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Accurately modeling the distribution of keystone species is of utmost importance to gain a comprehensive understanding of their complex ecological dynamics and to develop effective strategies for sustainable scientific management. In the coastal China ecosystem, the swordtip squid (Uroteuthis edulis) stands out as a keystone species with significant commercial and ecological value. Despite its importance, research on the ecological dynamics of this species remains limited and requires further investigation. To investigate the spatial and temporal variability in the distribution of U. edulis and identify the key environmental drivers in the East China Sea (ECS) and southern Yellow Sea across different seasons, we generated ensemble models using oceanographic variables and fishery-independent scientific survey data collected from 2016 to 2018. Our results revealed that U. edulis predominantly inhabited the central and southern regions of the ECS throughout the year. The primary environmental variables driving its distribution varied by season, with the sea surface temperature being the most important in spring, sea surface height in summer and autumn, and depth in winter. During summer and autumn, the suitable habitats of U. edulis were found to be largest and extended northwards towards the coastline. However, they migrated southwards to the waters near the edge of the ECS continental shelf with smaller suitable areas in the spring and winter. These results suggested that U. edulis exhibited season-specific habitat preferences and responded to changing environmental conditions throughout the year. The observed seasonal distribution patterns were likely influenced by the fluctuating mixture of waters (ocean currents) from different sources, with varying physical and chemical characteristics throughout the year. Our study provides baseline data for comprehending the population dynamics of U. edulis and highlights the significance of considering species' habitat preferences in a dynamic environment.
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Based on data collected from research vessel cruises performed in May 2020 off the East China Sea (ECS) and the southern Yellow Sea (YS) (26°30'-35°00' N, 120°30'-127°00' E), we analyzed the shrimp community and its relationships with environmental variables by using index of relative importance, biodiversity indices, and multivariate techniques. A total of 29 species were recorded, belonging to 11 families and 19 genera. The dominant species were Metapenaeopsis longirostris, Leptochela gracilis, Solenocera melantho, Crangon hakodatei, Parapenaeus fissuroides, Plesionika izumiae, and Trachypenaeus curvirostris, which together accounted for 82.9% of the total biomass and 90.8% of the total abundance of shrimps. Results of Cluster and NMDS analyses showed that three groups were identified for the shrimp community in the ECS and YS in spring, including group A (inshore of northern ECS and YS group), group B (offshore of northern ECS group) and group C (southern ECS group). ANOSIM and SIMPER analysis showed significant differences between group A and B, gourp A and C, and group B and C, with the dissimilarity of 92.2%, 95.8% and 91.6%, respectively. The typical species were T. curvirostris, C. hakodatei, L. gracilis and Palaemon gravieri in group A, and S. melantho in group B, and M. longirostris, P. fissuroides, P. izumiae and Solenocera alticarinata in group C. Significant differences were also detected in biomass, diversity index, species richness index and evenness index among groups, with significantly greater values in group C than those in A and B. Environmental variables and the substrate also displayed significant differences among groups. Results of canonical correspondence analysis showed that bottom temperature, bottom salinity, depth, and the substrate were the main environmental variables affecting spatial structure of shrimp community. Water mass characteristics and substrate type had important influences on the distribution of shrimp community in the ECS and YS in spring.
Asunto(s)
Penaeidae , Humanos , Animales , Estaciones del Año , Biodiversidad , Biomasa , ChinaRESUMEN
In this study, the complete mitochondrial genome of the Taiwan tai Argyrops bleekeri was determined for the first time by next-generation sequencing. The circular mtDNA molecule was 16,646 bp in size and the overall base composition was A (27.77%), C (28.95%), G (16.60%), and T (26.68%), with a slight bias toward A + T. The complete mitogenome encoded 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and a control region. Phylogenetic analysis based on the 13 PCGs of the Sparidae family revealed that Argyrops appears to be most closely related to Pagrus and Parargyrops, but further research is needed.
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The complete mitochondrial genome of Lepidotrigla alata was sequenced in this study. The genome sequence is 16,512 bp in length, comprising 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and one control region. Overall base composition is 26.46% A, 25.05% T, 17.22% G, and 31.27% C. Phylogenetic analysis indicated that L. alata was close to L. guentheri and L. microptera, and each genus in the family Triglidae was monophyletic. This study can provide valuable information for future evolutionary studies on L. alata and Triglidae.
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The fish-gut microbiota play a key role in the physiology, development, and fitness of its host. An understanding of fish-gut microbial communities and the factors influencing community composition is crucial for improving fish performance. In this study, we compared the gut microbiota of juvenile black sea bream Acanthopagrus schlegelii among habitats: (1) wild, (2) offshore cage-culture, and (3) pond-culture. We also explored the relationships between the gut microbiota and host-associated environmental factors. Gut samples and associated environmental compartments were investigated using 16S rRNA gene sequencing. Our results revealed significant habitat-specific differences among the gut microbiota of juvenile A. schlegelii. Wild populations of juvenile A. schlegelii had more diverse gut microbiota than populations cultured in pond habitats due to their omnivorous feeding habits and the corresponding abundance of natural food resources. Significant variations in the composition, core taxa, and diversity of the microbiota were also found between the gut and the environmental compartments. However, no significant differences were observed among the microbiota of the environmental compartments in the relatively isolated pond habitat. Source tracking analysis recovered connections between the fish-gut microbiota and the diet, water and sediment environmental compartments. This connection was especially strong between the microbiota of the fish gut and that of the diet in the pond habitat: the diet microbiota accounted for 33.48 ± 0.21% of the gut microbiota. Results suggested that all A. schlegelii shared a core gut microbiota, regardless of differences in diet and habitat. However, environmental factors associated with both diet and habitat contributed to the significant differences between the gut microbiota of fish living in different habitats. To the authors' knowledge, this study presents the first comparison of gut microbiota among juvenile A. schlegelii with different diets and habitats. These findings enrich our understanding of the gut microbiota of A. schlegelii and help to clarify the interaction between gut microbiota and environmental factors. Our results may also help to guide and improve fish ecological fitness via the regulation of gut microbiota, thereby increasing the efficacy of stock enhancement programs for this species.
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The complete mitochondrial genome of Heteropriacanthus cruentatus has been obtained and annotated through Illumina next-generation sequencing. This mitogenome was found to be 16,506 bp in length, containing 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNA), and 2 ribosomal RNA genes (rRNA). This overall base composition of the complete mitogenome for this species included 27.52% A, 24.46% T, 16.99% G and 31.04% C. The phylogenetic analysis revealed that the H. cruentatus has the closest relationship with Pristigenys niphonia. This study provides an important resource for reviewing the phylogenetic relationships and taxonomic status of this species.
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In this paper, the population structure of Trichiurus japonicus in East China Sea was analyzed based on the data of its age composition and anus length in 2002-2004, and the rational utilization of T. japonicus resources in the Sea was approached by using the catch (in mass) per recruit theory of Beverton-Holt model. The results revealed that: (1) there was a miniaturization trend of the T. japonicus population in East China Sea. The range of age composition changed from 0-6 year in the late 1950's to 0-4 year in the early 21st century, and the population was dominated by the group of 0-1 year now. The percentage of 2-year old T. japonicus decreased from 12.84% in the late 1950s' to 6.91% in the early 21st century, and that of 3-year old T. japonicus decreased from 4.92% in the late 1950s' to 0.57% in the early 21st century; (2) the exploitation rate of T. japonicus in the period of 2000-2003 was 0.864, which was beyond of the optimum exploitation rate of 0.51, suggesting that the T. japonicus in East China Sea was under over-fishing; and (3) to enhance the age value at first capture (t(c)) was the best measure of increasing the catch (in mass) per recruit of T. japonicus. The age at recruitment (t(r)) and the t(c) of T. japonicus in East China Sea was 0. 25 and 0.5 at present, respectively. If the t(c) changed from 0.5 to 1, the unit catch would be increased by 55.38%, and if the t(c) changed to 1.5, 2 or 2.75, it would be increased by 100.81%, 130.52% or 145.23%, respectively. It was suggested that due to the difficulties in greatly reducing catching intensity, it could be available to properly increase the to value while decrease the catching intensity to protect the T. japonicus resources in East China Sea and realize their sustainable use.
