Water Fish Research Articles

Photocatalytic Removal of the Endocrine Disruptor Chlorpyrifos using a ZnO.MoO3 Composite Supported on Al2O3

AbstractChlorpyrifos is an endocrine disruptor pesticide that induces breast cancer cell proliferation through Estrogen receptor alpha pathway in humans. It also has toxic effects on some beneficial insects like bees, wasps, and arthropods, even low levels of CP can kill fish in water. Thus, it is important to efficiently remove this compound from wastewaters to get rid of its hazardous effects. Al2O3 supported ZnO.MoO3 composite was prepared as an efficient material for photo‐degradation of chlorpyrifos under UV irradiation and characterized by SEM‐EDX, XRD and TG techniques. The XRD analysis showed the orthorhombic structures with band gap of 2.86 eV for ZnO.MoO3/Al2O3 which was 2.96 eV for MoO3/Al2O3. The kinetics of degradation depicted that ZnO.MoO3/Al2O3 afforded a complete degradation of chlorpyrifos with half life of only 3 minutes which otherwise was 24 minutes in the presence of MoO3/Al2O3. The complete mineralization of chlorpyrifos was confirmed by GC/MS analysis, where no peaks of intermediates were recorded. The prepared material also exhibited good recyclability without any leaching of Zn and Mo metals. Thus, ZnO.MoO3/Al2O3 is an efficient and cost effective material for removal of chlorpyrifos. Its potential may also be explored for the removal of other hazardous organic pollutants.

Use of Hydroacoustic Methods to Assess Ecological Status Based on Fish: A Case Study of Lake Dejguny (Poland)

The idea of the article was to verify the thesis that acoustic studies of ichthyofauna in lakes provide sufficient information to determine the necessity (or lack thereof) of carrying out a full procedure for assessing the ecological status based on fish. The manuscript compares acoustic data collected in 2008 and 2021 in Lake Dejguny (Poland) as a result of acquisition carried out with the same EY-500 echosounder, on the same routes (transects), and the echogram analyses were carried out using software dedicated to this echosounder. Target strength (TS) distribution was determined in the lake and in individual water layers with a thickness of 2 m, as well as, using the mapping method, changes in the distribution of fish in selected water layers. Large changes in TS distribution in the vertical profile were demonstrated between both years of the study, as well as a clear reduction in the space available for fish in waters below 24 m in 2021, which was associated with a reduction in the concentration of dissolved oxygen below this depth to a value lower than 2.5 mg L−1. It was suggested that it could be possible to develop a simple index enabling the assessment of changes in fish structure, based, similarly to the Large Fish Index, on the ratio of the number of large fish to small fish. The obtained results confirmed that the proposed methods of acoustic data analysis can be the basis for the decision on the necessity (or lack thereof) of conducting an assessment using the Polish national LFI-EN method based on the results of one-off fishing with Nordic multimesh gillnets.

Supply Chain Analysis of Traditional Fish Catches of Bagan Deli City Medan and Bagan Percut of Deli Serdang District

Traditional fishermen are fishermen who catch fish in waters which are traditional fishing rights that have been used for generations by local culture and wisdom. Fish is a marine product that is easily damaged or perishable, and this is due to enzymatic activity in the fish's body and the activity of microorganisms due to wrong handling. The cities of Medan and Deli Serdang are areas that have good potential for marine products. Enjoying fish products from the sea by consumers, fish distribution was carried out at Belawan Port, precisely at Belawan Ocean Fisheries Port and Fish Auction Place Bagan Percut, Deli Serdang. This study looks at the supply chain or supply chain for traditional fishermen in the North Sumatra region, especially in Medan City and Deli Serdang Regency. The research method used is descriptive qualitative research. The results of the study found that the supply chain of most fishermen caught in Bagan Deli through agents and distributors of fish was then brought to the market or auction place. There are also fishermen in Bagan Deli who directly sell their catch at the local market where the fishing group is located, namely the Bagan Deli and Belawan Traditional Markets. Meanwhile, Bagan Percut of Deli Serdang Regency shows that the role of fish agents and distributors in the supply chain of capture fishermen is very influential. Through these fish agents and distributors, distribution channels can be determined based on the amount or amount of fish caught.

Trajectory Tracking and Obstacle Avoidance of Robotic Fish Based on Nonlinear Model Predictive Control.

The attainment of accurate motion control for robotic fish inside intricate underwater environments continues to be a substantial obstacle within the realm of underwater robotics. This paper presents a proposed algorithm for trajectory tracking and obstacle avoidance planning in robotic fish, utilizing nonlinear model predictive control (NMPC). This methodology facilitates the implementation of optimization-based control in real-time, utilizing the present state and environmental data to effectively regulate the movements of the robotic fish with a high degree of agility. To begin with, a dynamic model of the robotic fish, incorporating accelerations, is formulated inside the framework of the world coordinate system. The last step involves providing a detailed explanation of the NMPC algorithm and developing obstacle avoidance and objective functions for the fish in water. This will enable the design of an NMPC controller that incorporates control restrictions. In order to assess the efficacy of the proposed approach, a comparative analysis is conducted between the NMPC algorithm and the pure pursuit (PP) algorithm in terms of trajectory tracking. This comparison serves to affirm the accuracy of the NMPC algorithm in effectively tracking trajectories. Moreover, a comparative analysis between the NMPC algorithm and the dynamic window approach (DWA) method in the context of obstacle avoidance planning highlights the superior resilience of the NMPC algorithm in this domain. The proposed strategy, which utilizes NMPC, demonstrates a viable alternative for achieving precise trajectory tracking and efficient obstacle avoidance planning in the context of robotic fish motion control within intricate surroundings. This method exhibits considerable potential for practical implementation and future application.

Invasi Spesies Amphilophus citrinellus Terhadap Ikan Lokal di Perairan Waduk Sanguling

Foreign fish in waters that are not their habitat can have a major impact on the balance of the ecosystem. One of the foreign fish living in Indonesian waters is the red devil foreign fish. The presence of red devil foreign fish (Amphilophus citrinellus) in Indonesian waters reduces biodiversity and is harmful to aquatic ecosystems. This study aimed to assess the negative impact of Amphilophus citrinellus in the Sanguling Reservoir, West Bandung Regency. This study used the desk study method and direct observations in the field. Data were collected using literature review and interview methods. The finding of red devil foreign fish species with the Latin name Amphilophus citrinellus in the Sanguling Reservoir provides information related to the negative impact of invasive foreign fish. This information can be used as a basis for developing regulations that are focused and directed towards invasive species, as well as to increase the active role of several sectors, such as research, and developing mitigation of the impacts caused by invasive species so that the Sanguling Reservoir ecosystem is maintained.

Keanekaragaman Ikan Invasif Di Perairan Umum Daratan Krueng Aceh

Aceh has a large potential for inland public water resources. One of the important inland waters is Krueng Aceh, Krueng Aceh is a river located in Aceh Province that originates at Cot Seukek, Aceh Besar District, passes through the city center (Peunayong) and empties into Lampulo, Banda Aceh City. The diversity of invasive fish in the inland waters of Krueng Aceh was carried out with the aim of identifying the types of invasive fish and to determine the diversity of invasive fish in the waters of Krueng Aceh as basic data in the management of inland common water resources. The research used a purposive sampling technique at sample points taken at 4 (four) points on the mainland of Krueng Aceh. Station 1 is located in Aneuk Galong Village, Station 2 is located in Bakoy Village, Station 3 is located in Pango Raya Village, Station 4 is located in Peunayong Village. The research results show that there are 9 types of fish in the public waters of the Krueng Aceh mainland which are dominated by baung fish. The station with the highest diversity results is station III located in Pango Raya which uses 4 types of fishing gear commonly used in the public waters of the Krueng Aceh mainland and gill net fishing gear is the most effective fishing gear used.

An effect assessment of microplastics and nanoplastics interacting with androstenedione on mosquitofish (Gambusia affinis)

An increasing number of microplastics have been detected in aquatic environments, causing various damage to organisms. The size of microplastics affects the toxicity once they enter the organisms. Meanwhile, there is an increasing variety of Endocrine-disrupting chemicals (EDCs) present in aquatic environments. Androstenedione (AED) is a typical EDC. In this study, we used polystyrene microspheres of 80 nm (NPs) and 8 μm (MPs) as materials to simulate environmental contaminants in the aquatic environment with AED. We used female mosquitofish (Gambusia affinis) as the research object to investigate the effects of microplastics on fish in waters containing AED. We compared different sizes of particles accumulation in some tissues of fish and variation of enzyme activities (SOD, LDH, CAT), and the content of MDA in the gut. MPs, NPs, and AED combined exposure test investigated mRNA profiles of immune-related genes (IL-1β, IL-6, IL-8, IL-10) and hormone receptor genes (ARα, ARβ, ERα, ERβ) in the liver of fish. Our results indicated that MPs emerged in various tissues (gill, gut, and liver) of mosquitofish. Besides, NPs and MPs caused enteric abnormal enzyme activity after 48 h of exposure, which was particularly pronounced in the MPs-AED group. MPs induced significant upregulation of inflammatory factors and gonadal factor genes after 96 h of exposure, which was more pronounced when co-exposed with AED. In conclusion, NPs and MPs caused mechanisms of immune damage and inflammatory response. MPs were found to be more likely to cause adverse reactions than NPs, and these responses were enhanced by the combined effects of AED. This study demonstrated that AED can exacerbate the negative effects of MPs and NPs on mosquitofish. It provided an important basis for the effective assessment of MPs and NPs on bioaccumulation and biochemical status of mosquitofish. Additionally, it serves as a foundation to investigate the interactive effects of microplastics and EDCs in living organisms.

Impact of Water Source and Quality on Survival, Growth and Health of Clarias gariepinus Fingerlings Reared in Indoor Concrete Tanks

This experiment investigated the impact of two water sources and their quality on the survival, growth and health of Clarias gariepinus fingerlings reared in indoor concrete tanks. 400 fingerlings of mean weight 15.33±3.47 g and total length 12.63±1.00 cm (mean±standard deviation) was randomly distributed into four concrete tanks of 12 m3 capacity each. Water quality was analyzed bi-weekly throughout study duration. Growth parameters such as mean weight gain (MWG), specific growth rate (SGR) and feed conversion rate (FCR) were calculated using standard procedures. At study termination, duplicate groups per treatment were assessed for survival rate and a health status check was determined by a hematological evaluation and microscopic examination of parasitic incidence. Results indicated that fish reared in water sourced from bore-hole [BH] performed comparatively significantly better in growth (p < 0.05) than fish in water from earthen pond [EP] as the MWG stood at 294.05±79.17 g for the former against 211.03±54.62 g for the latter with the survival rates for both treatments being in excess of 90%. Additionally, fish reared in EP presented with a higher infestation load of Trichodina spp., although there was no significant difference (U = 7, p > 0.05) between fish reared in EP and BH treatments with regards to their packed cell volume levels and white blood cells. The outcome of this study shed light on the impact a water source can have on the growth and health status of C. gariepinus with a recommendation of microbiological analysis of water supply from open/surface systems before usage for the African catfish aquaculture.

Fishing for hosts: Larval spurting by the endangered thick-shelled river mussel, Unio crassus.

Fishing for hosts: Larval spurting by the endangered thick-shelled river mussel, Unio crassus.

Water quality indicators in high-density cage farming of trout

Trout fishing means raising fish in water whose temperature does not exceed +18°C under completely or partially artificial conditions. Today, several fish belonging to the salmon family are bred in cold water fisheries in the world. These are river trout (Rainbow trout - Oncorhynchus mykiss), brook trout (Brown trout - Salmo trutta), and brown trout (Brook trout - Salvelinus fontinalis). Currently, river trout breeding dominates global production. Its cultivation has been mastered in almost all regions [8]. In the article, the water quality indicators were studied during high-density breeding of trout in the cage method at the “Golden Fish” fishery LLC, located in the Khojakent reservoir in the Tashkent region of Uzbekistan. This includes water temperature, dissolved oxygen content, and water hydrogen potential, as well as information on fish growth, development, nutrition, and reproduction.

PENGGUNAAN TEPUNG IKAN SAPU-SAPU (Pterygoplichthys pardalis) SEBAGAI SUMBER PROTEIN PAKAN PADA PENTOKOLAN UDANG VANAME (Litopenaeus vannamei)

Vannamei shrimp (Litopenaeus vannamei) is a fishery product that is able to generate foreign exchange for the country besides tiger prawns. This shrimp has the advantage of being more resistant to environmental conditions and disease. Feed plays an important role in its cultivation because it absorbs the largest cost of 60-70% of the total production cost. At present, there are still many farmers, both traditional and modern, who have not carried out effective feeding because of the high cost of providing feed. Amazon sailfin catfish, Pterygoplichthys pardalis are invasive fish in waters that need to be limited in population development by using them. One form of utilization is to make it a fish meal product and then it becomes a raw material for feed. This study aims to analyze the use of P. pardalis meal as feed for vaname shrimp. The test animals were vaname shrimp with a weight of 3.35±0.5 g; total length 6±0.5 cm, first acclimatized for 5 days. The percentages of using broomstick fish meal were 25%, 30%, 35% as treatment and commercial feed as control feed. The study used a completely randomized design (CRD) with 4 treatments and 3 replications. Research for 60 days, the dose of feed given is 5% with a frequency of 5 times a day. The parameters observed were: absolute growth (PM), daily growth (PH), daily growth rate (LPH), feed conversion (KP), feed efficiency (EF) and survival (KH). Data were analyzed for variance (ANOVA). The results showed that the higher the percentage of P. pardalis meal, the better the response of vannamei shrimp to growth parameters, but based on the analysis of variance, it showed that the treatment not significant all the parameters observed.

Использование рыбного белка в технологии инновационных хлебобулочных и мучных кондитерских изделий

The article presents research on improving the technology of bakery and flour confectionery products by enriching them with fish protein. There are presented the data of a survey of the dietary preferences of schoolchildren aged 15-16. It is noted that most teenagers prefer bakery and flour confectionery products as a snack. It is also established that children do not consume enough fish protein, which is complete and easily digestible. In this regard, the study solves the problem of improving the technology of wheat biscuits and rye-wheat loaves by enriching with a protein-mineral additive. In the first case, the problem is solved by introducing fermented minced cod into the dough, obtained by keeping the crushed muscle tissue of the fish in water at the specified parameters. In the case of obtaining loaves, a protein-mineral additive is a composition obtained by the destruction of muscle, integumentary and bone tissues of fish raw materials in a subcutaneous whey. To determine the optimal parameters of the process there was carried out mathematical planning of the experiment by using the central composition plan of the second order for two factors: the degree of grinding of fish raw materials (2 times) and the duration of disaggregation (4 times). The resulting protein-mineral additive is used in the production of rye-wheat loaves by introducing it into the dough. The baked finished product was an attractive bakery product from light gray to light brown, well baked, with a uniform structure, without signs of non-kneading, with a pleasant taste and smell with slightly pronounced fishy shades. The results of physico-chemical studies showed an increase in the amount of protein by 47.3%, mineral substances – by 96.3%. The indicator of the biological value of the protein was 124%, which characterizes its balance. It has been established that the loaves are characterized by a high content of mineral elements significant in nutrition (potassium, calcium, magnesium, sodium, phosphorus), so the new food product is functional.

Genetic Variation in Schizothorax kozlovi Nikolsky in the Upper Reaches of the Chinese Yangtze River Based on Genotyping for Simplified Genome Sequencing.

Simple SummarySchizothorax kozlovi Nikolsky is a unique cold−water fish in the upper reaches of the Yangtze River in China and has high economic value. In our study, genetic diversity and population structure analyses were performed on seven wild populations in the upper reaches of the Yangtze River by GBS. The above results indicate that the populations of S. kozlovi have different degrees of tolerance and selection pressure in response to temperature and altitude. The Wujiang population was genetically differentiated from the Jinsha River and Yalong River populations. The Wujiang intrapopulation has greater genetic diversity and differentiation than the Jinsha River and Yalong River populations, which demonstrates that the Jinsha and Yalong populations require more attention and resources for their protection. The results of this study will increase our understanding of the diversity of S. kozlovi in the upper reaches of the Yangtze River and provide a basis for the conservation and utilization of wild resources.Schizothorax kozlovi Nikolsky is a unique cold−water fish in the upper reaches of the Yangtze River in China and has high economic value. In our study, genetic diversity and population structure analyses were performed on seven wild populations (originating from the Jinsha River, Yalong River, and Wujiang River) in the upper reaches of the Yangtze River by genotyping by sequencing (GBS). The results indicated that a total of 303,970 single−nucleotide polymorphisms (SNPs) were identified from the seven wild populations. Lower genetic diversity was exhibited among the intrapopulations of the three tributaries, and the Wujiang River population had significant genetic differentiation when compared to the Jinsha River and Yalong River populations. Furthermore, the selected SNPs were enriched in cellular processes, environmental adaptation, signal transduction, and related metabolic processes between the Wujiang population and the other two populations. The above results indicate that the populations of S. kozlovi have different degrees of tolerance and selection pressure in response to temperature and altitude. The Wujiang intrapopulation has greater genetic diversity and differentiation than the Jinsha River and Yalong River populations, which demonstrates that the Jinsha and Yalong populations require more attention and resources for their protection. The results of this study will increase our understanding of the diversity of S. kozlovi in the upper reaches of the Yangtze River and provide a basis for the conservation and utilization of wild resources.

Structure design and dynamic analysis of a tensegrity-based carangiform robotic fish

<p indent="0mm">Bionic robots are widely used in various fields due to their high flexibility and mobility. When conducting complex underwater operations, it is expected to design a bionic robotic fish with good underwater navigation ability based on the excellent swimming performance of fish. At present, the tail swing mechanism of bionic robotic fish is mostly composed of serial rigid joints. Limited by their own materials and manufacturing process, the joints cannot undergo large elastic deformation, so the corresponding bionic robotic fish is far less flexible than fish in water. A flexible design is a natural choice to better mimic the movement of fish underwater. Tensegrity is a grid-like spatial structural system that consists of pre-tensioned strings and pre-compressed bars. Such structure has the advantages of light weight, flexible deformation, and impact resistance. Introducing tensegrity into the robot field has greater advantages than traditional rigid robots due to its flexibility and other characteristics. Based on a novel 2D tensegrity and the physiological characteristics of fish, this paper proposed a four-joint bionic robotic fish that imitates carangiform swimming motions. Referring to the shape characteristics of fish, the three-dimensional model of robotic fish is established using software. By simplifying several ropes as the external forces of the system, ignoring the parameters of gravity, buoyancy and mass of some parts, the dynamic equations of the two-joint model are established through the coordinate transformation matrix and further extended to the multi-joint system. Taking the single and four-joint systems as examples, the accuracy of the dynamic model is verified by Adams simulations, and the obtained results are consistent with the motion curve of fish during cruise. In order to improve the propulsion performance of robotic fish, some parameters of the system are analyzed. When the stiffness distribution between the joints is changed, the results show that reducing the spring stiffness of the tail fin joint can effectively reduce the influence on the front-end joint. Further analysis is carried out on reducing the stiffnesses of only side springs, or both side and center springs. It is found that reducing the stiffnesses of only side springs is more conducive to the improvement of the driving effect. The influence of the driving strategy on the dynamic performance of the system is discussed, and the application of step function and sinusoidal function to the robotic fish without/with damping is also analyzed. The results show that the fluctuation of the sinusoidal function driven system is larger under the condition of without damping, and the similar dynamic response can be obtained under the condition of damping. This work provides a theoretical basis and application reference for the design of flexible robotic fish. The proposed tensegrity-based carangiform robotic fish holds potential applications as exploration, search and rescue equipment in complex underwater environments.

Fishing around the South Georgia Islands and the ‘Question of the Falklands/Malvinas’: Unprecedented challenges for the Antarctic Treaty System

Despite lying outside the Antarctic Treaty area, the longstanding sovereignty dispute between Argentina and the United Kingdom over the Falklands/Malvinas, South Georgias, and the South Sandwich Islands (collectively known as the ‘Question of Falklands/Malvinas’) has significant implications for Antarctic governance. The South Georgias and South Sandwich Islands are within the CCAMLR Area and sites of significant fishing interest. Over the last four decades, CCAMLR has been able to avoid any confrontation between Argentina and the UK over regulation of fishing activities in waters surrounding these archipelagos. But at the 2021 CCAMLR meeting, Russia controversially blocked renewal of an existing conservation measure for international management of fishing for Patagonian toothfish in waters surrounding the South Georgias. Under the CCALMR regime, a provision known as the ‘Chairman’s Statement’ allows member states to use national law to regulate fishing in waters surrounding islands within the CCAMLR Area over which state sovereignty is recognised by all Contracting Parties. However, there are differing interpretations on whether the Chairman’s Statement allows a CCAMLR state to unilaterally use national law to allow fishing in waters surrounding islands which are under territorial dispute. While CCAMLR has so far avoided addressing this issue, as third parties’ interests are involved, it will likely need to take a more active role in the near future. This article therefore assesses the serious challenges this issue raises for CCAMLR and the wider ATS and concludes by presenting paths that the Antarctic community could explore to reduce the present tensions.

Deoxygenated toadfish turn up gill serotonin degradation to catch breath

Serotonin is probably most famed for its mood-altering role in the human brain. Yet, long before people began taking serotonin reuptake inhibitors to treat depression, the versatile neurotransmitter was known to cause blood vessels to constrict, which could be a problem for fish when oxygen levels in water plummet naturally. ‘Toadfish slow their heart rate, lower their blood pressure and breathe deeper when oxygen drops. These responses help maximize their oxygen absorption and usage’, says John Sebastiani from the University of Miami, USA. Knowing that the levels of serotonin in the blood are tightly maintained by a delicate balance between tissue absorption and destruction and excretion, Sebastiani, Allyson Sabatelli and Danielle McDonald, also from the University of Miami, decided to investigate how Gulf toadfish (Opsanus beta) manage serotonin levels in their blood when their oxygen supply drops a little.‘Toadfish are lazy and like to settle on the bottom, so it's pretty common for them to be accidentally caught in shrimping boat nets’, says Sebastiani, explaining that fishermen just throw them back. ‘As long as we have buckets of seawater and an air pump, we can collect the fish and safely transport them back to campus’, he adds. After returning to the lab, the team reduced the oxygen in the fish's water from 100% to 50% – which isn't too extreme for the fish – for 2 min, 40 min and 24 h respectively, before collecting samples of the fish's brains, gills, liver, kidneys and heart, as well as their bile and urine to monitor their ability to absorb serotonin and break it down.Checking the amount of serotonin circulating in the fish's blood, the team found that levels in the fish that experienced 40 min of lower oxygen had fallen by 34%, while the fish that had spent a whole day in reduced oxygen experienced a 54% drop. However, when the researchers checked which tissues were absorbing and destroying serotonin, they were surprised that the heart had reduced how much serotonin it was breaking down – potentially supplying the gills with more of the blood vessel constricting neurotransmitter, instead of removing it from the blood to dilate the gill blood vessels and allow them to absorb more oxygen from the depleted water. But the researchers had recorded that serotonin levels in the blood declined, so which other tissue was removing the neurotransmitter from the fish's blood?Next, the team measured serotonin breakdown in the gill when the fish experienced periods of reduced oxygen, and the level increased threefold. ‘These results suggest that serotonin clearance is upregulated during hypoxia and likely driven, in part, by mechanisms within the gill’, says Sebastiani.In addition, when measuring the quantity of serotonin being excreted in the bile produced by the liver, the researchers discovered that the neurotransmitter levels almost doubled after they replaced the fish's well-oxygenated water with poorly oxygenated water for 40 min. As well as breaking the neurotransmitter down, the fish also excrete it. However, the team points out that serotonin production in the liver, which is a major source of the neurotransmitter, could reduce when the fish experience a fall in oxygen, and they are curious to find out more about how serotonin impacts the fish's heart function when their oxygen supply dwindles.

Microbial assessment of water, sediment and tilapia fish of Lake Nasser, Egypt

ABSTRACT Lake Nasser is the main source of fresh water in Egypt. This study concerns microbial assessment of water, sediments and fish (Oreochromis niloticus) collected from 5 inlets or khors of Lake Nasser (Rahma, Garf Hussein, Korosko, Toushka and Abu Simbel). The results indicate that the water and sediment samples collected from the southern part of Lake Nasser (Toushka) recorded a higher microbial load than the northern part. The highest number of pathogenic bacteria was also recorded in the southern part of Lake Nasser (Toushka and Abu Simbel). Also a higher bacterial load in/on fish (O. niloticus) was recorded at Rahma and Toushka sites. In general, the results of this study show that Lake Nasser is exposed to pollution, especially in its southern part. Therefore, regular monitoring and assessment are necessary to maintain the quality of Lake Nasser.

Prevalence of Kudoa thyrsites (Myxozoa, Multivalvulida) in Atlantic Mackerel, Scomber scombrus L., in the Vicinity of the Faroe Islands

Atlantic mackerel Scomber scombrus is an important migratory fish in Faroese waters and the Northeast Atlantic at large. Similar to other fish species from marine environments, mackerel can be infected by the myxozoan parasite Kudoa thyrsites, leading to myoliquefaction that renders the fish commercially unviable. Despite the ecological and economic significance of K. thyrsites as a parasite, little is known regarding its prevalence in the Faroese mackerel fishery. Prior to analysing field samples, we examined 104 samples of Atlantic mackerel selected from a Faroese processing plant on the basis of visible soft-tissue. Using microscope smears we observed K. thyrsites in 98% of the soft-tissue mackerel specimens and a direct comparison with qPCR demonstrated strong agreement between the two techniques (Φ = 0.429, p&amp;lt;0.01; Fisher’s exact test). We used qPCR to analyze a total of 594 Atlantic mackerel specimens, collected from Faroese fishing grounds during 2017 and 2018. Overall prevalence was 4.1% (95% confidence interval; 2.5-5.7%) and ranged from 0-14% at different locations. Infection by K. thyrsites was documented in fish as young as 2 years (195g) and up to 14 years (615g) of age. A logistic regression model indicated the odds of infection were statistically associated with sampling location and month, but not gender, age, weight or length, although a Chi-squared test on age categories showed the oldest fish (&amp;gt;10 years) had highest prevalence (10.8%, CI: 4.2-17.5%). In order to investigate potential infection pathways we performed qPCR analysis on eDNA in water samples collected from the Faroese Plateau. However, we found no molecular evidence for K. thyrsites spores in Faroese plankton assemblages. Our data support the prevailing hypothesis that both the alternating invertebrate host and infection of Atlantic mackerel by K. thyrsites occurs in more southern waters.

Ti2C3Tx/Polyurethane Constructed by Gas-Liquid Interface Self-Assembly for Underwater Sensing.

Nowadays, multifunctional, easily prepared, and highly sensitive flexible sensors have attracted extensive attention and are gradually used in various scenarios. Here, we report the design of the Ti2C3Tx/polyurethane composites prepared by a facile gas-liquid interface self-assembly. The obtained flexible sensor has a wide detection range (∼900%), a low-stress detection limit (<1%), a high sensitivity (GF = 1.3, strain from 0 to 100%), and a fast response time (<140 ms). The multifunctional stress sensor can be applied to not only wearable motion monitoring and detection of various signals but also the detection of underwater human motion, as well as different motion states and swimming frequencies of toy fish in water, demonstrating its great prospects in a variety of applications, such as human movement monitoring and marine biological detection and research.

Siphoderina hustoni n. sp. (Platyhelminthes: Trematoda: Cryptogonimidae) from the Maori snapper Lutjanus rivulatus (Cuvier) on the Great Barrier Reef

A new cryptogonimid trematode, Siphoderina hustonin. sp., is reported, collected off Lizard Island, Queensland, Australia, from the Maori snapper Lutjanus rivulatus (Cuvier). The new species is moderately distinctive within the genus. It is larger and more elongate than most other species of Siphoderina Manter, 1934, has the shortest forebody of any, a relatively large ventral sucker, a long post-testicular zone, and is perhaps most recognisable for the substantial space in the midbody between the ventral sucker and ovary devoid of uterine coils and vitelline follicles, the former being restricted to largely posterior to the ovary and the latter distributed from the level of the anterior testis to the level of the ovary. In phylogenetic analyses of 28S ribosomal DNA, the new species resolved with the other nine species of Siphoderina for which sequence data are available, all of which are from Queensland waters and from lutjanid and haemulid fishes. Molecular barcode data were also generated, for the ITS2 ribosomal DNA and cox1 mitochondrial DNA markers. The new species is the first cryptogonimid known from L. rivulatus and the first metazoan parasite reported from that fish in Australian waters.