The severely degraded condition of many coral reefs worldwide calls for active interventions to rehabilitate their physical and biological structure and function, in addition to effective management of fisheries and no-take reserves. Rehabilitation efforts to stabilize reef substratum sufficiently to support coral growth have been limited in size. We documented a large coral reef rehabilitation in Indonesia aiming to restore ecosystem functions by increasing live coral cover on a reef severely damaged by blast fishing and coral mining. The project deployed small, modular, open structures to stabilize rubble and to support transplanted coral fragments. Between 2013 to 2015, approximately 11,000 structures covering 7,000 m 2 were deployed over 2 ha of a reef at a cost of US$174,000. Live coral cover on the structures increased from less than 10% initially to greater than 60% depending on depth, deployment date and location, and disturbances. The mean live coral cover in the rehabilitation area in October 2017 was higher than reported for reefs in many other areas in the Coral Triangle, including marine protected areas, but lower than in the no-take reference reef. At least 42 coral species were observed growing on the structures. Surprisingly, during the massive coral bleaching in other regions during the 2014-2016 El Niño-Southern Oscillation event, bleaching in the rehabilitation area was less than 5% cover despite warm water (≥30 ∘ C). This project demonstrates that coral rehabilitation is achievable over large scales where coral reefs have been severely damaged and are under continuous anthropogenic disturbances in warming waters.

Ecosystem restoration aims to restore biodiversity and valuable functions that have been degraded or lost. The Coral Triangle is a hotspot for marine biodiversity held in its coral reefs, seagrass meadows, and mangrove forests, all of which are in global decline. These coastal ecosystems support valuable fisheries and endangered species, protect shorelines, and are significant carbon stores, functions that have been degraded by coastal development, destructive fishing practices, and climate change. Ecosystem restoration is required to mitigate these damages and losses, but its practice is in its infancy in the region. Here we demonstrate that species diversity can set the trajectory of restoration. In a seagrass restoration experiment in the heart of the Coral Triangle (Sulawesi, Indonesia), plant survival and coverage increased with the number of species transplanted. Our results highlight the positive role biodiversity can play in ecosystem restoration and call for revision of the common restoration practice of establishing a single target species, particularly in regions having high biodiversity. Coastal ecosystems affect human well-being in many important ways, and restoration will become ever more important as conservation efforts cannot keep up with their loss.

Noctiluca scintillans is a bloom-forming heterotrophic dinoflagellate that can ingest (and grow on) a number of phytoplankton prey, including several potentially toxic phytoplankton species. The current study documented (1) a range of N. scintillans growth rates (μ = −0.09 to 0.83 d −1) on several species of harmful dinoflagellates and raphidophytes, including Heterosigma akashiwo and Akashiwo sanguinea, and (2) the first published growth rates on Lingulodinium polyedrum, Chattonella marina, and Alexandrium catenella. N. scintillans attained maximum growth rates (μ = 0.83 d −1) on the raphidophyte H. akashiwo and negative growth rates (i.e. significant mortality) on the dinoflagellates A. catenella (μ = −0.03 d −1) and A. sanguinea (μ = −0.08 d −1) and the raphidophyte C. marina (μ = −0.09 d −1). Toxin production by A. catenella did not appear to be responsible for negative effects on N. scintillans growth, as indicated by feeding experiments using mixed algal assemblages and the addition of high concentrations of purified dissolved saxitoxin (up to 16.73 ng ml −1). However, growth of both N. scintillans and H. akashiwo was negatively affected when exposed to A. catenella culture and cell-free filtrate. These results suggest (1) a species-specific role of N. scintillans in top-down control of toxic bloom-forming dinoflagellates and raphidophytes, (2) direct, though not necessarily saxitoxin-dependent, inhibition of N. scintillans growth by A. catenella, and (3) indirect effects of A. catenella on N. scintillans growth through reduction in the availability of high-quality prey. Together, these results provide insights into the potentially significant role of N. scintillans as a grazer of blooms of these species.

Marine debris is a global environmental problem especially apparent on small islands throughout the world. We implemented an educational outreach program to engage primary and secondary students in the scientific process using the tangible issue of marine debris on a typical small island in Indonesia (Barrang Lompo, Spermonde Islands, South Sulawesi). Over a 3-year period, students conducted systematic sampling of debris on their island's beaches. They quantified the enormity of the debris problem, discussed data, and compared experiences with partner schools in California. The program inspired a unique, local perspective on marine debris that includes greater awareness of human health impacts as well as a need for realistic solutions to this problem faced by small islands.