Changes in benthic cover were monitored over 2 years (five sampling periods) before-and-after the treatment was applied.
In applying the invasive macroalgae treatment, the control effort manually removed ∼19,000 kg of invasive macroalgae and ∼99,000 juvenile sea urchins were outplanted across to two patch reefs, totaling ∼24,000 m 2 of reef area.
To test the effectiveness of this approach in a natural reef ecosystem, four discrete patch reefs with high invasive macroalgae cover (15–26%) were selected, and macroalgae removal plus urchin biocontrol (treatment reefs, n = 2), or no treatment (control reefs, n = 2), was applied at the patch reef-scale. Second, hatchery-raised juvenile sea urchins ( Tripneustes gratilla), were outplanted to graze and control invasive macroalgae regrowth. Therefore, a two-tiered invasive macroalgae control approach was designed, where first, divers manually remove invasive macroalgae ( Eucheuma and Kappaphycus) aided by an underwater vacuum system (“The Super Sucker”). Invasive macroalgae control techniques, however, are limited and few successful large-scale applications exist. Several invasive macroalgae ( Eucheuma clade E, Kappaphycus clade A and B, Gracilaria salicornia, and Acanthophora spicifera) are established within Kāne‘ohe Bay (O‘ahu, Hawai‘i, USA), and reducing invasive macroalgae cover is a coral reef conservation and management priority. Invasive macroalgae pose a serious threat to coral reef biodiversity by monopolizing reef habitats, competing with native species, and directly overgrowing, and smothering reef corals.
Herbivore biocontrol and manual removal successfully reduce invasive macroalgae on coral reefs.
Cite this article Neilson BJ, Wall CB, Mancini FT, Gewecke CA. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. Licence This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. 2 Hawai‘i Institute of Marine Biology, University of Hawai‘i at Mānoa, Kāne‘ohe, Hawai‘i, United States of America DOI 10.7717/peerj.5332 Published Accepted Received Academic Editor James Reimer Subject Areas Conservation Biology, Ecology, Marine Biology, Zoology, Natural Resource Management Keywords Invasive species, Biocontrol, Macroalgae, Kaneohe bay, Kappaphycus, Eucheuma, Tripneustes, Gracilaria, Acanthophora, Coral reef Copyright © 2018 Neilson et al.