Reef Recovery Research Articles

Evolutionary History Drives Biogeographic Patterns of Coral Reef Resilience

Abstract Modern-day Indo-Pacific coral reefs are characterized by rapid recovery driven by pulses of coral recruitment, but Caribbean reefs exhibit low rates of recruitment and poor recovery following a wide range of disturbance events. The contrasting evolutionary history of coral taxa offers key insight into biogeographic patterns of coral resilience. Following the closure of the Isthmus of Panama approximately 2.8 million years ago, widespread extinction of Caribbean corals led to an evolutionary bottleneck that favored large and long-lived species with a relatively high reliance on asexual versus sexual reproduction. In contrast, adaptive radiation led to the evolution of superrecruiting tabular, digitate, and corymbose corals that drive the rapid recovery of modern-day Indo-Pacific reefs following disturbance. The dominance of branching growth forms and evolutionary absence of superrecruiting growth forms throughout the entire evolutionary history of the Caribbean (approximately 38 million years ago to present) may explain the exceptionally high recruitment rates on modern-day Indo-Pacific reefs and low historical recruitment on Caribbean reefs. The evolutionary history of the Caribbean coral reef-building taxa implies that, even with a reversal of ecosystem state, widespread recovery of Caribbean reefs may be limited.

Deeper, Larger, More Common: Cryptic Coral Species Podabacia Benefits from Reef Recovery

In 2000 a protected area of 20,000 ha was established in West Sumatra, Indonesia (MPA Pulau Pieh) and the partial reef recovery is well documented. During monitoring of destructed reefs, a new cryptic mushroom coral species, Podabacia kunzmanni, was detected. It is not common, with rather occasional occurrence and most specimens are small. During recent visits in 2018 and 2019, the authors detected numerous specimens, mainly at three locations within the MPA Pulau Pieh, mainly at Pulau Pandan. Most individuals were found in greater depth, down to 18 m, reaching diameters of up to 20 cm. With regard to size, depth distribution and abundance, three new records can be established for this species. There are two potential explanations for finding them mainly on dead reefs: either they are better survivors or they are better colonizers of dead coral substrata. The team is presently collecting more data on the distribution and the reasons behind the sudden rise in visibility.

Herbivorous Crabs Reverse the Seaweed Dilemma on Coral Reefs

Coral reefs are on a steep trajectory of decline, with natural recovery in many areas unlikely.1-3 Eutrophication, overfishing, climate change, and disease have fueled the supremacy of seaweeds on reefs,4,5 particularly in the Caribbean, where many reefs have undergone an ecological phase shift so that seaweeds now dominate previously coral-rich reefs.6-8 Discovery of the powerful grazing capability of the Caribbean's largest herbivorous crab (Maguimithrax spinosissimus)9 led us to test the effectiveness of their grazing on seaweed removal and coral reef recovery in two experiments conducted sequentially at separate locations 15km apart in the Florida Keys (USA). In those experiments, we transplanted crabs onto several patch reefs, leaving others as controls (n= 24 reefs total; each 10-20 m2 in area) and then monitored benthic cover, coral recruitment, and fish community structure on each patch reef for a year. We also compared the effectiveness of crab herbivory to scrubbing reefs by hand to remove algae. Crabs reduced the cover of seaweeds by 50%-80%, resulting in a commensurate 3-5-fold increase in coral recruitment and reef fish community abundance and diversity. Although laborious hand scrubbing of reefs also reduced algal cover, that effect was transitory unless maintained by the addition of herbivorous crabs. With the persistence of Caribbean coral reefs in the balance, our findings demonstrate that large-scale restoration that includes enhancement of invertebrate herbivores can reverse the ecological phase shift on coral reefs away from seaweed dominance.

Cryptic diversity in the macroalgal genus Lobophora (Dictyotales) reveals environmental drivers of algal assemblages

Stress-induced reductions in the world’s coral populations are, in many locations, giving way to an increase in macroalgae, for example the common brown macroalgal genus Lobophora. While many ecological studies report a single species (Lobophora variegata), DNA-based identification methods have recently shown that Lobophora is a highly diverse genus with over 100 reported species. Here, we aim to identify possible ecological differences among Lobophora species by investigating environmental drivers of Lobophora assemblages. We sampled Lobophora thalli from 12 reefs around Palau (Micronesia) at varying depths, wave exposure, and herbivore biomass. Using one mitochondrial marker (cox3) and two chloroplast markers (psbA, rbcL), we uncovered a striking cryptic diversity of 15 species, including 8 undescribed taxa. Associations between potential drivers and Lobophora assemblages varied at two spatial scales. At the larger scale of both island coastlines only a single variable—wave exposure—was found to be important. On a smaller geographic scale, confined to the east coast, all factors—wave exposure, depth and herbivory—were associated with assemblages of Lobophora. Widespread sampling indicates the presence of generalist species, which were found in most sampled habitats, and specialists, which occupy specific habitats. Such high levels of cryptic diversity have important implications for ecological studies. Given that species inhabit different environments, have a variable growth form, and have a threefold difference in thallus thickness, it seems likely that species differ in their function. If these differences manifest in competitive strengths, these results have broad implications for our understanding of coral reef recovery following perturbation.

The effects of rubble mobilisation on coral fragment survival, partial mortality and growth

The sliding and overturning of unconsolidated rubble by hydrodynamic forcing is expected to cause physical damage to settled coral recruits and asexual fragments by scouring and smothering. Yet, few empirical studies have tested the relationship between rubble mobilisation frequency and the survival and growth of these corals. Here, we tested the response of small coral fragments to varying levels of experimental scouring and smothering, proxies for rubble mobilisation impacts, on two coral species with distinct functional traits; Porites rus (robust, encrusting) and Pocillopora verrucosa (sensitive, branching). This study investigated: 1) how coral fragment survival was affected by inversion on rubble or sand substratum over ~2 w (i.e. smothering); and 2) how the survival, growth and tissue properties of fragments were affected by rubble being overturned (i.e. experiencing scouring or abrasion) at different frequencies over ~10 w. Smothering substratum had a profound influence on the probability of fragment survival. For both species, survival was <2% after 5 d when inverted on sand, whereas nearly all survived when inverted on rubble. Following scouring, most P. rus fragments survived over the ~10-w period irrespective of scour frequency. However, P. verrucosa showed high mortality (45% loss) across all treatments, likely influenced by initial handling and fragmentation. For P. rus, increasing scour frequency caused sublethal effects of significantly reduced tissue growth and pigmentation, and increased partial mortality. These findings indicate that small fragments – and potentially recruits – are unlikely to successfully recruit in frequently-mobilised rubble beds regardless of their functional morphotype, but may persist in rubble beds in lower-energy environments. This provides valuable insight into the limitations on coral recovery in rubble beds, which could inform reef recovery programs considering substratum stabilisation. Combined with an understanding of a reef's hydrodynamic environment, this research can assist managers in prioritising damaged reefs for active interventions.

Substrate stabilisation and small structures in coral restoration: State of knowledge, and considerations for management and implementation.

Coral reef ecosystems are under increasing pressure from local and regional stressors and a changing climate. Current management focuses on reducing stressors to allow for natural recovery, but in many areas where coral reefs are damaged, natural recovery can be restricted, delayed or interrupted because of unstable, unconsolidated coral fragments, or rubble. Rubble fields are a natural component of coral reefs, but repeated or high-magnitude disturbances can prevent natural cementation and consolidation processes, so that coral recruits fail to survive. A suite of interventions have been used to target this issue globally, such as using mesh to stabilise rubble, removing the rubble to reveal hard substrate and deploying rocks or other hard substrates over the rubble to facilitate recruit survival. Small, modular structures can be used at multiple scales, with or without attached coral fragments, to create structural complexity and settlement surfaces. However, these can introduce foreign materials to the reef, and a limited understanding of natural recovery processes exists for the potential of this type of active intervention to successfully restore local coral reef structure. This review synthesises available knowledge about the ecological role of coral rubble, natural coral recolonisation and recovery rates and the potential benefits and risks associated with active interventions in this rapidly evolving field. Fundamental knowledge gaps include baseline levels of rubble, the structural complexity of reef habitats in space and time, natural rubble consolidation processes and the risks associated with each intervention method. Any restoration intervention needs to be underpinned by risk assessment, and the decision to repair rubble fields must arise from an understanding of when and where unconsolidated substrate and lack of structure impair natural reef recovery and ecological function. Monitoring is necessary to ascertain the success or failure of the intervention and impacts of potential risks, but there is a strong need to specify desired outcomes, the spatial and temporal context and indicators to be measured. With a focus on the Great Barrier Reef, we synthesise the techniques, successes and failures associated with rubble stabilisation and the use of small structures, review monitoring methods and indicators, and provide recommendations to ensure that we learn from past projects.

Upper Visean (Mississippian) metazoan-microbial reefs from Guangxi, South China: Insights regarding reef recovery after the end-Devonian extinction

The Mississippian was an important interval for metazoan reef recovery after the collapse of stromatoporoid-coral reef ecosystems during the Late Devonian mass extinctions. Based on field observation and quantitative studies of biotic composition in thin sections, four different reef types were identified in the upper Visean strata in the Gandongzi section of Guangxi Province, South China. These are coral reef, coral-microbial-microproblematica-bryozoan reef, coral-microbial-bryozoan reef, and microbial-bryozoan-coral reef. Their positive topographic relief from one metre to ten metres is either directly observed in the section or by correlation to the coeval non-reef facies in the adjacent Longfeng section. These reefs are constructed primarily of different proportion of colonial rugose corals (Diphyphyllum and Siphonodendron), tabulate corals (Multithecopora and Syringopora), cystoporate bryozoans (Fistulipora), and calcimicrobes (e.g., Garwoodia and Renalcis). Reef dwellers are rich and diversified including crinoids, brachiopods, bryozoans, gastropods, heterocorals, calcispheres, green algae, foraminifers, and ostracods. Their composition and abundance vary among the different reef types. Facies analysis reveals a variable composition, including framestone and bindstone in reef facies, and rudstone, grainstone, packstone, dolomitic crinoidal packstone and dolostone in the strata intercalated with reefs. The microbial reef facies is characterized by abundant spar-filled cavities, which can be classified as stromatactis and fenestral fabrics. In the non-reef facies, geopetal structures are abundant. Relative sea-level changes controlled the growth and demise of the Gandongzi reefs. They commonly grew during relative sea-level rise and died during relative sea-level fall, as evident from increasing and decreasing abundance of micrite, and decreasing and increasing abundance of cortoids, green algae and sparry calcite in reefs and their overlying strata, respectively. However, the final demise of the Gandongzi reef succession was triggered by a dramatic relative sea-level rise, indicated by increased micrite abundance associated with articulated and convex-down brachiopod shells overlying the uppermost reef. The Gandongzi reefs resemble coeval similar reef types on other palaeocontinents, in terms of reef-builder composition and internal structures. The important role of corals in the framework building of the Gandongzi reefs coincided with the late Visean coral reef proliferation, which is a major phase for re-establishment of metazoan reef ecosystems after the end-Devonian mass extinction.

Coral Reef Recovery in the Mexican Caribbean after 2005 Mass Coral Mortality—Potential Drivers

In 2005, an extreme heatwave hit the Wider Caribbean, followed by 13 hurricanes (including hurricanes Emily and Wilma) that caused significant loss in hard coral cover. However, the drivers of the potential recovery are yet to be fully understood. Based on recent findings in the literature of coral cover recovery in the Mexican Caribbean after the mass bleaching event and associated hurricanes in 2005, this study analyzed, through random-effects meta-analysis, the hard coral and macroalgae benthic development and potential drivers of change between 2005 and 2016 in the Mexican Caribbean. Therefore, we tested the relative effect of sea surface temperature (SST), chlorophyll-a water concentration, coastal human population development, reef distance to shore, and geographical location on both hard coral and macroalgae cover over time. Findings revealed increases of both hard coral (by 6%) and algae cover (by ca. 14%, i.e., almost three times the increase of corals) over 12 years. Although our findings confirm the partial coral recovery after the 2005 Caribbean mass coral mortality event, they also indicate rapid colonization of algae across the region. Surprisingly, only SST correlated negatively with changes in coral cover. Contrary to expectations, there was a significantly greater algae cover increase in the Central section of the Mexican Caribbean, which is characterized by a low population density. However, a constant discharge of nutrient-rich freshwater may have facilitated algae growth there. This study reports partial regional reef recovery, but it also indicates that local factors, particularly eutrophication, facilitate algae growth at a speed that is much faster than coral recovery.

Community-led management lays the foundation for coral reef recovery in Cambodian marine protected areas

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Thermal stress-related spatiotemporal variations in high-latitude coral reef benthic communities

High-latitude coral reef communities have been postulated as the first areas to undergo reorganisation under climate change. Tropicalisation has been identified in some high-latitude communities and is predicted in others, but it is unclear how the resident benthic taxa are affected. We conducted a long-term (2007–2016) assessment of changes to benthic community cover in relation to thermal stress duration on the Southeast Florida Reef Tract (SEFRT). Thermal stress events, both hot and cold, had acute (thermal stress duration affected benthic cover that year) and chronic (thermal stress duration affected benthic cover the following year) impacts on benthic cover. Chronic heat stress was associated with declines in cover of the reef-building coral families Acroporidae, Montastraeidae, Meandrinidae, Mussidae and Siderastreidae, which coupled with the absence of cold stress and rising annual temperatures boosted macroalgae cover. Cover of smaller, weedy coral families, Poritidae, Agariciidae and Astrocoeniidae, was either unaffected or positively related to heat stress duration and rising mean temperature. Thermal stress was related to spatiotemporal variations in benthic cover on the SEFRT, likely enhanced by local stressors, such as elevated nutrients and sedimentation. Coral and octocoral cover declined within four of six sub-regions, sponge cover increased in half of the sub-regions, and macroalgae cover increased in four sub-regions during the study. Under current conditions, increased macroalgae and weedy coral cover are anticipated to inhibit reef recovery.

Long-term benefits of artificial reef modules for reef recovery in gulf of Mannar, Southeast India

The Gulf of Mannar (GoM) in southeastern India, once well known for its rich coral reefs, has been suffering for a long time from the vagaries of unprecedented threats posed by many natural and human-induced factors. The deployment of low-tech, low-cost artificial reef (AR) modules made of ferro-cement near Vaan Island in GoM helped enhance fishery production and enrich biodiversity. These modules remain strong even at the end of 15 years and continue to provide substrata to a significantly large population of coral colonies. In 2017, the density of the coral colonies attached to the ARs was found to be as high as 25.45 numbers per module (No.module−1). Recruits from 13 genera were observed on the modules, Turbinaria (5.4 No.module−1) and Favites (4.87 No.module−1) being the dominant genera. The modules have attracted the recruits of boulder type corals, which are important for long-term ecological services. Widespread deployment of these modules would aid in reef recovery by providing suitable substrate for coral recruits.

Disparities in Spawning Times Between in situ and ex situ Pillar Corals

Contrasts in spawning time between wild and onshore colonies of the pillar coral Dendrogyra cylindrus were conducted by comparing eight years of wild spawning observations with three years of observations on ex situ corals held in outdoor flow-through tanks. Wild colonies exhibited peak spawning 3 nights after the full moon and 90-96 minutes after sunset. Corals held ex situ peaked on night 4 after the full moon, with females continuing to spawn through night 8. Spawning occurred ~50 minutes later than in wild colonies, and the spawning window, particularly for females, was significantly greater. Fragments held ex situ for as few as 10 days exhibited this shift to later spawning, but corals held for greater than one year also exhibited significantly later spawning than those held less than one year. We propose that the wild colonies in Florida exhibit a historic natural spawning cycle. Lunar and solar cues determine date and time, but deviations in full moon from average dates affect time of sperm release. Comparisons with other spawning locations in the Caribbean suggest that sites closer to shore delay spawning until later in the evening. We propose that artificial light is altering the light spectrum that D. cylindrus colonies use to cue spawning time. Colonies held at onshore outdoor facilities, which are subject to high levels of artificial light, also have delayed and expanded spawning windows. The implications of widespread and increasing light pollution on spawning synchrony identify a potential stressor that could inhibit natural reef recovery.

Large-Scale Sea Urchin Culling Drives the Reduction of Subtidal Barren Grounds in the Mediterranean Sea

Increasing anthropogenic pressures are causing long-lasting regime shifts from high-diversity ecosystems to low-diversity ones. In the Mediterranean Sea, large extensions of rocky subtidal habitats characterized by high diversity have been completely degraded to barren state due to high grazing pressure exerted by sea urchins, which could persist for long time. In several areas of the world, a positive effect of sea urchin removal on the recovery of overexploited subtidal rocky habitats was found. This study assessed, for the first time in the Mediterranean Sea, the effects of extensive sea urchin culling on the recovery of subtidal reefs from the state of barrens. We tested this approach within a Marine Protected Area where a combination of oligotrophic conditions, general depletion of fish stocks, dramatically high sea urchin densities, and the large extension of barren grounds caused by date mussel fishery hampered the natural recovery of shallow rocky reefs. Culling intervention (through hammering) was carried out in spring 2015, covering an area of 1.2 hectares at about 5 m depth. The effects of sea urchin removal were monitored at regular intervals, for a time span of 3 years, and were compared with two control sites adjacent to the culling area. We documented a progressive reduction of the barren grounds in the fully protected area after the intervention. Also, very low re-colonization of sea urchins was observed during the experiment, so that no additional extensive culling was necessary. Our findings suggested sea urchin culling as a promising practice, also considering the limited costs of the intervention. However, since the reduction of barren grounds was largely driven by turf forming algae, caution is needed in the interpretation of the outcomes in terms of restoration, and results are discussed considering the factors involved in the observed shift and the synergies to be carried out for a full recovery of the system.

Impact of Large-Scale Reclamation on Resources and Environment in West Liaodong Bay and Remediation and Restoration Suggestions—A Case Study of Xingcheng Coastal Industrial Area

Based on the case study of reclamation in west Liaodong Bay in Xingcheng City, this paper analyzes the construction background and implementation process of reclamation in the coastal industrial area, and assesses the major resource and environmental issues arising from reclamation. Since the reclamation of Xingcheng Coastal Industrial Area has caused the losses of lagoon coastal wetlands, coastline resources, hydrodynamic environment of islands and reefs and ecology as well as the changes of hydrodynamic and scouring and silting environment in local sea areas. The paper suggests that measures, such as watercourse and coast remediation and restoration, coastal wetland restoration, hydrodynamic recovery of islands and reefs, water system construction, reproduction and release, should be taken to mitigate the adverse impact of reclamation on resources and the environment to a certain extent.

Controls on carbonate platform architecture and reef recovery across the Palaeozoic to Mesozoic transition: A high‐resolution analysis of the Great Bank of Guizhou

AbstractCarbonate platforms spanning intervals of global change provide an opportunity to identify causal links between the evolution of marine environment and depositional architecture. This study investigates the controls on platform geometry across the Palaeozoic to Mesozoic transition and yields new stratigraphic and palaeoenvironmental constraints on the Great Bank of Guizhou, a latest Permian to earliest Late Triassic isolated carbonate platform in the Nanpanjiang Basin of south China. Reconstruction of platform architecture was achieved by integrating field mapping, petrography, biostratigraphy, satellite imagery analysis and δ13C chemostratigraphy. In contrast to previous interpretations, this study indicates that: (i) the Great Bank of Guizhou transitioned during Early Triassic time from a low‐relief bank to a platform with high relief above the basin floor (up to 600 m) and steep slope angles (preserved up to 50°); and (ii) the oldest‐known platform‐margin reef of the Mesozoic Era grew along steep, prograding clinoforms in an outer‐margin to lower‐slope environment. Increasing platform relief during Early Triassic time was caused by limited sediment delivery to the basin margin and a high rate of accommodation creation driven by Indosinian convergence. The steep upper Olenekian (upper Lower Triassic) slope is dominated by well‐cemented grainstone, suggesting that high carbonate saturation states led to syndepositional or rapid post‐depositional sediment stabilization. Latest Spathian reef initiation coincided with global cooling following Early Triassic global warmth. The first Triassic framework‐building metazoans on the Great Bank of Guizhou were small calcareous sponges restricted to deeper water settings, but early Mesozoic reef builders were volumetrically dominated by Tubiphytes, a fossil genus of uncertain taxonomic affinity. In aggregate, the stratigraphic architecture of the Great Bank of Guizhou records sedimentary response to long‐term environmental and biological recovery from the end‐Permian mass extinction, highlighting the close connections among marine chemistry, marine ecosystems and carbonate depositional systems.

Change in fish and benthic communities in Belizean patch reefs in and outside of a marine reserve, across a parrotfish capture ban

The role of a marine reserve and fisheries regulations in restoring fish populations on reefs disturbed by climate impacts was evaluated. Eight patch reefs, divided equally between no-fishing and fished zones in the remote Glover’s Reef atoll lagoon, were studied for 22 yr: 13 yr before and 9 yr after a ban on parrotfish capture. Findings indicate that the main effect of the fisheries closure was the recovery of targeted carnivorous species, notably snappers, jacks, and groupers. Recovery continued for most of the time series, including the later period when parrotfish capture was banned. Parrotfish abundance slowly declined in both management zones and across the ban period. The loss occurred for both small non-fished species, such as the striped parrotfish Scarus iserti, and for larger fished species, such as the stoplight Sparisoma viride and red-band parrotfish Sparisoma aurofrenatum. Consequently, parrotfish abundance appeared to be controlled by the ecology of these patch reefs rather than fishing mortality. We suggest that the high and persistent cover of late-successional algae reduces the renewal rates of algae, which had negative consequences for all studied parrotfish populations. Low ocean currents and physical energy in the lagoon appeared to promote algal persistence. Thus, parrotfish bans may be more effective in promoting reef recovery in environments that promote rapid algal turnover. Fisheries regulations are unlikely to rapidly restore hard corals on these patch reefs, which have slowly transitioned to algal dominance since first described in 1970.

Benthic foraminifera as ecological indicators in the Tunda Island Waters, Serang District, Banten Province, Indonesia

Abstract. Nurruhwati I, Ardiansyah F, Yuniarti, Yuliadi LPS, Partasasmita R. 2020. Benthic foraminifera as ecological indicators in the Tunda Island Waters Serang District, Banten Province, Indonesia. Biodiversitas 21: 3142-3148. Coral reef communities all across Southeast Asia are experiencing intense pressures from extensive tourism and massive coastal development. A prediction regarding coral reefs’ capacity to recover is a necessity since it is constantly exposed to damaging events such as mass bleaching and increased erosion. Tunda Island (which is highly rich in biodiversity and include coral reefs, mangrove forests, seagrass, and algae meadows) was sampled at 10 different sites in August 2019. Coral reefs are highly influenced by ecological factors such as temperature variability, salinity, DO, and pH. The assessments were conducted using the FORAM Index (FI) to accurately predict the capacity of coral reefs to recover based on relative abundances of symbiont-bearing larger benthic foraminifera in reef sediments. The FI values ranged from 3.7 to 7.9 with a median of 4.7 and the average of 5 indicates that the water quality should support the recovery of reefs by reef-building corals and symbiont-bearing larger benthic foraminifers. The lowest FI value sampled was recorded from a site with extensive human activities (FI=3.4), while the highest one was recorded from a site with minimal to none human activities (FI=7.9), which indicates that the deterioration of water quality is caused by wastes from tourism activities near the coastal area.

Extensive coral reef decline in Nha Trang Bay, Vietnam: Acanthaster planci outbreak: the final event in a sequence of chronic disturbances

Nha Trang Bay (NTB), located off the south-east coast of Vietnam, is a famous tropical tourist site. In the past, the bay was characterised by flourishing coral reefs but, by the end of 2019, more than 90% of the corals were gone. In addition to chronic and complex anthropogenic effects, there was an extensive outbreak of crown-of-thorns starfish (Acanthaster planci), the main natural predator of reef-building corals in the Indo-Pacific, among the remnant coral communities in NTB. By 2019, the mean abundance of A. planci in NTB reached 4.2 starfish per 100m2. Coral surveys conducted on 10 target sites over a 3-year period ending in 2019 revealed that mean coral cover decreased by 64.4% (coral loss varied from 43 to 95%). The greatest declines were in Acropora and Montipora, with 80.6 and 82.3% reductions in the coverage of these taxa respectively. The combination of nutrient enrichment and predator removal is thought to determine the extent of the outbreak of A. planci in the bay. The present trends in environmental conditions in NTB do not indicate a positive outcome for coral reef recovery in in this area in the near future.

Coral reef resilience to thermal stress in the Eastern Tropical Pacific.

Coral reefs worldwide are threatened by thermal stress caused by climate change. Especially devastating periods of coral loss frequently occur during El Niño-Southern Oscillation (ENSO) events originating in the Eastern Tropical Pacific (ETP). El Niño-induced thermal stress is considered the primary threat to ETP coral reefs. An increase in the frequency and intensity of ENSO events predicted in the coming decades threatens a pan-tropical collapse of coral reefs. During the 1982-1983 El Niño, most reefs in the Galapagos Islands collapsed, and many more in the region were decimated by massive coral bleaching and mortality. However, after repeated thermal stress disturbances, such as those caused by the 1997-1998 El Niño, ETP corals reefs have demonstrated regional persistence and resiliency. Using a 44year dataset (1970-2014) of live coral cover from the ETP, we assess whether ETP reefs exhibit the same decline as seen globally for other reefs. Also, we compare the ETP live coral cover rate of change with data from the maximum Degree Heating Weeks experienced by these reefs to assess the role of thermal stress on coral reef survival. We find that during the period 1970-2014, ETP coral cover exhibited temporary reductions following major ENSO events, but no overall decline. Further, we find that ETP reef recovery patterns allow coral to persist under these El Niño-stressed conditions, often recovering from these events in 10-15years. Accumulative heat stress explains 31% of the overall annual rate of change of living coral cover in the ETP. This suggests that ETP coral reefs have adapted to thermal extremes to date, and may have the ability to adapt to near-term future climate-change thermal anomalies. These findings for ETP reef resilience may provide general insights for the future of coral reef survival and recovery elsewhere under intensifying El Niño scenarios.

Performance of ecological restoration in an impaired coral reef in the Wuzhizhou Island, Sanya, China

Coral restoration is becoming popular to help restoring degraded coral reefs. However, few studies have tried to monitor the long-term recovery of coral reefs, which makes it difficult to assess the performance of the restoration. We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artificial reefs (ARs) from October 2014 to September 2018 during which there were several attacks of typhoons. Results show that two staghorn Acropora species had the highest growth rates (11.0–12.1 cm/a), followed by table coral A. divaricate (5.6 cm/a) and P. damicornis (4.8 cm/a). A linear growth pattern was found for the three Acropora species; the pattern gradually slowed in P. damicornis. There was a strong interspecific competition for space among the corals on ARs, and it led to the sharply declined occurrence of slow-growing P. darmicornis colonies in 2017. Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity. However, the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon. Therefore, concrete and environmental-friendly materials should be used in future restoration. This study is the first report on long-term monitoring and assessment of coral reef restoration in China. The results offer future guide of reef restoration for impaired coral reefs in regions easily affected by typhoons.