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Anthocidaris crassispina is a very popular edible sea urchin distributed along the coast of the South China Sea. In this study, we performed whole-genome sequencing and generated a chromosome-level assembly of this species. The total length of the genomic contig sequence was 891.02 Mb, and contig N50 was 808.15 kb when Hifiasm was used for assembly. The Hi-C library was constructed and sequenced, yielding approximately 68.61 Gb of data. After Hi-C assembly, approximately 886.72 Mb of sequence was able to be mapped onto 21 chromosomes, accounting for 99.52% of the total genome length. Among the sequences located on the chromosomes, those for which the order and direction could be determined accounted for approximately 826.82 Mb, or 93.24% of the total length. These results provide valuable resources for further study of A. crassispina at the genetic level. [ABSTRACT FROM AUTHOR]

Simple Summary: Preliminary investigations revealed that purple sea urchins are distributed in both the stone and algal areas of Daya Bay, with a greater density in the stone area than in the large algal area. This raises important scientific questions: What do the purple sea urchins in the stone area feed on? What is the dietary range of purple sea urchins? Therefore, we focused on purple sea urchins and employed stable isotope technology and 16S rDNA and 18S rDNA high-throughput sequencing techniques to conduct a systematic study on the feeding habits and gut microbiota community structure of purple sea urchins in the stone and algal areas of the central islet sea area of Daya Bay. We aimed to elucidate the feeding habits and dietary range of purple sea urchins. The results of this study provide a theoretical basis for the restoration of wild purple sea urchin resources and the selection of areas for restocking and release. Sea urchins play an important role in marine ecosystems. Owing to limitations in previous research methods, there has been insufficient understanding of the food sources and ecological functional value of purple sea urchins, leading to considerable controversy regarding their functional positioning. We focused on Daya Bay as the research area, utilizing stable isotope technology and high-throughput sequencing of 16S rDNA and 18S rDNA to analyze sea urchins and their potential food sources in stone and algae areas. The results showed that the δ13C range of purple sea urchins in the stone area is −11.42~−8.17‰, and the δ15N range is 9.15~10.31‰. However, in the algal area, the δ13C range is −13.97~−12.44‰, and the δ15N range is 8.75~10.14‰. There was a significant difference in δ13C between the two areas (p < 0.05), but there was no significant difference in δ15N (p > 0.05). The main food source for purple sea urchins in both areas is sediment. The sequencing results of 18S rDNA revealed that, in the algal area, the highest proportion in the sea urchin gut was Molluska (57.37%). In the stone area, the highest proportion was Arthropoda (76.71%). The sequencing results of 16S rDNA revealed that, in the algal area, Bacteroidetes was the dominant group in the sea urchin gut (28.87%), whereas, in the stone area, Proteobacteria was the dominant group (37.83%). Diversity detection revealed a significant difference in the number of gut microbes and eukaryotes between the stone and algal areas (p < 0.05). The results revealed that the main food source of purple sea urchins in both areas is sediment, but the organic nutritional value is greater in the algal area, and the richness of microbiota and eukaryotes in the gut of purple sea urchins in the stone area is greater. These results indicated that purple sea urchins are likely omnivores and that the area where they occur impacts their growth and development. The results of this study provide a theoretical basis for the restoration of wild purple sea urchin resources and the selection of areas for restocking and release. [ABSTRACT FROM AUTHOR]

Transportation is of high risk and cannot be avoided during the productive practice of Lates calcarifer fry. To achieve an optimal transporting protocol, the changes of physico‐chemical indexes and immune genes expression of fry after transportation were evaluated. The fish were simulated transported at the density of 7 kg/m3 for different time (T1 = 4 h, T2 = 8 h, T3 = 12 h, T4 = 16 h, T5 = 20 h, T6 = 24 h) and at three densities (D1 = 14 kg/m3, D2 = 21 kg/m3, D3 = 28 kg/m3) for 24 h. With the intensive stress, a decrease in pH and an increase in NH4+‐N were observed. At transporting density experiment, the cortisol of every group except T3 had a significant difference with the control. ALT, AST and ACP activity were all close to a rise first and then decline trend. IL‐8, TNF and IFN‐γ1 were activated to promote inflammation at different degrees of transportation pressure, while the tendency of L10 and TGF‐β1 was similar. CRP also had no significant increase under different transporting durations stress. HSP70 undertook main repair work as expression level of it increased gradually. Complement did not reach its release standard at duration experiment expect for T3 group of C3. However, density experiment had no obviously positive effects on physico‐chemical indexes and the relative expression of immune genes. The results indicated that when the transporting time exceeded 8 h at the density of 7 kg/m3, significant immune response started happening to fish. The transporting density stress has stimulated the fries but the immune response was still under the inhibited state owing to the ammonia toxicity reduction by much lower pH. [ABSTRACT FROM AUTHOR]

The complete mitogenome ofLateolabrax maculatuswas determined through high-throughput DNA sequencing technology. The circular mtDNA molecule was 16 723 bp in size and comprised 37 genes and two non-coding regions, with the gene arrangement and content identical to other typical vertebrate mitogenomes. The identity analysis revealed that the mitogenome sequence ofL. maculatusshared the highest identity with that ofL. japonicus(91.3%) among 12 species. The neighbor-joining tree indicated that 13 species clustered into three distinct clades strongly supported. Within Moronidae clade,L. maculatusfirst clustered together withL. japonicus, and then gathered with twoDicentrarchusspecies andMorone saxatilis. Finally, Moronidae clade grouped with Percichthyidae clade and Serranidae clade. This finding agreed with the opinion classifyingLateolabraxinto the family Moronidae but not Serranidae or its own family, Lateolabracidae. These results provided useful molecular information for phylogenetic relationships and further studies on the population genetic ofL. maculatus. [ABSTRACT FROM PUBLISHER]

The complete mitogenome of the yellowbelly threadfin bream,Nemipterus bathybius, has been reported for the first time in this study. The circular mtDNA molecule was 17 353 bp in size and the overall nucleotide composition of H-strand was 29.0% A, 28.3% T, 16.5% G, and 26.2% C, with an A + T bias. The complete mitogenome encoded 13 protein-coding genes, 2 rRNAs, 22 tRNAs, and 2 non-coding regions, as found in other typical vertebrate mitogenomes. The D-loop located betweentRNAProandtRNAPhegenes and the length was 1603 bp, rich in A + T (73.0%). The phylogenetic tree of complete mitogenome sequences of 12 families and 26 species showed that the family Nemipteridae was in the basal position of the suborder Percoidei, whereas its two associated families (Sparidae and Lethrinidae) were clustered together with other 7 families, which supported a non-monophyly of superfamily Sparoidea. [ABSTRACT FROM AUTHOR]

The transportation of fish larvae or juveniles from hatcheries to rearing farms is a crucial process in aquaculture, as most fish farms are located far from hatcheries. Among abiotic parameters, light intensity is an important factor affecting the physiology and biochemistry of teleost fish. To date, most studies on fish transportation have focused on identifying the optimum stocking density, while little is known about the optimum light intensity for transporting hatchery-produced juvenile Crimson snapper (Lutjanus erythropterus). Therefore, this study aimed to evaluate the effects of light intensity on antioxidative stress, digestive enzymes, and ATPases in Lutjanus erythropterus during long-hour transportation. The results of this study revealed that a light intensity between 100 and 500 Lux is recommended for the long-hour transport of L. erythropterus juveniles. Complete darkness increased the concentration of ammonia in the water by about 15 % and induced oxidative stress, whereas high light intensities reduced dissolved oxygen levels (up to 6 %) and pH (up to 6 %), increased water temperature (about 10 %), and caused significant oxidative stress in the fish. It is also worth noting that α-amylase activity increased significantly, while ATPase activity decreased significantly under both complete darkness (α-amylase activity = +40 %; ATPase activity = up to -130 %) and high light intensities (α-amylase activity = +21-52 %; ATPase activity = up to -43 %). The findings of this study can provide a guideline for improving current transportation techniques, thereby minimizing stress on L. erythropterus in a cost effective manner., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)