Common Marine Research Articles

Study of the Impact of Lactiplantibacillus plantarum I on the Health Status of Queen Scallop Aequipecten opercularis

The objective of this research was to isolate and identify lactic acid bacteria living in the digestive tract of the queen scallop Aequipecten opercularis and further test it as a probiotic culture on the growth of the bivalve during one month in captivity. Classic microbiological techniques (API and MALDI TOF) were used and four different strains of Lactiplantibacillus and one Lactococcus were identified and further analyzed, namely: Lactiplantibacillus plantarum I, Lactiplantibacillus plantarum 1, Lactiplantibacillus plantarum 2, Lactococcus lactis, and Lactiplantibacillus brevis. The isolated cultures were further tested for the highest antimicrobial activity towards the most common marine pathogens and survival at different temperatures and pH levels. The strain Lactiplantibacillus plantarum I had the best results, with the highest antimicrobial activity (77–85% pathogen growth inhibition) and the best safety standards showing no antibiotic resistance, and no ability to synthesize biogenic amine and degrade red blood cells. Considering all the abovementioned characteristics, the strain Lpb. plantarum I was further tested on the growth and health status of the bivalve Aequipecten opercularis during a month of cultivation in captivity. The results showed that the incorporation of Lpb. plantarum I led to a decrease in the quantity of test microorganisms in the bivalve and an increase in both the growth rate weight and growth rate length of the queen scallop A. opercularis. Furthermore, the scallops fed with the algae culture + Lpb. plantarum I gained significantly higher meat yield (33.15 ± 2.63%) compared with the control scallops fed only with the algae culture (29.66 ± 2.87%). To conclude, the results from this research indicate that including Lpb. plantarum I as a dietary supplement could enhance growth performance and serve as a feasible approach to reduce pathogen levels while cultivating A. opercularis in captivity.

Frequent occurrence of tetrodotoxin in the marine gastropod \(\textit{Nassarius glans}\) causing a food poisoning in Khanh Hoa province, Vietnam in 2020

A fatal neurotoxic poisoning case happened in Khanh Hoa province in 2020 after eating a certain number of marine gastropods, later identified as Nassarius glans, one of the common marine gastropods in Vietnam. As the remaining causative food in the incident, 62 specimens were collected to examine tetrodotoxin toxicity individual variation and frequency of toxic specimens by using HILIC/MS-MS analysis. 100% of studied specimens exhibited toxicity (556 ± 821 MU/g) beyond the regulatory level of consumption (10 MU/g) for puffer(fish) recommended in Japan and extensive variation (18–4,046 MU/g). The result pointed out that only 5 g of soft tissue from N. glans (equivalent to 2–3 specimens) containing maximum toxicity detected in the present study may cause human death if consumed. Fhe first time, this study identified TTXs in the gastropods as a causative toxin in the poisoning in Vietnam. Moreover, 65.5% of studied specimens with high toxicity higher than 100 MU/g, including 16.1%, showing extremely high toxicity (> 1,000 MU/g). The results suggested that this gastropod is quite dangerous for human consumption and should be alerted to public awareness.

Bioconcentration of pharmaceuticals in benthic marine organisms (Holothuria tubulosa, Anemonia sulcata and Actinia equina) exposed to environmental contamination by atenolol and carbamazepine

The present work assess the bioconcentration kinetics of atenolol (ATN) and carbamazepine (CBZ) in common marine organisms including Holothuria tubulosa, Anemonia sulcata and Actinia equina under controlled laboratory conditions. CBZ exhibited higher uptake and excretion rates resulting higher bioconcentration factor (BCF) (41–537 L/kg for CBZ vs 7–50 L/kg for ATN) although both are below the limits established by the European Union (EU). The measured BCF using kinetic data showed some differences with those predicted using the concentrations measured at the steady-state, probably explained because the steady state was not ready reached. The animal-specific BCF followed the order of Holothuria tubulosa >Actinia equina >Anemonia sulcata for ATN while was the opposite for CBZ. The study highlighted between-tissues differences in the digestive tract and the body wall of the Holothuria tubulosa. The work presented is the first to model bioconcentration of ATN and CBZ in holothurian and anemone animal models.

Revealing the Impacts of Chemical Complexity on Submicrometer Sea Spray Aerosol Morphology.

Sea spray aerosol (SSA) ejected through bursting bubbles at the ocean surface is a complex mixture of salts and organic species. Submicrometer SSA particles have long atmospheric lifetimes and play a critical role in the climate system. Composition impacts their ability to form marine clouds, yet their cloud-forming potential is difficult to study due to their small size. Here, we use large-scale molecular dynamics (MD) simulations as a "computational microscope" to provide never-before-seen views of 40 nm model aerosol particles and their molecular morphologies. We investigate how increasing chemical complexity impacts the distribution of organic material throughout individual particles for a range of organic constituents with varying chemical properties. Our simulations show that common organic marine surfactants readily partition between both the surface and interior of the aerosol, indicating that nascent SSA may be more heterogeneous than traditional morphological models suggest. We support our computational observations of SSA surface heterogeneity with Brewster angle microscopy on model interfaces. These observations indicate that increased chemical complexity in submicrometer SSA leads to a reduced surface coverage by marine organics, which may facilitate water uptake in the atmosphere. Our work thus establishes large-scale MD simulations as a novel technique for interrogating aerosols at the single-particle level.

Bone mineral density and microarchitecture change during skeletal growth in harbor seals (Phoca vitulina) from the German coast

Across species, the skeletal system shares mutual functions, including the protection of inner organs, structural basis for locomotion, and acting as an endocrine organ, thus being of pivotal importance for survival. However, insights into skeletal characteristics of marine mammals are limited, especially in the growing skeleton. Harbor seals (Phoca vitulina) are common marine mammals in the North and Baltic Seas and are suitable indicators of the condition of their ecosystem. Here, we analyzed whole-body areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) and lumbar vertebrae by high-resolution peripheral quantitative computed tomography (HR-pQCT) in neonate, juvenile, and adult harbor seals. Along skeletal growth, an increase in two-dimensional aBMD by DXA was paralleled by three-dimensional volumetric BMD by HR-pQCT, which could be attributed to an increasing trabecular thickness while trabecular number remained constant. Strong associations were observed between body dimensions (weight and length) and aBMD and trabecular microarchitecture (R2 = 0.71–0.92, all p < 0.001). To validate the results of the DXA measurement (i.e., the standard method used worldwide to diagnose osteoporosis in humans), we performed linear regression analyses with the three-dimensional measurements from the HR-pQCT method, which revealed strong associations between the two imaging techniques (e.g., aBMD and Tb.Th: R2 = 0.96, p < 0.0001). Taken together, our findings highlight the importance of systematic skeletal investigations in marine mammals during growth, illustrating the high accuracy of DXA in this context. Regardless of the limited sample size, the observed trabecular thickening is likely to represent a distinct pattern of vertebral bone maturation. As differences in nutritional status, among other factors, are likely to affect skeletal health, it appears essential to routinely perform skeletal assessments in marine mammals. Placing the results in the context of environmental exposures may allow effective measures to protect their populations.

Determination of Fatty Acid Content in Six Common Marine Fishes in Bangladesh

A comparative study on the fatty acid contents of six common marine fishes: Poa (Poa poa), Rupchanda (Chinese pomfret), Hilsha (Tenualosa ilisha), Loita (Harpadon nehereus), Baila (Hemibagrus menoda) and Chapila (Gudusia chapra) were carried out by Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS). &nbsp;Saturated and unsaturated fatty acids, notably monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were shown to be more advantageous; these fatty acids are found in marine fishes. The polyunsaturated fatty acids Eicotetraenoic acid (C20:4), 12Z, and 15Z-heneicosadienoic acid (C21:2) are found in Rupchanda fish. Hilsha fish contained the monounsaturated fatty acids- Palmitoleic acid (C16:1) and Oleic acid (C18:1), which are respectively omega-7 and omega-9. Chapila fish contained the monounsaturated fatty acids such as cis-10 pentadecanoic acid (C15:1) and cis-15-tetracosenoic acid (C24:1). Only one mono unsaturated fatty acid, pentadecanoic acid (cis-10) (C15:1) is found in Loita fish species. However, the six selected marine fishes also showed several saturated fatty acids. Pentadecanoic acid (C15:0) was the most common saturated fatty acid identified in all studied marine fishes. However, this study suggests that, fatty acid profiles and concentration of the marine fishes will evaluate the fatty acids contents of that fishes to appraise the health benefits.

Protective Effects of Epigallocatechin-3-gallate (EGCG) against the Jellyfish Nemopilema nomurai Envenoming.

Jellyfish stings are the most common marine animal injuries worldwide, with approximately 150 million envenomation cases annually, and the victims may suffer from severe pain, itching, swelling, inflammation, arrhythmias, cardiac failure, or even death. Consequently, identification of effective first aid reagents for jellyfish envenoming is urgently needed. Here, we found that the polyphenol epigallocatechin-3-gallate (EGCG) markedly antagonized the hemolytic toxicity, proteolytic activity, and cardiomyocyte toxicity of the jellyfish Nemopilema nomurai venom in vitro and could prevent and treat systemic envenoming caused by N. nomurai venom in vivo. Moreover, EGCG is a natural plant active ingredient and widely used as a food additive without toxic side effects. Hence, we suppose that EGCG might be an effective antagonist against systemic envenoming induced by jellyfish venom.

Synergistic effects of alginate oligosaccharide and cyanidin-3-O-glucoside on the amelioration of intestinal barrier function in mice

Emerging evidence shows that dietary oligosaccharides are important prebiotics that can improve intestinal flora, while dietary polyphenols can act directly on intestinal cells. However, information about their synergistic effects on gut health is still limited. In this study, alginate oligosaccharide (AOS) and cyanidin-3-O-glucoside (C3G) were selected as a common marine plant oligosaccharide and terrestrial plant polyphenol, respectively, to study their effects on intestinal health. The results show that, in comparison to their individual applications, the combination of AOS and C3G (mass ratio, 3:1) displayed a stronger ability to up-regulate the expression of tight junction proteins, while enhanced intestinal epithelial barrier was also observed and levels of mucin-2 and β-defensins were simultaneously increased in the intestinal mucus. Interestingly, the secretion of immunoglobulin A and immune-related cytokines were approximately doubled by the AOS + C3G mixture. In addition, the AOS + C3G mixture was found to be more conducive to the positive transformation of intestinal flora, which stimulated the growth of beneficial bacteria Akkermansia, Lachnospiraceae and Feacalibaculum while inhibiting the growth of harmful bacteria Helicobacter and Turicibacter. The data generated herein thus suggests that dietary oligosaccharides and dietary polyphenols may be more beneficial to intestinal health when applied in combination than their individual effects alone.

A Deep-Sea Bacterium Is Capable of Degrading Polyurethane.

Plastic wastes have been recognized as the most common and durable marine contaminants, which are not only found in the shallow water, but also on the sea floor. However, whether deep-sea microorganisms have evolved the capability of degrading plastic remains elusive. In this study, a deep-sea bacterium Bacillus velezensis GUIA was found to be capable of degrading waterborne polyurethane. Transcriptomic analysis showed that the supplement of waterborne polyurethane upregulated the expression of many genes related to spore germination, indicating that the presence of plastic had effects on the growth of strain GUIA. In addition, the supplement of waterborne polyurethane also evidently upregulated the expressions of many genes encoding lipase, protease, and oxidoreductase. Liquid chromatography-mass spectrometry (LC-MS) results showed that potential enzymes responsible for plastic degradation in strain GUIA were identified as oxidoreductase, protease, and lipase, which was consistent with the transcriptomic analysis. In combination of in vitro expression and degradation assays as well as Fourier transform infrared (FTIR) analysis, we demonstrated that the oxidoreductase Oxr-1 of strain GUIA was the key degradation enzyme toward waterborne polyurethane. Moreover, the oxidoreductase Oxr-1 was also shown to degrade the biodegradable polybutylene adipate terephthalate (PBAT) film indicating its wide application potential. IMPORTANCE The widespread and indiscriminate disposal of plastics inevitably leads to environmental pollution. The secondary pollution by current landfill and incineration methods causes serious damage to the atmosphere, land, and rivers. Therefore, microbial degradation is an ideal way to solve plastic pollution. Recently, the marine environment is becoming a hot spot to screen microorganisms possessing potential plastic degradation capabilities. In this study, a deep-sea Bacillus strain was shown to degrade both waterborne polyurethane and biodegradable PBAT film. The FAD-binding oxidoreductase Oxr-1 was demonstrated to be the key enzyme mediating plastic degradation. Our study not only provided a good candidate for developing bio-products toward plastic degradation but also paved a way to investigate the carbon cycle mediated by plastic degradation in deep-sea microorganisms.

Genetic study reveals local differentiation persisting in the face of high connectivity and a genomic inversion likely linked with sexual antagonism in a common marine fish

Abstract Sustainable harvest of wild populations requires knowledge of the underlying population structure. The focus of this study is on goldsinny wrasse (Ctenolabrus rupestris), a small marine fish inhabiting coastal waters of the north-eastern Atlantic. This species is caught in large numbers to serve as cleaner fish in salmonid aquaculture. We genotyped 2073 goldsinny wrasse from 43 sites along the Scandinavian coastline with 143 SNPs. Seven of the SNPs were linked and likely reside within a large genomic inversion dominated by one haplotype. The heterokaryotype of the putative inversion displayed sex-specific growth patterns, potentially resolving sexual antagonism for this trait. The unlinked 134 SNPs showed modest isolation-by-distance with samples from the northernmost locations showing highest divergence, whereas sites farther south were much more interconnected. Genetic divergence (FST) was highly variable among sites within regions, suggesting a varying degree of connectivity and local divergence. We conclude that despite a high degree of gene-flow mediated through pelagic dispersal in early life stages, regional and some local population structure remains due to limited adult movement in addition to other unidentified factors. Consequently, the species might be more vulnerable to local disturbances than previously anticipated.

Warm acidified seawater: a dolomite solution

ABSTRACTThe “dolomite problem” is the product of two distinct observations. First, there are massive amounts of ancient marine limestone (CaCO3) deposits that have been replaced by the mineral dolomite (MgCa(CO3)2). However, recent (Holocene and Pleistocene) marine deposits contain relatively minuscule amounts of dolomite, although the occurrence of small quantities of dolomite is observed in many modern settings, from deep marine to supratidal. Second, low-temperature synthesis of dolomite in laboratory settings has been elusive, particularly in comparison to the ease with which common marine calcium carbonate minerals (aragonite and calcite) can be synthesized. Since low-temperature solid-state diffusion can be discounted as a method for Mg incorporation into calcium carbonate (as it operates on time scales too long to matter), the replacement of CaCO3 by dolomite is one of dissolution followed by precipitation. Therefore, an often overlooked but required factor in the replacement of limestone by dolomite is that of undersaturation regarding the original calcium carbonate mineral during replacement. Such conditions could conceivably be caused by rapid dolomite growth relative to aragonite and calcite dissolution–precipitation reactions, but laboratory studies, modern systems analyses, and observations of ancient deposits all point to this possibility being uncommon because dolomite growth is kinetically inhibited at low temperature. Pressure solution by force of dolomite crystallization is a second possible driver for CaCO3 undersaturation, but requires a confining stress most likely attained through burial. However, based on petrographic observations, significant amounts of ancient dolomite replaced limestone before burial (synsedimentary dolomite), and many such platforms have not suffered any significant burial. Because these possibilities of undersaturation caused by dolomite precipitation and crystal growth can be largely discounted, the undersaturation required for “dolomitization” to proceed is most likely to be externally forced. In modern natural systems, undersaturation and selective CaCO3 dissolution in marine porewaters is very common, even in warm-water environments, being forced by the breakdown of organic matter. Such dissolution is frequently attended, to varying degrees, by precipitation of a kinetically-less-favored but thermodynamically more stable phase of CaCO3. Laboratory studies as well as observations of modern systems show that when undersaturation is reached with respect to all common marine CaCO3 phases, dolomite assumes the role of this kinetically-less-favored precipitate. This degree of undersaturation is uncommon in modern shallow marine pore systems in warm-water settings, but it was more common during times of elevated atmospheric CO2, and ocean acidification. Furthermore, because oxidation of organic matter drives dolomite formation, near-surface organic-rich deposits such as the remains of microbial mat communities, were more predisposed to dolomite replacement in the acidified oceans of the ancient past relative to contemporaneous deposits that contained less organic matter. These observations lend to a more harmonious explanation for the abundance and occurrence of dolomite through time.

Microbe‐mediated, marine authigenic formation of ooidal chamosite: Insights from upper Ordovician carbonates of the South‐Western Yangtze platform (China)

AbstractChamosite is a common marine authigenic mineral and microbial involvement has been often assumed during its formation. However, the fossil record of such microbial activity is ambiguous. Chamosite oolitic ironstones widely occur in the Upper Ordovician of the Yangtze Platform, but their origin remains unclear. In this study, detailed sedimentological and mineralogical investigations on ironstones from the Haima section (south‐western Yangtze Platform) helped unravel the critical role of cyanobacterial activity during marine chamosite authigenesis. Stratigraphically, deposition of the Haima oolitic ironstones corresponded with an early Katian transgression, temporally equivalent to many other early Palaeozoic counterparts worldwide. Petrographic observations revealed that different chamosite forms (ooids, peloids and matrix) all developed in close association with calcified cyanobacteria, suggesting that cyanobacteria‐involved chamosite formation existed across a wide range of hydrodynamic conditions from above fair‐weather wave base to below storm wave base. Further mineralogical characterization (backscatter imaging and electron‐microprobe analyses) at single‐grain scale revealed clear mineral zonation from the matrix (dispersed iron oxide and microquartz) through the calcified cyanobacterial sheaths (dispersed chamosite) to the ooid (chamosite). This zonation is best explained by cyanobacterial microbial mats that created benthic reducing and high‐pH conditions. These conditions drove near‐seafloor, dispersed iron oxide and microquartz (primary precipitates formed in oxic seawater) to form chamosite. The authigenic chamosite, originally dispersed within and surrounding the microbial mats, could be reworked to develop other chamositic grains. It is proposed here that the early Katian transgression was responsible for the chamosite–oolitic–ironstone development. The marine transgression submerged earlier‐exposed lands and likely supplied Fe‐Al‐rich colloidal materials to an open marine setting for the chamosite authigenesis. Moreover, transgression likely triggered upwelling, delivered ferruginous deeper water as an extra Fe source and provided nutrients for the cyanobacterial microbial‐mat development, which was essential for the widespread chamosite authigenesis across the south‐western Yangtze Platform.

Diversity of digeneans parasitizing Mullus barbatus and Mullus surmuletus (Teleostean, Mullidae) off the coast of Algerian.

Mullus barbatus and Mullus surmuletus (Perciformes, Mullidae) are a common marine teleost of great commercial importance in many coastal areas. We studied the communities of Digenea species in two congeneric Mullidae hosts collected on the Algerian coast in the southern Mediterranean. Five hundred and seven M. barbatus and one hundred and twenty-three M. surmuletus were examined. During this work, we collected six species of parasitic Digenea which are related to five different families: Hemiuridae represented by Lecithocladium excisum, Fellodistomidae by Proctoeces maculatus and which is reported only from M. surmuletus, Derogenidae by Derogenes latus, Monorchiidae by Proctotrema bacilliovatum and finally Opecoelidae represented by two species Opecoeloides furcatus and Poracanthium furcatum. A critical systematic study revealed an apparent overlap in morphometric data of the six Digenean species from two host fishes. Therefore, the two mullet species are likely to share the same parasite community, and the stenoxenic specificity of Digenean parasites is briefly argued. Prevalence values showed that in the midst of six hundred and thirty Mullidae, one hundred and ninety-six are parasitized (31.11 %). Statistical tests showed that the most parasitized fish hosts are M. surmuletus with a high prevalence value (47.15 %), and on the other hand, they proved that small fish are more parasitized than others. Also, the lack of homogeneity between the different parasites is reported. We also note that the use of factorial correspondence analysis (FCA) allowed us, for the first time to highlight the distribution of the parasite species identified in the two mullets according to the seasons.

Ichnological evidence of marine incursions in the lacustrine–palustrine Bembridge Limestone Formation (Eocene), Isle of Wight, southern England

Trace fossils are described from the Eocene Bembridge Limestone Formation from the Isle of Wight and used to constrain the paleoenvironmental interpretation. The lacustrine–palustrine succession contains three limestone beds, which are separated by clay and marl. The middle and upper limestone beds reveal complex burrow systems developed at their top. Based on their characteristics, these burrow systems are assigned to the ichnotaxon Balanoglossites triadicus Mägdefrau, which is associated with the shallow superficial grooves Sulcolithos variabilis Knaust. B. triadicus is a common marine trace fossil mainly known from shallow-marine carbonate successions throughout the Phanerozoic. It is accompanied by other marine ichnotaxa such as Arachnostega gastrochaenae Bertling, Gastrochaenolites isp. aff. G. ornatus Kelly and Bromley, Spongeliomorpha iberica Saporta and Thalassinoides suevicus (Rieth). This ichnological evidence confirms the occurrence of short-term marginal-marine incursions in a predominantly lacustrine to palustrine environment.

Valanginian–Hauterivian vegetation inferred from palynological successions from the southern Perth Basin, Western Australia

The stepwise fragmentation of Gondwana had a lasting impact on Southern Hemisphere ecosystems, but its consequences remain difficult to ascertain without detailed knowledge of the biota colonizing the supercontinent before and during breakup. This palynological study characterizes the Early Cretaceous vegetation of the southern Perth Basin, a key location during the separation of Greater India from Western Australia. The well-preserved palynological assemblages recorded here include marine and putative freshwater dinoflagellate cysts and diverse spore and pollen associations. The palynomorphs indicate lacustrine, fluvial and estuarine depositional settings in the southern Perth Basin between the Berriasian and Hauterivian. The estuarine assemblages are characterized by rare to common marine dinoflagellate cysts, which indicate the early stages of marine deposition, conditions that later prevailed across most of the basin. The Early Cretaceous vegetation of the study area, as inferred from spores and pollen, is interpreted to consist mainly of conifer forests dominated by Araucariaceae, Podocarpaceae and Cheirolepidiaceae with an understory of ferns (Osmundaceae, Schizaeaceae) and other spore-producers (clubmosses, mosses, liverworts and hornworts). Two vegetation-types are hypothesized for the region with their distribution related to substrate characteristics and water availability: a more mesic, structurally complex, riverine forest within paleovalleys and topographic lows, and a more open forest accross the hinterland.

Paleoecological and paleobiogeographical inferences of the Paleocene ostracods from Sinai, Egypt

The present study aims to detect the paleoecology and paleobiogeography of the Paleocene ostracods from Sinai, Egypt. In order to reach our goals, the Paleocene rocks were examined in four outcrops (El Dokh, El Qussaima, Matulla, and Ekma sections) from Sinai, Egypt. The recognized rock units include Dakhla Formation (at the base) and Tarawan Formation (at the top). The investigation of the ostracod fauna yielded 49 species and subspecies, which enabled the recognition of one Paleocene biozone, Mauritsina teiskotensis - Ordoniya ordoniya Zone. The Early and Middle Paleocene have diverse assemblages, while the Late Paleocene showed a rarity of ostracods. Based on the shape of the carapaces and the surface ornamentation, four ostracod morphogroups were recognized. Morphogroup 4 is the most common group in all the studied sections. The structure of ostracod assemblages (abundance, richness and the morphogroups) besides the lithology pointed out to middle - outer neritic depositional environment for the studied Paleocene sections. The identified species have a wide geographic range, extending from West Africa, North africa to the Middle East. The paleobiogeographic framework is carried out with the aid of multivariate analyses. The suggested matrix consists of 25 ostracod species from 10 countries, including Egypt, Libya, Tunisia, Algeria, Jordan, Israel, Senegal, Ivory Coast, Niger and Mali. The outcomes of the Q-mode cluster analysis indicate that the selected countries may be categorized into three provinces, North Africa (Libya, Algeria, Tunisia and Egypt), West Africa (Senegal, Mali, Ivory Coast and Niger), and Middle East (Israel and Jordan). The similarity of ostracod assemblages between North Africa, including Egypt, with that of Jordan and Israel, suggests the migration and exchange through the southern Tethyan coast. The common deep marine species between North and West Africa may be migrated along the West African coast on the Atlantic Ocean, while shallow species migrated through the trans-Saharan seaway.

Marine biological injuries and their medical management: A narrative review.

The marine environment can be extremely dangerous, and the harm caused by marine organisms when they contact the human body can be especially harmful, even deadly. Contact includes stings, bites, wounds, and consumption as food. In this article, the characteristics of the common marine biological injuries are summarized, the major marine organisms causing damage in China's marine waters are described, and injury prevention and treatment methods are discussed.

DNA barcoding of the most common marine ornamental fish species spilled over from a small-sized marine protected area, Bali Barat National Park, Indonesia

Abstract. Wiadnya DGR, Kurniawan N, Hariati AM, Astuti SS, Paricahya AF, Dailami M, Kusuma WE. 2023. DNA barcoding of the most common marine ornamental fish species spilled over from a small-sized marine protected area, Bali Barat National Park, Indonesia. Biodiversitas 243: 47-54. Healthy coral reefs within a protected area may function as a source of recruitment to the surroundings through spill-over and export larvae. This study aims to generate a list of common species of marine ornamental fishes for the aquarium trade in Indonesia, mainly collected adjacent to Bali Barat National Park (BBNP). Lived-fish samples were collected from six fish collectors in two villages surrounding BBNP, Sumber Kima, Bali, and Bangsring, Banyuwangi. All species were checked by three active fishermen in both villages for confirmation of the most common species and not belonging to the target. A total of 82 separate groups out of 145 specimens were identified based on their morphological characters. All samples were then sequenced based on mitochondrial cytochrome oxidase subunit I (COI) gene amplification. The sequence read lengths for all the specimens were between 655 and 658 bp. All the findings from this DNA barcoding approach were in line with morphological species identification. Wrasses (Family: Labridae) were the most dominant (41 species) representing the group, followed by Pomacentridae (24 species), Acanthuridae (14 species), Pomacanthidae (14 species) and Gobiidae (10 species). Among the species, only green sergeant, Amblyglyphidodon batunaorum, belonged to the Vulnerable (VU) category based on IUCN criteria. The rest were either Least Concern (LC), Data Deficient (DD), or Not Evaluated (NE). It implied that no catch species were under fishing pressure except for the green sergeant. Considering a total of 28 target species by local fishermen (recorded in an earlier article), small-scale fishermen can easily catch more than 100 species in one trip. The results significantly contributed to the need to generate a list of common ornamental fish species specifically exported from Indonesia as an aquarium trade commodity.

Promoting Effect of Common Marine Cations on Hydrate Dissociation and Structural Evolution under a Static Electric Field

Natural gas hydrate, a potential energy resource, is attracting worldwide attention. In this study, we propose a new method of hydrate dissociation which uses seawater and electrostatic fields (SE method) cooperatively. The hydrate molecular dissociation mechanism of gas hydrate is a key issue in studying the kinetic properties of gas hydrate using the SE method. Therefore, molecular dynamics simulations were used to investigate the thermodynamic properties and structural changes of methane hydrate (MH) in multiple kinds of salt solutions under an electrostatic field. The results show that the electric field can drive cations into the MH phase to form a series of random semiopen cages, which are essentially temporary and metastable. The variation in free energy indicates that it is more difficult for divalent cations to enter the hydrate phase than monovalent cations, meaning that the hydrate structures formed with divalent cations are more unstable. Then, the ion current occurred in the hydrate phase (called ion migration in this study), which greatly accelerated hydrate dissociation. In contrast, the promotion effect of cations with the same charge on MH dissociation is as follows: Sr2+ > K+ ≈ Na+ > Ca2+ ≈ Mg2+. In general, the presence of common marine cations enhanced the promotion effect of the electric field on gas hydrate dissociation.

Assessment of mercury contamination and food composition in commercially important marine fishes in the southern South China Sea

This study examined mercury contamination in common commercial marine fish caught from the South China Sea. Specifically, the muscle tissue mercury levels of four species (n = 10), one each from the Scombridae, Serranidae, Carangidae, and Nemipteridae families, was examined using a direct mercury analyzer (MA-3000); their trophic level was assessed using TrophLab tm software. Provisional tolerable weekly intake levels (PTWI) and the relationships between length–mercury concentration and weight–mercury concentration of species using Pearson correlation coefficient were identified. Samples from the Serranidae family had the highest muscle mercury concentrations, followed by Nemipteridae, Carangidae, and Scombridae in descending order. The results show that the highest mercury concentrations were found in Epinephelus heniochus (2.34 ±0.22μg/g) from the Serranidae family, while the lowest mercury concentrations were found in Scomberomorus guttatus (0.05 ± 0.00 μg/g) from the Scombridae family. This study suggests that factors such as size, composition of food in the fish gut, and habitat had the greatest influence on the mercury levels found in these fishes. The PTWI data showed that only 31% of the species in the current study had not exceeded the recommended safety level of 1.6 μg/kg BW/week methylmercury intake. A consideration of PTWI can help to reduce fish consumption risks to consumers by providing a recommended consumption level of each fish.