral predators such as predatory mollusks (e.g., Drupella) and echinoderms (e.g., crown-of-thorns starfish, Acanthaster). Remove these on sight from the strictly protected bleaching-resistant zones and adjacent managed susceptible areas.
- Implement regular surveys of sea urchins, such as Diadema, which can occur in large infestations and inhibit growth of coral recruits.
- Control harvest of herbivorous fishes in recovery sites, to enable them to graze on algae that overgrow, and exclude coral recruits from establishing themselves.
- To help keep algal biomass low, consider either direct restocking or natural replenishment of areas with the naturally occurring suite of grazing invertebrates and fishes.
- Mechanically reduce macro-algal mats that inhibit coral settlement, survival or growth.
After a bleaching event, outbreaks of crown-of-thorns starfish can impair recruitment and recovery. To ehance recovery of the ecosystem, direct removal of the predators may be necessary. Photo © S. Kilarski/TNC
Resources
Acanthaster Removal Project in Thailand
Great Barrier Reef MPA Response to Acanthaster
Hawaii DLNR press release on the use of native collector urchins
Baby Sea Urchins Released In Kaneohe Bay
Sea urchins the perfect janitors to keep Kaneohe coral clean