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Coral reefs worldwide are declining due to high sea surface temperatures, causing coral bleaching and the endosymbiosis rupture between the coral polyps and the unicellular algae Symbiodinaceae. Bleached corals will likely die because Symbiodinaceae algae provide most of the energy coral colonies need. Among the newly developed strategies to prevent coral bleaching is thermal preconditioning, i.e., applying sub-lethal temperature on corals before heat stress, which has shown promising results in slowing coral bleaching. However, the cellular mechanisms that increase heat tolerance by thermal preconditioning are still unknown. This study showed that thermal preconditioning on the coral species Pocillopora damicornis postponed the adverse effects of heat stress-inducing bleaching. Thermal preconditioning was performed by exposing the coral colonies to the sub-lethal temperature of 28°C for one week, after which thermal stress was applied at 31°C for another seven days. We assessed coral bleaching by analyzing the Symbiodinaceae density, taxonomical identification, and chlorophyll concentration (Chl). Moreover, we compared the expression of Heat shock protein 70 (Hsp70), a molecular chaperone involved in cell protein protection, the activity of three antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase and the lipid peroxidation in preconditioned, non-preconditioned and control colonies. Our results showed that Chl concentration and symbiont density were higher in preconditioned corals than in non-preconditioned corals. In addition, no difference in Symbiodinaceae identity was observed. Then, preconditioned colonies had higher antioxidant enzyme activity and higher expression of Hsp70 compared to non-preconditioned colonies. According to our findings, thermal preconditioning can potentially delay coral bleaching by reducing oxidative stress and ensuring cellular homeostasis. This indicates that thermal preconditioning could be a helpfu

Coral reefs worldwide are declining due to high sea surface temperatures, causing coral bleaching and the endosymbiosis rupture between the coral polyps and the unicellular algae Symbiodinaceae. Bleached corals will likely die because Symbiodinaceae algae provide most of the energy coral colonies need. Among the newly developed strategies to prevent coral bleaching is thermal preconditioning, i.e. applying sub-lethal temperature on corals before heat stress which has shown promising results in slowing coral bleaching. However, the cellular mechanisms that increase heat tolerance by thermal preconditioning are still unknown. This study showed that thermal preconditioning on the two coral species, namely Pocillopora damicornis and Stylophora pistillata, postponed the adverse effects of heat stress-inducing bleaching. Thermal preconditioning was performed by exposing the coral colonies to the sub-lethal temperature of 28°C for one week, after which thermal stress was applied at 31°C for another seven days. We assessed coral bleaching by analyzing the Symbiodinaceae density, taxonomical identification, and chlorophyll concentration (Chl). Moreover, we compared the expression of Heat shock protein 70 (Hsp70), a molecular chaperone involved in cell protein protection, the activity of three antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase and the lipid peroxidation in preconditioned, non-preconditioned and control colonies. Our results showed that Chl concentration and symbiont density were higher in preconditioned corals than non-preconditioned corals in both coral species. In addition, no difference in Symbiodinaceae identity was observed. Then, preconditioned S. pistillata and P. damicornis had higher antioxidant enzymes activity and higher expression of Hsp70 compared to non-preconditioned colonies. Therefore, our results suggest that thermal preconditioning delayed coral bleaching in both S. pistillata and P. damicornis by mitigat

Microplastic pollution is an increasing threat to coral reefs, which are already strongly challenged by climate change -related heat stress. Although it is known that scleractinian corals can ingest microplastic, little is known about their egestion and how microplastic exposure may impair corals at physiological and cellular levels. In addition, the effects of microplastic pollution at current environmental concentration have been little investigated to date, particularly in corals already impacted by heat stress. In this study, the combined effects of these environmental threats on Pocillopora damicornis were investigated from a physical and cellular perspective. Colonies were exposed to three concentrations of polyethylene microplastic beads (no microplastic beads: [No MP], 1 mg/L: [Low MP]; 10 mg/L: [High MP]), and two different temperatures (25 degrees C and 30 degrees C) for 72 h. No visual signs of stress in corals, such as abnormal mucus production and polyp extroflection, were recorded. At [Low MP], beads adhered to colonies were ingested but were also egested. Moreover, thermally stressed colonies showed a lower adhesion and higher egestion of microplastic beads. Coral bleaching was observed with an increase in temperature and microplastic bead concentration, as indicated by a general decrease in chlorophyll concentration and Symbiodiniaceae density. An increase in lipid peroxidation was measured in colonies exposed to [Low MP] and [High MP] and an up -regulation of stress response gene hsp70 was observed due to the synergistic interaction of both stressors. Overall, our findings showed that heat stress still represents the main threat to P. damicornis, while the effect of microplastics on coral health and physiology may be minor, especially at control temperature. However, microplastics could exacerbate the effect of thermal stress on cellular homeostasis, even at [Low MP]. While reducing ocean warming is critical for preserving coral reefs, effective man

The Mediterranean is known for its marine biodiversity, especially gorgonian forests. Unfortunately, these are experiencing rapid declines due to climate change, manifested by repeated marine heat waves resulting in mass mortality events since the early 1990 s. To better understand why gorgonians are declining, more systematic approaches to investigate the exact causes are needed, and pathology may aid in this goal. We described gross and microscopic pathology of tissue loss in three key gorgonian species in the Mediterranean region, Paramuricea clavata, Eunicella cavolini, and Leptogorgia sarmentosa, that were all experiencing various degrees of acute to subacute tissue loss characterized by exposed axial skeleton sometimes partly colonized by epibionts and thinning of adjacent tissues. The most significant variety of lesions was seen in P. clavata followed by L. sarmentosa and E. cavolini. For all species, dissociation of gastrodermal cells was the dominant microscopic lesion followed by necrosis of the gastrodermis. Ciliates invading gastrodermis and associated with necrosis of polyps were seen only in E. cavolini. Epidermal tissue loss was seen only in L. sarmentosa, while P. clavata was distinguished by a prominent inflammatory response and unidentified dark round structures within the tentacle epidermis and gastrodermis with no host response. Further work to understand the cause of death in gorgonians is needed, particularly to elucidate the role of ciliates and environmental co-factors or infectious agents not visible on light microscopy, as well as applications of additional tools such as cytology.

The Maldives is renowned for its exceptional coral reefs, yet limited scientific attention has been given to other significant marine ecosystems such as mangrove forests. Mangrove forests of the archipelago are vital ecosystems that provide numerous ecological services and support high biodiversity. Within the diverse fauna inhabiting mangrove ecosystems, macrobenthos in mangrove sediment play a vital role in maintaining ecosystem function, nutrient cycling, supporting biodiversity, and providing food and habitat for other organism. Understanding the diversity and distribution patterns of infaunal macrobenthos within these unique habitats is essential for effective conservation and management. This study aimed to investigate the diversity and distribution of infaunal macrobenthos in the mangrove forests of the Maldives archipelago. Field surveys were conducted in seven representative mangrove sites across the Maldives archipelago, covering different geographical locations and environmental conditions. A standardised sampling protocol involving sediment core sampling was employed to collect infaunal macrobenthic organisms. The collected samples were analysed in the laboratory, where macrobenthic organisms were sorted and identified. Species richness, abundance, and diversity indices were calculated to assess the overall biodiversity of the macrobenthos. The distribution patterns of different taxonomic groups were analysed using statistical techniques. Results indicate a diverse assemblage of infaunal macrobenthos in the mangrove forests of the Maldives. The identified taxa include polychaetes, bivalves, gastropods, and crustaceans, among others. Species richness and abundance varied among sites, suggesting potential local environmental factors influencing community composition. Site-specific variations in the composition of infaunal macrobenthic communities were observed. Environmental variables, such as sediment characteristics, salinity, and temperature, were ident

Mangroves are, on a biological and ecological point of view, one of the most important ecosystems in the world, supporting various terrestrial, estuarine, and marine species. They provide them crucial habitat and food, but also provide several ecosystem services, including fisheries enhancement, coastal protection, carbon storage and sequestration. However, in the Maldives, even though their role is even more important, knowledge about their distribution and biodiversity is scarce and their importance is still underestimated. The aim of our project is to conduct the first-ever survey of all mangroves in the Maldives to enhance and increase the understanding of its unique ecosystems in order to take more action to preserve them from human impact and help research teams plan mangrove-related activities in the archipelago. As a first step, we reviewed all the information about mangroves in the Maldives and found 11 true and 4 controversial mangrove species, unevenly distributed from north to south on 109 islands (9% of all islands) with various fauna and flora species associated. The next step was a preliminary exploration of the Maldives. We visited several islands, particularly those in the Gnaviyani and Addu Atolls, finding 2 islands with previously unreported mangroves. In addition, we noted the presence of the four macro-types of mangroves, i.e. fringing, lacustrine-based, banked and swamp-based, with different sub-types and instances of different types even within a single island. In relation to biodiversity, seven mangrove species and several crab and fish species were visually identified with distribution influenced according to the mangrove type. Future prospects will be the nationwide assessment of the mangrove species’ composition and distribution and related fauna and flora with the help of molecular analyses, aerial mapping of areas, and the assessment of the temperature, pH, and salinity of these environments, with the fund of National Biodiversity Future

Over the last decades, the biodiversity of the Mediterranean Sea has experienced rapid decline due to climate change and human activities. Marine heat waves, mass mortality events, and increasing pollution in coastal areas, particularly from plastics and emerging contaminants (ECs) are among the most significant threats, problem that has become even more pronounced in the aftermath of the recent pandemic. In this context, the present work aimed to assess, for the first time, the occurrence of phthalic acid esters (PAEs) and pharmaceutical and personal care products (PPCPs) in four key species of Mediterranean benthic community: Cladocora caespitosa, Eunicella cavolini, Madracis pharensis, and Parazoanthus axinellae. For PAEs and PPCPs determination in the coral tissue solid phase microextraction (SPME) and liquid chromatography couple to tandem mass spectrometry (LC- MS/MS) were performed. All the specimens were found to be contaminated with at least one type of ECs over the quantification limit. The PAEs displayed an average concentration of 17.23 ± 11.39 ng/g with a maximum value of 44.17 ng/g, while the PPCPs average concentration was 25.89 ± 16.99 ng/g with a maximum value of 57.49 ng/g. The most abundant were DBP (10.35 ± 5.59 ng/g) and ketoprofen (16.97 ± 17.05 ng/g) respectively. Interestingly, they were found in higher concentrations in the same species, P. axinellae, suggesting a higher susceptibility to adsorb both contaminants. Furthermore, the other three species demonstrated an adsorption capacity two-fold lower, possibly due to varying environmental conditions related to depth, currents, and shelter, which exposed them differently to the contaminants. Given the crucial role of these species in forming the habitat of benthic communities along the Mediterranean coastal environment, it is important to investigate the potential human impact in the form of PAEs and PPCPs more thoroughly.

The hydrozoan family Cladocorynidae inhabits tropical to temperate waters and comprises the two genera Pteroclava and Cladocoryne. Pteroclava lives in association with some octocorals and hydrozoans, whereas Cladocoryne is more generalist in terms of substrate choice. This work provides a thorough morpho-molecular reassessment of the Cladocorynidae by presenting the first well-supported phylogeny of the family based on the analyses of three mitochondrial and four nuclear markers. Notably, the two nominal genera were confirmed to be monophyletic and both morphological and genetic data led to the formal description of a new genus exclusively associated with octocorals, Pseudozanclea gen. nov. Maggioni & Montano. Accordingly, the diagnosis of the family was updated. The ancestral state reconstruction of selected characters revealed that the symbiosis with octocorals likely appeared in the most recent common ancestor of Pteroclava and Pseudozanclea. Additionally, the presence of euryteles aggregation in the polyp stage and the exumbrellar nematocyst pouches with euryteles represent synapomorphies of all cladocorynid taxa and probably emerged in their most recent common ancestor. The analysis of several Pteroclava krempfi colonies from Indo-Pacific and Caribbean localities associated with several host octocorals revealed a high intra-specific genetic variability. Single- and multi-locus species delimitations resulted in three to five species hypotheses, but the statistical analysis of morphometric data showed only limited distinction among the clades of P. krempfi. However, P. krempfi clades showed differences in both host specificity, mostly at the octocoral family level, and geographic distribution, with one clade found exclusively in the Caribbean Sea and the others found in the Indo-Pacific.

Coral restoration initiatives are gaining significant momentum in a global effort to enhance the recovery of degraded coral reefs. However, the implementation and upkeep of coral nurseries are particularly demanding, so that unforeseen breaks in maintenance operations might jeopardize well-established projects. In the last 2 years, the COVID-19 pandemic has resulted in a temporary yet prolonged abandonment of several coral gardening infrastructures worldwide, including remote localities. Here we provide a first assessment of the potential impacts of monitoring and maintenance breakdown in a suite of coral restoration projects (based on floating rope nurseries) in Colombia, Seychelles, and Maldives. Our study comprises nine nurseries from six locations, hosting a total of 3,554 fragments belonging to three coral genera, that were left unsupervised for a period spanning from 29 to 61 weeks. Floating nursery structures experienced various levels of damage, and total fragment survival spanned from 40 to 95% among projects, with Pocillopora showing the highest survival rate in all locations present. Overall, our study shows that, under certain conditions, abandoned coral nurseries can remain functional for several months without suffering critical failure from biofouling and hydrodynamism. Still, even where gardening infrastructures were only marginally affected, the unavoidable interruptions in data collection have slowed down ongoing project progress, diminishing previous investments and reducing future funding opportunities. These results highlight the need to increase the resilience and self-sufficiency of coral restoration projects, so that the next global lockdown will not further shrink the increasing efforts to prevent coral reefs from disappearing.

Capitate hydrozoans are a morphologically and ecologically diverse hydrozoan suborder, currently including about 200 species. Being grouped in two clades, Corynida and Zancleida, these hydrozoans still show a number of taxonomic uncertainties at the species, genus and family levels. Many Capitata species established symbiotic relationships with other benthic organisms, including bryozoans, other cnidarians, molluscs and poriferans, as well as with planktonic dinoflagellates for mixotrophic relationships and with bacteria for thiotrophic ectosymbioses. Our study aimed at providing an updated and comprehensive phylogeny reconstruction of the suborder, at modelling the evolution of selected morphological and ecological characters, and at testing evolutionary relationships between the symbiotic lifestyle and the other characters, by integrating taxonomic, ecological and evolutionary data. The phylogenetic hypotheses here presented shed light on the evolutionary relationships within Capitata, with most families and genera being recovered as monophyletic. The genus Zanclea and family Zancleidae, however, were divided into four divergent clades, requiring the establishment of the new genus Apatizanclea and the new combinations for species in Zanclea and Halocoryne genera. The ancestral state reconstructions revealed that symbiosis arose multiple times in the evolutionary history of the Capitata, and that homoplasy is a common phenomenon in the group. Correlations were found between the evolution of symbiosis and morphological characters, such as the perisarc. Overall, our results highlighted that the use of genetic data and a complete knowledge of the life cycles are strongly needed to disentangle taxonomic and systematic issues in capitate hydrozoans. Finally, the colonization of tropical habitat appears to have influenced the evolution of a symbiotic lifestyle, playing important roles in the evolution of the group.

Massive coral bleachingepisodes induced by thermal stress areone of the first causes of coral death worldwide. Overproduction ofreactive oxygen species (ROS) has been identified as one of the potentialcauses of symbiosis breakdown between polyps and algae in corals duringextreme heat wave events. Here, we propose a new strategy for mitigatingheat effects by delivering underwater an antioxidant to the corals.We fabricated zein/polyvinylpyrrolidone (PVP)-based biocomposite filmsladen with the strong and natural antioxidant curcumin as an advancedcoral bleaching remediation tool. Biocomposites' mechanical,water contact angle (WCA), swelling, and release properties can betuned thanks to different supramolecular rearrangements that occurby varying the zein/PVP weight ratio. Following immersion in seawater,the biocomposites became soft hydrogels that did not affect the coral'shealth in the short (24 h) and long periods (15 days). Laboratorybleaching experiments at 29 and 33 & DEG;C showed that coral coloniesof Stylophora pistillata coated withthe biocomposites had ameliorated conditions in terms of morphologicalaspects, chlorophyll content, and enzymatic activity compared to untreatedcolonies and did not bleach. Finally, biochemical oxygen demand (BOD)confirmed the full biodegradability of the biocomposites, showinga low potential environmental impact in the case of open-field application.These insights may pave the way for new frontiers in mitigating extremecoral bleaching events by combining natural antioxidants and biocomposites.

I libri di testo hanno un ruolo fondamentale nella trasmissione dei saperi a scuola. In occasione del decennio ONU dedicato alle scienze del mare si è voluto analizzare come i libri di testo per la scuola primaria affrontino questo spazio. La visione del mare che è veicolata da questi strumenti è fortemente terracentrica, il mare è prevalentemente descritto come il limite della terra ferma. Dal punto di vista iconografico si riscontrano delle contraddizioni tra testo e immagini, inoltre il mare è prevalentemente rappresentato sulla falsa riga della sua immagine turistica.

The red gorgonian Paramuricea clavata is a fundamental ecosystem engineer of coralligenous biocenosis in the Mediterranean Sea, where it plays crucial ecological functions and enhances the habitat biodiversity. However, this species is strongly endangered due to climate change-related stressors such as mucilage events, which have increased in recent decades causing extensive damage and mortality, but whose impacts at the molecular and cellular levels are still unexplored. In this study, different cellular stress biomarkers were analyzed in mucilage-colonized P. clavata specimens living in the Portofino Marine Protected Area (Ligurian Sea, Italy), in order to elucidate the cellular pathways affected by mucilage and the cellular defense mechanisms adopted. Within these colonies, portions of healthy tissue located at different distances from mucilage-induced necrosis were considered. Our results showed that mucilage affected the cellular oxidative status and impaired lipid cell membranes of the whole P. clavata colony. Indeed, an increase in the superoxide dismutase (SOD) and glutathione reductase (GR) enzymatic activity and in the level of lipid peroxidation (LPO) was detected in colonies showing mucilage-induced necrotic tissues compared to healthy ones. In particular, fragments sampled just next to the necrotic tissue displayed the highest levels of SOD and LPO, indicating that harmful oxidative damage was in progress, especially in portions neighboring the mucilage colonization. In this context, the up-regulation of the antioxidant mechanisms might represent a defense and a barrier from hypoxic or anoxic conditions created by mucilage overgrowth or by the invasion of toxic organisms embedded in the mucilaginous aggregates. On the contrary, the cellular protein homeostasis, analyzed by the expression of the 60-kDa Heat shock protein (Hsp60), was not altered by the mucilage. This analysis contributes to provide new insights into the cellular and molecular response of

Tourism is the main income source for the Maldives, but concurrently, it represents a growing threat to its marine ecosystem. Here, we monitored the bioaccumulation of 15 emerging contaminants (ECs) in the Maldivian reef sponges Spheciospongia vagabunda collected in two resort islands (Athuruga and Thudufushi, Ari Atoll) and an inhabited island (Magoodhoo, Faafu Atoll), and we analysed their impact on different sponge cellular stress biomarkers. Caffeine and the insect repellent DEET were detected in sponges of all the islands, whereas the antibiotic erythromycin and the UV filter 4-methylbenzylidene camphor were found in resort islands only. Although concentrations were approximately a few ng/g d.w., we quantified various induced cellular effects, in particular an increase of the levels of the enzyme glutathione S-transferase involved in cell detoxification. Our results highlight the importance to increase awareness on ECs pollution, promoting the use of more environmental friendly products to achieving the sustainable development goals.

The intensity and frequency of coral bleaching events have increased worldwide especially due to thermal stress and seawater pollution. Although it has been observed that metal concentration in seawater can affect the coral’s ability to adopt cellular defensive mechanisms to counteract bleaching, more investigations are needed to better understand the role of metals in coral physiology. In this study, we analyzed the individual and combined effects of prolonged heat stress and manganese (Mn) and iron (Fe) enrichments at the cellular level on the coral Stylophora pistillata. Thermal stress caused an up-regulation in the expression of the host Heat shock proteins (Hsps) 60 and 70, which showed a parallel pattern of modulation in all treatments, as well as an increase of lipid peroxidation (LPO) in the holobiont. Fe enrichment did not induce any change in Hsp expression or in the oxidative status of the corals both at the ambient temperature of 26°C or at increased temperature, suggesting that Fe didn’t seem to play a role in mitigating the cellular damages and the coral bleaching. Mn or MnFe enrichment at 26°C seemed to increase the oxidative stress in zooxanthellae, since high LPO and glutathione reductase (GR) levels were recorded, but it did not cause any effect on polyp Hsp expression, probably due to the antioxidant action of GR. With the temperature increase, Mn enrichments prevented any increase in Hsp levels and caused a significant decrease of LPO and GR activity, strengthening a previous hypothesis suggesting that Mn could mitigate the negative cellular effects produced by the thermal stress.

An integrated approach using morphological and genetic data is needed to disentangle taxonomic uncertainties affecting the hydrozoan families Sphaerocorynidae and Zancleopsidae. Here we used this approach to accurately characterise species in these families, identify the previously unknown polypstages of the genera Euphysilla and Zancleopsis, which were originally described exclusively based on the medusa stages, describe a new sphaerocorynid genus and species, and assess the phylogenetic position of the two families within the Capitata. The monotypic genus Astrocoryne was found to be a synonym of Zancleopsis. Astrocoryne cabela was therefore transferred to the genus Zancleopsis as Zancleopsis cabela comb. nov. The new polyp-based genus and species Kudacoryne diaphana gen. nov. sp. nov. was erected within the Sphaerocorynidae. Both taxa are primarily based on genetic data, but the introduction of this new genus was made necessary by the fact that it clustered with the genera Heterocoryne and Euphysilla, despite showing Sphaerocoryne-like polyps. Interestingly, the species analysed in this work showed contrasting biogeographical patterns. Based on our data and literature records, some species appear to have a wide circumtropical range, whereas others are limited to few localities. Overall, these results lay the ground for future investigations aimed at resolving the taxonomy and systematics of these two enigmatic families.

The crown-of-thorns starfish (COTS) is a coral predator that is widely distributed in Indo-Pacific Oceans. A previous phylogenetic study using partial mitochondrial sequences suggested that COTS had diverged into four distinct species, but a nuclear genome-based analysis to confirm this was not conducted. To address this, COTS species nuclear genome sequences were analysed here, sequencing Northern Indian Ocean (NIO) and Red Sea (RS) species genomes for the first time, followed by a comparative analysis with the Pacific Ocean (PO) species. Phylogenetic analysis and ADMIXTURE analysis revealed clear divergences between the three COTS species. Furthermore, within the PO species, the phylogenetic position of the Hawaiian sample was further away from the other Pacific-derived samples than expected based on the mitochondrial data, suggesting that it may be a PO subspecies. The pairwise sequentially Markovian coalescent model showed that the trajectories of the population size diverged by region during the Mid-Pleistocene transition when the sea-level was dramatically decreased, strongly suggesting that the three COTS species experienced allopatric speciation. Analysis of the orthologues indicated that there were remarkable genes with species-specific positive selection in the genomes of the PO and RS species, which suggested that there may be local adaptations in the COTS species.

Waminoa spp. are acoel flatworms mainly found as ectosymbionts on scleractinian corals. Although Waminoa could potentially represent a threat to their hosts, not enough information is available yet regarding their ecology and effect on the coral. Here, the Waminoa sp.–coral association was analyzed in Singapore reefs to determine the prevalence, host range, and preference, as well as the flatworm abundance on the coral surface. Moreover, the impact of Waminoa sp. on the expression of putative immune-and stress-response genes (C-type lectin, C3, Hsp70 and Actin) was exam-ined in the coral Lobophyllia radians. The association prevalence was high (10.4%), especially in sites with lower sedimentation and turbidity. Waminoa sp. showed a wide host range, being found on 17 coral genera, many of which are new association records. However, only few coral genera, mostly characterized by massive or laminar morphologies appeared to be preferred hosts. Waminoa sp. individuals displayed variable patterns of coral surface coverage and an unequal distribution among different host taxa, possibly related to the different coral growth forms. A down-regulation of the expression of all the analyzed genes was recorded in L. radians portions colonized by Waminoa individuals compared to those without. This indicated that Waminoa sp. could affect components of the immune system and the cellular homeostasis of the coral, also inhibiting its growth. Therefore, Waminoa sp. could represent a potential further threat for coral communities already subjected to multiple stressors.

The cushion seastar Culcita schmideliana has gained major attention in the last few years because of its selective predation on juvenile corals, as well as its ability to generate large demographic assemblages, causing delays in coral recovery after large mortality events in the Republic of Maldives. However, a lack of data regarding the factors affecting its distribution and habitat selection still persists in this area. Here, we adopted a novel approach in the study of corallivorous seastar habitat selection that combined ecological and digital photogrammetry data. In this regard, we tested 3 different parameters as factors influencing seastar habitat choice in the South-East region of Faafu Atoll, Republic of Maldives, namely prey abundance, Linear Rugosity Index (LRI), and Average Slope (AS). The analysis of selectivity coefficient (Ei) of seastars for different habitat types showed a preference for reefs characterized by medium AS values (Ei = 0.268), a LRI included between 2 and 2.5 (Ei = 0.180), and a juvenile coral density ranging between 10 and 20 colonies m−2 (Ei = 0.154). A multiple linear regression analysis showed that different AS and LRI values explained the 43.1% (R2 = 0.431, P = 0.007) and the 48.1% (R2 = 0.481, P = 0.024) of variance in seastars abundance, respectively, while juvenile coral densities did not significantly affect this (R2 = 0.132, P = 0.202). These results provide new information on the distribution and behaviour of an important corallivore of Maldivian reefs, such as C. schmideliana.

Microplastics are a persistent and ubiquitous source of pollution in the marine environment, representing a severe threat to tropical coral reefs. The effects of microplastics on reef-building (hard) corals have been documented (interference with normal digestion process, polyp retraction, oxidative stress, impairment of the photosynthetic machinery, bleaching). However, the impact of microplastics on soft corals, the second most abundant benthos of tropical reefs, remains to be thoroughly studied. In this work, we analysed the effects of a short-term microplastic exposure on the cellular physiology of the soft coral Coelogorgia palmosa. We found that samples exposed to >50 mg l−1 of microplastic showed significant increase in the activities of the antioxidant enzymes glutathione reductase, catalase, and superoxide dismutase, suggesting a rise in oxidative stress. Furthermore, exposure to microplastics increased lipid peroxidation, indicating oxidative damage. Overall, our results show that similar to hard corals, microplastic ingestion causes oxidative stress and cellular damage in soft corals. Our study provides a first assessment of physiological effects of microplastic exposure on the soft coral, Coelogorgia palmosa, highlighting the need for further investigations about these contaminants and their influence on marine benthic fauna. Such information is crucial to understand how different reef organisms respond to microplastic pollution and who the ecological winners or losers will be in an increasingly polluted marine environment. Key policy highlights The effect of microplastic contamination at the cellular and molecular level has never been investigated before in alcyonacean corals. Concentrations of 50–70 mg l−1 of polyethylene caused significant rise in oxidative stress in Coelogorgia palmosa after 48 h. After 48 h exposure to 50 mg l−1 significant oxidative damage was recorded. No significant modulation in the expression of the cytoprotective protein Hs

Although corallivory is recognized as a threat affecting the structure and integrity of coral reef habitats, ecological data on most species of coral consumers remain limited, slowing down the development of conservation and restoration strategies of the reef ecosystems. In this study, the population distribution and corallivorous behaviour of the cushion sea star Culcita sp. were investigated in the south region of Faafu Atoll, Maldives. Most sea stars were found on reef slopes within 0–10 m depth and in areas characterized by low live coral cover. Several coral genera were preyed on by the sea star. Although most of the consumed corals belong to the genus Acropora, a feeding preference for the genera Pocillopora and Pavona and a consistent avoidance of the genus Porites were observed. Furthermore, the majority of the prey corals were small colonies (< 10 cm diameter), even though Culcita sp. appeared to be capable of partially consuming larger colonies. Dietary preferences for specific coral colonies or genera have the potential to generate local shifts in coral community composition and structure and may affect reef recovery following natural and anthropogenic disturbance in an already impacted environment such as the Maldivian reefs.

Ciguatera Fish Poisoning (CFP) is the most frequently seafood-toxin illness in the world, with big substantial physical and functional impact. Toxins produced by Dinoflagellates are often found associated with Macrophyte Algae and dead Corals. Herbivorous fishes become toxic after ingesting macroalgae or parts of dead coral. Herbivorous fishes are preyed upon by carnivorous fishes which in turn become toxic. Man becomes infected by eating fish and poisoned herbivores and carnivores. CTX (Ciguatoxin) is odourless and tasteless, resists cooking. It caused gastrointestinal, neurologic and/or cardiovascular symptoms which last days to weeks, or even months. The purpose of this review of literature about the toxins, just to clarify causes, species and symptom, treatment, method of analysis, research of quick test and provide information about management and prevention of CFP.

Interspecific associations are common in coral reefs, but those involving hydrozoans and octocorals have not been widely investigated. The hydroid Pteroclava krempfi (Hydrozoa, Cladocorynidae) lives in association with different soft coral taxa (Alcyonacea), showing a widespread distribution. However, very little information is available on the ecology of these relationships. Here, we tested for differences in the taxon-specific prevalence and habitat preference of the symbiosis and determined ecological traits of the P. krempfi-host associations in central Red Sea reefs. P. krempfi was found associated with the alcyonacean genera Lobophytum, Rhytisma, Sarcophyton and Sinularia, updating its host range and geographic distribution. The symbiosis prevalence was high in the area and especially at inshore sites compared to midshore and offshore sites. Rhytisma was the most common host, while the association with Lobophytum showed the lowest taxon-specific prevalence. P. krempfi did not show a clear preference for a specific alcyonacean size, and an increase in host size automatically led to an increase in the surface occupied by hydrozoans, although they rarely colonized more than 50% of the upper surface of the host. The spatial distribution of the hydroids on the host surface appeared related to the host genus and size as well as to the coverage of the hydroids. Despite the nature of this symbiosis requiring further investigation, P. krempfi did not seem to play a role in affecting the bleaching susceptibilities of the host colonies. The study shows that the Red Sea coral reef symbioses are more widespread than previously known and therefore deserve more attention.

Food-item authentication and traceability is an issue of primary concern, due to both socio-economical and health implications. DNA-based methods are increasingly being recognised as powerful tools to assess the reliability of supplier labels for any type of food. This is especially true for products characterised by a short shelf life and high-processing supply chain, such as seafood. In this work, a DNA barcoding approach was applied to assess the accuracy of species labelling in 150 cephalopod seafood products sold in the Italian market. Overall, high levels of mislabelling in squid, cuttlefish, and octopus items were identified, and in some cases, even species not included in the current food Regulations. Additionally, an application of the recently developed naked-eye detection tool ‘NanoTracer’, consisting in the combination of DNA barcoding with gold nanoparticle-based, was demonstrated to authenticate common cuttlefish (Sepia officinalis) seafood. The primer pairs used to set the fast detection system for S. officinalis were designed based on the most comprehensive DNA barcoding (COI and 16s rRNA) datasets ever assembled for cephalopods, assuring the specificity of the method. ‘NanoTracer’ allowed a simple, rapid, accurate and cost-effective authentication, revealing its potential adaptability to any type of seafood and other food categories.

Outbreaks of the corallivorous crown-of-thorns seastars have received increasing attention due to their negative impacts on coral reefs in the Indo-Pacific Ocean. However, outbreaks in remote and dislocated islands are still poorly understood. This study aims to begin filling informational gaps regarding outbreaks of Acanthaster planci in the remote islands of the central Ari Atoll, Republic of Maldives. The population of A. planci was monitored during three periods over 2 years (2015–2016) to evaluate variations in abundance and to characterise size structure and feeding behaviour. The outbreak appeared to be severe and active throughout the entire study period. The size structure analysis revealed a multimodal distribution dominated by individuals between 20 and 30 cm, suggesting that the outbreak may have resulted from a few nearby mass spawning events. Additionally, the most abundant live coral was Porites, which was also the most consumed genus; however, the electivity index showed a preference for corals of the genera Favites and Pavona. Finally, we also highlighted the need for more geographically extended surveys to better understand local patterns regarding outbreaks of A. planci in the Republic of Maldives