Acanthaster Planci Research Articles

Preparing for and managing crown-of-thorns starfish outbreaks on reefs under threat from interacting anthropogenic stressors

Crown-of-thorns starfish (CoTS) outbreaks rank among the greatest threats to coral throughout the Indo-Pacific. In the future, reefs already stressed by CoTS will be further burdened by overfishing and nutrient loading. How much these two factors will exacerbate CoTS outbreak severity is still uncertain. Furthermore, the CoTS management literature has focused on the Great Barrier Reef, whereas outbreak damage is rising across the Indo-Pacific. Here, we use a metacommunity model to simulate CoTS outbreaks in areas with high and growing levels of fishing pressure and offshore nutrient input. We model outbreaks on reefs adjacent to two cities within the range of CoTS that have less prior literature coverage: Cebu City, Philippines, and Jeddah, Saudi Arabia. We observe that the combination of population increases and urbanization of previously rural areas can drive complex patterns of multi-stressor interaction. We find that CoTS removal on intermediate spatial scales significantly improves regional-scale coral health, and provide guidelines under which each of four CoTS management strategies is optimal for conservation. We find that coral decline due to overfishing can be sharper on reefs with CoTS, and that nutrification can induce a shift from discrete outbreak waves to continuous CoTS presence. Our work shows the importance of long-term planning for reef management, and highlights how reef stressors can interact in potentially unforeseen ways.

Phytoplankton community structure and environmental factors during the outbreak of Crown-of-Thorns Starfish in Xisha Islands, South China Sea

The “larval starvation hypothesis” proposed that the growing frequency of Crown-of-Thorns Starfish (CoTS) outbreaks could be attributed to increased availability of phytoplankton. However, comprehensive field investigation on the living environment of CoTS larvae and the availability of phytoplankton are still lacking. A cruise was conducted in June 2022 in Xisha Islands, South China Sea, to study the interaction between environmental conditions and phytoplankton communities during CoTS outbreak period. The average concentrations of dissolved inorganic phosphorus (0.05 ± 0.01 μmol L−1), dissolved inorganic nitrogen (0.66 ± 0.8 μmol L−1) and chlorophyll a (0.05 ± 0.05 μg L−1) suggested that phytoplankton may be limited for CoTS larvae in Xisha Islands. Microscopic observation and high-throughput sequencing were used to study the composition and structure of the phytoplankton communities. Bacillariophyta predominated in phytoplankton communities with the highest abundance and species richness. 29 dominant species, including 4 species with size-range preferred by CoTS larvae, were identified in Xisha Islands. The diversity index of all stations indicated a species-rich and structure-stable phytoplankton community in Xisha Islands during the period of CoTS outbreak, which may contribute to CoTS outbreak. These findings revealed the structure of phytoplankton community and environmental factors in the study area during CoTS outbreak, providing the groundwork for future research into the causes and processes of CoTS outbreak.

Ecological Effects of Predator Harvesting and Environmental Noises on Oceanic Coral Reefs.

Coral reefs provide refuge for prey and are important for the preservation of an oceanic ecosystem. However, they have been experiencing severe destruction by environmental changes and human activities. In this paper, we propose and analyze a tri-trophic food chain model consisting of coral, Crown-of-thorns starfish (CoTS), and triton in deterministic and stochastic environments. We investigate the effects of harvesting in the deterministic system and environmental noises in the stochastic system, respectively. The existence of possible steady states along with their stability is rigorously discussed. From the economic perspective, we examine the existence of the bionomic equilibrium and establish the optimal harvesting policy. Subsequently, the deterministic system is extended to a stochastic system through nonlinear perturbation. The stochastic system admits a unique positive global solution initiating from the interior of the positive quadrant. The long-time behaviors of the stochastic system are explored. Numerical simulations are provided to validate and complement our theoretical results. We show that over-harvesting of triton is not beneficial to coral reefs and modest harvesting of CoTS may promote sustainable growth in coral reefs. In addition, the presence of strong noises can lead to population extinction.

Identification of Crown of Thorns Starfish (COTS) using Convolutional Neural Network (CNN) and attention model.

Coral reefs play important roles in the marine ecosystem, from providing shelter to aquatic lives to being a source of income to others. However, they are in danger from outbreaks of species like the Crown of Thorns Starfish (COTS) and the widespread coral bleaching from rising sea temperatures. The identification of COTS for detecting outbreaks is a challenging task and is often done through snorkelling and diving activities with limited range, where strong currents result in poor image capture, damage of capturing equipment, and are of high risks. This paper proposes a novel approach for the automatic detection of COTS based Convolutional Neural Network (CNN) with an enhanced attention module. Different pre-trained CNN models, namely, VGG19 and MobileNetV2 have been applied to our dataset with the aim of detecting and classifying COTS using transfer learning. The architecture of the pre-trained models was optimised using ADAM optimisers and an accuracy of 87.1% was achieved for VGG19 and 80.2% for the MobileNetV2. The attention model was developed and added to the CNN to determine which features in the starfish were influencing the classification. The enhanced model attained an accuracy of 92.6% while explaining the causal features in COTS. The mean average precision of the enhanced VGG-19 with the addition of the attention model was 95% showing an increase of 2% compared to only the enhanced VGG-19 model.

Ultrasensitive and on-site eDNA detection for the monitoring of crown-of-thorns starfish densities at the pre-outbreak stage using an electrochemical biosensor

The coral reef crisis has significantly intensified over the last decades, mainly due to severe outbreaks of crown-of-thorns starfish (COTS). Current ecological monitoring has failed to detect COTS densities at the pre-outbreak stage, thus preventing early intervention. In this work, we developed an effective electrochemical biosensor modified by a MoO2/C nanomaterial, as well as a specific DNA probe that could detect trace COTS environmental DNA (eDNA) at a lower detection limit (LOD = 0.147 ng/μL) with excellent specificity. The reliability and accuracy of the biosensor were validated against the standard methods by an ultramicro spectrophotometer and droplet digital PCR (p > 0.05). The biosensor was then utilized for the on-site analysis of seawater samples from SYM-LD and SY sites in the South China Sea. For the SYM-LD site suffering an outbreak, the COTS eDNA concentrations were 0.33 ng/μL (1 m, depth) and 0.26 ng/μL (10 m, depth), respectively. According to the ecological survey, the COTS density was 500 ind/hm2 at the SYM-LD site, verifying the accuracy of our measurements. At the SY site, COTS eDNA was also detected at 0.19 ng/μL, but COTS was not found by the traditional survey. Hence, larvae were possibly present in this region. Therefore, this electrochemical biosensor could be used to monitor COTS populations at the pre-outbreak stages, and potentially serve as a revolutionary early warning method. We will continue to improve this method for picomolar or even femtomolar detection of COTS eDNA.

Novel rubble-dwelling predators of herbivorous juvenile crown-of-thorns starfish (Acanthaster sp.)

Crown-of-thorns starfish (CoTS) are a pervasive coral predator prone to population outbreaks that have damaged coral reefs across Australia and the wider Indo-Pacific. CoTS population control through predation has been suggested as a primary mechanism that suppresses their outbreaks. However, the nature and rates of predation on CoTS are poorly resolved, especially for early life-history stages where they are expected to be most vulnerable. Here, we provide results from the first investigation of predators of CoTS during their rubble-dwelling, herbivorous, juvenile phase. We assessed the capacity of 104 common species of the rubble cryptofauna found across Heron Reef, Great Barrier Reef, Australia, to consume early-stage juvenile CoTS (0.8–3.8 mm) using controlled feeding experiments with laboratory-raised juveniles. We identified 26 novel CoTS predators, but only 10 species that regularly consumed juvenile CoTS in their entirety. Most cases of predation resulted in severed bodies and missing arms (i.e. sublethal predation) but not total consumption. We highlight one crustacean predator, Schizophrys aspera, the red decorator crab, which consumed whole juvenile CoTS in 89% of feeding trials and in excess of 5 CoTS d−1 in natural rubble mesocosms with alternative prey. This work emphasises the importance of predators at the critical juvenile stage that may control the build-up of CoTS populations prior to being detectable as an outbreak population.

Chloroform Fraction from Methanol Extract of Starfish Acanthaster planci Stimulates Catfish (Clarias sp.) Macrophage Immunomodulatory Activity

Catfish (Clarias sp.) is Indonesia's most important and popular freshwater commodity, widely cultured and intensively grown. This study is aimed to find out the effects of the chloroform fraction from a methanol extract of Acanthaster planci on non-specific immunity in Clarias sp. Thin Layer Chromatography analysis of the methanol extract's chloroform fraction yielded three fractions: FrKl3.1, FrKl3.2, and FrKl3.3. The FrKl3.3 fraction of Acanthaster planci had a significant influence on Phagocytic Activity at doses of 0.1 (54.09 ± 8.99 %), 0.3 (48.16 ± 3.34 %), 0.5 (50.39 ± 5.71 %), and 0.7 mg/kg Body Weight (46.58 ± 0.37 %). At 0.5 mg/kg Body Weight (4.03 ± 1.40 %), the Phagocytic Index of FrKl3.2 was significantly higher than the control. At 0.5 mg/kg Body Weight (38.22 ±1.43 cell 106/ml) and 0.7 mg/kg BW (40.41 ± 1.92 cell 106/ml), the number of leukocytes/white blood cells was significantly higher than the control. Nitroblue Tetrazolium and Total Plasma Protein were not significantly different from the control. Based on the results, the FrKl3.3 was leading on phagocytic capacity and number of leukocytes

Molecular basis for inactivity of mammalian delta iGluRs.

Ionotropic glutamate receptors (iGluRs) are ligand-gated cation channels that mediate fast excitatory signaling between neurons. Transmembrane current through most iGluRs is activated by the binding of neurotransmitter agonists glutamate, glycine, and/or D-serine to the extracellular ligand binding domain. Delta-type iGluRs appear unique, as isolated rat and human delta iGluRs are not activated by these neurotransmitters, despite evidence for cell surface expression of the receptors and binding of D-serine and glycine to the ligand binding domain. We questioned the molecular basis for this unique function and therefore examined the broader delta iGluR family and its relation to other iGluRs. We utilized phylogenetic analysis, electrophysiological experiments with delta iGluRs from different animals, and site-directed mutagenesis. First, our phylogenetic analysis showed that delta iGluRs are found in numerous bilaterian animals and that they are closely related to AMPA- and kainate-type iGluRs. Secondly, electrophysiology experiments revealed that delta iGluRs from various invertebrates are indeed functional transmitter-activated ion channels, and interestingly they are gated not only by glutamate, glycine and D-Serine but also by the transmitter GABA. Robust heterologous expression of the delta iGluR from starfish Acanthaster planci enabled pharmacological characterization of this receptor. This showed, for example, sensitivity to AMPA/kainate receptor-type competitive antagonists such as NBQX and DNQX, reflecting the shared ancestry of delta iGluRs and their AMPA/kainate receptor cousins. Finally, we have dissected the molecular basis for the loss of transmitter-gated currents during the evolution of rat/human delta iGluRs with mutagenesis and electrophysiology. Our comparative analysis identified certain amino acid residues whose substitution likely gave rise to the mysterious inactivity rat/human delta iGluRs. Our results offer insight into the mechanism of iGluR activation and highlight the use of comparative approaches in understanding protein function.

Settlement cue selectivity by larvae of the destructive crown-of-thorns starfish.

Population irruptions of crown-of-thorns starfish (COTS) cause extensive degradation of coral reefs, threatening the structure and function of these important ecosystems. For population irruptions to initiate and spread, large numbers of planktonic larvae have to successfully transition into their benthic life-history stage (i.e. settlement), whereby larval behaviour and the presence of settlement cues may shape spatial patterns of recruitment and adult densities. Our results demonstrate that a wide range of coralline algae species induce COTS larvae to settle; however, the capacity to promote settlement success varied manyfold among algal species, ranging from greater than 90% in Melyvonnea cf. madagascariensis to less than 2% in Lithophyllum cf. kotschyanum and two Porolithon species at 24 h. Because many coralline algae species that promote high settlement success are prevalent in shallow reef habitats, our findings challenge the hypothesis that COTS larvae predominantly settle in deep water. Considering both larval behaviour and algal ecology, this study highlights the ecological significance of coralline algae communities in driving recruitment patterns of COTS. More specifically, the local abundance of highly inductive coralline algae (especially, Melyvonnea cf. madagascariensis) may explain some of the marked spatial heterogeneity of COTS populations and the incidence of population irruptions.

Conditions of Megabenthos on Coral Reef Ecosystem in Seribu Islands National Park, Jakarta, Indonesia

Seribu Islands National Park is located off the north coast of Jakarta and consists of 110 islands. This study aims to determine the distribution and density of megabenthos in coral reef ecosystems in the Seribu Islands National Park. This research was conducted in November 2021 in the Seribu Islands National Park waters. Megabenthos observations were carried out using the Benthos Belt Transect method, a development of the Belt Transect Method for monitoring megabenthos combined with the Reef Check Benthos method. Based on observations in the waters of the Seribu Islands National Park, five types of megabenthos were found, including clams (Tridacna sp.), lola (Trochus sp.), Crown-of-torns starfish (Acanthaster planci), drupella (Drupella sp.), and sea urchins (Diadema sp.). The highest density of megabenthos was found on Kayuangin Genteng Island, with a density of 8,786 ind/ha, while the lowest was on Peteloran Barat Island, with 429 ind/ha. Based on the type of megabenthos at all observation stations, the most abundant megabenthos found was Diadema sp., with a density of 43,397 ind/ha. In comparison, the least was Acanthaster planci of 214 ind/ha. Megabenthos in the Seribu Islands National Park waters are in various conditions.

Neuritogenic steroid glycosides from crown-of-thorns starfish: Possible involvement of p38 mitogen-activated protein kinase and attenuation of cognitive impairment in senescence-accelerated mice (SAMP8) by peripheral administration

Novel steroid glycosides, acanthasterosides A1, B1, and B3, have been isolated from the crown-of-thorns starfish Acanthaster planci. Acanthasterosides B1 and B3 having two separated xyloses induced neurite outgrowth as like as nerve growth factor (NGF) in the rat pheochromocytoma cell line PC12, whereas acanthasteroside A1, having one xylose, did not induce neurite outgrowth. The acanthasteroside B3 induced neuritogenesis via the significant activation of p38 mitogen-activated protein kinase after the activation of the small G-protein Cdc42 rather than via Ras–MEK–ERK pathway that is predominantly activated by NGF. Following subcutaneous administration, acanthasteroside B3 attenuated cognitive impairment of senescence-accelerated mice (SAMP8) in two different cognitive tests. Liquid chromatography–mass spectrometry-assisted quantitative analysis demonstrated that acanthasteroside B3 could be transported into the brain via the circulatory system in mice. Thus, acanthasteroside B3 (and possibly B1) are a novel class of potential drug candidates for neurodegenerative diseases.

Sex-specific expression of pheromones and other signals in gravid starfish

BackgroundMany echinoderms form seasonal aggregations prior to spawning. In some fecund species, a spawning event can lead to population outbreaks with detrimental ecosystem impacts. For instance, outbreaks of crown-of-thorns starfish (COTS), a corallivore, can destroy coral reefs. Here, we examine the gene expression in gravid male and female COTS prior to spawning in the wild, to identify genome-encoded factors that may regulate aggregation and spawning. This study is informed by a previously identified exoproteome that attracts conspecifics. To capture the natural gene expression profiles, we isolated RNAs from gravid female and male COTS immediately after they were removed from the Great Barrier Reef. ResultsSexually dimorphic gene expression is present in all seven somatic tissues and organs that we surveyed and in the gonads. Approximately 40% of the exoproteome transcripts are differentially expressed between sexes. Males uniquely upregulate an additional 68 secreted factors in their testes. A suite of neuropeptides in sensory organs, coelomocytes and gonads is differentially expressed between sexes, including the relaxin-like gonad-stimulating peptide and gonadotropin-releasing hormones. Female sensory tentacles—chemosensory organs at the distal tips of the starfish arms—uniquely upregulate diverse receptors and signalling molecules, including chemosensory G-protein-coupled receptors and several neuropeptides, including kisspeptin, SALMFamide and orexin.ConclusionsAnalysis of 103 tissue/organ transcriptomes from 13 wild COTS has revealed genes that are consistently differentially expressed between gravid females and males and that all tissues surveyed are sexually dimorphic at the molecular level. This finding is consistent with female and male COTS using sex-specific pheromones to regulate reproductive aggregations and synchronised spawning events. These pheromones appear to be received primarily by the sensory tentacles, which express a range of receptors and signalling molecules in a sex-specific manner. Furthermore, coelomocytes and gonads differentially express signalling and regulatory factors that control gametogenesis and spawning in other echinoderms.

Megabenthos monitoring in Ternate, North Maluku

Several megabenthos groups have important economic and ecological values- also play an important role in the condition and stability of coral reef ecosystems. The important role of this megabenthos group makes it a potential object as an indicator to assess coral reef health. This study aimed to determine the condition of coral reefs by monitoring the megabenthos. The targeted megabenthos in this study consisted of eight groups (Holothuria sp., Diadema sp., Blue Starfish, Tridacna spp., Drupella, Trochus niloticus, Acanthaster planci, and Lobsters). Data collection was carried out in Ternate Waters at 14 stations using the Benthos Belt Transect method. The analysis was carried out by examining the presence and the number of species, distribution and density of each station, density of each type of megabenthos, and ecological indices (dominance index, diversity index, and evenness index). The results of the study found a total of 375 individuals. The group of megabenthos species that were always found at each station was coral polyp-eating snails (Drupella). On the other hand, Acanthaster planci and lobster were groups of megabenthos species found only at a few stations. Overall, Drupella was the most dominant type of megabenthos during observation, which may be related to overfishing at that location. Several groups of fish were natural predators of Drupella. Their numbers in the wild are decreasing due to overfishing. The dominance that occurred during observations was closely related to the health condition of coral reefs and the diversity of coral species as the habitat of megabenthos.

Biochemical metabolomic profiling of the Crown-of-Thorns Starfish (Acanthaster): New insight into its biology for improved pest management

The Crown-of-Thorns Starfish (COTS), Acanthaster species, is a voracious coral predator that destroys coral reefs when in outbreak status. The baseline metabolite and lipid biomolecules of 10 COTS tissues, including eggs from gravid females, were investigated in this study to provide insight into their biology and identify avenues for control. Targeted and untargeted metabolite- and lipidomics-based mass spectrometry approaches were used to obtain tissue-specific metabolite and lipid profiles. Across all COTS tissues, 410 metabolites and 367 lipids were identified. Most abundant were amino acids and peptides (18.7%) and wax esters (17%). There were 262 metabolites and 192 lipids identified in COTS eggs. Wax esters were more abundant in the eggs (30%) followed by triacylglycerols (TG), amino acids, and peptides. The diversity of asterosaponins in eggs (34) was higher than in tissues (2). Several asterosaponins known to modulate sperm acrosome reaction were putatively identified, including glycoside B, asterosaponin-4 (Co-Aris III), and regularoside B (asterosaponin A). The saponins saponin A, thornasteroside A, hillaside B, and non-saponins dictyol J and axinellamine B which have been shown to possess defensive properties, were found in abundance in gonads, skin, and radial nerve tissues. Inosine and 2-hexyldecanoic acid are the most abundant metabolites in tissues and eggs. As a secondary metabolite of purine degradation, inosine plays an important role in purine biosynthesis, while 2-hexyldecanoic acid is known to suppress side-chain crystallization during the synthesis of amphiphilic macromolecules (i.e., phospholipids). These significant spatial changes in metabolite, lipid, and asterosaponin profiles enabled unique insights into key biological tissue-specific processes that could be manipulated to better control COTS populations. Our findings highlight COTS as a novel source of molecules with therapeutic and cosmetic properties (ceramides, sphingolipids, carnosine, and inosine). These outcomes will be highly relevant for the development of strategies for COTS management including chemotaxis-based biocontrol and exploitation of COTS carcasses for the extraction of commercial molecules.

A new species of crown-of-thorns sea star, Acanthaster benziei sp. nov. (Valvatida: Acanthasteridae), from the Red Sea

A new species of crown-of-thorns sea star (CoTS), Acanthaster benziei sp. nov., is described based on four specimens collected from Saudi Arabia's Red Sea coast where it inhabits coral reefs. Species delimitation from congeners in the species complex, i.e., Acanthaster planci, Acanthaster mauritiensis and Acanthaster cf. solaris, is primarily based on distinct and diagnostic mitochondrial DNA sequence regions. Species separation of Acanthaster benziei is additionally justified due to diagnostic morphological characters: fewer arms; narrower and thinner spines; fanned spine tips in primary and latero-oral spines; a wider tip or tapering shape in circumoral spines; and rhombus-shaped oral pedicellariae.

A Review of the Giant Triton (Charonia tritonis), from Exploitation to Coral Reef Protector?

Charonia tritonis (Charoniidae), one of the largest marine gastropods and an echinoderm specialist, preys on Crown-of-Thorns starfish (CoTS), a recurring pest that continues to be a leading cause of coral mortality on Indo-Pacific reefs. Widespread historical exploitation has impacted their numbers, with standing populations considered rare throughout their habitat. Their life-stage attributes, i.e., teleplanic larvae, planktotrophic phase spanning years permitting transoceanic dispersal, and recruitment to coral reefs through oceanic influx with intense larval mortality, have likely hindered their recovery. Decline in numbers is hypothesised to account partially for periodic CoTS outbreaks, yet predator-prey dynamics between these two species that might influence this are poorly understood. The C. tritonis excretory secretome elicits a proximity deterrence effect on CoTS, the nature of which is under investigation as a possible tool in CoTS biocontrol scenarios. However, specificity and zone of impact in situ are unknown, and whether the mere presence of C. tritonis and/or predation pressure has any regulatory influence over CoTS populations remains to be established. The fundamental taxonomy and distinctive characteristics, biology and ecology of C. tritonis is summarized, and knowledge gaps relevant to understanding their role within coral reefs identified. Information is provided regarding exploitation of C. tritonis across its habitat, and prospects for conservation interventions, including captive rearing and stock enhancement to repopulate local regions, are discussed. Its predator-prey ecology is also examined and potential to mitigate CoTS considered. Recommendations to direct future research into this predator and for its inclusion in a CoTS integrated pest management strategy to improve coral reef health are offered.

Molecular and Functional Characterization of a Novel Kunitz-Type Toxin-like Peptide in the Giant Triton Snail Charonia tritonis.

It has been reported that the giant triton snail (Charonia tritonis) inserts its large proboscis and then injects venom or acid saliva from its salivary gland into its prey, the crown-of-thorns starfish Acanthaster planci (COTS), paralyzing it. A full-length cDNA sequence of the C. tritonis Ct-kunitzin gene was obtained by RACE PCR based on a transcriptomic database constructed by our laboratory (data not published), which contains an open reading frame (ORF) sequence with a length of 384 bp including a 1-32aa Kunitz domain. The Ct-kunitzin peptide was synthesized by solid-phase polypeptide methods according to its conserved amino acid sequence, with a molecular weight of 3746.0 as well as two disulfide bonds. Renatured Ct-kunitzin was injected into mice ventricles to evaluate its potential function. Compared with the normal control group (physiological saline), the spontaneous locomotor activity of the Ct-kunitzin group decreased significantly. There was a significant effect on Ct-kunitzin on mice grip strength in the grip strength test. In addition, Ct-kunitzin exhibited remarkable biological activity in suppressing pain in the pain thresholds test. There were no significant differences between the Ct-kunitzin group and the normal control group in terms of various hematological indexes and histopathological observations. When tested in COTS, the most significant histological change was the destruction, disorganization, and significant reduction in the amount of COTS tube feet tissues. Altogether, the potential paralyzing effect on mice suggests that Ct-kunitzin is a possible agent for novel drug development.

Prevalence and abundance of coral disease in Aceh Besar regency Aceh, Indonesia

The aims of this research was to knew the prevalence, abundance and types of coral diseases detected in Peukan Bada Aceh Besar Regency. Method used in this research was a 20x2m belt transect with 3 replicates. Results show that the prevalence value was between 27,94% – 58,25%. The value was quite higher if compared with other prevalence on some place in indonesia. Average value of coral disease abundance in this research was 0,23 ind/m2. There was 13 types of coral disease found during sampling, including Fish Bite, Drupella Predation, Acanthaster planci Predation, White Syndrome, Ulcerative White Spot, Focal Bleaching, Non-Focal Bleaching, Invertebrate Galls, Sponge Overgrowth, Cyanobacteria, Pigmentation Response, Sedimentation Damage, Algae Overgrowth. The most infected coral genus was Acropora with branching growth form.Keywords:AbundanceConditionCoral diseasePrevalence

Hubungan kepadatan megabentos dan padatan tersuspensi terhadap tutupan terumbu karang pada Kawasan Konservasi Pesisir dan Pulau-Pulau Kecil (KKP3K) Tapanuli Tengah, Sumatera Utara

This research was conducted in March 2022 in the Marine Conservation Area, Tapanuli Tengah Sumatera Utara. This study aims to determine the relationship between coral cover, total suspended solid and the density of megabenthos found in the Marine Conservation Area, Tapanuli Tengah Sumatera Utara. The method used in this study is a survey method and spatial analysis tools method. Coral cover data was collected using the LIT (Line Intercept Transect) method and megabenthos data was collected using the BBT (Benthos Belt Transect) method. The results showed that Marine Conservation Area, Tapanuli Tengah, Sumatera Utara had a good percentage of coral cover. Not all types of megabenthos are present at every station, the highest density of megabenthos is Tridacninae, while the lowest density is Acanthaster planci. Then it was also found that there was an effect of the percentage of coral cover on economic and non-economic megabenthos. Total suspended solid consentration in this area was found with an average of 8.27 mg/l. Based on the regression analysis in this study, showed that there was an effec of total suspended solid on percentage of coral cover.

Hubungan kondisi tutupan terumbu karang dengan kepadatan megabentos di perairan Pulau Talam Kabupaten Tapanuli Tengah Provinsi Sumatera Utara

This research was conducted in March 2022 in the waters of Talam Island, Central Tapanuli Regency, North Sumatra Province. This study aims to determine the relationship between coral cover and the density of megabenthos in the Talam Island area. The method used in this research is a survey method. Coral cover data were collected using the LIT (Line Intercept Transect) method and megabenthos data were collected using the BBT (Benthos Belt Transect) method. Observations were made at three station points with each station with a depth of 4 meters, 6 meters and 8 meters. The results showed that Talam Island had a good percentage of coral cover with an average of 54.74%. The highest density of megabenthos was Tridacninae found at each station, while the lowest density was Acanthaster planci. The overall megabenthos density has an average of 10.033 ind/ha. Coral reef cover relationship has an influence on the density of megabenthos, there is a strong positive effect on economic megabenthos and a strong negative on non-economic megabenthos.