Herbivore biocontrol and manual removal successfully reduce invasive macroalgae on coral reefs
- Published
- Accepted
- 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.
- 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. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Herbivore biocontrol and manual removal successfully reduce invasive macroalgae on coral reefs. PeerJ Preprints 6:e26796v1 https://doi.org/10.7287/peerj.preprints.26796v1
Abstract
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. 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. However, invasive macroalgae control techniques are limited and few successful large-scale applications exist. 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”). Second, hatchery-raised juvenile sea urchins (Tripneustes gratilla), were outplanted to graze and control invasive macroalgae regrowth. 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. 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 m2 of reef area. Changes in benthic cover were monitored over two years (five sampling periods) before-and-after the treatment was applied. Over the study period, removal and biocontrol reduced invasive macroalgae cover by 85 % at treatment reefs. Our results show that manual removal in combination with hatchery raised urchin biocontrol is an effective management approach for controlling invasive macroalgae at reef-wide spatial scales and temporal scales of months to years.
Author Comment
This is a submission to PeerJ for review.