Dominant Coral Research Articles

Seabird nutrients increase coral calcification rates and boost reef carbonate production

While excessive anthropogenic nutrient loads are harmful to coral reefs, natural nutrient flows can boost coral growth and reef functions. Here we investigate if seabird-derived nutrient subsidies benefit the growth of two dominant corals on lagoonal reefs, submassive Isopora palifera and corymbose Acropora vermiculata, and if enhanced colony-level calcification rates can increase reef-scale carbonate production. I. palifera and A. vermiculata colonies close to an island with high seabird densities displayed 1.4 and 3.2-times higher linear extension rates, 1.8 and 3.9-times faster planar area increase, and 1.6 and 2.7-times higher calcification rates compared to colonies close to a nearby island with low seabird densities, respectively. While benthic ReefBudget surveys in combination with average coral growth rates did not indicate differences in reef-scale carbonate production across sites, coral carbonate production was 2.2-times higher at the seabird-rich island when using site-specific linear growth rates and skeletal densities. This study shows that seabird-derived nutrients benefit fast-growing branching as well as previously unstudied submassive coral taxa. It also demonstrates that nutrient subsidies benefit colony-scale and reef-scale calcification rates, which underpin important geo-ecological reef functions. Restoring natural nutrient pathways should thus be a priority for island and reef management.

Patterns of fish assemblage structure on reefs with varying degrees of hard coral and soft coral dominance in Okinawa Island, Japan

Patterns of fish assemblage structure on reefs with varying degrees of hard coral and soft coral dominance in Okinawa Island, Japan

Population genetic structure of Montipora digitata coral-algal symbiosis in the South China Sea

Species genetic diversity can reflect their adaptability to environmental changes. Coral reefs worldwide are in rapid decline due to climate change and human activities, highlighting the need for conservation intervention. The South China Sea (SCS) is an important biodiversity hotspot, particularly in the Xisha Islands (XS) that contain the majority of coral species in the SCS. However, few studies exist on coral genetic diversity in the SCS. Montipora digitata is the dominant reef-building coral species in the XS. In this study, two mitochondrial DNA fragments and 11 microsatellite markers were employed to investigate the genetic diversity of coral host of M. digitata, and ITS amplicon sequencing was employed to investigate the Symbiodiniaceae community structure. We sampled five wild populations of M. digitata in Hainan Island and the Xisha Islands. Montipora digitata showed low genetic diversity across populations in the SCS. We found significant genetic differentiation between the Sanya (SY) and XS populations but no significant genetic differentiation within XS populations. We identified four Symbiodiniaceae genera, with Cladocopium and Durusdinium being the most common, as well as Gerakladium and Fugacium. The Symbiodiniaceae types of SY and XS are significantly different, C15 is abundant in all populations, while D1a is also abundant in SY. We analyzed the correlation between 16 environmental factors and the genetic diversity of symbionts, genetic diversity of coral host and Symbiodiniaceae community was significantly correlated with sea surface temperature (SST) and other environmental factors. Our study provided a detailed paradigm from the perspective of genetic diversity of how a dominant coral species can be indicative of poor environmental adaptation potential.

High diversity and abundance of fish and coral in an artificial breakwater in Colombo, Sri Lanka

The diversity of reef fishes and the diversity and abundance of corals in artificial breakwaters were studied between June and August 2023 in Port City, Colombo in the Western Province of Sri Lanka. Four methods were used: visual census using video, photographs, stationary point count and environmental DNA (eDNA). A total of 137 fish species, 74 coral species and 175 other species were recorded using the four methods. There were similarities and differences between the methods for recording fish, corals and other species. Only three fish species: Moon wrasse (Thalassoma lunare); Yellowtail fusilier (Caesio cuning) and Diamond fish (Monodactylus argenteus) were recorded by all methods. The highest number of fish species was recorded by video, followed by photographs, eDNA and stationary point count in the sequence. Coral cover ranged from 9 to 50.8% and mean live coral varied from 24.4% to 34.5 ± 5.2%. The dominant coral species was Pocillopora damicornis. Rare observations of coral bleaching (n=1) and frequent observations of marine debris (n=20) and coral damage (n=25) were recorded. Species detection using eDNA is a biomonitoring tool that did not add significantly to the list of fish and corals, but included many microscopic groups such as bacteria, diatoms and ciliates that were not recorded using other methods, and provided new ecological insights into marine systems. This is the first use of multiple monitoring tools to identify and compare methods for the biodiversity of marine fish, coral and other species in Sri Lankan marine waters.

Bioerosion and encrustation in Late Triassic reef corals from Iran

Hard substrate communities can impact coral reef growth by adding or removing calcium carbonate when they act as encrusters or bioeroders, respectively. Although such sclerobiont communities are known across the Phanerozoic, the Triassic saw a substantial increase in reef macrobioerosion. This study provides the first quantitative assessment of sclerobionts in a Late Triassic (Norian) reef coral community (from the Nayband Formation in central Iran) and establishes some post-Paleozoic trends in reef bioerosion. Sclerobionts were common on the dominant coral Pamiroseris rectilamellosa and covered between 0 and 26.4% of total coral surface area among the 145 colonies investigated. Encrustation was significantly more prevalent (1.78% of total area) than bioerosion (0.36% of total area). The underside of corals was 3.5 times more affected by sclerobionts than the upper surfaces. This suggests that the sclerobionts preferentially colonized dead parts of the corals. The main encrusting taxa were polychaete worms (76.2%), followed by bivalves (11.9%). The main bioeroders were Polychaeta (51.4%), Porifera (22.2%), and Bivalvia (20.7%). The lack of a correlation between encrustation and bioerosion intensity suggests that the number of sclerobionts is not simply a function of exposure time before final burial. Our review of the published literature suggests a declining trend in the relative importance of bivalves, polychaetes and cirripeds in reefs, whereas sponges increased in importance from the Triassic until today.

Incidence of ghost nets in the Tioman Island Marine Park of Malaysia

Ghost nets are major contributor to ocean pollution with extensive social, economic and environmental impacts. Ghost nets trap marine life, build up sediment, and smother and damage sensitive bottom habitats such as coral reefs and seagrass beds. Data on ghost nets are widely available for many coastal locations but there has been very limited information from Malaysia specifically Tioman Island. In 2015, Reef Check Malaysia started training local islanders to locate and remove ghost nets from reefs and beaches around Tioman Island. A reporting hotline was set up to gather information on ghost nets. Once vital information was gathered, the local islanders retrieved them and recorded the ghost nets and sent them for proper disposal. A total of 145 ghost nets weighing over 21 t were retrieved from Tioman Island from 2016 to 2022. The volume of ghost nets retrieved showed an increasing trend and were often found in March, April and September. The ghost nets originated from fishermen operating illegally inside the marine protected area (MPA) and legal fishermen operating outside the MPA. Ghost nets find their way to Tioman Island with strong currents and monsoonal winds. Most of the ghost nets retrieved were inside the MPA and on the western side of Tioman Island. Higher human population, shallower waters, shoreline morphology, dominant coral growth design and reef rugosity on the western side of Tioman Island are reasons for higher ghost nets sightings, thus retrieval and management efforts should focus on this side.

Shifts in dominance of benthic communities along a gradient of water temperature and turbidity in tropical coastal ecosystems.

Tropical coastal benthic communities will change in species composition and relative dominance due to global (e.g., increasing water temperature) and local (e.g., increasing terrestrial influence due to land-based activity) stressors. This study aimed to gain insight into possible trajectories of coastal benthic assemblages in Raja Ampat, Indonesia, by studying coral reefs at varying distances from human activities and marine lakes with high turbidity in three temperature categories (<31°C, 31-32°C, and >32°C). The benthic community diversity and relative coverage of major benthic groups were quantified via replicate photo transects. The composition of benthic assemblages varied significantly among the reef and marine lake habitats. The marine lakes <31°C contained hard coral, crustose coralline algae (CCA), and turf algae with coverages similar to those found in the coral reefs (17.4-18.8% hard coral, 3.5-26.3% CCA, and 15-15.5% turf algae, respectively), while the higher temperature marine lakes (31-32°C and >32°C) did not harbor hard coral or CCA. Benthic composition in the reefs was significantly influenced by geographic distance among sites but not by human activity or depth. Benthic composition in the marine lakes appeared to be structured by temperature, salinity, and degree of connection to the adjacent sea. Our results suggest that beyond a certain temperature (>31°C), benthic communities shift away from coral dominance, but new outcomes of assemblages can be highly distinct, with a possible varied dominance of macroalgae, benthic cyanobacterial mats, or filter feeders such as bivalves and tubeworms. This study illustrates the possible use of marine lake model systems to gain insight into shifts in the benthic community structure of tropical coastal ecosystems if hard corals are no longer dominant.

Corals survive severe bleaching event in refuges related to taxa, colony size, and water depth

Marine heatwaves are increasing in frequency and duration, threatening tropical reef ecosystems through intensified coral bleaching events. We examined a strikingly variable spatial pattern of bleaching in Moorea, French Polynesia following a heatwave that lasted from November 2018 to July 2019. In July 2019, four months after the onset of bleaching, we surveyed > 5000 individual colonies of the two dominant coral genera, Pocillopora and Acropora, at 10 m and 17 m water depths, at six forereef sites around the island where temperature was measured. We found severe bleaching increased with colony size for both coral genera, but Acropora bleached more severely than Pocillopora overall. Acropora bleached more at 10 m than 17 m, likely due to higher light availability at 10 m compared to 17 m, or greater daily temperature fluctuation at depth. Bleaching in Pocillopora corals did not differ with depth but instead varied with the interaction of colony size and Accumulated Heat Stress (AHS), in that larger colonies (> 30 cm) were more sensitive to AHS than mid-size (10–29 cm) or small colonies (5–9 cm). Our findings provide insight into complex interactions among coral taxa, colony size, and water depth that produce high spatial variation in bleaching and related coral mortality.

Current status of coral disease prevalence at Karimunjawa Island: correlation between land zonation and lesion occurrence.

Coral diseases have contributed significantly to the decline of coral populations at both local and global scales. The Karimunjawa Archipelago, located off the coast of Java in Indonesia, is a marine national park with a zonation-based approach, designated by the local government due to its rich coral reef biodiversity. Unfortunately, there is a limited amount of research regarding the prevalence of coral diseases in coral reefs located on the islands. We analyzed the coral reef lesion assemblages at 6 sites within 3 designated zones, namely Tourism, Aquaculture, and Core zones. Our investigation aimed to determine (1) the types, prevalence, and patterns of coral lesions, (2) the correlation between coral cover and lesion prevalence, and (3) the susceptibility of coral taxa to lesions. A significant difference of 80.54% in the total number of coral lesions was observed between the tourism zone (24.34%) and the core zone (10.36%). Fourteen different lesion types were identified; among the non-disease lesions, sediment damage was the most prevalent (9.95%), followed by disease lesions caused by white syndrome (3.7%). A correlation was found between the cover of dominant coral taxa and the prevalence of lesions (disease and non-disease) at all sites. Mean lesion prevalence across all zones ranged from moderate to high categories. These findings present current data on the distribution of coral lesions and their patterns across zones around Karimunjawa Island. Research on the etiology and epidemiology of coral lesions should be promoted to identify ways to prevent the spread of coral diseases in Karimunjawa.

Transglobal spread of an ecologically relevant sea urchin parasite.

Mass mortality of the dominant coral reef herbivore Diadema antillarum in the Caribbean in the early 1980s contributed to a persistent phase shift from coral- to algal-dominated reefs. In 2022, a scuticociliate most closely related to Philaster apodigitiformis caused further mass mortality of D. antillarum across the Caribbean, leading to >95% mortality at affected sites. Mortality was also reported in the related species Diadema setosum in the Mediterranean in 2022, though the causative agent of the Mediterranean outbreak has not yet been determined. In April 2023, mass mortality of Diadema setosum occurred along the Sultanate of Oman's coastline. Urchins displayed signs compatible with scuticociliatosis including abnormal behavior, drooping and loss of spines, followed by tissue necrosis and death. Here we report the detection of an 18S rRNA gene sequence in abnormal urchins from Muscat, Oman, that is identical to the Philaster strain responsible for D. antillarum mass mortality in the Caribbean. We also show that scuticociliatosis signs can be elicited in Diadema setosum by experimental challenge with the cultivated Philaster strain associated with Caribbean scuticociliatosis. These results demonstrate the Philaster sp. associated with D. antillarum mass mortality has rapidly spread to geographically distant coral reefs, compelling global-scale awareness and monitoring for this devastating condition through field surveys, microscopy, and molecular microbiological approaches, and prompting investigation of long-range transmission mechanisms.

Presence of coral-killing sponges in Okinawan mesophotic coral ecosystems

Shallow reefs worldwide are degrading due to multiple threats. Mesophotic coral ecosystems (MCEs; 30–150 m depth) have been investigated for their diversity and potential to serve as a coral refuge and re-seed shallow reefs. However, recent studies showed that MCEs are also disturbed by various factors, including diseases, pollution, storms, and thermal-induced bleaching. Among the disturbances, coral-killing sponges are also known to decimate many Indo-Pacific shallow reefs but are rarely reported at mesophotic depths. Here, we report the first comprehensive assessment of the coral-killing sponges Chalinula nematifera (de Laubenfels, 1954) and Terpios hoshinota Rützler and Muzik, 1993 in MCEs. Specifically, we investigated (1) their prevalence, (2) sponge-affected corals, and (3) coral-sponge interaction types at 40 m depth in Okinawa, southern Japan. We found that C. nematifera and T. hoshinota were present but at low prevalences, with the highest mean cover of 3.8% and 1.8%, respectively. Although both species appeared to be substrate-generalists, they mainly affected the dominant coral taxa, such as branching corals Acropora tenella and Seriatopora sp. Both sponges mainly interacted with corals by overgrowth, followed by tissue and peripheral contact. Due to lack of prior knowledge, it is unclear whether the current observation of the coral-killing sponges captured their expansion, decline, or steady state in Okinawan MCEs. Thus, this study provides unprecedented insights about coral-killing sponges at mesophotic depths which highlights the need to monitor more MCEs globally, prioritizing regions with shallow reefs that are already threatened by these sponges.

Divergent bleaching and recovery trajectories in reef-building corals following a decade of successive marine heatwaves.

Increasingly frequent marine heatwaves are devastating coral reefs. Corals that survive these extreme events must rapidly recover if they are to withstand subsequent events, and long-term survival in the face of rising ocean temperatures may hinge on recovery capacity and acclimatory gains in heat tolerance over an individual's lifespan. To better understand coral recovery trajectories in the face of successive marine heatwaves, we monitored the responses of bleaching-susceptible and bleaching-resistant individuals of two dominant coral species in Hawai'i, Montipora capitata and Porites compressa, over a decade that included three marine heatwaves. Bleaching-susceptible colonies of P. compressa exhibited beneficial acclimatization to heat stress (i.e., less bleaching) following repeat heatwaves, becoming indistinguishable from bleaching-resistant conspecifics during the third heatwave. In contrast, bleaching-susceptible M. capitata repeatedly bleached during all successive heatwaves and exhibited seasonal bleaching and substantial mortality for up to 3 y following the third heatwave. Encouragingly, bleaching-resistant individuals of both species remained pigmented across the entire time series; however, pigmentation did not necessarily indicate physiological resilience. Specifically, M. capitata displayed incremental yet only partial recovery of symbiont density and tissue biomass across both bleaching phenotypes up to 35 mo following the third heatwave as well as considerable partial mortality. Conversely, P. compressa appeared to recover across most physiological metrics within 2 y and experienced little to no mortality. Ultimately, these results indicate that even some visually robust, bleaching-resistant corals can carry the cost of recurring heatwaves over multiple years, leading to divergent recovery trajectories that may erode coral reef resilience in the Anthropocene.

Cellular plasticity facilitates phenotypic change in a dominant coral’s Symbiodiniaceae assemblage

Coral-associated dinoflagellates (Symbiodiniaceae) are photosynthetic endosymbionts that influence coral acclimation, as indicated by photo-endosymbiotic phenotypic variance across different environmental conditions. Symbiont shuffling (shifts in endosymbiont community composition), changes in endosymbiont cell density, and cellular plasticity have all been proposed as acclimation mechanisms. However, few studies have been able to partition which of the three strategies were responsible for observed phenotypic variance. Using a combination of metabarcoding and flow cytometry, we simultaneously characterized Acropora pulchra-associated Symbiodiniaceae assemblages at the community, population, and individual level under natural environmental conditions to deduce whether seasonal phenotypic change and site-related phenotypic variation of Symbiodiniaceae assemblages is a product of symbiont shuffling or cellular plasticity. Symbiodiniaceae assemblages displayed season-specific phenotypic variance, while Symbiodiniaceae community composition was geographically structured and cell density showed limited data structure. Based on these patterns, we reveal that cellular plasticity of Symbiodiniaceae was the source of a phenotypic variation, thus indicating that cellular plasticity is a mechanism for acclimation to mild environmental change.

Bathymetric segregation among demersal benthos and its contributions to the differences in the bycatches on bottom fisheries in the Emperor Seamounts area, Northwestern Pacific Ocean

The need for the management of commercially targeted species and surrounding ecosystems has become more apparent in conjunction with the thriving commercial exploration of open seas. Despite the growing global interest in how fishing activity impacts seamount ecosystems, data regarding to the fishing impacts of gillnets on seamount ecosystems are scarce, and quantitative comparisons between trawls and gillnets are surprisingly limited. Our quantitative comparative studies using observer data collected at the southern Emperor Seamounts area revealed that the quantity and quality of bycatches of four key demersal benthos, denoted as Vulnerable marine ecosystem (VME) indicator taxa designated in the convention text of The North Pacific Fisheries Commission (three orders of dominant corals, Antipatharia, Scleractinia, and “Gorgonian” (Alcyonacea with solid axis), and Porifera), were not inherently different between the gear types, and operational tactics, such as depth or positions, might be prior factors largely affecting bycatches of benthic assemblages in the fishing activities carried out at Emperor Seamounts. Additionally, assessments of multiyear operational data revealed temporal shifts in the species composition of cold-water coral bycatches. Overall, the synthesis of bycatch occasions provided by scientific observers enabled us to reveal (1) the variations in bathymetric distributions and the contribution of local topographies toward demersal benthic organisms and (2) fishing operational features, such as operation positions and depth, which may strongly affect bycatches.

The rising threat of peyssonnelioid algal crusts on coral reefs

For more than a century, coral reefs have been exposed to increasing anthropogenic disturbances that have profoundly altered their community structure. These perturbations continue to challenge coral reefs in new ways as ecological paradigms are recast in the Anthropocene Epoch1. In recent decades, macroalgal blooms have blighted Caribbean reefs2, but the appearance of aggressive peyssonnelioid algal crusts (PAC) that are rapidly increasing in abundance to become dominant members of the benthos on Caribbean and Indo-Pacific reefs is a novel phenomenon in tropical seas3. By pre-empting vacant space, overgrowing corals, deterring the settlement of coral larvae, and favouring a phase transition from coral to algae4, PAC are likely to accelerate the decline in dominance of corals on global reefs (Figure 1).

Modern-type reef in ancient time - Palaeoecology of a Middle Devonian coral community from Madène el Mrakib (Anti-Atlas, Morocco)

The southernmost Devonian reefs formed along the north-western margin of Gondwana. One of the best-preserved reefal palaeoecosystems of this area is found in the Givetian of Madène el Mrakib (Anti-Atlas, Morocco), exposing a vast, at least ∼1.2 km2 area of reef strata. This contribution documents the ecological succession, taxonomical structure and palaeoecology of this exceptionally diverse reef community. Combined evidence from the sedimentary succession and faunal changes records a trend of progressive shallowing. The ecological succession is characterised by an upsection increase in the abundance and diversity of the reef-building biota, accompanied by a shift in the dominant morphotypes of tabulate corals from platy (pioneering and diversification stages) to branching and massive forms (climax stage). The exceptionally rich, shallow-water reef community occurs in the uppermost part of the succession. The climax community is dominated by extraordinarily large, branching tabulate corals (mostly Thamnopora), with the notable role of massive alveolitid, heliolitid and favositid tabulates, as well as large, solitary rugose corals. A surprising feature of this assemblage is the rather subordinate role of stromatoporoids, generally regarded as a main component of the shallow-water Devonian reefs. Remarkably, the observed community structure is closer to that typical of modern shallow-water reefs, dominated by branching scleractinian corals from the family Acroporidae, than to the archetypal Paleozoic reefs. These distinctive traits of the Madène el Mrakib community make it particularly suitable for comparative studies between Devonian and modern reef ecosystems, showing that these communities shared notable similarities in terms of their ecological successions, zonation patterns, dominance of branching corals and high morphological variability in shallow-water environments, and adaptations of corals to turbulent conditions.

Effects of elevated temperature and copper exposure on the physiological state of the coral Galaxea fascicularis

The co-occurrence of elevated seawater temperature and local stressors (heavy metal contamination) affects the ecophysiology of phototrophic species, and represents a risk to the environmental quality of coral reefs. Therefore, we investigated the effects of both Cu alone and Cu in combination with elevated temperature (ET) on the physiology of the coral Galaxea fascicularis, and measured the parameters related to the photo-physiology and oxidative state. G.fascicularis is one of the dominant coral species in the South China Sea which exhibits strong adaptability to environmental stress. We exposed the common coral species G.fascicularis to a series of environmentally relevant concentrations of Cu at 29 °C (normal temperature, NT) and 32 °C (elevated temperature, ET) for 96 h. Single polyps were used in the experiments, which reduced individual variability when compared to the coral colonies. The results suggested that: i) Cu or ET had significant negative effects on the actual operating ability of photosystem Ⅱ (PSII), but not on the maximal chlorophyll fluorescence in darkness (Fv/Fm). ii) Symbiodiniaceae density was significantly reduced by high Cu concentrations, for Cu-NT and Cu-ET, a high concentration of Cu (40 μg/L) significantly impacted Symbiodiniaceae density, causing a 75.4% and 81.0% decrease, respectively. iii) the content of malondialdehyde (MDA) in coral tissues increased significantly under Cu-ET. iv) a certain range of copper concentration (25–30 μg/L) increased the pigment content of the Symbiodiniacea. Our results indicated that the combined stressors of Cu and ET made the coral tissue sloughed, caused the coral tissue damaged by lipid oxidation, reduced the photosynthetic capacity of the Symbiodiniacea, and led to the excretion of Symbiodiniacea.

Microbiomes and metabolomes of dominant coral reef primary producers illustrate a potential role for immunolipids in marine symbioses

The dominant benthic primary producers in coral reef ecosystems are complex holobionts with diverse microbiomes and metabolomes. In this study, we characterize the tissue metabolomes and microbiomes of corals, macroalgae, and crustose coralline algae via an intensive, replicated synoptic survey of a single coral reef system (Waimea Bay, Oʻahu, Hawaii) and use these results to define associations between microbial taxa and metabolites specific to different hosts. Our results quantify and constrain the degree of host specificity of tissue metabolomes and microbiomes at both phylum and genus level. Both microbiome and metabolomes were distinct between calcifiers (corals and CCA) and erect macroalgae. Moreover, our multi-omics investigations highlight common lipid-based immune response pathways across host organisms. In addition, we observed strong covariation among several specific microbial taxa and metabolite classes, suggesting new metabolic roles of symbiosis to further explore.

Good coral cover and high diversity of corals in non-MPA reefs of the Verde Island Passage as a basis for increased protection and conservation

The Verde Island Passage (VIP) is a region in the Philippines with very high marine biodiversity. Baseline coral assessments were conducted in selected sites in the four provinces of the VIP (Batangas, Marinduque, Occidental Mindoro, and Oriental Mindoro) to compare coral abundance and biodiversity in Marine Protected Area (MPA) and non-MPA sites that were subjected to anthropogenic stressors. A total of eight sites were surveyed to measure average hard coral cover (HCC) relative to other benthic components. Generic richness and the dominant coral genera were also obtained for the eight sites. The average HCC and generic richness of Batangas MPA and Batangas non-MPA were (39.82 ± 7.59%, 22 coral TAUs) and (38.80 ± 5.56%, 27 coral TAUs), respectively. The average HCC and generic richness of Marinduque MPA and Marinduque non-MPA were (25.58 ± 2.37%, 13 coral TAUs) and (35.73 ± 4.05%, 17 coral TAUs), respectively. The average HCC and generic richness of Occidental Mindoro MPA and Occidental Mindoro non-MPA were (49.49 ± 4.50%, 26 coral TAUs) and (32.32 ± 5.60%, 19 coral TAUs), respectively. The average HCC and generic richness of Oriental Mindoro MPA and Oriental Mindoro non-MPA were (25.02 ± 4.72%, 24 coral TAUs) and (5.93 ± 2.10%, 10 coral TAUs), respectively. Batangas non-MPA and Marinduque non-MPA showed potential to become MPAs due to their higher HCC and generic richness which were attributed to natural disturbances and duration of local reef management in their MPA counterparts. Continued monitoring and assessment should be done to build on the growing database of biodiversity data that is being compiled for the VIP.

Study of the sea urchins (echinoidea) influence on the coral reef communities in the Nusa Dua Bali conservation area

Coral reef ecosystems are crucial for marine ecosystems as they support various other marine organisms. Sea urchins, such as Diadema setosum and Echinometra mathaei influence the coral reef communities by consuming algae that disrupt coral growth. This study aims to determine reef star coral media quantity, identify the dominant coral species at three points (BTN, Coral Garden, and Cluster 5) in Nusa Dua Beach, and assess the influence of sea urchins on coral reefs. The sampling method used was Purposive sampling, and visual observations which were conducted from June 27 to June 30, 2022. Results showed the varying sea urchin populations, with Acropora sp. and Pocillopora sp. dominating at BTN, Acropora sp. and Pectinia sp. at Coral Garden, and Acropora sp. at Cluster 5. The findings suggest that sea urchins play a key role in maintaining coral reefs by consuming macroalgae and supporting coral survival.