The aim of ecological restoration is to establish self-sustaining and resilient systems. In coral reef restoration, transplantation of nursery-grown corals is seen as a potential method to mitigate reef degradation and enhance recovery. The transplanted reef should be capable of recruiting new juvenile corals to ensure long-term resilience. Here, we quantified how coral transplantation influenced natural coral recruitment at a large-scale coral reef restoration site in Seychelles, Indian Ocean. Between November 2011 and June 2014 a total of 24,431 nursery-grown coral colonies from 10 different coral species were transplanted in 5,225 m 2 (0.52 ha) of degraded reef at the no-take marine reserve of Cousin Island Special Reserve in an attempt to assist in natural reef recovery. We present the results of research and monitoring conducted before and after coral transplantation to evaluate the positive effect that the project had on coral recruitment and reef recovery at the restored site. We quantified the density of coral recruits (spat <1 cm) and juveniles (colonies 1-5 cm) at the transplanted site, a degraded control site and a healthy control site at the marine reserve. We used ceramic tiles to estimate coral settlement and visual surveys with 1 m 2 quadrats to estimate coral recruitment. Six months after tile deployment, total spat density at the transplanted site (123.4 ± 13.3 spat m -2 ) was 1.8 times higher than at healthy site (68.4 ± 7.8 spat m -2 ) and 1.6 times higher than at degraded site (78.2 ± 7.17 spat m -2 ). Two years after first transplantation, the total recruit density was highest at healthy site (4.8 ± 0.4 recruits m RESEARCH ARTICLE Launched to accelerate biodiversity conservation A peer-reviewed open-access journalPhanor Hernando Montoya-Maya et al. / Nature Conservation 16: 1-17 (2016) 2 have a positive influence on coral recruitment and juveniles. The effect of key project techniques on the results are discussed. This study supports the application of large-scale, science-based coral reef restoration projects with at least a 3-year time scale to assist the recovery of damaged reefs.

Small island states receive unprecedented amounts of the world’s plastic waste. In March 2019, we removed as much plastic litter as possible from Aldabra Atoll, a remote UNESCO World Heritage Site, and estimated the money and effort required to remove the remaining debris. We removed 25 tonnes at a cost of $224,537, which equates to around $10,000 per day of clean-up operations or $8,900 per tonne of litter. We estimate that 513 tonnes (95% CI 212–814) remains on Aldabra, the largest accumulation reported for any single island. We calculate that removing it will cost approximately $4.68 million and require 18,000 person-hours of labour. By weight, the composition is dominated by litter from the regional fishing industry (83%) and flip-flops from further afield (7%). Given the serious detrimental effects of plastic litter on marine ecosystems, we conclude that clean-up efforts are a vital management action for islands like Aldabra, despite the high financial cost and should be integrated alongside policies directed at ‘turning off the tap’. We recommend that international funding be made available for such efforts, especially considering the transboundary nature of both the marine plastic litter problem and the ecosystem services provided by biodiversity-rich islands.

Green turtles Chelonia mydas have been subject to high levels of anthropogenic exploitation, with harvesting at their nesting sites especially pronounced throughout the late 19th and early 20th centuries, leading to worldwide declines. Due to their delayed sexual maturity, long-term protection and monitoring is crucial to allow and accurately demonstrate population recovery. Subsequent to their exploitation, Aldabra Atoll (Republic of Seychelles) has offered the longest continuous protection for nesting green turtles anywhere in the Western Indian Ocean, beginning in 1968. Here, we document the continuing recovery of that population by estimating clutch production within 12 mo nesting seasons over 50 yr of monitoring. An estimated mean of 15297 clutches were laid annually between December 2014 and November 2019. This represents an increase of 173% since Aldabra’s intensive monitoring programme was initiated in 1980, and 410-�665% since 1968. Clutch number increases were recorded at all but 1 of 6 monitored beach groups around the atoll but were most pronounced at Settlement Beach, where exploitation of nesting females was historically most intense. Seasonality data since 2000 showed a year-round nesting season, with elevated activity in April-June peaking on average in May, and a potential shift to later in the year over time. This study highlights the considerable contribution of Aldabra Atoll to regional green turtle numbers and the benefit of long-term protection and monitoring at what can be considered a global reference site for this species.

No abstract

The failure to meet global biodiversity targets clearly indicates the need for biodiversity management and conservation efforts to be more effective, and this in turn requires better understanding of the current barriers to success. Islands are known as biodiversity hotspots but nowhere has biodiversity loss been so acute as in island ecosystems. To identify the barriers to effective island ecosystem conservation, we conducted 32 semistructured interviews with conservation and management practitioners from island nations in the Western Indian Ocean region. Practitioners described 33 barriers to meeting their objectives under 12 overarching topics and suggested 14 solutions to these. Most barriers described by interviewees existed at organization level (55%), followed by national (24%) and site/project level (21%). Of the 33 barriers described by practitioners, the most commonly associated cause was limited capacity (23.5%), followed by lack of government coordination and limited resources (both 21.6%), lack of incentives (11.8%), poor leadership (11.7%), and finally interpersonal issues interfering with progress (9.8%). Most solutions centered around bridging capacity gaps. By defining these barriers, we can bring them forward for discussion and allocate resources and efforts to bridging them. Only by doing so can we increase the effectiveness of our management efforts and maximize our chances of achieving global biodiversity targets.

SummaryThe once ‘Critically Endangered’ Seychelles Magpie-robin was down to just 12 individuals in 1960 on one island of the granitic Seychelles. In 2015, due to intensive long-term management the population stands at around 280 birds on five islands, marking a significant success for this species. Translocations to the islands of Cousin and Cousine have led to population saturation and stability, a translocation to Denis Island has resulted in a continuing population increase and the founder population on Frégate Island is likewise increasing. The latest translocation to Aride Island in 2002 resulted in population increase then stability but is now showing a steep decline throughout 2014 into 2015. Reasons for this decline are yet unknown though disease, lack of recruitment, the impacts of social conflict and the possibility of genetic issues are discussed. This report summarises the history of management for this species, compiling all available published and unpublished information, to provide a comprehensive account of the Seychelles Magpie-robin recovery.

Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world’s coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming’s widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems.

Around the world, declines in the mean size of nesting sea turtles have been reported with concerns of a concomitant decrease in the reproductive output of populations. Here, we explore this possibility using long-term observations of green turtles (Chelonia mydas) at Aldabra Atoll, Seychelles. Based on > 4500 individual measurements over 21 years (1996–2016), we found the curved carapace length of nesting females declined by about 0.64 cm per decade, from 111.43 to 110.08 cm. For 391 individuals that were measured more than once with measurement interval of 2.8–19 years apart, the mean growth rate was 0.14 cm year−1. Comparisons between the size of adult females and males were based on 23 and 14 weight measurements, 107 and 33 carapace length measurements and 103 and 33 carapace width measurements, respectively, taken during 1981–1983. Adult females were larger than males, with the sexual dimorphism index, i.e. the ratio of size of the larger sex to the smaller, being 1.09 and 1.10 for carapace length and width, respectively, and 1.25 for weight. Smaller females tended to lay fewer eggs per clutch but the decrease in female mean size was accompanied by increases in numbers of turtles nesting annually, such that the estimated total numbers of eggs per year increased from 1.3 million to 2.0 million between 1996 and 2016. Therefore, a decrease in mean size of nesting females has not compromised egg production for this population.