Hypoxia-inducible factor-1α promotes macrophage functional activities in protecting hypoxia-tolerant large yellow croaker (Larimichthys crocea) against Aeromonas hydrophila infection.

The immune system requires a high energy expenditure to resist pathogen invasion. Macrophages undergo metabolic reprogramming to meet these energy requirements and immunologic activity and polarize to M1-type macrophages. Understanding the metabolic pathway switching in large yellow croaker (Larimichthys crocea) macrophages in response to lipopolysaccharide (LPS) stimulation and whether this switching affects immunity is helpful in explaining the stronger immunity of hypoxia-tolerant L. crocea. In this study, transcript levels of glycolytic pathway genes (Glut1 and Pdk1), mRNA levels or enzyme activities of glycolytic enzymes [hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase A (LDHA)], aerobic respiratory enzymes [pyruvate dehydrogenase (PDH), isocitrate dehydrogenase (IDH), and succinate dehydrogenase (SDH)], metabolites [lactic acid (LA) and adenosine triphosphate (ATP)], levels of bactericidal products [reactive oxygen species (ROS) and nitric oxide (NO)], and transcripts and level changes of inflammatory factors [IL1ß, TNFα, and interferon (IFN) γ] were detected in LPS-stimulated L. crocea head kidney macrophages. We showed that glycolysis was significantly induced, the tricarboxylic acid (TCA) cycle was inhibited, and metabolic reprogramming occurred, showing the Warburg effect when immune cells were activated. To determine the potential regulatory mechanism behind these changes, LcHIF-1α was detected and found to be significantly induced and transferred to the nucleus after LPS stimulation. LcHif-1α interference led to a significant reduction in glycolytic pathway gene transcript expression, enzyme activity, metabolites, bactericidal substances, and inflammatory factor levels; a significant increase in the aerobic respiration enzymes; and decreased migration, invasion, and phagocytosis. Further ultrastructural observation by electron microscopy showed that fewer microspheres contained phagocytes and that more cells were damaged after LcHif-1α interference. LcHif-1α overexpression L. crocea head kidney macrophages showed the opposite trend, and promoter activities of Ldha and Il1ß were significantly enhanced after LcHif-1α overexpression in HEK293T cells. Our data showed that LcHIF-1α acted as a metabolic switch in L. crocea macrophages and was important in polarization. Hypoxia-tolerant L. crocea head kidney showed a stronger Warburg effect and inhibited the TCA cycle, higher metabolites, and bactericidal substance levels. These results collectively revealed that LcHif-1α may promote the functional activities of head kidney macrophages in protecting hypoxia-tolerant L. crocea from Aeromonas hydrophila infection.

Lumpfish, Cyclopterus lumpus, distribution in the Gulf of Maine, USA: observations from fisheries independent and dependent catch data.

The Gulf of Maine (GoM) is one of the fastest-warming parts of the world's oceans. Some species' distributional shifts have already been documented, especially for commercially-important species. Less is known about species that are not currently exploited but may become so in the future. As a case study into these issues, we focus on lumpfish (Cyclopterus lumpus) because of the recognized and timely need to understand wild lumpfish population dynamics to support sustainable fisheries and aquaculture developments. Using occurrence data from five different fisheries-dependent and independent surveys, we examined lumpfish distribution over time in the GoM. We found that lumpfish presence was more likely in Fall and correlated with deeper waters and colder bottom temperatures. Since 1980, lumpfish presence has increased over time and shifted north. Given a limited set of data, these findings should be interpreted with caution as additional work is needed to assess if the actual distribution of lumpfish is changing. Nevertheless, our work provides preliminary information for resource managers to ensure that lumpfish are harvested sustainably for use in emergent lumpfish aquaculture facilities.

Genome-wide characterization, phylogenetic and expression analysis of Galectin gene family in Golden pompano Trachinotus ovatus.

Galectins (Gals) are a type of S-type lectin that are widespread and evolutionarily conserved among metazoans, and can act as pattern recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs). In this study, 10 Gals (ToGals) were identified in the Golden pompano (Trachinotus ovatus), and their conserved domains, motifs, and collinearity relationships were analyzed. The expression of ToGals was regulated following infection to Cryptocaryon irritans and Streptococcus agalactiae, indicating that ToGals participate in immune responses against microbial pathogens. Further analysis was conducted on one important member, Galectin-3, subcellular localization showing that ToGal-3like protein is expressed both in the nucleus and cytoplasm. Recombinant protein obtained through prokaryotic expression showed that rToGal-3like can agglutinate red blood cells of rabbit, carp and golden pompano and also agglutinate and kill Staphylococcus aureus, Bacillus subtilis, Vibrio vulnificus, S. agalactiae, Pseudomonas aeruginosa, and Aeromonas hydrophila. This study lays the foundation for further research on the immune roles of Gals in teleosts.

NEW INSIGHTS BASED ON MORPHOLOGICAL AND MOLECULAR DATA REVEAL THE TAXONOMIC STATUS OF HALIOTREMA PTEROISI (MONOGENOIDEA: DACTYLOGYRIDAE) INFECTING DEVIL FIREFISH PTEROIS MILES (PERCIFORMES: SCORPAENOIDEI: SCORPAENIDAE) IN THE RED SEA OFF EGYPT.

HALIOTREMA PTEROISI: Paperna, 1972 (Monogenoidea: Dactylogyridae) was found parasitizing the gill lamellae of devil firefish, Pterois miles (Bennet) (Perciformes: Scorpaenidae), in the Red Sea off Safaga (26°44'N, 33°56'E), Egypt. The parasite species was described based on morphological features of available specimens and transferred to PlatycephalotremaKritsky and Nitta, 2019 (Dactylogyridae) as Platycephalotrema pteroisi (Paperna, 1972) n. comb. The occurrence of Pl. pteroisi off Safaga, Egypt, represented a range extension for the helminth of about 160 km to the southwest of the southern end of the Gulf of Aqaba. The transfer of the species to Platycephalotrema based on an evaluation of morphological features was supported by an analysis of molecular sequences of the 28S rDNA gene of Pl. pteroisi and 49 other dactylogyrid species. Maximum-likelihood, Bayesian inference, and maximum parsimony analyses of this dactylogyrid sequence data revealed H. pteroisi to nest with significant support within the clade of Platycephalotrema spp. During the literature review of dactylogyrid species infecting scorpionfishes, it was determined that Ancyrocephalus sp. of Dyer et al. from luna lion fish Pterois lunulata Temminck and Schlegel collected off Okinawa-jima, Japan represented an undescribed species of Platycephalotrema.

Hidden rivals: the negative impacts of dolphinfish on seabird foraging behaviour.

Marine predators often aggregate at the air-sea boundary layer to pursue shared prey. In such scenarios, seabirds are likely to benefit from underwater predators herding fish schools into tight clusters thereby enhancing seabirds' prey detectability and capture potential. However, this coexistence can lead to competition, affecting not only immediate foraging strategies but also their distribution and interspecies dynamics. We investigated both the longitudinal relationships and instantaneous interactions between streaked shearwaters (Calonectris leucomelas) and common dolphinfish (Coryphaena hippurus), both preying on Japanese anchovy (Engraulis japonicus). Using GPS data from 2011 to 2021, we calculated behavioural parameters for streaked shearwaters as an index of time spent and distance travelled. Despite the abundance of Japanese anchovies, we found that streaked shearwaters might increase their foraging time in the presence of underwater predators. Moreover, video loggers provided direct evidence of streaked shearwaters and common dolphinfish attacking the same fish schools, potentially interfering with bird foraging by dolphinfish. Our results suggest that the presence of underwater predators in a given patch might increase the time spent by seabirds foraging without affecting the distance travelled. This highlights the need for future studies that consider the potential adverse effects of other top predators on seabird prey availability.

Lunar rhythms and their carry-over effects may shape environmental sex determination in a coral reef fish.

Lunar rhythms shape spawning phenology and subsequent risks and rewards for early life-history stages in the sea. Here, we consider a perplexing spawning phenology of the sixbar wrasse (Thalassoma hardwicke), in which parents spawn disproportionately around the new moon, despite the low survival of these larvae. Because primary sex determination in this system is highly plastic and sensitive to social environments experienced early in development, we ask whether this puzzling pattern of spawning is explained by fitness trade-offs associated with primary sexual maturation. We used otoliths from 871 fish to explore how spawning on different phases of the moon shapes the environments and phenotypes of settling larvae. Offspring that were born at the new moon were more likely to settle (i) before other larvae, (ii) at a larger body size, (iii) at an older age, (iv) to the best quality sites, and (v) as part of a social group-all increasing the likelihood of primary maturation to male. Selection of birthdates across life stage transitions suggests that the perplexing spawning phenology of adults may reflect an evolutionarily stable strategy that includes new moon spawning for compensatory benefits later in life, including preferential production of primary males at certain times.

The first report of digenean infecting short mackerel (Rastrelliger brachysoma) from Chon Buri Province, the Gulf of Thailand.

Rastrelliger brachysoma (Bleeker, 1851), the short mackerel, is a dietary staple and of significant economic demand in Southeast Asia and Thailand. However, the demand for short mackerel has precipitated an overfishing crisis, leading to a depletion of fish stocks. Overfishing, coupled with parasitism, may result in a decline in the population of R. brachysoma. Digenetic trematode infection is prevalent in marine fish and has a considerable impact on the overall health of the fish. Here, to identify digenetic trematodes infecting R. brachysoma, we aim to determine the identity, prevalence, and intensity of digenean infections in R. brachysoma from the Gulf of Thailand. A total of 194 short mackerel were obtained from Chon Buri Province, where digeneans were isolated and identified. The molecular identity of the digeneans was confirmed using the nuclear 28S rRNA gene. Of the 194 short mackerel, 100% were found to be infected with digeneans, comprising of Lecithocladium, Prodistomum, Opechona, and Aphanurus. Lecithocladium was the most prevalent (98%) and had the highest intensity of infection (37 mean intensity), followed by Prodistomum (75% prevalence and 17 mean intensity). Our study thus presents the first evidence of digeneans infecting the economically important short mackerel from the Gulf of Thailand. The high infection rate of digenetic trematodes may have implications on the health of R. brachysoma, further driving their population decline. These data underscore the importance of safeguarding fisheries resources in the Gulf of Thailand, and downstream conservation efforts are crucial for evidence-based management decisions to safeguard the long-term sustainability of fish resources.

TWO NEW CERATOMYXA SPECIES (MYXOSPOREA: CERATOMYXIDAE) INFECTING THE GALL BLADDER OF MARINE FISHES FROM THE SOUTH-CENTRAL COAST OF VIETNAM.

Myxospores discovered floating free in the bile of marine fishes from the south-central coast of Vietnam were identified using morphological and molecular methods, leading to the description of 2 new species. Ceratomyxa chauvanminhi n. sp. was detected in 16% (8/50) of cultured barramundi Lates calcarifer (Bloch) specimens, and Ceratomyxa sekoi n. sp. was found in 20% (5/25) of wild largehead hairtail Trichiurus lepturus Linnaeus specimens. The spores of C. chauvanminhi n. sp. are very shallowly ovoid, slightly crescent shaped, and 11.5 ± 0.5 (10.7-12.4) µm thick, 5.8 ± 0.2 (5.4-6.1) µm long, and 5.5 ± 0.2 (5.2-5.7) µm wide. Their posterior angles are slightly concave at 158.7° ± 4.2° (151.3°-164.8°), and they possess 2 equal spherical polar capsules 2.5 ± 0.2 (2.1-2.9) µm in diameter. The spores of C. sekoi n. sp. are 5.6 ± 0.2 (5.0-6.1) µm long, 75.5 ± 4.8 (68.9-90.0) µm thick, and 5.5 ± 0.1 (5.4-5.6) µm wide, with 2 equal, slightly anterior spherical polar capsules 2.1 ± 0.2 (1.7-2.4) µm in diameter. Although C. sekoi n. sp. spores resemble those of species of MyxodavisiaZhao, Zhou, Kent, and Whipps, 2008, characterized by long tapering valves, genetic analyses distinctly place this new species within the Ceratomyxa Thélohan, 1892 lineage. This study contributes to the understanding myxosporean diversity in Vietnamese waters and highlights the difficulty associated with distinguishing between the genera Ceratomyxa and Myxodavisia.

Adult sex change leads to extensive forebrain reorganization in clownfish.

BACKGROUND: Sexual differentiation of the brain occurs in all major vertebrate lineages but is not well understood at a molecular and cellular level. Unlike most vertebrates, sex-changing fishes have the remarkable ability to change reproductive sex during adulthood in response to social stimuli, offering a unique opportunity to understand mechanisms by which the nervous system can initiate and coordinate sexual differentiation. METHODS: This study explores sexual differentiation of the forebrain using single nucleus RNA-sequencing in the anemonefish Amphiprion ocellaris, producing the first cellular atlas of a sex-changing brain. RESULTS: We uncover extensive sex differences in cell type-specific gene expression, relative proportions of cells, baseline neuronal excitation, and predicted inter-neuronal communication. Additionally, we identify the cholecystokinin, galanin, and estrogen systems as central molecular axes of sexual differentiation. Supported by these findings, we propose a model of sexual differentiation in the conserved vertebrate social decision-making network spanning multiple subtypes of neurons and glia, including neuronal subpopulations within the preoptic area that are positioned to regulate gonadal differentiation. CONCLUSIONS: This work deepens our understanding of sexual differentiation in the vertebrate brain and defines a rich suite of molecular and cellular pathways that differentiate during adult sex change in anemonefish.

This study provides key insights into brain sex differences in sex-changing anemonefish (Amphiprion ocellaris), a species that changes sex in adulthood in response to the social environment. Using single nucleus RNA-sequencing, the study provides the first brain cellular atlas showing sex differences in two crucial reproductive areas: the preoptic area and telencephalon. The research identifies notable sex-differences in cell-type proportions and gene expression, particularly in radial glia and glutamatergic neurons that co-express the neuropeptide cholecystokinin. It also highlights differences in preoptic area neurons likely involved in gonadal regulation. This work deepens our understanding of sexual differentiation of the brain in vertebrates, especially those capable of adult sex change, and illuminates key molecular and cellular beginning and endpoints of the process.

Analyses of the Mx family members in lumpfish: Molecular characterization, phylogeny, and gene expression analyses.

Members of the myxovirus resistance (Mx) protein family play an essential role in antiviral immunity. They are Dynamin-like GTPases, induced by interferons. In the current study, we have characterized two predicted MX genes (MX1 and MX2) from lumpfish (Cyclopterus lumpus L.), having 12 and 13 exons, respectively. Mx2 has two isoforms (Mx2-X1 and Mx2-X2) which differ in exon 1. The lumpfish Mx proteins contain an N-terminal Dynamin-like GTPase domain, the middle domain (MD) and GTPase effector domain (GED) characteristic for Mx proteins. Phylogenetic analyses grouped all the lumpfish Mx sequences in group 1, and synteny analyses showed that both genes were localized at chromosome 5 in proximity to the genes Tohc7, Atxn7 and Psmd6. In vitro stimulation experiment showed that both MX1 and MX2-X2 were highly upregulated upon exposure to poly(I:C), but not bacteria, 24 h post exposure, indicating their role in antiviral immunity.

Genome assembly, Full-length transcriptome, and isoform diversity of Red Snapper, Lutjanus argentimaculatus.

The mangrove red snapper, Lutjanus argentimaculatus, is a marine food fish of economic and aquaculture importance. The application of genomic selection-based breeding programs for this species is limited by the absence of a reference genome and transcriptome profiles. The current study attempted to fill this void by generating genomic and transcriptomic resources for red snapper. Using PacBio long reads, and Arima Hi-C linked reads, a scaffold-level genome assembly was generated for L. argentimaculatus. The assembly is of 1.03 Gb comprising of 400 scaffolds with N50 of 33.8 Mb and was assessed to be 97.2% complete upon benchmarking with BUSCO. Full-length transcriptome generated with PacBio Iso-Sequencing strategy using six tissues (muscle, gills, liver, kidney, stomach, and gonad) contained 56,515 isoforms belonging to 18,108 unique genes with N50 length of 3,973 bp. The resources generated will have potential applications in the functional studies, conservation, broodstock management and selective breeding programmes of L. argentimaculatus.

Exploring the cobia (Rachycentron canadum) genome: unveiling putative male heterogametic regions and identification of sex-specific markers.

BACKGROUND: Cobia (Rachycentron canadum) is the only member of the Rachycentridae family and exhibits considerable sexual dimorphism in growth rate. Sex determination in teleosts has been a long-standing basic biological question, and the molecular mechanisms of sex determination/differentiation in cobia are completely unknown. RESULTS: Here, we reported 2 high-quality, chromosome-level annotated male and female cobia genomes with assembly sizes of 586.51 Mb (contig/scaffold N50: 86.0 kb/24.3 Mb) and 583.88 Mb (79.9 kb/22.5 Mb), respectively. Synteny inference among perciform genomes revealed that cobia and the remora Echeneis naucrates were sister groups. Further, whole-genome resequencing of 31 males and 60 females, genome-wide association study, and sequencing depth analysis identified 3 short male-specific regions within a 10.7-kb continuous genomic region on male chromosome 18, which hinted at an undifferentiated sex chromosome system with a putative XX/XY mode of sex determination in cobia. Importantly, the only 2 genes within/between the male-specific regions, epoxide hydrolase 1 (ephx1, renamed cephx1y) and transcription factor 24 (tcf24, renamed ctcf24y), showed testis-specific/biased gene expression, whereas their counterparts cephx1x and ctf24x, located in female chromosome 18, were similarly expressed in both sexes. In addition, male-specific PCR targeting the cephx1y gene revealed that this genomic feature is conserved in cobia populations from Panama, Brazil, Australia, and Japan. CONCLUSION: The first comprehensive genomic survey presented here is a valuable resource for future studies on cobia population structure and dynamics, conservation, and evolutionary history. Furthermore, it establishes evidence of putative male heterogametic regions with 2 genes playing a potential role in the sex determination of the species, and it provides further support for the rapid evolution of sex-determining mechanisms in teleost fish.

Nocturnal substrate association of four coral reef fish groups (parrotfishes, surgeonfishes, groupers and butterflyfishes) in relation to substrate architectural characteristics.

Although numerous coral reef fish species utilize substrates with high structural complexities as habitats and refuge spaces, quantitative analysis of nocturnal fish substrate associations has not been sufficiently examined yet. The aims of the present study were to clarify the nocturnal substrate associations of 17 coral reef fish species (nine parrotfish, two surgeonfish, two grouper and four butterflyfish) in relation to substrate architectural characteristics. Substrate architectural characteristics were categorized into seven types: (1) eave-like space, (2) large inter-branch space, (3) overhang by protrusion of fine branching structure, (4) overhang by coarse structure, (5) uneven structure without large space or overhang, (6) flat and (7) macroalgae. Overall, fishes were primarily associated with three architectural characteristics (eave-like space, large inter-branch space and overhang by coarse structure). The main providers of these three architectural characteristics were tabular and corymbose Acropora, staghorn Acropora, and rock. Species-specific significant positive associations with particular architectural characteristics were found as follows. For the nine parrotfish species, Chlorurus microrhinos with large inter-branch space and overhang by coarse structure; Ch. spilurus with eave-like space and large inter-branch space; Hipposcarus longiceps with large inter-branch space; Scarus ghobban with overhang by coarse structure; five species (Scarus forsteni, S. niger, S. oviceps, S. rivulatus and S. schlegeli) with eave-like space. For the two surgeonfish species, Naso unicornis with overhang by coarse structure; N. lituratus with eave-like space. For the two grouper species, Plectropomus leopardus with eave-like space; Epinephelus ongus with overhang by coarse structure. For the four butterflyfish species, Chaetodon trifascialis with eave-like space and large inter-branch space; C. lunulatus and C. ephippium with large inter-branch space; C. auriga showed no significant associations with any architectural characteristics. Four species (Ch. microrhinos, H. longiceps, S. niger and N. unicornis) also showed clear variations in substrate associations among the different fish size classes. Since parrotfishes, surgeonfishes and groupers are main fisheries targets in coral reefs, conservation and restoration of coral species that provide eave-like space (tabular and corymbose Acropora) and large inter-branch space (staghorn Acropora) as well as hard substrates with coarse structure that provide overhang (rock) should be considered for effective fisheries management in coral reefs. For butterflyfishes, coral species that provide eave-like space (tabular Acropora) and large inter-branch space (staghorn Acropora) should also be conserved and restored for provision of sleeping sites.

Gobionellus stomatus Starks 1913 (Oxudercidae: Gobionellinae): range extension for the coastal zone of the Brazilian Amazon region.

Gobionellus stomatus, a fish species endemic to Brazil, was previously known to occur from the State of Piauí to the State of Rio Grande do Sul. Here we present the first record of this species for the State of Maranhão, specifically for the Upaon-Açu island, extending its distribution further west, to the coastal zone of the Amazon region. This species inhabits estuarine ecosystems susceptible to environmental pressures, such as pollution and the introduction of non-native species. Despite G. stomatus being classified as of least concern for conservation, it is crucial to highlight potential risks associated with human activities in these environments, emphasizing the importance of preservation measures to mitigate future impacts on the populations of this species, as well as of other estuarine gobies.

Dietary effects of vitamin C on antioxidant capacity, intestinal microbiota and the resistance of pathogenic bacteria in cultured Silver pomfret (Pampus argenteus).

As most teleosts are unable to synthesize vitamin C, supplemental diets containing vitamin C diets play a crucial role in fish health. The aim of this study was to investigate the effect of dietary vitamin C on the intestinal enzyme activity and intestinal microbiota of silver pomfre (Pampus argenteus). Four experimental diets were supplemented with basic diets containing 300 mg of vitamin C/kg (group tjl3), 600 mg of vitamin C/kg (group tjl6), and 1200 mg of vitamin C/kg (group tjl12), as well as vitamin C-free supplemental basic diet (group tjl0), respectively. The four diets were fed to juvenile P. argenteus (average initial weight: 4.68 ± 0.93 g) for 6 weeks. The results showed that the activity of SOD (superoxide dismutase) and CAT (catalase) increased significantly while that of MDA (malondialdehyde) decreased significantly in group tjl3 compared to vitamin group tjl0. At the genus level, groups tjl0, tjl6, and tjl12 contained the same dominant microbial community, Stenotrophomonas, Photobacterium, and Vibrio, whereas group tjl3 was dominated by Stenotrophomonas, Delftia, and Bacteroides. Among the fish fed with a basic diet containing 300 mg of vitamin C/kg, the intestines exhibited a notable abundance of probiotic bacteria, including lactic acid bacteria (Lactobacillus) and Bacillus. The abundance of Aeromonas in groups tjl3 and tjl6 was lower than that of the vitamin C-free supplemental basic diet group, whereas Aeromonas was not detected in group tjl12. In addition, a causative agent of the disease outbreak in cultured P. argenteus, Photobacterium damselae subsp. Damselae (PDD) was the dominant microbiota community in groups tjl0, tjl6 and tjl12, whereas the abundance of PDD in group tjl3 was the lowest among the diets. Taken together, the diets supplied with vitamin C could influence the composition microbial community of P. argenteus. The low level of vitamin C (300 mg of vitamin C/kg per basic diet) supplementation could not only improve the antioxidant capacity but also resist the invasion of pathogenic bacteria.

Epidemiological investigation on diseases of Larimichthys crocea in Ningbo culture area.

Introduction: Due to the high-density farming of Larimichthys crocea over the years, diseases caused by pathogens such as bacteria, viruses, and parasites frequently occur in Ningbo, posing a huge threat and challenge to the sustainable and healthy development of the L. crocea's bay farming industry. In order to understand the diseases occurrence in L. crocea farming in Ningbo area, an epidemiological investigation of L. crocea diseases was carried out through regular sampling in 2023. Methods: From April to October 2023, routine sampling of L. crocea was conducted monthly in various farming areas in Ningbo. Each time, live or dying L. crocea with obvious clinical symptoms were sampled, with a total number of 55 L. crocea collected. The samples were preserved in ice bags and transported to the laboratory for pathogen detection(including bacterial isolation and identification,virus identification, and parasites detection). Results: A total of fifty-five fish dying L. crocea with obvious clinical symptoms were collected in this study, of which 78.18% (43/55) were detected with symptoms caused by pathogenic infection, while 21.82% (12/55) did not have identified pathogens, which were presumed to be breeding abrasions, nutritional metabolic disorders, unconventional pathogens infection or other reasons. A total of twenty-five pathogenic bacteria strains were isolated, which mainly were Pseudomonas plecoglossicida and Vibrio harveyi, accounting for 52% (13/25) and 32% (8/25) of the pathogenic bacteria strains, respectively. Among them, both V. harveyi and Streptococcus. iniae co-infected one fish. Additionally, three other bacterial strains including Nocardia seriolae, Staphylococcus Saprophyticus, and Photobacterium damselae subsp.damselae were isolated. Microscopic examination mainly observed two parasites, Cryptocaryon irritans and Neobenedenia girellae. In virus detection, the red sea bream iridovirus (RSIV) was mainly detected in L. crocea. Statistical analysis showed that among the fish with detected pathogens, 55.81% (24/43) had bacterial infections, 37.21% (16/43) had parasitic infections, and 37.21% (16/43) had RSIV infections. Among them, five fish had mixed infections of bacteria and parasites, three had mixed infections of bacteria and viruses, three had mixed infections of parasites and viruses, and one L. crocea had mixed infections of viruses, bacteria, and parasites. Discussion: These findings indicate that these three major types of diseases are very common in the L. crocea farming area in Ningbo, implying the complexity of mixed infections of multiple diseases.

METAZOAN PARASITE COMMUNITY OF THE YELLOW SNAPPER LUTJANUS ARGENTIVENTRIS: FACTORS THAT INFLUENCING SPECIES COMPOSITION AND RICHNESS.

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.

Expression Patterns of TGF-ß1, TßR-I, TßR-II, and Smad2 Reveal Insights into Heterosis for Growth of Hybrid Offspring between Acanthopagrus schlegelii and Pagrus major.

TGF-ß1/Smads is a classic signaling pathway, which plays important roles in the development process of organisms. Black porgy Acanthopagrus schlegelii and red porgy Pagrus major are valuable economic fishes, and their hybrid offspring show excellent heterosis traits. Yet the molecular regulation mechanism of the heterosis traits is less clear. Here, we explored the TGF-ß1/Smads pathway's molecular genetic information for heterosis in A. schlegelii ♂ × P. major ♀ (AP) and A. schlegelii ♀ × P. major ♂ (PA) in terms of growth and development. The mRNA expression levels of TGF-ß1, TßR-I, TßR-II, and Smad2 genes in different developmental stages of A. schlegelii were detected. Furthermore, the expression levels of TGF-ß1, TßR-I, TßR-II, and Smad2 genes in different tissues of adult (mRNA level) and larva (mRNA and protein level) of A. schlegelii, P. major, and their hybrids were determined by both real-time quantitative PCR and Western blot techniques. The results indicated the ubiquitous expression of these genes in all developmental stages of A. schlegelii and in all tested tissues of A. schlegelii, P. major, and its hybrids. Among them, the mRNA of TGF-ß1, TßR-I, and TßR-II genes is highly expressed in the liver, gill, kidney, and muscle of black porgy, red porgy, and their hybrid offspring. There are significant changes in gene and protein expression levels in hybrid offspring, which indirectly reflect hybrid advantage. In addition, there was no correlation between protein and mRNA expression levels of Smad2 protein. The results provide novel data for the differential expression of growth and development genes between the reciprocal hybridization generation of black porgy and red porgy and its parents, which is conducive to further explaining the molecular regulation mechanism of heterosis in the growth and development of hybrid porgy.

Acoustic monitoring of artificial reefs reveals Atlantic cod and weakfish spawning and presence of individual bottlenose dolphins.

The artificial reefs in New York's waters provide structure in areas that are typically flat and sandy, creating habitat for a multitude of species as an area to spawn, forage, and reside. Passive acoustic data collected on the Fire Island and Shinnecock artificial reefs between 2018 and 2022 detected spawning-associated calls of weakfish (Cynoscion regalis) and Atlantic cod (Gadus morhua), as well as the presence of individual bottlenose dolphins (Tursiops truncatus) through their signature whistles. Weakfish and Atlantic cod were more vocally active on the Fire Island reef, where Atlantic cod grunts peaked during a new moon phase in December, and weakfish spawning experienced variable peaks between mid-July and mid-August on both reefs. Fifty-seven individual bottlenose dolphins were identified, with whistle repeats ranging from seconds to years apart. Passive acoustic monitoring allows for simultaneous collection of information on multiple species at different trophic levels as well as behavioral information that helps managers understand how these animals utilize these habitats, which can lead to improved conservation measures.

Consistencies in the dietary and isotopic niche of spotted seatrout, Cynoscion nebulosus, across a salinity gradient within a coastal Louisiana estuary.

Estuaries are essential habitats for recreational and commercial fish that are shaped by both natural and anthropogenic processes. In Louisiana a combination of climate change and planned coastal restoration actions is predicted to increase freshwater introduction to coastal estuaries. As such there is a need to quantify the relationships between estuarine fish ecology and salinity to aid in predicting how species will respond to shifts in salinity. We investigated the relative abundance and dietary niches of adult (24.5 ± 5.4 cm standard length) spotted seatrout Cynoscion nebulosus across varying salinity regimes (oligohaline, mesohaline, and polyhaline) within Barataria Bay, Louisiana, using a combination of net sampling and gut content and stable isotopes analysis. We found that the relative abundance of C. nebulosus was lowest at the oligohaline site, translating to approximately five fewer fish captured for every single psu decrease in a site's average annual salinity. In contrast, we found that diets and, to a lesser extent, isotopic niches had a high degree of overlap across sites with differing salinity regimes. Fish and penaeid shrimp were the most common and important prey taxa recovered from guts at all sites. The small isotopic differences found among sites were likely due to spatial variation in hydrogeochemical baselines, and the observed isotopic overlap provides support for the idea that C. nebulosus move between adjacent salinity regimes and forage throughout Barataria Bay. Our results contribute to a greater understanding of the salinity preference and trophic ecology of C. nebulosus that can aid in predicting their responses to future salinity and habitat changes within Barataria Bay associated with predicted climate change and planned coastal restoration actions.