Search Results (15,914)

Dung beetle leg joints exhibit a remarkable capacity to support substantial loads, which is a capability significantly influenced by their surface microstructure. The exploration of biomimetic designs inspired by the surface microstructure of these joints holds potential for the development of efficient self-locking structures. However, there is a notable absence of research focused on the surface microstructure of dung beetle leg joints. In this study, we investigated the structural characteristics of the surface microstructures present in dung beetle leg joints, identifying the presence of fish-scale-like, brush-like, and spike-like microstructures on the tibia and femur. Utilizing these surface microstructural characteristics, we designed a self-locking structure that successfully demonstrated functionality in both the rotational direction of the structure and self-locking in the reverse direction. At a temperature of 20 °C, the biomimetic closure featuring a self-locking mechanism was capable of generating a self-locking force of 18 N. The bionic intelligent joint, characterized by its unique surface microstructure, presents significant potential applications in aerospace and various engineering domains, particularly as a critical component in folding mechanisms. This research offers innovative design concepts for folding mechanisms, such as those utilized in satellite solar panels and solar panels for asteroid probes. Full article

The impacts of hydropower plants and their reservoirs on floodplains can potentially create new environmental filters and reduce the exchange of organisms and access to habitats. In this study, we aimed to compare the fish assemblage associated with aquatic macrophytes between floodplain lakes under natural conditions and a regulated floodplain lake in the Environmental Protection Area of Rio Pandeiros, Brazil. We tested the hypothesis that in the regulated floodplain lake, there would be a lower richness and a greater of abundance of macrophytes and fish than is natural. We also verified the influence of the seasons, macrophyte bank richness, and biomass on the fish assemblage abundance. The fish assemblages differed between the regulated and natural floodplains due to the higher richness and abundance of fish in the natural floodplains. The presence of non-native and generalist species in the regulated floodplain influenced the dissimilarity between the floodplains. Migratory species have been found only in natural floodplains. Fish abundance was negatively related to macrophyte richness on the regulated lake. There was a lower fish abundance and macrophyte richness in the regulated lake. There was no evidence that macrophyte biomass affected the abundance and richness of fishes. Our results confirm that the Pandeiros small hydroelectric dam affects the fishes’ assemblage and the macrophyte community, since the regulated floodplain lake has a lower richness and abundance of fish. The regulated floodplain lake is connected to a reservoir created by a small hydroelectric dam, which will be removed in the coming years. The removal of this dam might change these dynamics, and this must be evaluated when the change is implemented. Full article

Background/Objectives: To propose criteria for retreating previously embolized PAVMs and determining the effectiveness of the criteria to prevent paradoxical embolization. Methods: A retrospective review of patients with PAVMs treated at a single HHT center of excellence between 1 January 2013, and 10 September 2023, was performed. Patients with PAVM recurrence were either retreated or observed based on the following criteria for PAVM reintervention: 1. Embolic device(s) not creating a sufficiently dense matrix, such that a channel through them may be >/ 2 mm; 2. Accessory feeding artery or pulmonary collateral >/ 2 mm; 3. Hemoptysis in a patient with no other explanation. Results: A total of 438 PAVMs were treated in 151 patients, including 106 patients with definite, 14 possible, and 31 doubtful HHT. Post-embolization PAVM recurrence occurred in 36 patients (36/151, 23.8%), including 15 patients (15/151, 9.9%) with 22 PAVMs (22/438, 5.0%) meeting criteria for reintervention. A total of 21 patients (21/151, 13.9%) with recurrence did not meet reintervention criteria and were therefore observed. Pre-treatment paradoxical embolization occurred in 36 patients (36/151) for a lifetime prevalence rate of 23.7%. Post-treatment paradoxical embolization did not occur in any patients following PAVM embolization (0/151). There was one case of iatrogenic paradoxical embolization in a patient being treated for systemic collateral reperfusion and hemoptysis. However, this was not included given that it was not a spontaneous event. Conclusions: Utilizing modern embolization techniques and devices, the proposed reintervention criteria, and screening intervals, paradoxical embolizations can be effectively prevented in patients with PAVMs. Full article

In recirculating aquaculture systems (RASs), ammonia excreted by fish must be converted to the less toxic nitrate before recirculation. Nitrifying microorganisms in biofilters used for this transformation can be sensitive to changes in salinity, which can present issues for systems that raise anadromous fish such as Atlantic salmon. Freshwater biofilters maintained at a low level of salinity (such as biofilters operated in coastal areas) may be better equipped to handle more drastic salinity shifts; therefore, experiments were performed on freshwater and low-salinity (3 ppt) biofilters to assess their ability to recover nitrification activity after an abrupt change in salinity (3, 20, and 33 ppt). Two-week tests showed full nitrification recovery in freshwater biofilters after a shift to 3 ppt but no ammonia oxidation in 20 or 33 ppt. Low-salinity-adapted filters (transitioned from 0 to 3 ppt) showed a small recovery (about 11%) after a shift to 20 ppt, and no activity when shifted to 33 ppt. Illumina sequencing revealed that, while nitrification was slowed or stopped with shifting salinities, the nitrifiers survived the salinity increases; conversely, the heterotrophic communities were more greatly affected and were reduced in proportion with increasing salinity. This work indicates that biofilters operated at low salinity may recover more quickly after large salinity changes, though this slight benefit may not outweigh the cost of low-level salinity maintenance. Further research into halotolerant heterotrophs in biofilms may increase the effectiveness of nitrifying biofilters under variable salinities. Full article

Phoenix barb (Spinibarbus denticulatus denticulatus) is a notable fish species in South China and is valued for its ecological and economic importance. To elucidate the molecular basis underlying its growth, we collected transcriptome profiles from the brains and livers of individual fish with different growth rates and compared differentially expressed genes (DEGs) at 3 and 9 months after hatching (MAH). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the pathways associated with growth were predominantly enriched in fatty acid biosynthesis, AMPK signaling, PI3K-Akt signaling, estrogen signaling, and protein metabolism. Notably, a greater number of DEGs from the fast-growing group were associated with these pathways at the early growth stage (3 MAH) than at the later stage (9 MAH). Real-time quantitative PCR results further validated that the genes involved in these pathways exhibited higher expression levels in fast-growing samples. This study enhances our understanding of the genetic mechanisms underlying growth rate differences and provides valuable genetic resources for future growth-related molecular breeding programs of phoenix barbs. Full article

Small-sized fish are a vital food source for large predatory commercial fish and play a key role in marine food webs, bridging lower and higher trophic levels. They are indispensable in maintaining the energy flow and material cycling within aquatic ecosystems. This study utilized bottom-trawl survey data from 2017 to 2020 along the south inshore of Zhejiang, China, complemented by concurrent environmental data, to examine the influence of environmental factors on the resource density and seasonal distribution patterns of four dominant small-sized fish species. The research findings indicated that SSH (sea surface height) and Chl (chlorophyll-a concentration) emerged as the key environmental factors influencing resource densities, with all four species exhibiting similar preferences toward these variables. However, significant disparities were observed in their preferences for SST (sea surface temperature), SSS (sea surface salinity), and DO (dissolved oxygen). The various species’ resource density and distribution patterns underwent significant seasonal variations. Additionally, the seasons and regions with the highest resource densities consistently aligned, occurring predominantly in autumn within the northern waters of the study area. This research further elucidated the environmental predilections and seasonal spatial distribution traits of small-sized fish in the south inshore of Zhejiang, an important feeding ground for economic fish species in the East China Sea. This provides scientific backing for forecasting alterations in coastal fishery resources under environmental and climate change scenarios and supports ecosystem-based fisheries management strategies. Full article

(1) Background: Mercury and lead contamination resulting from various anthropogenic activities represents a global environmental problem and a considerable risk to the health of the human population. (2) Methods: The objective of this research was to evaluate the concentrations of mercury (Hg) and Lead (Pb) in the blood of the child population in the municipalities in the Atrato River basin using a direct Hg analyzer and graphite furnace atomic absorption spectrometry. (3) Results: In total, 171 children (5–14 years of age) were taken into account, and 18.71% (32) of the children had concentrations of Hg and Pb above the permissible values established by the WHO. In the municipality of UN, 19 children had blood Hg concentrations between 5.29 and 17.71 μg/L. In CA, two children had concentrations of 5.03 and 8.43 μg/L, separately. In the case of Pb, seven children showed concentrations between 3.60 and 4.83 μg/dL in the municipality of RQ, three in UN (3.59, 3.61, and 4.60 μg/dL), and one in Carmen de Atrato (5.47 μg/dL). (4) Conclusions: The levels of Hg and Pb in the blood of children living in the riparian areas of the Atrato River basin are related to gold mining activities in the basin and the consumption of contaminated fish. Full article

Microplastics have emerged as a significant global environmental concern in the recent decade. The aim of this study was to elucidate microplastic contamination of commercial fish species in a natural lagoon environment. Microplastic contamination was examined in the gastrointestinal tracts and gills of 157 commercial fish from 18 species with varying feeding habits in a vital and sensitive lagoon ecosystem, which connects to the Indian ocean. Microplastics were extracted using digestion, followed by stereomicroscopic inspection using Nile Red stain, and identified via μ-FTIR analysis. Over half of studied fishes ingested microplastics (54.14%). Filaments (50%) and blue items (43%) were the most commonly ingested. Of all the fish species, Eubleekeria splendens had the highest average concentration of microplastics in GIT (1.41 ± 2.52 items/g w.w. tissues), although no statistically significant difference in amount of ingested microplastics (items/g w.w. tissues) was observed among species. The highest concentrations of inhaled microplastics were recorded in Sillago vincenti (1.38 ± 1.30 items/g w.w. tissues). The majority of the extracted microplastics (33%) belonged in the size class 500–1500 μm with rayon, polyethylene terephthalate, and polypropylene as the primary polymers. This study found no correlation between microplastic ingestion and fish species and feeding habits, but a positive correlation with fish size was observed. These findings reveal widespread microplastic contamination in edible fish, posing potential risks to commercially important species due to increasing pollution in lagoon ecosystems. Full article

Background: Sichuan taimen (Hucho bleekeri) is a fish species endemic to China’s upper Yangtze River drainage and has significant value as an aquatic resource. It was listed as a first-class state-protected wild animal by the Chinese government due to its very limited distribution and wild population at present. Methods: To elucidate the diversity of microorganisms in rearing water environments for H. bleekeri, metagenomic sequencing was applied to water samples from the Maerkang and Jiguanshan fish farms, where H. bleekeri were reared. Results: The results revealed that Pseudomonadota was the dominant phylum in the microbial communities of the water samples. Among the shared bacterial groups, Cyanobacteriota, Actinomycetota, Planctomycetota, Nitrospirota, and Verrucomicrobiota were significantly enriched in the water environment of Jiguanshan (p < 0.01), while Bacteroidota was more enriched in that of Maerkang (p < 0.01). Additionally, the Shannon diversity and Simpson index of the microbial community in the water environment of Maerkang were lower than in that of Jiguanshan. Conclusions: The present study demonstrated the similarities and differences in the microbial compositions of rearing water environments for H. bleekeri, which are expected to benefit the artificial breeding of H. bleekeri in the future. Full article

Japanese flounder is usually gonochoristic, with gonads that are either testes or ovaries. Here, we report an unusual case of hermaphroditism in Japanese flounder captured from the Bohai Sea. In the intersex flounder, the membrane of the upper ovary was closely connected to the abdominal muscles and internal organs, and the eggs filled the entire abdomen. The lower ovary was small and closely connected to the testes. The testes contained few fully mature sperm. Both eggs and sperm were capable of fertilization. The levels of several reproduction-related hormones (17β-estradiol, 11-ketotestosterone, 17α, 20β-dihydroxyprogesterone, luteinizing hormone, follicle-stimulating hormone, and testosterone) in the intersex flounder were intermediate, between those in females and males. The results showed that the heterozygosity of the intersex flounder was 0.632, and there were 28 single-nucleotide polymorphisms in the cyp21a gene. Compared with that of wild flounder, the activity of 21-hydroxylase was reduced by approximately 20.0%, and expressions of cyp19a, amh, and dmrt1 differed. We present the first report of its kind, detailing the anatomy, hormonal endocrinology, molecular biology, and physiology of the intersex Japanese flounder. Full article

Real-time estimation of fish biomass plays a crucial role in real-world fishery production, as it helps formulate feeding strategies and other management decisions. In this paper, a dense fish counting network called Swin-CSRNet is proposed. Specifically, the VGG16 layer in the front-end is replaced with the Swin transformer to extract image features more efficiently. Additionally, a squeeze-and-excitation (SE) module is introduced to enhance feature representation by dynamically adjusting the importance of each channel through “squeeze” and “excitation”, making the extracted features more focused and effective. Finally, a multi-scale fusion (MSF) module is added after the back-end to fully utilize the multi-scale feature information, enhancing the model’s ability to capture multi-scale details. The experiment demonstrates that Swin-CSRNet achieved excellent results with MAE, RMSE, and MAPE and a correlation coefficient R² of 11.22, 15.32, 5.18%, and 0.954, respectively. Meanwhile, compared to the original network, the parameter size and computational complexity of Swin-CSRNet were reduced by 70.17% and 79.05%, respectively. Therefore, the proposed method not only counts the number of fish with higher speed and accuracy but also contributes to advancing the automation of aquaculture. Full article

In multi-vessel collision avoidance decision-making, the collision between merchant and fishing vessels is a significant challenge. This paper proposes a fuzzy fusion method for making avoidance decisions under the influence of the navigation environment. First, C-means clustering was used to collect and analyze Automatic Identification System (AIS) data from fishing vessels. On this basis, the environment collision risk was determined using fuzzy reasoning. Second, the basic collision risk is obtained by calculating the DCPA and TCPA, and the integrated Collision Risk Index (CRI) is concluded by fuzzy logic through basic collision risk and the environment collision risk. The similar cases are extracted from the fuzzy case database, and collision avoidance decisions for merchant vessels are formulated following fuzzy adjustments. Finally, to validate the method, data from Chengshantou coastal waters is employed for verification. The results show that it can provide theoretical guidance and practical value for merchant vessels in making collision avoidance decisions. Full article

The fish fauna of Rio de Janeiro has been extensively studied, resulting in a comprehensive database of species collected over more than three centuries. This study aimed to provide a checklist of species, to identify patterns of diversity and the distribution of freshwater ichthyofauna, to delineate biogeographic units, and to explore changes in faunal composition among different areas. Analyzing data from ichthyological collections and the literature on original species descriptions revealed 206 freshwater fish species: 183 native and 23 allochthonous. The checklist includes updated species names. The sampling effort in Rio de Janeiro is extensive, especially in coastal lowlands. The findings indicate that inventory work is still needed in some areas, particularly within the Rio Paraíba do Sul basin. Seven bioregions of freshwater ichthyofauna were identified, including a major region of higher species richness and smaller areas with higher endemism of restricted-range species. This biogeographic assessment underscores the diverse and distinctive freshwater fish fauna in the basins of Rio de Janeiro, with well-defined biogeographic units. Full article

The research introduces a revolutionary Internet of Things (IoT)-based system for fish farming, designed to significantly enhance efficiency and cost-effectiveness. By integrating the NodeMcu12E ESP8266 microcontroller, this system automates the management of critical water quality parameters such as pH, temperature, and oxygen levels, essential for fostering optimal fish growth conditions and minimizing mortality rates. The core of this innovation lies in its intelligent monitoring and control mechanism, which not only supports accelerated fish development but also ensures the robustness of the farming process through automated adjustments whenever the monitored parameters deviate from desired thresholds. This smart fish farming solution features an Arduino IoT cloud-based framework, offering a user-friendly web interface that enables fish farmers to remotely monitor and manage their operations from any global location. This aspect of the system emphasizes the importance of efficient information management and the transformation of sensor data into actionable insights, thereby reducing the need for constant human oversight and significantly increasing operational reliability. The autonomous functionality of the system is a key highlight, designed to persist in adjusting the environmental conditions within the fish farm until the optimal parameters are restored. This capability greatly diminishes the risks associated with manual monitoring and adjustments, allowing even those with limited expertise in aquaculture to achieve high levels of production efficiency and sustainability. By leveraging data-driven technologies and IoT innovations, this study not only addresses the immediate needs of the fish farming industry but also contributes to solving the broader global challenge of protein production. It presents a scalable and accessible approach to modern aquaculture, empowering stakeholders to maximize output and minimize risks associated with fish farming, thereby paving the way for a more sustainable and efficient future in the global food supply. Full article