Dominant Coral Research Articles

Coral bleaching impacts from back-to-back 2015\u20132016 thermal anomalies in the remote central Indian Ocean

Studying scleractinian coral bleaching and recovery dynamics in remote, isolated reef systems offers an opportunity to examine impacts of global reef stressors in the absence of local human threats. Reefs in the Chagos Archipelago, central Indian Ocean, suffered severe bleaching and mortality in 2015 following a 7.5 maximum degree heating weeks (DHWs) thermal anomaly, causing a 60% coral cover decrease from 30% cover in 2012 to 12% in April 2016. Mortality was taxon specific, with Porites becoming the dominant coral genus post-bleaching because of an 86% decline in Acropora from 14 to 2% cover. Spatial heterogeneity in Acropora mortality across the Archipelago was significantly negatively correlated with variation in DHWs and with chlorophyll-a concentrations. In 2016, a 17.6 maximum DHWs thermal anomaly caused further damage, with 68% of remaining corals bleaching in May 2016, and coral cover further declining by 29% at Peros Banhos Atoll (northern Chagos Archipelago) from 14% in March 2016 to 10% in April 2017. We therefore document back-to-back coral bleaching and mortality events for two successive years in the remote central Indian Ocean. Our results indicate lower coral mortality in 2016 than 2015 despite a more severe thermal anomaly event in 2016. This could be caused by increased thermal resistance and resilience within corals surviving the 2015 thermal anomaly; however, high bleaching prevalence in 2016 suggests there remained a high sensitivity to bleaching. Similar coral mortality and community change were seen in the Chagos Archipelago following the 1998 global bleaching event, from which recovery took 10 yr. This relatively rapid recovery suggests high reef resiliency and indicates that the Archipelago’s lack of local disturbances will increase the probability that the reefs will again recover over time. However, as the return time between thermal anomaly events becomes shorter, this ability to recover will become increasingly compromised.

Abiotic and biotic controls on coral recovery 16\xa0years after mass bleaching

As climate changes increase heat stress on tropical ecosystems, the long-term persistence of coral reefs requires rapid coral recovery following coral bleaching events. Using the extent of coral cover return to a pre-bleaching baseline as a benchmark, recovery of fast-growing and stress-tolerant coral growth forms suggests that reefs can bounce back between repeated disturbances if given adequate time and protection from anthropogenic disturbances.However, long-term recovery dynamics of coral communities following severe bleaching and mass mortality are limited, particularly for fringing reefs along inhabited coastlines where human stressors may compromise recovery potential. Here, we examine the dynamics and drivers of coral recovery in Seychelles, where 12 reefs returned to pre-bleaching coral cover levels after a severe bleaching event caused > 95% coral mortality. Six reefs with initially low cover ( < 25%) recovered within 7–12 yr and, after 16 yr, exceeded pre-bleaching cover levels by 132–305%. In contrast, six reefs with initially high cover (20–60%) remained at 48–93% of pre-bleaching levels, with recovery projected to take 17–29 yr. Abiotic and historic conditions constrained recovery rates, with the slowest recovery times observed on deep and wave-exposed reefs with high pre-bleaching coral cover. Reefs with high juvenile coral densities and low nitrogen levels recovered fastest, possibly due to the interplay between nutrient enrichment, algal proliferation, and coral recruitment. Our findings emphasize the importance of understanding small-scale variation in recovery potential, whereby recovery times were governed by natural limits on growth rates and modified by coral recruitment and nutrient enrichment. Ultimately, climate-impacted reefs can recover to moderate coral cover levels, but, if bleaching causes repeated high coral mortality, short recovery windows will prevent a return to historic levels of coral dominance.

Newly dominant benthic invertebrates reshape competitive networks on contemporary Caribbean reefs

Competition is a fundamental process structuring ecological communities. On coral reefs, space is a highly contested resource and the outcomes of spatial competition can dictate community composition. In the Caribbean, reefs are increasingly dominated by non-scleractinian species like sponges, gorgonians, and zoanthids, yet there is a paucity of data on interactions between these increasingly common organisms and historically dominant corals. Here, we investigated interactions among these groups of sessile benthic invertebrates to better understand the role of spatial competition in shaping benthic communities on Caribbean reefs. We coupled surveys of competitive interactions on the reef with a common garden competition experiment to determine the frequency and outcome of interference competition among eight focal species. We found that competitive interactions were pervasive on Florida reefs, with 60% of sessile benthic invertebrates interacting with at least one other invertebrate. Increasingly common non-scleractinian species were some of the most abundant taxa and consistently outcompeted the contemporarily common scleractinian species Porites porites and Siderastrea siderea. The encrusting gorgonian, Erythropodium caribaeorum, was the most aggressive species, reducing the live area of its competitors on average 42% ± 7.04 (SE) over the course of 5 months. Surprisingly, the most aggressive species declined in size when competing, while some less aggressive species were able to increase or maintain area, suggesting a trade-off between aggressiveness and growth. Our findings suggest that competition among sessile invertebrates is likely to remain an important process in structuring coral reefs, but that the optimal strategies for maintaining space on the benthos may change. Importantly, many non-scleractinian species that now dominate reefs appear to be superior competitors, potentially increasing the stress on corals on contemporary reefs.

Changes in the population and community structure of corals during recent disturbances (February 2016-October 2017) on Maldivian coral reefs

Climate change is the greatest threat to coral reef ecosystems. In particular, increasing ocean temperatures are causing severe and widespread coral bleaching, contributing to extensive coral loss and degradation of coral reef habitats globally. Effects of coral bleaching are not however, equally apportioned among different corals, leading to shifts in population and community structure. This study explored variation in bleaching susceptibility and mortality associated with the 2016 severe mass bleaching in the Central Maldives Archipelago. Five dominant coral taxa (tabular Acropora, Acropora humilis, Acropora muricata, Pocillopora and massive Porites) were surveyed in February 2016 and October 2017 to test for changes in abundance and size structure. Substantial taxonomic differences in rates of mortality were observed; the most severely affected taxa, Acropora, were virtually extirpated during the course of this study, whereas some other taxa (most notably, massive Porites) were relatively unaffected. However, even the least affected corals exhibited marked changes in population structure. In February 2016 (prior to recent mass-bleaching), size-frequency distributions of all coral taxa were dominated by larger size classes with over-centralized, peaked distributions (negatively skewed with positive kurtosis) reflecting a mature population structure. In October 2017, after the bleaching, coral populations were dominated by smaller and medium size classes, reflecting high levels of mortality and injury among larger coral colonies. Pronounced changes in coral populations and communities in the Maldives, caused by coral bleaching and other disturbances (outbreaks of crown-of-thorns starfish and sedimentation), will constrain recovery capacity, further compounding upon recent coral loss.

Broadening the taxonomic scope of coral reef palaeoecological studies using ancient DNA.

Marine environments face acute pressures from human impacts, often resulting in substantial changes in community structure. On the inshore Great Barrier Reef (GBR), palaeoecological studies show the collapse of the previously dominant coral Acropora from the impacts of degraded water quality associated with European colonization. Even more dramatic impacts can result in the replacement of corals by fleshy macroalgae on modern reefs, but their past distribution is unknown because they leave no fossil record. Here, we apply DNA metabarcoding and high-throughput sequencing of the 18S rDNA gene on palaeoenvironmental DNA (aeDNA) derived from sediment cores at two sites on Pandora Reef (GBR), to enhance palaeoecological studies by incorporating key soft-bodied taxa, including macroalgae. We compared temporal trends in this aeDNA record with those of coral genera derived from macrofossils. Multivariate analysis of 12 eukaryotic groups from the aeDNA community showed wide variability over the past 750years. The occurrence of brown macroalgae was negatively correlated only with the dominant coral at both sites. The occurrence of coralline and green macroalgae was positively correlated with only the dominant coral at one of the sites, where we also observed a significant association between the whole coral community and the occurrence of each of the three macroalgae groups. Our results demonstrate that reef sediments can provide a valuable archive for understanding the past distribution and occurrence of important soft-bodied reef dwellers. Combining information from fossils and aeDNA provides an enhanced understanding of temporal changes of reefs ecosystems at decadal to millennial timescales.

Spatial and Intergeneric Variation in Physiological Indicators of Corals in the South China Sea: Insights Into Their Current State and Their Adaptability to Environmental Stress

AbstractIt is well known that coral thermal bleaching is mainly caused by abnormally high temperatures, but the spatial/intergeneric variation in coral‐algal symbiosis and its linkage to coral bleaching susceptibility is not well understood. In this study, 654 coral samples were collected from six coral reef regions (CRRs) in the South China Sea (SCS), between the Nansha Islands (~10°N) and Daya Bay (22°50′N). They were analyzed to explore how geographical/environmental variation affects coral bleaching susceptibility. The results showed significant spatial and intergeneric variation in zooxanthellae density, Chlacontent, and tissue biomass. Massive corals generally showed higher values than branching corals for all three parameters across CRRs. Spatial analysis showed that these parameters were lowest in the Nansha Islands and highest in Daya Bay, indicating increases with latitude. Several factors may have accounted for this trend, with the most important being sea surface temperature and nutrients. Additionally, we observed a relationship between physiological parameters and bleaching susceptibility, which was that branching corals had greater bleaching susceptibility than massive corals. Coral community composition and live coral cover data showing increasing dominance of massive corals in the SCS support the above inference. Relatively high‐latitude areas have been proposed as potential refuges for corals under continued global warming and the physiological parameters in the present study seem to support this. However, in spite of the aforementioned results, the smallest live coral cover was found in the northern CRRs. This suggests that this refuge function is currently compromised, mainly due to increasing destructive anthropogenic actions.

Individual and Population Level Variation in the Reproductive Potential of Deep-Sea Corals From Different Regions Within the Gulf of Maine

Deep-sea corals are of conservation concern in the North Atlantic due to prolonged disturbances associated with the exploitation of natural resources and a changing environment. As a result, two research cruises in the Gulf of Maine region during 2014 and 2017 collected samples of two locally dominant coral species, Primnoa resedaeformis and Paramuricea placomus, at six locations to investigate reproductive ecology. Remotely operated vehicles (ROVs) were used to collect specimens that were examined via paraffin histology, and coincident video surveys were used to determine size class distributions. Both species were identified as gonochoristic, and sampled locations exhibited dissimilarities in spermatocyst development and oocyte size except for those in close geographic proximity. Fecundities exhibited substantial ranges across sample locations and average oocyte sizes ( SD) were 140  117 m for P. resedaeformis and 64  46 m for P. placomus. In addition, colony size distributions were also significantly different across sampling locations. Notably, the Outer Schoodic Ridge sample location, with larger colony and oocyte sizes, was identified as a potential key source population of reproductive material in the Gulf of Maine. These data were used to calculate differences in reproductive potential based on relationships between colony morphology and reproductive output using height as a predictive proxy. Furthermore, calculated age at first reproduction, 7.6-19.8 years for P. resedaeformis and 20.7-37 years for P. placomus, which may be dependent on sex of the colony, provides a metric for estimating the amount of time these coral habitats will take to recover. This investigation, in response to historical population impacts and environmental change, links reproductive and morphometric relationships to inform population scale reproductive models, while also establishing an understanding of regional scale gametogenic variability within the Gulf of Maine region.

Drivers of recovery and reassembly of coral reef communities.

Understanding processes that drive community recovery are needed to predict ecosystem trajectories and manage for impacts under increasing global threats. Yet, the quantification of community recovery in coral reefs has been challenging owing to a paucity of long-term ecological data and high frequency of disturbances. Here we investigate community re-assembly and the bio-physical drivers that determine the capacity of coral reefs to recover following the 1998 bleaching event, using long-term monitoring data across four habitats in Palau. Our study documents that the time needed for coral reefs to recover from bleaching disturbance to coral-dominated state in disturbance-free regimes is at least 9-12 years. Importantly, we show that reefs in two habitats achieve relative stability to a climax community state within that time frame. We then investigated the direct and indirect effects of drivers on the rate of recovery of four dominant coral groups using a structural equation modelling approach. While the rates of recovery differed among coral groups, we found that larval connectivity and juvenile coral density were prominent drivers of recovery for fast growing Acropora but not for the other three groups. Competitive algae and parrotfish had negative and positive effects on coral recovery in general, whereas wave exposure had variable effects related to coral morphology. Overall, the time needed for community re-assembly is habitat specific and drivers of recovery are taxa specific, considerations that require incorporation into planning for ecosystem management under climate change.

Megabenthos and benthopelagic fishes on Southeast Atlantic seamounts

In a descriptive study of megafauna of several Southeast Atlantic seamounts, multiple video-transects on upper slopes and summits documented the occurrence of benthic invertebrate taxa, primarily corals, regarded as indicators of vulnerable marine ecosystems (VMEs) as defined in international guidelines. At Schmitt-Ott Seamount there was a pronounced dominance of gorgonian corals (seafans, Alcyonacea). In all other study areas the diversity was greater, and more scleractinians (stony corals, Scleractinia) were observed. Scleractinian corals were mainly dead, and much of the coral framework and rubble may have been ancient. In the Valdivia complex and on Ewing Seamount, which are open to fisheries, scleractinians seemed restricted to some slopes of knolls, and on Valdivia Bank and the subarea denoted Valdivia West the summit substrate was mostly bare rock. Pelagic armourhead Pseudopentaceros richardsoni and splendid alfonsino Beryx splendens (two targets of commercial fisheries in the area) were observed at a few sites, but did not appear to be abundant in the main former fishing areas of the Valdivia area. Orange roughy Hoplostethus atlanticus was common in video records around the summit at Ewing Seamount. The deep-sea red crab Chaceon erytheiae was abundant in the Valdivia area and at Ewing Seamount, and crabs were distributed across a more extensive depth range than the fishes. In areas with high densities of live coral, the video records suggested that the benthic communities were intact and not impacted by fishing. Evidence of past fishing activities included observations of lost pots and rope at Vema Seamount and in the Valdivia area.

Scale‐dependent spatial patterns in benthic communities around a tropical island seascape

Understanding and predicting patterns of spatial organization across ecological communities is central to the field of landscape ecology, and a similar line of inquiry has begun to evolve sub‐tidally among seascape ecologists. Much of our current understanding of the processes driving marine community patterns, particularly in the tropics, has come from small‐scale, spatially‐discrete data that are often not representative of the broader seascape. Here we expand the spatial extent of seascape ecology studies and combine spatially‐expansive in situ digital imagery, oceanographic measurements, spatial statistics, and predictive modeling to test whether predictable patterns emerge between coral reef benthic competitors across scales in response to intra‐island gradients in physical drivers. We do this around the entire circumference of a remote, uninhabited island in the central Pacific (Jarvis Island) that lacks the confounding effects of direct human impacts. We show, for the first time, that competing benthic groups demonstrate predictable scaling patterns of organization, with positive autocorrelation in the cover of each group at scales &lt; ~1 km. Moreover, we show how gradients in subsurface temperature and surface wave power drive spatially‐abrupt transition points in group dominance, explaining 48–84% of the overall variation in benthic cover around the island. Along the western coast, we documented ten times more sub‐surface cooling‐hours than any other part of the coastline, with events typically resulting in a drop of 1–4°C over a period of &lt; 5 h. These high frequency temperature fluctuations are indicative of upwelling induced by internal waves and here result in localized nitrogen enrichment (NO2 + NO3) that promotes hard coral dominance around 44% of the island's perimeter. Our findings show that, in the absence of confounding direct human impacts, the spatial organization of coral reef benthic competitors are predictable and somewhat bounded across the seascape by concurrent gradients in physical drivers.

Resistance to temperature stress and Drupella corallivory may promote the dominance of Platygyra acuta in the marginal coral communities in Hong Kong

The wide fluctuation in seawater temperature (from 14 °C in winter to 31 °C in summer) has been suggested as one of the factors affecting the diversity of marginal coral communities like those in Hong Kong. We proposed in a previous study that branching corals like Acropora valida were more susceptible to low temperature stress during, and weakened corals became more vulnerable to corallivorous attack by the snails Drupella spp. In the following spring. Acropora spp., however, are not the most common species found in Hong Kong. In the present study, we examined comparable temperature effects, both low and elevated, on Platygyra acuta, one of the most dominant coral species in Hong Kong. Platygyra acuta fragments were exposed to six temperature levels ranging from 14 °C to 32 °C for 7 days before they were exposed to prey-choice experiments with Drupella. Results from these experiments indicated that P. acuta fragments were generally tolerant to temperature changes within the range tested. In contrast to those observed for A. valida, they were not found to be attractive to the subsequent Drupella corallivory. The greater tolerance of P. acuta to both these environmental and biological stresses may have contributed to its dominance in Hong Kong coral communities.

Coral reefs respond to repeated ENSO events with increasing resistance but reduced recovery capacities in the Lakshadweep archipelago

The resilience of reefs to repeated, increasingly frequent thermal disturbance is a dynamic balance between resistance and recovery pathways. The Lakshadweep archipelago in the central Indian Ocean has experienced three El Nino Southern Oscillation (ENSO) events in 1998, 2010 and 2016. Using a multi-decadal monitoring of 6 shallow reefs, we estimated reef resistance and coral recovery after each of these bleaching events. Even as the severity of each ENSO event increased over time, coral mortality decreased from 87% post-1998 to 44% after 2010 and 31% after 2016. In contrast, benthic recovery after 2010 was more protracted than after 1998, with a fourfold decrease in recovery rates between the two time periods. This has resulted in a 40% decline in absolute coral cover in the last 2 decades from 51.6% in 1998 to 11% in 2017. We examined the demographic and compositional mechanisms underlying these two recovery trajectories by monitoring coral recruitment, juvenile, and young adult compositions for 5 yr after 1998 and 2010. While coral juvenile densities were comparable after each of these disturbances, densities of fast-growing Acroporids had reduced from > 1 m−2 post-1998 to 0.09 m−2 post-2010. This was reflected in the composition of coral communities in 2003 and 2015, which differed in its dominant coral taxa, with a dramatic decline in Acropora and an increase in the cover of Porites by 2015. While the dominance of resistant taxa like Porites signals a shift to a system adapting to recurrent thermal anomalies, the reduction in fast-growing, habitat-forming corals like Acropora is driving a major decline in recovery rates with time. Given the frequency of current warming events, the increased reef resistance over the last 2 decades is likely not sufficient to also ensure gains in coral cover in Lakshadweep’s reefs.

Abnormal density of Culcita schmideliana delays recovery of a reef system in the Maldives following a catastrophic bleaching event

Culcita spp. are facultative corallivores that can have a selective effect on coral composition due to their feeding preference for Acropora spp. and Pocillopora spp. Although Culcita are normally rare (&amp;lt;0.5 per 100m2), mean densities of up to 9.2 sea stars per 100m2 were observed on a Maldivian reef system, with the highest numbers on the reef flat and reef crest. Culcita fed on 12 genera of corals, but showed a distinct preference for Pocillopora (51%) and Acropora (21%). Formerly the dominant corals on Maldivian reefs, these genera sustained 80–95% mortality from coral bleaching in 2016. Low numbers of juvenile acroporids and pocilloporids were slowly recolonising the reef, but 24% had recently been eaten by Culcita schmideliana. The abnormal abundance of C. schmideliana and high number of recently dead juvenile corals suggest that chronic predation by C. schmideliana could delay the recovery of reefs damaged by the 2016 mass bleaching event.

Detection of changes in shallow coral reefs status: Towards a spatial approach using hyperspectral and multispectral data

Coral reef degradation due to environmental change, including anthropogenic disturbances, is a major concern worldwide. Detecting and assessing both temporal and spatial changes in benthic cover is a crucial requirement to inform policy makers and guide conservation measures. Here, we introduce a spatial approach based on high resolution multispectral and hyperspectral image analysis, developed in order to detect and quantify changes in benthic cover in a highly heterogeneous shallow coral reef flat in Reunion Island in the South-West Indian Ocean. We propose a new index called HCAI (Hyperspectral Coral to Algae Index), defined as the ratio of living coral cover to the sum of living coral and algal covers. Benthic cover estimates were derived from airborne hyperspectral image processing using water column correction and unmixing models implemented with the four main coral reef benthic components: corals, algae, seagrass and sand. Ground truth and LIDAR data acquired simultaneously were used to validate processing accuracy. A significant positive correlation (adjusted R2 = 0.72, p-value < 0.001) was obtained between coral cover recorded in situ and estimated from image analysis. Moreover, 13 habitat classes based on the four main benthic component covers were mapped at a scale of an entire reef. Diachronic analyses of hyperspectral images between 2009 and 2015 revealed an overall decrease of the HCAI index and a decrease in the area of all the dominant coral classes along the reef (−28.24% for the coral class for example), while the area of habitat classes dominated by algae strongly increased during the same period. Moreover, we detected and documented the spatial and temporal evolutions of coral geomorphological features composed with coral rubble deposits called rubble tongues (RTs) using different available sensors (i.e. hyperspectral, satellite, and orthophotography). Since 2003, four detected (RTs) have spread shoreward at a mean rate of 8.4 m.y−1 including significant loss of reef structural complexity and heterogeneity, a spreading pattern which was confirmed by 2009 and 2015 hyperspectral data. Remote sensing and more specifically airborne hyperspectral approaches open new perspectives for coral reef monitoring, at high temporal and spatial resolutions.

Nutrients and herbivory, but not sediments, have opposite and independent effects on the tropical macroalga, Padina boryana

Multiple anthropogenic stressors including overfishing, nutrient loading, and sediments are major drivers that may support the proliferation of macroalgae on coral reefs; however, few studies have investigated all three simultaneously. We evaluated the effects of all three stressors (nutrient enrichment, small and large sediment grain sizes, and herbivory) on biomass accumulation of the dominant coral reef macroalga Padina boryana in a multifactorial field experiment on a fringing reef in Mo’orea, French Polynesia. Biomass accumulation of P. boryana was controlled by the separate, but not interactive, effects of herbivory and nutrients; although we did not detect effects of sediments, these may have been obscured by high variability leading to low statistical power. With herbivores, biomass remained the same or decreased up to 50% in 12 days compared to ~50–100% increases in biomass without herbivores. Overall, enriched P. boryana grew ~ 4-fold greater compared to ambient treatments, both with and without herbivory. Our results suggest that any release from bottom-up and/or top-down controls that may occur simultaneously on these nearshore reefs may facilitate proliferation of this tropical macroalga, and, in contrast to the prevailing paradigm, we found these effects can function independently.

Transient Grazing and the Dynamics of an Unanticipated Coral–Algal Phase Shift

Extreme disturbances often lead to community reorganisations, yet sometimes ecosystems unexpectedly fail to recover. Such surprising outcomes may pinpoint important yet overlooked mechanisms that drive ecosystems into undesirable states. Using long-term field observations, experimental manipulations and mechanistic modelling, we document the drivers of an unexpected phase shift from coral to macroalgal dominance following typhoon disturbance on reefs in Palau (Micronesia). After extensive coral mortality, an ephemeral bloom of a canopy-forming macroalga (Liagora sp.) provided physical refuge from herbivore grazing, resulting in the establishment of a secondary, understory macroalga (Lobophora spp.). After disappearance of Liagora canopies and resulting loss of grazing refuge, the Lobophora patches continued to expand and led to a macroalgal (Lobophora-) dominated state that has persisted for more than 2 years. We developed a mechanistic model of Lobophora patch dynamics parameterised with rates of growth measured in situ to simulate the observed proliferation of Lobophora under variable grazing refuges in space and time. Model simulations showed that short-term escapes from grazing were pivotal in allowing establishment of patches of Lobophora. Ephemeral grazing refuges created an opportunity to reach a cover above which Lobophora growth exceeds grazing, so that Lobophora could expand after disappearance of Liagora canopies. Critically, in the absence of grazing refuge, herbivore biomass was sufficient to prevent the establishment of Lobophora patches. Our model demonstrates that with rapid algal growth and low grazing, a relatively minor grazing refuge (6 month) is sufficient to escape herbivore control after extensive coral mortality, leading to unexpected recovery failure. Transient fluctuations in the intensity of control mechanisms, such as herbivore grazing, can have disproportionate and long-lasting effects on community structure. Overall, this study stresses that our perception of reef dynamics must integrate the time scales at which reefs can be sensitive to transient changes in mechanisms promoting coral dominance.

A Baseline Assessment of Coral Reef in Malacca Straits, Malaysia

Coral reefs along the Malacca Straits (MS) are poorly developed mainly due to turbidity and sedimentation. This study describes the health status and community structure of the corals in Cape Rachado, West Coast of Peninsular Malaysia (WCPM), utilizing the Coral Video Transect (CVT) technique. All the survey transects were categorized as ‘fair’ coral conditions (27.39 ± 5.41%–48.56 ± 18.96%) with the reef floor mainly covered by corals and sediment. Twelve families of coral comprised of 25 distinct genera were identified. Coral communities were differentiated into four clusters with each being predominated by Galaxea, Diploastrea, Fungia and Pectinia respectively. Among all, Pectinia is the most spectacular genera and dominated the survey area. Along the MS, Favia, Favites and Porites are commonly found while Porites and Pectinia dominated the reefs. Low coral cover and diversity was recorded in MS as compared to the reefs in the South China Sea (SCS). The most prominent results include changes in the dominant coral from Porites to Pectinia while some species such as Acropora were absent from the study area. Based on the presented data, the reef in the study area was predominantly occupied by sediment and the coral communities were formed by a species with a high tolerance to turbidity and sedimentation.

Simultaneous synergist, antagonistic and additive interactions between multiple local stressors all degrade algal turf communities on coral reefs

Abstract Ecological communities are subjected to multiple anthropogenic stressors at both global and local scales that are increasing in number and magnitude. Stressors can interact in complex ways and are classified as additive, synergistic or antagonistic; the nature of the interaction is key to predicting changes and understanding community resilience. Coral reefs are among the most impacted communities and have shifted from coral‐ to algal‐dominated states, and overfishing, nutrient enrichment and sedimentation are local stressors that often co‐occur and may support degraded algal states. Short algal turfs are abundant benthic space holders on healthy reefs that may be pushed by local stressors to long algal turfs, a more degraded state that may prevent recovery to coral dominance. We conducted a fully crossed three‐factor field experiment on short algal turf communities manipulating herbivory pressure (+/−cages), nutrients (+/−fertilizer) and sediments (natural accumulation/removal). We applied stressors for 16 days, removed them and monitored turf height during and after manipulations. We found that significant pair‐wise interactions between all stressors pushed the community towards a degraded state with longer algal turfs. All three types of interactions (additive, synergistic and antagonistic) were common and occurred in equal frequency, suggesting more investigations into all types are needed to accurately predict community responses to multiple stressors. For example, when herbivores were present, nutrients and sediments interacted additively, while in the absence of herbivores, nutrients and sediments interacted synergistically. All interactions broke down following termination of experimental manipulations and all effects were undetectable after 49 days, indicating that this reef may be resilient, at least when stressors are applied on a short time‐scale. Synthesis. Because management of local stressors is often more tractable than global stressors, local management has been proposed as a means to offset global stressors. However, ecological communities often experience multiple local stressors simultaneously, and interactions between stressors, including synergisms and antagonisms, may be the source of nonlinear shifts in communities or “ecological surprises.” The majority of interactions in our study were both strong and nonlinear, and we suggest that, if pervasive across systems, nonlinear interactions may drive the recent global increase in “ecological surprises.”

Biodiversitas dan Sebaran Karang Jamur (Fungiidae) di Perairan Teluk Amurang, Minahasa Selatan

&lt;strong&gt;Biodiversity and Distribution of Mushroom Coral (Fungiidae) in The Amurang Bay, South Minahasa.&lt;/strong&gt; Mushroom coral is the one of sclerectinians that has essential role to form coral reefs. This kind of species act as a microhabitat for other marine organisms such as shrimp. cryptobenthic fish, barnacle and crab. Most of these unique species have an ability to move from one habitat to another during benthic phase. The aim of this research was to determine the community structure and distribution of mushroom corals. This research was conducted in February 2017 at 4 research stations using belt transect method with 50x2m&lt;sup&gt;2&lt;/sup&gt; length of transects. The results showed that 431 individuals consisting of 19 species and 11 genus were recorded. Generally, the range of values of diversity index (H) was between 0,85-1,06 (low to medium level). The evennes index (J) values was ranged from 0,81 to 0,89 (high level) while the richness index (D) was 2,47-3,58 (low level). Lythophyllon repanda, Lythophyllon concinna and Fungia fungites were the most dominant mushroom coral spesies in the Amurang Bay waters.

Shifting communities after-- typhoon damage on an upper mesophotic reef in Okinawa, Japan.

Very few studies have been conducted on the long-term effects of typhoon damage on mesophotic coral reefs. This study investigates the long-term community dynamics of damage from Typhoon 17 (Jelawat) in 2012 on the coral community of the upper mesophotic Ryugu Reef in Okinawa, Japan. A shift from foliose to bushy coral morphologies between December 2012 and August 2015 was documented, especially on the area of the reef that was previously recorded to be poor in scleractinian genera diversity and dominated by foliose corals. Comparatively, an area with higher diversity of scleractinian coral genera was observed to be less affected by typhoon damage with more stable community structure due to less change in dominant coral morphologies. Despite some changes in the composition of dominant genera, the generally high coverage of the mesophotic coral community is facilitating the recovery of Ryugu Reef after typhoon damage.