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Genetic diversity is a fundamental component of biodiversity. Examination of global patterns of genetic diversity can help highlight mechanisms underlying species diversity, though a recurring challenge has been that patterns may vary by molecular marker. Here, we compiled 6862 observations of genetic diversity from 492 species of marine fish and tested among hypotheses for diversity gradients: the founder effect hypothesis, the kinetic energy hypothesis, and the productivity-diversity hypothesis. We fit generalized linear mixed effect models (GLMMs) and explored the extent to which various macroecological drivers (latitude, longitude, temperature (SST), and chlorophyll-a concentration) explained variation in genetic diversity. We found that mitochondrial genetic diversity followed geographic gradients similar to those of species diversity, being highest near the Equator, particularly in the Coral Triangle, while nuclear genetic diversity did not follow clear geographic patterns. Despite these differences, all genetic diversity metrics were correlated with chlorophyll-a concentration, while mitochondrial diversity was also positively associated with SST. Our results provide support for the kinetic energy hypothesis, which predicts that elevated mutation rates at higher temperatures increase mitochondrial but not necessarily nuclear diversity, and the productivity-diversity hypothesis, which posits that resource-rich regions support larger populations with greater genetic diversity. Overall, these findings reveal how environmental variables can influence mutation rates and genetic drift in the ocean, caution against using mitochondrial macrogenetic patterns as proxies for whole-genome diversity, and aid in defining global gradients of genetic diversity.

This study offers an in-depth analysis of the mitochondrial genome of Selene dorsalis (Gill 1863), a species native to the Eastern Atlantic Ocean. The circular mitochondrial DNA molecule measures 16,541 base pairs and comprises 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA genes, and a control region (CR). The nucleotide composition exhibits a notable adenine-thymine (AT) bias, accounting for 53.13%, which aligns with other species in the Carangidae family. Most PCGs initiate with the ATG codon, with the exception of Cytochrome C oxidase subunit I, which starts with GTG. Analysis of relative synonymous codon usage reveals that leucine and serine are the most prevalent amino acids in the mitochondrial genome of S. dorsalis and its congeners (S. vomer and S. setapinnis). All tRNAs display the typical cloverleaf structure, though tRNA Serine (S1) lacks a dihydrouracil arm. Pairwise comparisons of synonymous and nonsynonymous substitutions for all PCGs yielded values below '1', indicating strong purifying selection. The CR spans 847 bp, representing 5.12% of the mitochondrial genome, and is characterized by high AT content (62.81%). It is situated between tRNA-Pro (TGG) and tRNA-Phe (GAA). The CR contains conserved sequence blocks, with CSB-1 being the longest at 22 bp and CSB-D the shortest at 18 bp. Phylogenetic analysis, using Bayesian and Maximum-likelihood trees constructed from concatenated PCGs across 72 species, successfully differentiates S. dorsalis from other carangids. This study also explores how ocean currents and gyres might influence lineage diversification and parapatric speciation of Selene species between the Atlantic and Pacific Oceans. These results highlight the importance of the mitochondrial genome in elucidating the structural organization and evolutionary dynamics of S. dorsalis and its relatives within marine ecosystems. [ABSTRACT FROM AUTHOR]

The evolutionary history of emperors, particularly in the Atlantic and Indo-West Pacific Oceans, remains largely unmapped. This study explores the maternal lineage evolution of Lethrinids by examining the complete mitogenome of Lethrinus atlanticus, which is endemic to the Eastern Atlantic Ocean. Utilizing advanced next-generation sequencing, we found that the mitogenome spans 16,789 base pairs and encompasses 37 genes, including 13 protein-coding genes (PCGs), two ribosomal RNAs, 22 transfer RNAs, and an AT-rich control region (CR). Our analysis indicates a preference for AT base pairs in the L. atlanticus mitogenome (53.10%). Most PCGs begin with the ATG codon, except for COI, which starts with GTG. Relative synonymous codon usage reveals high frequencies for alanine, leucine, proline, serine, and threonine. The ratio of nonsynonymous to synonymous substitutions suggests strong negative selection across all PCGs in Lethrinus species. Most transfer RNAs exhibit typical cloverleaf structures, with the exception of tRNA-serine (GCT), which lacks a dihydrouracil stem. Comparative analysis of conserved sequence blocks across the CRs of three Lethrinus species shows notable differences in length and nucleotide composition. Phylogenetic analysis using concatenated PCGs clearly distinguishes all Lethrinus species, including L. atlanticus, and sheds light on the evolutionary relationships among Spariformes species. The estimated divergence time of approximately 20.67 million years between L. atlanticus and its Indo-West Pacific relatives provides insights into their historical separation and colonization during the late Oligocene. The distribution of Lethrinids may be influenced by ocean currents and ecological factors, potentially leading to their speciation across the Eastern Atlantic and Indo-West Pacific. This study enhances our understanding of the genetic diversity and phylogenetic relationships within Lethrinus species. Further exploration of other emperor fish mitogenomes and comprehensive genomic data could provide vital insights into their genetic makeup, evolutionary history, and environmental adaptability in marine ecosystems globally. [ABSTRACT FROM AUTHOR]

Aim: Geographic range shifts are a common species' response to climate change. While occurrence data are commonly used to estimate species' geographical range shifts, ongoing debate suggests that local abundance data may be increasingly important for the estimates, but few studies have investigated differences between the above two types of data. We aimed to explore whether occurrence and abundance data would result in different patterns of geographic range shifts for marine fishes. Location: Northeast US Continental Shelf, North Sea, and East Bering Sea. Methods: We used bottom trawl datasets since 1968 in the three large marine communities to assess whether data types would affect estimated shifts in marine fish species. The range centroids of individual species were first estimated every year and linear regressions were fitted to estimate shift rates in both longitudinal and latitudinal directions. The average range centroids of the last 5 years were used to compare differences between the data types in species' shifts. We then grouped species by traits to overview species compositions. Results: Significant differences in shift trends between regressions based on annual occurrence‐ and abundance‐based range centroids were found in species' longitudinal shifts, particularly in the Northeast US Continental Shelf and North Sea. Approximately 38.5%–45.9% of fish species in the large marine communities had inconsistent shift directions when estimated by different data types. In comparison with the average range centroids of the last 5 years between the two data types, large changes were identified in the magnitudes of the shift distances towards the east and west. Fish species with inconsistent shifts between the two data types were mostly composed of commercial and demersal species. Main Conclusions: The results provide observed differences over decades and suggest caution on the estimation of species' geographic range shifts using occurrence and abundance data and highlight the differences for future assessments of marine species shifts under climate change. [ABSTRACT FROM AUTHOR]

The potential effects of Astragalus polysaccharides (APS) were evaluated in coral trout (Plectropomus leopardus). Five APS levels (0%, 0.05%, 0.10%, 0.15%, and 0.20%) were added to the diet of coral trout, and a 56-day growth trial (initial weight 18.62 ± 0.05 g) was conducted. Dietary APS enhanced growth performance, with the highest improvement observed in fish fed the 0.15% APS diet. This concentration also enhanced the antioxidant capacity and immunomodulation of the fish by regulating the expression of genes associated with antioxidant enzymes and immune responses. Intestinal microbiota analysis revealed that APS supplementation significantly increased the Chao1 index and relative abundance of beneficial bacteria (Firmicutes and Bacillus). A high level of APS (0.20%) did not provide additional benefits for growth and health compared to a moderate level (0.15%). These findings indicate that an optimal APS dose promotes growth, enhances antioxidant activity, supports immune function, and improves intestinal microbiota in coral trout. Based on a cubic regression analysis of the specific growth rate, the optimal APS level for the maximal growth of coral trout was determined to be 0.1455%. [ABSTRACT FROM AUTHOR]

This is the first study investigating the aberrant otolith morphology in the Lessepsian lizardfish Saurida lessepsianus in the Aegean Sea, Turkey. A Leica Emspira 3 digital microscope was used to determine the aberrant otoliths examined. Two female specimens measuring 230 and 274 mm in total length (TL) were examined and showed an aberrant otolith on both sides of their head. These deformities might have been instigated by the impacts of changing water factors related to diverse pollutants in the Aegean Sea. Characteristics of otolith deformities are of immeasurable significance for aquatic habitats and other otolith studies. [ABSTRACT FROM AUTHOR]

The impacts of climate change-related stressors are becoming more noticeable in the ocean, particularly in coastal marine ecosystems. Yet limited information still exists on the physiological state and ecological resilience of marine fish species, especially during their early life stages (i.e., larvae and juveniles). The present study investigated the effects of chronic exposure to seawater warming (OW; ΔT = +4 °C) and acidification (OA; ΔpH = −0.3 pH units, equivalent to pCO2~1000 µatm), acting alone or combined (OWA), on juvenile zebra seabream (Diplodus cervinus) physiological resilience, considering distinct levels of biological organization (i.e., biochemical, cell, organ and individual levels). After 60 days of exposure, both stressors, in isolation or combination, significantly decreased specific growth rate (−11% in OW, −42% in OA and −49% in OWA) and leukocyte counts (from −29% in OA and OWA up to −37% in OW) in relation to the control treatment. In addition, a decreased Fulton's condition index (K) was observed under warming and acidification in combination (−35% in OWA). At the cell level, OW, OA and OWA triggered different biomarker responses in D. cervinus (i.e., up-regulation, down-regulation, or absence of significant effect). In general, the results are suggestive of an antagonistic effect when warming and acidification are combined. OWA yielded the highest integrated biomarker response (IBR) index value in the whole organism, muscle, brain and gills of D. cervinus juveniles, therefore suggesting that the effects of these stressors are more severe when they act together. The distinct patterns observed in each stress scenario highlight the importance of carrying out further studies adjusted to the specificities of different regions, i.e., accounting not only for the type and degree of severity of environmental stressors already felt and/or projected for that specific area, but also the physiological plasticity of species that inhabit a particular ecosystem. The gathered knowledge will allow one to determine the vulnerability of particular marine species and geographic areas and, most importantly, to draw up effective and tailor-made conservation strategies to overcome climate change impacts. [ABSTRACT FROM AUTHOR]

This study presents the first record of T. lindbergi from the southwestern Atlantic Ocean, based on specimens collected from the smalleye croaker Nebris microps Cuvier (Sciaenidae), off the coast of Maranhão Island, State of Maranhão, Brazil. Our approach included a morphological analysis complemented by DNA sequencing (28S, ITS2 rDNA, and cox1 mtDNA). Our phylogenetic analysis revealed the affinity of T. lindbergi to its congener T. laticaudi Parukhin, 1969, a digenean parasite commonly found in hydrophiine snakes inhabiting the Pacific Ocean. The interspecific divergence between T. lindbergi and T. laticaudi measures 3.80% for 28S, 7.49–7.64% for ITS2, and 16.29–16.70% for cox1. Our findings expand the documented geographic range of T. lindbergi into the southwestern Atlantic Ocean, report a novel host record, and increase the number of hemiurids known from Brazil to 30 species. Additionally, this study represents the initial documentation of a marine digenean fish within the North Brazil Shelf. [ABSTRACT FROM AUTHOR]

The polychaeta Neanthes japonica is a common by-product in mariculture ponds. It is rich in essential nutrients, but has not been well-explored. Therefore, this 56-day experiment investigated the effects of substituting N. japonica meal for dietary fishmeal on juvenile tiger puffer (15.49 ± 0.02 g, n = 450 fish). The control diet (CON) contained 40% fishmeal. Freeze-dried N. japonica meal (FNM) was supplemented into CON at the levels of 3% (FNM3), 6% (FNM6), and 9% (FNM9), replacing fishmeal. The fifth diet contained 6% oven-dried N. japonica meal (ONM6), replacing fishmeal. The results indicated that no significant difference was observed in growth, feed efficiency, and somatic index among all the treatment groups. The feed intake of the FNM6 group was significantly higher compared to CON. No significant difference was detected in fish proximate composition, as well as the fatty acid composition, amino acid composition, and muscle texture. The supplementation of N. japonica meal decreased the activities of intestinal lipase and α-amylase. The addition of freeze-dried N. japonica meal significantly up-regulated the expression of the intestinal amino-glycine transporter pat1. It was concluded that adding 9% N. japonica meal to the feed had no significant effect on the growth performance and body composition of juvenile tiger puffer. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the microplastic contamination of fresh and pindang fish and its health impact on the coast of Muncar, Banyuwangi Regency, Indonesia. In this study, a total of 115 respondents participated, providing questionnaire data on their fish consumption habits and health problems. Subsequently, spearman's correlation coefficient, a non-parametric statistical test, was used to analyze the questionnaire data. This study also included 100 samples of marine fish, consisting of 89 fresh fish and 11 pindang fish from various types of marine species. The content of microplastic polymers detected through FTIR (Fourier-Transform Infrared Spectroscopy) was around 3-5 microplastic polymers/fish samples, and the most dominant were Polyethylene, Polyester, Polycaprolactam (Nylon 6) and Polyamide. This study showed that 94 percent of fish samples contained microplastics and only 6 percent of samples did not contain microplastics. The intensity of pindang fish consumption was positively correlated with respondents' health symptoms and problems. Subsequently, implementing effective waste management systems and educational programs in the coastal areas is crucial in reducing the pollution of seawater resulting from inadequate waste disposal practices. [ABSTRACT FROM AUTHOR]

The primary line of defense against pathogens from the environment is often fish epidermis tissue. Nevertheless, little is understood about the physiological mechanisms that underlie the non-specific and/or specific protection that these cells can offer. The exact nature of the relationship between the evolution of ostariophysan fish club cells and chemical warning signals is still unknown and controversial. Fish epidermis layer cells comprise mucus cells, lymphocytes, macrophage cells, cuboidal and squamous epithelial cells, and cells specific to certain fish species. Club cells, also called "alarm cells," are chemical alarms that sound in the event of a potentially hazardous scenario. These cells will burst in the presence of a predator, releasing pheromones that, if the skin is physically damaged, trigger an avoidance and terror reaction. In sturgeon larvae, mucus cells were visible in week 1, but club cells did not appear until week 4. Due to their later development during ontogenesis and after wounding, club cells may not have as much of a protective effect during wound healing as filament or mucus cells. Club cells are mostly found in the epidermis of the skin, and it is thought that when they work in tandem with mucus and goblet cells to fight infections, they serve as the body's first line of defense.

Fish productivity has long been the subject of studies using traditional Chinese medicine (TCM). To validate TCM's effectiveness on weight gain rate (WGR) and specific growth rate (SGR), a meta-analysis study was conducted. Of the 58 studies collected from PubMed, Scopus, and Cochrane Library, 4 eligible studies were analyzed quantitatively. The extracted data were then analyzed using Review Manager (RevMan) online to determine the standard mean difference (SMD), random effect, heterogeneity, and 95% confidence intervals (95% CI). As a result, TCM administration had a favorable effect on WGR (SMD = 8.33; p = 0.0001) and SGR (SMD = 8.12; p = 0.0004). In conclusion, this meta-analysis study emphasized the efficacy of TCM to improve fish production performance.

The impacts of climate change-related stressors are becoming more noticeable in the ocean, particularly in coastal marine ecosystems. Yet limited information still exists on the physiological state and ecological resilience of marine fish species, especially during their early life stages (i.e., larvae and juveniles). The present study investigated the effects of chronic exposure to seawater warming (OW; ΔT = +4 °C) and acidification (OA; ΔpH = −0.3 pH units, equivalent to pCO2~1000 µatm), acting alone or combined (OWA), on juvenile zebra seabream (Diplodus cervinus) physiological resilience, considering distinct levels of biological organization (i.e., biochemical, cell, organ and individual levels). After 60 days of exposure, both stressors, in isolation or combination, significantly decreased specific growth rate (−11% in OW, −42% in OA and −49% in OWA) and leukocyte counts (from −29% in OA and OWA up to −37% in OW) in relation to the control treatment. In addition, a decreased Fulton’s condition index (K) was observed under warming and acidification in combination (−35% in OWA). At the cell level, OW, OA and OWA triggered different biomarker responses in D. cervinus (i.e., up-regulation, down-regulation, or absence of significant effect). In general, the results are suggestive of an antagonistic effect when warming and acidification are combined. OWA yielded the highest integrated biomarker response (IBR) index value in the whole organism, muscle, brain and gills of D. cervinus juveniles, therefore suggesting that the effects of these stressors are more severe when they act together. The distinct patterns observed in each stress scenario highlight the importance of carrying out further studies adjusted to the specificities of different regions, i.e., accounting not only for the type and degree of severity of environmental stressors already felt and/or projected for that specific area, but also the physiological plasticity of species that inhabit a particular ecosystem. The gathered knowledge will allow one to determine the vulnerability of particular marine species and geographic areas and, most importantly, to draw up effective and tailor-made conservation strategies to overcome climate change impacts.

This study presents the first record of T. lindbergi from the southwestern Atlantic Ocean, based on specimens collected from the smalleye croaker Nebris microps Cuvier (Sciaenidae), off the coast of Maranhão Island, State of Maranhão, Brazil. Our approach included a morphological analysis complemented by DNA sequencing (28S, ITS2 rDNA, and cox1 mtDNA). Our phylogenetic analysis revealed the affinity of T. lindbergi to its congener T. laticaudi Parukhin, 1969, a digenean parasite commonly found in hydrophiine snakes inhabiting the Pacific Ocean. The interspecific divergence between T. lindbergi and T. laticaudi measures 3.80% for 28S, 7.49–7.64% for ITS2, and 16.29–16.70% for cox1. Our findings expand the documented geographic range of T. lindbergi into the southwestern Atlantic Ocean, report a novel host record, and increase the number of hemiurids known from Brazil to 30 species. Additionally, this study represents the initial documentation of a marine digenean fish within the North Brazil Shelf.

The effects of feeding frequency on Hippocampus reidi broodstock were examined using oocyte fatty acid profile, reproduction, and larval resistance to starvation as evaluation criteria. Twelve breeding pairs (approx. 27 g; 18 cm per individual) were fed to satiation with defrosted enriched caridean shrimp Palaemon sp. in one (F1), two (F2), three (F3), or four (F4) meals per day. Three broodstock pairs were subjected to each feeding regime and treatments were continued for 101 days. Fish of both sexes fed once a day had lower weight gain and specific growth rates than broodstock from the other treatments (p < 0.05). Newly born larvae produced by the pairs in F3 and F4 treatments presented similar weight and length (mean 2.06 ± 0.11 mg; 7.9 ± 0.06 mm, respectively) and were larger than those produced by pairs that received one or two daily feedings (mean 1.62 ± 0.17 mg; 6.7 ± 0.05 mm) (p < 0.05). Mean number of larvae per parturition in F3 and F4 (928.5) was almost two times the mean number of larvae in F1 and F2. The total mortality of the starved larvae was observed after 72 h in the couples of treatments F1 and F2, while in treatments F3 and F4 it occurred after 96 h. The highest concentrations of polyunsaturated fatty acids, arachidonic acid (AA), and docosahexaenoic acid (DHA) were observed in the oocytes produced by fish subjected to the F4 treatment. It is recommended that when broodstock H. reidi are given defrosted enriched shrimp to apparent satiation, they should be fed three to four times per day to promote egg production and to give good quality larvae. [ABSTRACT FROM AUTHOR]

Simple Summary: In fish farming, diseases have commonly been fought with the abusive use of antibiotics, which have caused antibiotic (multi)resistances in bacteria. Consequently, it is necessary to explore safe and environmentally friendly alternative approaches to improve the fish health and avoid the treatment of bacterial diseases with antibiotics such as the use of probiotics. This study focuses on bioinformatic and functional analyses of the genome sequences of Streptococcus salivarius MDI13 and Latilactobacillus sakei MEI5, two Lactic Acid Bacteria (LAB) isolated from the gut of European hakes (Merluccius merluccius, L.), a highly valued marine fish for Spanish gastronomy. The potential probiotic characteristics of both bacteria, and the lack of antibiotic resistance genes and virulence were confirmed. In addition, genes encoding three antimicrobial peptides (known as bacteriocins) were identified in the genome of S. salivarius MDI13. One of these in vitro-synthesized bacteriocins (BlpK) showed antimicrobial activity against two fish pathogens (namely Lactococcus garvieae and Streptococcus parauberis). Altogether, our results suggest that S. salivarius MDI13 and L. sakei MEI5 have a strong potential as probiotics to prevent bacterial diseases in fish farming. Frequently, diseases in aquaculture have been fought indiscriminately with the use of antibiotics, which has led to the development and dissemination of (multiple) antibiotic resistances in bacteria. Consequently, it is necessary to look for alternative and complementary approaches to chemotheraphy that are safe for humans, animals, and the environment, such as the use of probiotics in fish farming. The objective of this work was the Whole-Genome Sequencing (WGS) and bioinformatic and functional analyses of S. salivarius MDI13 and L. sakei MEI5, two LAB strains isolated from the gut of commercial European hakes (M. merluccius, L.) caught in the Northeast Atlantic Ocean. The WGS and bioinformatic and functional analyses confirmed the lack of transferable antibiotic resistance genes, the lack of virulence and pathogenicity issues, and their potentially probiotic characteristics. Specifically, genes involved in adhesion and aggregation, vitamin biosynthesis, and amino acid metabolism were detected in both strains. In addition, genes related to lactic acid production, active metabolism, and/or adaptation to stress and adverse conditions in the host gastrointestinal tract were detected in L. sakei MEI5. Moreover, a gene cluster encoding three bacteriocins (SlvV, BlpK, and BlpE) was identified in the genome of S. salivarius MDI13. The in vitro-synthesized bacteriocin BlpK showed antimicrobial activity against the ichthyopathogens Lc. garvieae and S. parauberis. Altogether, our results suggest that S. salivarius MDI13 and L. sakei MEI5 have a strong potential as probiotics to prevent fish diseases in aquaculture as an appropriate alternative/complementary strategy to the use of antibiotics. [ABSTRACT FROM AUTHOR]

This study examined preserved marine fish specimens collected from numerous field surveys conducted along Türkiye's Black Sea, Marmara, Aegean, and Mediterranean coasts since 1965. Our review and categorization of these materials revealed that the specimens belong to 360 species from 131 families. Current data shows that the museum collection includes 20 species of cartilaginous fish and 8 species of bony fish listed as endangered on the IUCN Red List, alongside 54 non-native fish species. Prepared according to museum standards by Ege University Fisheries Faculty's Scientific Material (ESFM), this collection of Turkish marine fish constitutes 66% of all Turkish marine fish fauna. This makes it the largest and oldest marine fish collection in Türkiye. Considering Türkiye's maritime borders with neighboring countries, this collection is significant nationally and globally. Given the diverse marine fish species in Turkish seas over the past half-century, this preserved material is a vital reference for local and foreign ichthyologists. If organized and transformed into a visitable museum, this extensive collection could raise awareness about the diversity of marine fish species in our seas. As a result, we have established the "biological repository of Turkish Marine Fish Department" in the Faculty Museum, now known as the Fisheries Faculty's Scientific Material (ESFM) at Ege University. We present the fish in the collection as a species list. [ABSTRACT FROM AUTHOR]

The marine environment is the largest ecological habitat on Earth, albeit one of the least explored, particularly in terms of its microbial inhabitants. The marine fish gut is host to a diverse microbial community from which diverse bioactive molecules can be sourced. Due to the unique environmental pressures these microbial communities experience, the bioactive molecules they produce often evolve unique adaptations that give them diverse structures and activities, differentiating them from terrestrial homologues. Of particular interest, due to their structural and functional diversity, are the ribosomally-synthesized antimicrobial peptides (bacteriocins). With increasing pressure from emerging antibiotic-resistant disease and industrial demand for novel therapeutics, the marine fish gut microbiome represents a relatively untapped resource of novel bacteriocins that could prove beneficial to human health and aquaculture. This review presents an overview of the marine fish gut microbiome and explores its potential as a source of bacteriocins for human health with considerations for applications and future research in this area. [ABSTRACT FROM AUTHOR]

Objective: The copepod Parvocalanus crassirostris has recently increased its use as live food in marine fish hatcheries. Methods: To investigate the bacterial community of P. crassirostris nauplii and explore the potential use of nauplii as a vector for probiotics, adult copepods were reared with or without a probiotic consortium (Bacillus spp. and Lactobacillus spp.). Nauplii from both treatments were either enriched with probiotics or not, resulting in four treatments: control rearing and nonenriched, control rearing and probiotic enriched, probiotic rearing and nonenriched, and probiotic rearing probiotic enriched. A next‐generation sequencing analysis of the 16S ribosomal RNA gene was performed. Result: The bacterial community of nauplii without probiotics was dominated by the phyla Proteobacteria (mean ± standard deviation = 51.5 ± 8.0%) and Bacteroidetes (27.6 ± 6.7%); from these phyla, the most abundant orders were Rhodobacterales (21.8 ± 2.0%), Flavobacteriales (13.5 ± 9.4%), Chitinophagales (9.7 ± 1.8%), Alteromonadales (9.5 ± 4.0%), and Burkholderiales (3.8 ± 0.8%). Opportunistic pathogenic bacterial genera, such as Vibrio spp. and Pseudomonas spp., were detected at very low relative abundances (<1.2%), indicating that P. crassirostris nauplii could be considered a safe microbiological live feed. Furthermore, P. crassirostris nauplii were a good vector for probiotics delivery, as the adhesion of probiotics on the copepod exoskeleton was successful. Bacillus spp. abundance was 5–6× greater than the abundance of Lactobacillus spp. in P. crassirostris nauplii. The highest mean values of probiotics relative abundance (Bacillus spp. 41 ± 6.0%, Lactobacillus spp. 6.0 ± 3.0%) were observed in nauplii that were reared with probiotics and also enriched with probiotics. Conclusion: Parvocalanus crassirostris nauplii stages I–II appear to be good vectors to provide probiotics to first‐feeding fish larvae. Impact statementMarine fish aquaculture relies on quality live feed for optimal protein production. Assessing copepod nauplii's microbiological safety as fish larvae prey and their role as probiotics vectors is an important contribution to marine fish aquaculture. [ABSTRACT FROM AUTHOR]

A total of 366 individuals of Lutjanus argentiventris (Peters, 1869) were collected over a 5-yr period (October 2018 to June 2022) from Acapulco Bay, Mexico. Parasite communities in Lutjanus argentiventris were quantified and analyzed to determine the main factors that generate changes in species richness and/or species composition over time. The digeneans and copepods were the best-represented parasite groups. The parasite communities were characterized by a high numerical dominance of ectoparasites, mainly isopod larvae. Species richness at the component community level (9–23 species) was similar to the reported richness in other Lutjanus spp. The parasite communities of Lutjanus argentiventris exhibited high variability in species composition, suggesting that each parasite species may respond differently to environmental changes. However, the species richness and diversity were fairly stable over time; therefore, a clear pattern of interannual variation was not observed. Variations in the community structure probably were due to factors such as host traits (e.g., feeding behavior and body size), and possible interannual differences in environmental factors amplified by the occurrence of the anomalous event of La Niña. [ABSTRACT FROM AUTHOR]

In this study, the collected fish species were identified based on morphological observations and then evaluated by DNA barcoding. The COI gene has been recognized as a biological marker for fish species identification and the objective of this study is to analyze the variable region of the COI gene in subunit I. The mitochondrial cytochrome (COI) oxidase subunit I gene was analyzed as a suitable molecular maker for the identification of three specimens of the fish species Hipposcarus harid, widely distributed in the Red Sea. The COI gene sequences in the variable region revealed variations among the fish species. The COI gene sequences in the variable region were similar to the variable region of Hipposcarus harid collected from the Northern Red Sea and all three were named: H. harid H13, H. harid H2c, and H. harid H12. The identification of the fish species collected from the Red Sea in Saudi Arabia would help ichthyologists improve the management, conservation and monitoring of economically important long-nose parrotfish species in Saudi Arabia. [ABSTRACT FROM AUTHOR]

Gene regulatory divergence is thought to play an important role in adaptation, yet its extent and underlying mechanisms remain largely elusive for local adaptation with gene flow. Local adaptation is widespread in marine species despite generally high connectivity and is often associated with tightly linked genomic architectures, such as chromosomal inversions. To investigate gene regulatory evolution under gene flow and the role of inversions associated with local adaptation to a steep thermal gradient, we generated RNA-seq data from Atlantic silversides (Menidia menidia) from two locally adapted populations and their F1 hybrids, reared under two temperatures. We found substantial divergence in gene expression and thermal plasticity between populations, with up to 31% of genes being differentially expressed. Reduced thermal plasticity, temperature-dependent gene misexpression, and the disruption of coexpression networks in hybrids point toward a role of regulatory incompatibilities in local adaptation, particularly under colder temperatures. Chromosomal inversions show an accumulation of regulatory incompatibilities but are not consistently enriched for differentially expressed genes. Together, these results suggest that gene regulation can diverge substantially among populations despite gene flow, partly due to the accumulation of temperature-dependent regulatory incompatibilities within inversions. [ABSTRACT FROM AUTHOR]

Diphyllobothriosis, a fish-borne zoonosis in South America, is mainly caused by the Pacific broad tapeworm Adenocephalus pacificus Nybelin, 1931, a parasite of considerable concern in fishery resources due to its impact on public health. A new diphyllobothrid, Diphyllobothrium sprakeri Hernández-Orts et al. Parasites Vectors 14:219, 2021, was recently described from sea lions from the Pacific Coast, but marine fish acting as intermediate hosts are unknown. The objective of this study was to confirm the presence of plerocercoid larvae of Diphyllobothriidae Lühe, 1910 (Cestoda: Diphyllobothriidea) in nine fish species of commercial importance in Peru. Of a total of 6999 fish (5861 Engraulis ringens, 853 Sciaena deliciosa, 6 Sciaena callaensis, 171 Scomber japonicus, 40 Trachurus murphyi, 40 Ariopsis seemanni, 18 Merluccius peruanus, 5 Sarda chiliensis, and 5 Coryphaena hippurus), 183 were infected with plerocercoid larvae, representing a total prevalence of 2.61% and a mean intensity of 3.2. Based on mtDNA cox1 sequences of 43 plerocercoids, a phylogenetic analysis revealed that 41 belong to A. pacificus and two to D. sprakeri. These findings are first molecular data for D. sprakeri larvae, and the infections of E. ringens and T. murphyi by plerocercoid larvae represent the first records of intermediate/paratenic hosts for this species. Hence, the findings of the current study enhance our understanding of the presence of diphyllobothriid species in commercial fish from the Southeastern Pacific Ocean and their potential impact on seafood safety for local human populations. [ABSTRACT FROM AUTHOR]

Twenty-seven specimens of the fish species Terapon jarbua and 4 specimens of the fish species Terapon theraps were collected from the Cat Ba Archipelago marine area, and examined for parasite infection. Among these, 4 specimens of T. jarbua and 1 specimen of T. theraps were infected with a total of 42 monogeneans. The intensity of infection ranged from 1 to 16 worms per fish. Four monogenean species were identified, three of which belong to the Protogyrodactylidae: Protogyrodactylus gussevi (14 specimens) and Protogyrodactylus perforatus (12 specimens) were found on T. jarbua, while Protogyrodactylus solidus (1 specimen) was identified on T. theraps. The species Microcotyle helotes (17 specimens) was recorded for the first time in Vietnam, found in two individuals of the new host T. jarbua. Additionally, a redescription of M. helotes was provided. [ABSTRACT FROM AUTHOR]

ABSTRACT Fish, like all other species, can be impacted by a variety of environmental conditions, including parasitic infections. Although there are several parasitological researche on ectoparasitic monogeneans, few are published on those that infect sparid fish. Forty samples of Acanthopagrus bifasciatus were collected during this study from coastal regions along the Arabian Gulf (Saudi Arabia). Gills from all fish were isolated and examined to identify monogeneans. The parasites were studied morphologically using light microscopy. Overall prevalence and mean intensity were 20% and 9, respectively. Eight out of 40 (20%) fish samples were found to be naturally infected with a monogenetic species, namely, Bivagina pagrosomi (Murray, 1931) Dillon and Hargis, 1965 belonging to Microcotylidae (order Mazocraeidea). This parasite is characterized by the presence of haptor provided 43-47 clamps of microcotylid-type that deeply penetrated the gill lamellae and caused severe pathological impacts including hyperplasia, telangiectasis, and deformity of the respiratory epithelial cells Our finding indicates that this is the first report of A. bifasciatus being infected with B. pagrosomi from Saudi marine waters as well as the research of its deleterious effects on its host gills. More research is needed to confirm the parasite species’ taxonomic status at the molecular level.

Marine protected areas are set up across the globe to safeguard biodiversity and support coastal ecosystem functioning. In Hong Kong, partially protected marine parks and a no-take marine reserve have been managed under legislation for years, yet a comprehensive evaluation of their conservation impact is still pending despite the region’s reputation for high marine diversity. Most studies assess conservation effectiveness solely in terms of taxonomic diversity, without delving into the contributions of functional and phylogenetic diversity. In this study, we used environmental DNA combined with multifaceted diversity indicators to assess the impact of the level of protection on the fish community in Hong Kong waters. Our results indicated that the marine protected areas significantly contributed to fish community conservation. The no-take marine reserve exhibited the highest taxonomic and phylogenetic diversity, while partially protected marine parks showed the most balanced community composition. No significant increase in fish functional diversity was found in the protected areas. Water quality, hydrological condition, and protection level were the primary factors affecting community variation for taxonomic, functional, and phylogenetic diversity, respectively. Fish species composition significantly varied with different protection levels, and species turnover was the main component of the dissimilarity. Future management of marine protected areas should assess multifaceted biological indicators and establish a rational conservation scheme.

The biological concentration effect of radionuclides in marine fish has exacerbated public anxiety about seafood security in the context of Fukushima nuclear-contaminated water discharged into the ocean. However, the most polluted port near the Fukushima Daiichi Nuclear Power Plant (FDNPP) has seldom been investigated, especially for radioactivity in marine fish. In this study, decadal observations of radiocesium in marine fish and seawater from the most polluted port were simultaneously established after the Fukushima Nuclear Accident. We found a generally decreasing trend of historical 137Cs activity in seawater, with seasonal variations modulated by precipitation. Seasonal variations were elucidated with finer detail and divided into exponential decline in the dry season and steady variation in the wet season. A novel method was proposed to estimate the continuing source term of 137Cs derived from the FDNPP, which was 3.9 PBq in 2011 and 19.3 TBq between 2012 and 2022 on the basis of historical 137Cs. The biological concentration effect of marine fish is quantitatively emphasized according to the higher ratio of overstandards for radiocesium in marine fish relative to that in seawater. Long-term observation and analysis of radiocesium in marine fish and seawater from the most polluted port would provide insights into the scientific evaluation of the effectiveness of the decommissioning of the FDNPP in the past and share lessons on the fate of Fukushima-derived radionuclides in the future. [ABSTRACT FROM AUTHOR]

China is a major player in the marine fish trade. The price prediction of marine fish is of great significance to socio-economic development and the fisheries industry. However, due to the complexity and uncertainty of the marine fish market, traditional forecasting methods often struggle to accurately predict price fluctuations. Therefore, this study adopts an intelligent combination model to enhance the accuracy of food product price prediction. Firstly, three decomposition methods, namely empirical wavelet transform, singular spectrum analysis, and variational mode decomposition, are applied to decompose complex original price series. Secondly, a combination of bidirectional long short-term memory artificial neural network, extreme learning machine, and exponential smoothing prediction methods are applied to the decomposed results for cross-prediction. Subsequently, the predicted results are input into the PSO–CS intelligence algorithm for weight allocation and to generate combined prediction results. Empirical analysis is conducted using data illustrating the daily sea purchase price of larimichthys crocea in Ningde City, Fujian Province, China. The combination prediction accuracy with PSO–CS weight allocation is found to be higher than that of single model predictions, yielding superior results. With the implementation of weight allocation intelligent combinatorial modelling, the prediction of marine fish prices demonstrates higher accuracy and stability, enabling better adaptation to market changes and price fluctuations. [ABSTRACT FROM AUTHOR]

This study investigates the presence and concentrations of ten specific heavy metals in the muscle tissues and gonads of three commercially important marine fish species: Garfish (Belone belone), European barracuda (Sphyraena sphyraena), and Anglerfish (Lophius piscatorius) collected from the Aegean Sea in Türkiye. The results indicate variations in metal accumulation, both between genders and among species. The fish species tend to accumulate higher levels of heavy metals in their gonads than in muscle tissues (p<0.05). While Cr, Cd, and Pb were not detected, Zn, Cu, and Fe are the predominant metals in muscle tissues due to their essential biological roles. However, within toxic elements, Hg was predominant, and L. piscatorius , a benthic fish, exceeded its recommended safety limits. A health risk assessment suggests that except for L. piscatorius , consuming these fish species from the Aegean Sea is generally safe, with estimated weekly intake (EWI) values below permissible limits. Total Hazard Quotient (THQ) values for most metals are below 1, indicating no significant non-carcinogenic health risks for consumers. This study emphasizes the critical need for regularly monitoring heavy metal levels in marine fish from the Aegean Sea, Turkiye. While overall safety in consuming these fish is highlighted, exceptions exist, notably concerning Hg levels in L. piscatorius. Therefore, persistent monitoring of heavy metal concentrations, especially in L. piscatorius , is advised to ensure ongoing safety and mitigate potential risks of metal accumulation. [ABSTRACT FROM AUTHOR]

A total of sixty random samples of marine fish, including sardine, seabream, and seabass (20 of each), were chosen from the commercially significant species of harvested marine fish from retail markets in Alexandria province for chemical and microbiological assessment. The study revealed that the average values of histamine, Trimethylamine (TMA), and total volatile nitrogen (TVN) in the analyzed samples of sardine, seabream, and seabass were as follows: for sardine, the values were (0.41 ± 0.002, 0.44 ± 0.02, and 0.19 ± 0.01mg/100g); for seabream, the values were (8.53 ± 0.033, 18.03 ± 0.27, and 12.92 ± 0.45 mg/100g); and for seabass, the values were (18.52 ± 0.62, 19.61 ± 0.29, and 17.64 ± 0.13 mg/100g). The average total bacterial count in the analyzed samples of sardine, seabream, and seabass were 17.8×105 ± 2.6×105, 3.2×105 ± 0.61×105, and 1.95×105 ± 0.49×105 Cfu/g, respectively. The Enterobacteriaceae count in the same examined samples were 5.8×104 ± 3.6×104, 3.1×10³ ± 0.63×10³, and 2.3×10³ ± 0.54×10³ cfu/g, respectively. Additionally, the mean values of coliforms were 2.2×10³ ± 0.51×10³, 8.1×10² ± 1.02×10², and 7.4×10² ± 0.8×10² Cfu/g, respectively. E.coli and salmonella were detected in 20 and 10% of examined sardine sample, and both organisms failed to be detected in seabream and seabass, respectively, While Vibrio parahaemolyticus were detected in only one sample of examined sardine, seabream, and seabass with an incidence level (5% of each type). In conclusion, Sardine had the highest level of contamination with pathogenic organisms such as E. coli, V. parahaemolyticus and salmonella, therefore, conduct regular audits and inspections of fish processing facilities, fishing vessels, and storage areas to ensure compliance with hygiene and safety standards. [ABSTRACT FROM AUTHOR]

This study examined the occurrence of microplastics (MPs) in the gastrointestinal tract (GIT) of 384 fishes classified into four species from 11 sites in 2022 from the southern part of the Caspian Sea. GITs of fishes were collected and digested in H2O2 and KOH at 45 °C for 72 h. After filtration, extracted MPs were observed under a stereomicroscope, and selected MP particles were identified using FTIR. Presence of MPs was 68.98% in the GIT of the investigated fish. The mean abundance of MPs was 5.9 ± 0.9 MPs/GIT in Rutilus kutum, 9.2 ± 1.2 MPs/GIT in Chelon auratus, 3.6 ± 0.7 MPs/GIT in Alosa braschnikowi, and 2.7 ± 0.5 MPs/GIT in Vimba vimba. The predominant form of MPs was fiber (58.21%), followed by fragment (34.77%). Black (34.4%), white (19.07%), and blue (14.58%) were the most frequently detected colors of MPs. Overall, 6 MP polymers were identified, dominantly polypropylene (42.86%), polystyrene (17.86%), and cellophane (14.28%). The western part of the Caspian Sea (mostly tourist spots and urban areas) showed more MP pollution in fish compared to the eastern part. Polymer hazard index (PHI) revealed alarming microplastic contamination in the southern Caspian Sea. The PHI value of the present study showed that PES (PHI = 8403.78) and PS (PHI = 535.80) were "Extreme danger" and "Danger" risk categories, respectively. [ABSTRACT FROM AUTHOR]

Fish is a valued source of heath-benefiting protein and other indispensable nutrients. This study aimed to investigate the proximate components (e.g. protein, lipid, moisture and ash) of eleven noncommercial marine fish species namely Johnius argentatus, Harpodon nehereus, Cynoglossus lingua, Johnius elongatus, Sillaginopsis panijus, Pomadasys hasta, Setipinna phasa, Megalaspis cordyla, Rita rita, Gonialosa manmina and Scatophagus argus obtained from the Bay of Bengal. The samples were collected from raw fish (as a whole), different body parts (head, middle and tail) and processed fish (boiled and dried). This study further compared the nutrition values in relation to the price of individual species. Protein content (13.27-33.56%) between species and methods of cooking varied considerably. The highest amounts of protein (19.18 to 33.55%) were found in the fried fish, while the raw and boiled fish contained almost similar amount (protein, 14.00 to 19.57%). Fat content differed between species ranged from 0.38 to 4% in raw fish, 0.78 to 3.43% in boiled fish, and 15.72 to 33.78% in fried fish. The ash content also differed among raw (1.05 to 3.76%), boiled (0.51 to 3.00%) and fried (1.72 to 9.06%) fishes. Lowest moisture content was observed in fried fish (28.6 to 53.30%), while raw and boiled fishes showed higher moisture content (71.00 to 84.85%). Between body parts, lipid and ash values were marginally high in middle and tail muscle respectively, while protein and moisture values were comparable. The regression analysis revealed that fish price increased with the increase of their protein contents. The study has provided the nutritional information of these selected fishes which are mostly consumed by the general coastal inhabitants in Bangladesh. [ABSTRACT FROM AUTHOR]

Fishes of the genus Acanthurus (Acanthuridae) are strongly related to reef environments, in a broad biogeographic context worldwide. Although their biological aspects are well known, cytogenetic information related to this genus remains incipient. In this study, Acanthurus species from populations inhabiting coastal regions of the Southwest Atlantic (SWA), South Atlantic oceanic islands (Fernando de Noronha Archipelago and Trindade Island), Greater Caribbean (GC), and Indo-Pacific Ocean (the center of the origin of the group) were analyzed to investigate their evolutionary differentiation. For this purpose, we employed conventional cytogenetic procedures and fluorescence in situ hybridization of 18S rDNA, 5S rDNA, and H3 and H2B-H2A histone sequences. The Atlantic species (A. coeruleus, A. chirurgus, and A. bahianus) did not show variations among them, despite their vast continental and insular distribution. In contrast, A. coeruleus from SWA and GC diverged from each other in the number of 18S rDNA sites, a condition likely associated with the barrier created by the outflows of the Amazonas/Orinoco rivers. The geminate species A. tractus had a cytogenetic profile similar to that of A. bahianus. However, the chromosomal macrostructures and the distribution of rDNA and hisDNA sequences revealed moderate to higher rates of diversification when Acanthurus species from recently colonized areas (Atlantic Ocean) were compared to A. triostegus, a representative species from the Indian Ocean. Our cytogenetic data covered all Acanthurus species from the Western Atlantic, tracked phylogenetic diversification throughout the dispersive process of the genus, and highlighted the probable diversifying role of ocean barriers in this process. [ABSTRACT FROM AUTHOR]

As the most important digestive and immune organ of the body, intestinal microbiome is complex and diverse, which plays a crucial role in the growth and health of the host. For the large number of marine fishes, much progress has been made in the study of gut microbiome. This paper reviews the research progress of intestinal microbiome of marine fishes at home and abroad, including the research methods, composition and influencing factors, as well as the influence mechanism of gut microbiome on marine fishes, in order to provide some guidances and help to promote the healthy, efficient, green and sustainable development of marine fishes. [ABSTRACT FROM AUTHOR]

Bombay duck Harpodon nehereus has undergone a dramatic shift from a by-catch fish species to the dominant species in the southeast coast of China. This shift has led to economic growth in the fishery and has had a significant impact on community structure, biodiversity, and resource competition in the ecosystem. Strong hypoxia tolerance may be one of the contributing factors for its population growth. This study compared the transcriptional regulation and alternative splicing in H. nehereus from the normoxic and hypoxic zone near the Yangtze Estuary. Compared with normoxia, the number of alternative splicing events increased in the gill and heart but decreased in the muscle after hypoxia, among which exon skipping was the most prevalent type in different tissues. Enrichment analysis showed that differentially expressed genes and genes with differentially alternative exons were mainly enriched in transmembrane transport and glycerophospholipid metabolic process in gill, cell cycle, and FoxO signaling pathway in heart, as well as cell cycle and reduced metabolic rate in muscle. Key candidate genes may be associated with gill remodeling, elevated heart rate, and muscle angiogenesis function. This study provides valuable genetic clues for evaluating molecular regulation strategies related to hypoxia tolerance in marine fishes. [ABSTRACT FROM AUTHOR]

The blackfin snook, Centropomus medius, is a valuable fish in American and Mexican markets, mainly from catches. Nonetheless, information and studies about the biology of this species still need to be made available; thus, its aquaculture should be developed. This study aimed to describe the seasonal changes of proximate composition during a reproductive cycle of C. medius, analyzing differences between tissues and their changes related to the reproductive process. The snook specimens were collected in Magdalena Bay, Baja California Sur, Mexico, and measured every month from September 2001 to November 2002. Liver, gonads, muscle tissue, and intraperitoneal fat (IPF) were sampled and weighed. The gonadosomatic index (GSI), hepatosomatic index (HSI), IPF ratio, and condition factor index (K) were calculated. The biochemical composition was analyzed in the gonad, liver, and muscle. The reproductive period (RP) of wild C. medius in Baja California Sur, Mexico, was from June to December. The spawning period was recorded at summer temperature (25-30°C) and photoperiod (>13 h daylight) starting in September. High GSI values (gonad development), low HSI values (lipid reserve mobilization), low IPF, and low K ratio were related to elevated temperatures. Moreover, variations were observed in protein, total lipid, triglycerides, and glycogen content in muscle, liver, and gonad according to the reproductive phase. A positive correlation was demonstrated between protein contents in muscle, gonad, and K, with lower concentrations during RP, while liver protein composition showed an opposite pattern. Lipids were mainly present in the liver, and the concentration decreased during RP while muscle increased. The results obtained in this study show differences in the proximate analyses in the liver, muscle, and gonads throughout the year concerning different phases of the reproductive cycle, indicating a great dependence of this process on the mobilization of reserves during C. medius reproduction. Therefore, understanding the feeding requirements to pursue the management of this species in captivity for aquaculture development is greatly important. [ABSTRACT FROM AUTHOR]

Understanding how marine organisms adapt to local environments is crucial for predicting how populations will respond to global climate change. The genomic basis, environmental factors and evolutionary processes involved in local adaptation are however not well understood. Here we use Atlantic herring, an abundant, migratory and widely distributed marine fish with substantial genomic resources, as a model organism to evaluate local adaptation. We examined genomic variation and its correlation with environmental variables across a broad environmental gradient, for 15 spawning aggregations in Atlantic Canada and the United States. We then compared our results with available genomic data of northeast Atlantic populations. We confirmed that population structure lies in a fraction of the genome including likely adaptive genetic variants of functional importance. We discovered 10 highly differentiated genomic regions distributed across four chromosomes. Nine regions show strong association with seasonal reproduction. One region, corresponding to a known inversion on chromosome 12, underlies a latitudinal pattern discriminating populations north and south of a biogeographic transition zone on the Scotian Shelf. Genome–environment associations indicate that winter seawater temperature best correlates with the latitudinal pattern of this inversion. The variation at two so‐called 'islands of divergence' related to seasonal reproduction appear to be private to the northwest Atlantic. Populations in the northwest and northeast Atlantic share variation at four of these divergent regions, simultaneously displaying significant diversity in haplotype composition at another four regions, which includes an undescribed structural variant approximately 7.7 Mb long on chromosome 8. Our results suggest that the timing and geographic location of spawning and early development may be under diverse selective pressures related to allelic fitness across environments. Our study highlights the role of genomic architecture, ancestral haplotypes and selection in maintaining adaptive divergence in species with large population sizes and presumably high gene flow. [ABSTRACT FROM AUTHOR]

A brain-infecting myxozoan, Kudoa yasunagai (Hsieh & Chen, 1984), was identified using both morphological and molecular methods in a marine fish from Van Phong Bay, Khanh Hoa province, Vietnam. Cysts containing spores were observed in the brain of one out of 10 Siganus virgatus (Valenciennes) individuals (10%). The myxospores were radially symmetrical, containing a majority of 7 equal shell valves and polar capsules. The spores measured 6.6 ± 0.1 (6.4-6.7) µm in length, 7.6 ± 0.5 (7.0-8.4) µm in width, and 7.0 ± 0.4 (6.5-7.7) µm in thickness. Polar capsules measured 2.8 ± 0.2 (2.6-3.0) µm in length and 1.4 ± 0.1 (1.2-1.5) µm in width, containing a filament inside. The SSU rDNA sequence from the Vietnamese specimen showed > 99.94 % identity with K. yasunagai from Japan and Australia. This report marks a new geographical and host record for K. yasunagai. [ABSTRACT FROM AUTHOR]

Coastal areas offer a diversity of habitats providing refugia and nursery for fish, promoting their biodiversity and associated contributions to people. Yet, natural coastlines are replaced by artificial infrastructures such as seaports and the influence of this artificialization on fish biodiversity remains poorly known. Here, we assessed fish biodiversity indicators using environmental DNA metabarcoding inside seaports and adjacent natural habitats including no‐take marine reserves. We found that species assemblages within seaports were primarily influenced by their area and habitat. We detected a similar species richness in seaports and reserves during lockdown, but seaports host more threatened species than natural habitats. Yet, species turnover between seaports was lower than between natural areas, reflecting biotic homogenization. Seaport managers should consider that complexifying artificial infrastructures could increase habitat diversity and coastal fish biodiversity. Our study illustrates that eDNA‐based indicators can be integrated in management and policy applications toward greener marine artificial infrastructures. [ABSTRACT FROM AUTHOR]

This study aimed to estimate the relationship between fish size and otolith size of four creek-associated fishes (Anodontostoma chacunda, Epinephelus diacanthus, Johnius glaucus and Mugil cephalus) collected from the north-eastern Arabian Sea from November 2021 to November 2022. The numerical relations were established using regression between fish size (Total length-TL and Body weight-BW) and otolith dimensions (Length-OL, Weight-Owt, Area-OA, Width-OW and Perimeter-OP). All regressions between the fish size and otolith morphometric measurements were highly correlated (R2 > 0.8), which indicates the robustness of the model. Taxonomists can use findings from this study for species confirmation and reconstruction of past species assemblages. These findings might provide insight into predicting the prey size in food and feeding studies to explore the food web dynamics. [ABSTRACT FROM AUTHOR]

This study reports on diseased Chelidonichthys spinosus fish that were originally obtained from the Taiwan Strait for exhibition in an aquarium. These fish showed abnormal swimming behavior, eye damage and skin lesions. Gross examination and histopathology revealed that the C. spinosus was suffering from severe nematode infections in the pyloric caeca, liver and mesentery. Marine nematodes from internal organs were verified by partially sequencing the internal transcribed spacer (ITS) gene. Sequencing results revealed that the nematodes shared 99.75% sequence identity with Raphidascaris lophii (GenBank accession No. MW132926). Additionally, secondary Vibrio harveyi infections were also detected in some C. spinosus. This is the first report of R. lophii infection in C. spinosus. [ABSTRACT FROM AUTHOR]

Marine fish is an important source of high-quality, yet relatively cheap animal protein in the Egyptian's diet. Although most parasitic diseases might not cause direct losses of fish, it has deleterious effects on their weight gain and marketability and weaken the fish's immune system paving the way for more serious secondary infections. In this study, we recorded the most common parasitic infestations in marine fish in Egypt in the period between winter 2019 to summer 2021 and described their associated pathologic effects. Four hundred fish from seven different fish species (Mugil cephalus, Pomadasys incisus, Gilthead sea bream, Pagrus Pagrus, Morone labrax (sea bass), thunnus thynnus and Caranx crysos) were randomly collected from the Mediterranean and the Red Sea. Out of the 400 examined fish, 197 (49.25%) infestations were recorded. The isolated parasites were a crustacean, two cestodes, and a nematode and were morphologically identified as follows: Ceratothoa oestroides, Callitetrarhynchus gracilis, Tetraphyllidean larvae and Hysterothylacium deardorffoverstreetorum). Among the infested fish, the highest prevalence of infestation was recorded by Ceratothoa oestroides (43.65%) followed by Hysterothylacium deardorffoverstreetorum (31.98%) and Callitetrarhynchus gracilis (24.37%), and the lowest prevalence rate was recorded by the Tetraphyllidean larvae (15.74%). The pathologic macroscopic and microscopic lesions associated with each type of infestation are described underscoring the importance of continuous search for and application of possible safe control measures for marine fish parasites to spare the fish industry the detrimental effects of these infestations. [ABSTRACT FROM AUTHOR]

Parabens (p-hydroxybenzoic acid esters) commonly used preservatives (in cosmetics, pharmaceuticals, and foods) can pose potential effects on environmental health. In this study, seven parabens were quantified in marine fish samples using an ultra-high performance liquid chromatography triple quadrupole mass spectrometer (UHPLC-MS/MS) system. Parabens in the fish samples were extracted and purified by a rapid, simple, and effective procedure comprising sample homogenization with solvent, solid-phase extraction clean-up, and solvent evaporation. Results demonstrated that the recoveries of seven compounds (with relative standard deviation < 15%) were 88–103% in matrix-spike samples and 86–105% in surrogate standards. The method detection limits and method quantification limits of seven parabens were 0.015–0.030 and 0.045–0.090 ng/g-ww (wet weight), respectively. The optimized method was applied to measure the concentration of parabens in the 37 marine fish samples collected from Vietnam coastal waters. The concentration ranges of seven parabens found in round scad and greater lizardfish samples were 6.82–25.3 ng/g ww and 6.21–17.2 ng/g-ww, respectively. Among parabens, methylparaben accounted for the highest contribution in both fish species (43.2 and 44.9%, respectively). Based on the measured concentrations of parabens in marine fish samples, the estimated daily intake was calculated for children and adults with the corresponding values of 0.0477 µg/kg/day and 0.0119 µg/kg/day, respectively. However, the presence of parabens in Vietnamese marine fish may not pose a significant risk to human health. [ABSTRACT FROM AUTHOR]

ABSTRACT Fish is considered one of the nutritive protein sources affected by various parameters including parasitism. Monogeneans are an ectoparasitic species infecting fish’s skin, fins, and gills. During the present investigation, a total of 40 fish samples of the twobar seabream, Acanthopagrus bifasciatus (Perciformes: Sparidae) were collected from the coastal region along the Arabian Gulf (Saudi Arabia). The collected fish samples were dissected and examined for the presence of monogenetic parasites. The recovered parasite species were collected and identified by applying light microscopic examinations. Five out of 40 (12.5%) fish samples were found to be naturally infected with 2 monogenetic species belonging to two families within Polyopisthocotylea (order Mazocraeidea). They recorded two parasite species, namely, Pseudodiscocotyla opakapaka Yamaguti, 1965 and Kannaphallus raphidium Kritsky and Martin, 2023 belonging to families Discocotylidae and Heteraxinidae, respectively. Morphological and morphometric characterizations revealed some differences between the present species and others detected previously. The present findings of P. opakapaka and K. raphidium in A. bifasciatus (fish host) of the Arabian Gulf represent a new host and geographical record for these parasites. Furthermore, more studies are required to include the advanced molecular tools for these monogenetic species and their associated histopathological effects on the infection site.

Carbaryl is a widely used carbamate pesticide that has been detected in the marine environment, but its effects on marine fish are still unknown. This study was aimed to investigate the effects of long-term exposure of carbaryl on male marine medaka. For this purpose, we set up five exposure concentration groups of 0, 0.1, 1, 10, and 100 µg/L for 180 days. On the one hand, we observed increased aggression and decreased ability to avoid predators in males after exposure, which was affected by the levels of HPA-axis hormones, especially decreased cortisol level. On the other hand, after exposure, HPG axis hormone levels and gene transcription levels were disturbed. Males exhibited a decreased gonadosomatic index and a notable reduction in mature sperm proportion and the F1 generation displayed a significant increase in malformation rate. Additionally, the number of apoptotic cells and the transcription level of apoptosis-related genes in the brains of male marine medaka substantially increased after exposure. Apoptosis of brain cells may be responsible for the disturbance of HPA and HPG axes, consequently leading to behavioral and reproductive abnormalities. These findings provide novel insights into evaluating the toxic effects of carbaryl on male marine medaka and emphasizing the criticality of exploring the potential environmental risks posed by carbaryl in the marine environment, thus providing toxicity value basis for further strengthening marine environmental monitoring and the protection of biological resources.

ObjectiveTo investigate the infection of stage Ⅲ Anisakis spp. larvae in marine fish in five areas of Fujian Province.MethodsMarine fish of different species were purchased from seafood markets from October 2021 to May 2022 and were directly dissected. The internal organs and muscles were artificially digested to identify stage Ⅲ Anisakis larvae， and the species were identified via light microscopy. The infection of Anisakis larvae was then analyzed by geographic area and species.ResultsA total of 133 marine fish from 18 species were dissected， with 68 fishes of 12 species being infected with Anisakis larvae； 2 214 larvae were detected. The detection rate， total infection rate and infection degree of Anisakis larvae were 66.7% （12/18）， 51.1% （68/133） and 32.6 larvae/tail （2 214/68）， respectively. Among the fish species， the infection rate of Trichiurus lepturus was 416 larvae/tail. The marine fish species in which Anisakis larvae were not detected were Acanthopagrus latus， Hypomesus olidus， Oriental grouper， cuttlefish， whitefish， and cream fish. According to regional distribution， the Changle area had the highest infection rate （66.7%）， while the highest detection rate of different marine fish varieties among the different areas was in Xiangcheng City （71.4%）.ConclusionThe infection of stage Ⅲ Anisakis larvae in marine fish in the five areas of Fujian Province was serious. The distribution density of Anisakis larvae in marine fish and the detection rate of Anisakis larvae in each area were high. Hence， residents in these five areas of the Fujian Province have a high risk of infection.

The bio-logging method could be a valuable approach to studying the underwater movement of marine fish. We investigated the horizontal and vertical movement patterns of two yellowtails Seriola quinqueradiata weighing 8.7 kg and 9.5 kg with a pop-up satellite archival tag from October 2020 to January 2021 in the East Sea of Korea. Our results showed that a yellowtail migrated northward in October and November, and then shifted southward in mid-December. The average swimming depth and temperature of the fish monitored over 82 days were 24.9 ± 9.3 m (average ± SD) and 16.5 ± 1.9°C, respectively, and the total traveled distance was 1,172.4 km. The fish swam significantly deeper during the daytime (33.70 ± 14.80 m) than at nighttime (20.65 ± 8.44 m) from November to December (p < 0.05). These results suggest that the horizontal migratory route of yellowtails in accordance with the East Korea Warm Current which is the main branch of Tsushima Warm Current in the fall and early winter seasons, and showed significant diel vertical movement patterns from November to December.