ABSTRACT The Bulago Lucustrine Protected Area (LPA) was established on Lake Victoria, Uganda, as a sanctuary for severely depleted fish stocks, a breeding and spawning ground and a biodiversity conservation zone. Despite its ecological importance, no studies have been conducted on the Bulago LPA since its creation in 2010. This study assessed the total fish catch, fishing effort and catch per unit effort (CPUE) within the LPA, as well as at 33 fish landing sites along the fishing line outside the LPA in Mukono District. Five‐year quarterly data were used to analyse trends across silver cyprinid, Nile tilapia and Nile perch. Results indicated an initial rise in catch outside the LPA for all fish species, followed by a decline linked to increasing fishing effort, with Southern sites experiencing a more consistent drop in CPUE compared to the Northern ones. Within the LPA, catch and effort remained consistently low, and CPUE was generally higher for both Nile perch and Nile tilapia. CPUE in the Southern sites showed no influence on CPUE within the LPA, while a positive correlation was observed between CPUE in the Northern and Southern areas. These findings suggest LPAs in freshwater ecosystems can contribute to species conservation and may facilitate a potential spillover effect from protected to adjacent fishing grounds, although confirming spillover remains challenging. The study recommends further research to understand species life histories, movement patterns, home ranges and broader ecosystem dynamics within and outside LPA, as well as regular collaborative monitoring and surveillance of fishing activities.
Environmental DNA (eDNA) methods are now commonly used for aquatic biodiversity monitoring, yet a lack of protocol standardization and the high cost of commercial samplers hinder broader application and results comparisons. Here, we present eDIYsampler, a compact, low-cost, and reproducible filtration system for eDNA sampling. The system allows rapid field deployment, thanks to its parallel filtration system, and high compatibility with all filter types and sizes, all for <500€. The device is highly modulable and modifiable and we propose some improvements at the end.
Mahfud Mahfud, Nanda Muhammad Razi, Muhammad Nasir
et al.
The southwestern coast of Aceh Province is among the areas vulnerable to heavy metal pollution originating from human activities, including mining, agriculture, and household waste. Chue snails (Faunus ater) are among the aquatic organisms that can be used as a bioindicator of water pollution. Therefore, this study aimed to evaluate the content of Lead (Pb), Cadmium (Cd) and Mercury (Hg) in F. ater snails originating from seven estuary areas in the southwestern coast area of Aceh Province. Analysis was also carried out to determine the environmental factors affecting metal accumulation and potential risks to public health. Sampling was performed in various areas, including the Jembatan Kembar River (Aceh Singkil), Trumon River (South Aceh), Kuala Lama Tuha (Southwest Aceh), Peunaga Cut Ujong River (Nagan Raya), Suak Ribe Puteh (West Aceh), Teunom River (Aceh Jaya), and Leupung River (Aceh Besar). This study used a laboratory analysis method with Atomic Absorption Spectrophotometry (AAS) instruments to measure metal concentrations in F. ater tissue. The results showed that all samples from seven areas were contaminated with Pb, Cd, and Hg at levels ranging from 0.691 - 1.575 mg/kg, 0.285 - 0.311 mg/kg, and 0.001 – 0.030 mg/kg, respectively. Pb and Cd content showed high heavy metal content, which exceeded the safe threshold according to the Food and Drug Administration (BPOM), Republic of Indonesia, with the greatest concentration found in the Southwest Aceh Regency. These results showed that the consumption of F. ater had the potential to endanger public health. Therefore, it is necessary to conduct outreach to the community to increase environmental awareness and food safety.
Keywords:
Heavy Metal
Bioaccumulation
Estuary
Bioindicators
Faunus ater
SDGs 13
SDGs 14
Spring viremia of carp virus (SVCV) is highly pathogenic in cyprinid fishes, and spring viremia of carp (SVC) has been listed as a notifiable disease by the World Organization for Animal Health. Spring viremia of common carp (<i>Cyprinus carpio</i>) is a viral infectious disease prevalent in Europe, Asia, and North America. In 2002, SVC was detected for the first time in China and spread rapidly throughout the country, posing a huge threat to the carp farming industry in China. It was listed as a second-class animal disease. So far, early, rapid, and accurate diagnosis remains an important means to control its spread and prevalence. At present, commonly used methods to detect SVCV require specific amplification equipment and temperature cycles and are prone to false negatives. Moreover, they have high equipment and personnel requirements and a long detection cycle. Fast and effective daily testing is also difficult to complete. Recombinase-aided amplification (RAA) is a rapid amplification technique of nucleic acid at constant temperature, which can achieve nucleic acid amplification at constant temperature and is easy to operate. Regular clustered interspaced short palindromic repeats (CRISPR) and their associated proteins (Cas) systems, such as CRISPR-Cas12 and CRISPR-Cas13, are combined with isothermal amplification to improve the specificity and sensitivity of RNA virus detection. This technology is characterized by constant temperature, fast reaction speed, and miniaturization, and it is suitable for rapid diagnosis and regular monitoring in the field. As an SVC international reference laboratory recognized by WOAH, this research team has been cooperating with the SVC reference laboratory in the UK to carry out the screening, comparison, and optimization of nucleic acid rapid detection. Based on the CRISPR/Cas13a system and recombinase-mediated isothermal nucleic acid amplification technology, RAA amplification primers and corresponding crRNA primers were designed for the highly conserved region of SVCV polymerase L gene by aligning the whole gene sequence of SVCV registered on GenBank, and a preliminary RAA-CRISPR/Cas13a detection method was established for the rapid detection of SVCV in the field. It can cover four genotypes of SVCV (<i>Ia</i>, <i>Ib</i>, <i>Ic</i>, <i>Id</i>). In accordance with the detection and verification procedures recommended by the World Organization for Animal Health, results confirmed that some of the detection results were reproducible, the minimum detection concentration was 115 copies/μL, and it did not cross-react with other pathogens. The detection of 60 samples isolated and stored in the laboratory for the monitoring of inbound and outbound aquatic animal diseases, the monitoring of major aquatic animal diseases in China, and the challenge experiment indicated that the results of RAA-CRISPR/Cas13a detection are consistent with those of nested fluorescent RT-PCR. The results of RT-PCR and virus isolation and culture were also consistent, and the diagnostic sensitivity and specificity were both 100%. Under the same conditions, 20 samples were tested in four laboratories, and the results of the four laboratories were consistent. The results proved the good reproducibility of the study. This study is the first to use the CRISPR-Cas13a system for SVCV detection. The developed method could be applied in the rapid diagnosis and prevention of SVCV.
Recent observations of superconductivity in twisted bilayer WSe$_2$ have extended the family of moiré superconductors beyond twisted graphene. In WSe$_2$ two different twist angles were studied, 3.65° and 5.0°, and two seemingly distinct superconducting phase diagrams were reported, raising the question of whether the superconducting phases in the two devices share a similar origin. Here we address the question by experimentally mapping the evolution of the phase diagram across devices with twist angles spanning the range defined by the initial reports, and comparing the results to twist angle-dependent theory. We find that the superconducting state evolves smoothly with twist angle and at all twist angles is proximal to a Fermi surface reconstruction with, presumably, antiferromagnetic ordering, but is neither necessarily tied to the Van Hove singularity, nor to the half band insulator. Our results connect the previously distinct phase diagrams at 3.65° and 5°, and offer new insight into the origin of the superconductivity in this system and its evolution as the correlation strength increases. More broadly, the smooth phase diagram evolution, repeatability between different devices, and dynamic gate tunability within each device, establish twisted transition metal dichalcogenides as a unique platform for the study of correlated phases as the ratio of interaction strength to bandwidth is varied.
Twisted bilayer graphene (TBG) exhibits flat electronic bands at the so-called magic angle ($\sim 1.1^\circ$), leading to strong electron correlations and emergent quantum phases such as superconductivity and correlated insulating states. However, beyond the magic angle, the band structure generally remains dispersive, diminishing interaction-driven phenomena. In this work, we explore the equivalence between pressure-induced flatbands and the magic-angle flatband in large-angle TBG by systematically analyzing the role of interlayer coupling modifications under perpendicular pressure. We show that pressure-induced flatbands exhibit spatial localization similar to magic-angle TBG, with charge density concentrated in the AA-stacked regions. Furthermore, the Hall conductivity and magneto-transport properties under an external magnetic field reveal that these pressure-induced flatbands share key signatures with the quantum Hall response of magic-angle TBG. The obtained Hofstadter spectrum shows four consistent low-energy gaps across all twist angles under pressure, which align with the calculated Hall conductivity plateaus. Our findings suggest that pressure offers an alternative pathway to engineer flat electronic bands and correlated states in TBG, extending the landscape of tunable moiré materials beyond the constraints of the magic angle.
This article is about the (minimal) sector containing the numerical range of the principal part of a linear second-order elliptic differential operator defined by a form on closed subspaces V of the first-order Sobolev space $W^{1,2}(Ω)$ incorporating mixed boundary conditions. We collect a comprehensive array of results on the angle of sectoriality and the $H^\infty$-angle attached to realizations of the elliptic operator. We thereby consider the operator in several scales of Banach spaces: the Lebesgue space, the negative Sobolev space, and their interpolation scale. For the latter two types of spaces, we rely on recent results regarding the Kato square root property. We focus on minimal assumptions on geometry, and we consider both real and complex coefficients. Not all results presented are new, but we strive for a streamlined and comprehensive overall picture from several branches of operator theory, and we complement the existing results with several new ones, in particular aiming at explicit estimates built on readily accessible problem data. This concerns for example a new estimate on the angle of the sector containing the numerical range of a linear, continuous and coercive Hilbert space operator, but also an explicit estimate for the angle of sectoriality for the elliptic operator on $L^p(Ω)$ with complex coefficients without any assumptions on geometry and a general transfer principle for the Crouzeix-Delyon theorem from bounded operators to sectorial ones, keeping the explicit constant.
Abstract Gizzard Shad Dorosoma cepedianum have been introduced into Western South Dakota reservoirs and shown to improve the growth and size structure of sportfish, particularly Walleye Sander vitreus . Black Crappies Pomoxis nigromaculatus are a popular sportfish in these reservoirs, but influences Gizzard Shad have on these populations have not been well documented. We used 10 years of annual sampling data to evaluate changes in Black Crappie population characteristics (i.e. recruitment, growth, size structure and condition) in four Western South Dakota reservoirs after Gizzard Shad were introduced. We also compared Black Crappie population characteristics after shad introductions to populations in three reservoirs never having shad. We found Black Crappie populations in Western South Dakota reservoirs are characterized by variable recruitment, generally experiencing some level of recruitment failure. Reservoirs with Gizzard Shad showed greater mean length‐at‐age and higher proportional size distributions (PSD and PSD‐P) for Black Crappie after the shad introductions and higher values than observed in reservoirs never having shad. We found no meaningful differences in abundance, and mean condition of Black Crappie populations whether Gizzard Shad were present or not. The addition of Gizzard Shad did not appear to negatively affect Black Crappie populations but rather improved crappie size structure. Our results indicate that introductions of Gizzard Shad are a viable management option for producing quality Black Crappie fisheries in Western South Dakota reservoirs.
Qathrunnada Salsabila, Catur Retnaningdyah, Luchman Hakim
Graphical Abstract
Highlight Research
Highlights from this results research:
• Restoration is a method to restore degraded mangrove ecosystems
• The success of restoration is measured by improvements in ecosystem services such as water quality, mangrove diversity, phytoplankton community structure and diversity
• Phytoplankton as bioindicator of water quality
• Anthropogenic activities are the main factor causing degradation of mangrove ecosystems
Abstract
The mangrove ecosystems in Bawean Island are degraded due to anthropogenic activities and land conversion. Plantation has carried out periodic which was continued in several mangrove ecosystems. This study was conducted to evaluate the physicochemical water quality of several mangrove ecosystems in Bawean Island, and phytoplankton as bioindicators. The evaluation of mangroves in Bawean Island was carried out at 11 locations based on different naturalness and human activities surrounding. The physical and chemical parameters of water observed were air temperature, water temperature, pH, TSS, dissolved oxygen (DO), biochemical oxygen demand (BOD), salinity, conductivity, nitrate, and orthophosphate. Community structure and plankton diversity measured include the Importance Value Index (IVI), Shannon-Wiener diversity index (H'), Simpson dominance index (Id), evenness index (E), trophic diatom index (TDI), and pollution tolerant value (% PTV). The physical parameters of water chemistry show that it meets the quality standards based on Indonesian Government Regulation No. 22 of 2021 except for nitrate and orthophosphate, but it is still under plankton tolerant. A total of 63 species from 7 phytoplankton classes were found based on the importance value index. Based on the TDI index, mangrove ecosystems Sawahmulya, Sidogedungbatu, Hijau Daun, Pamona, Pasir Putih, Sungai Rujing, Bangsal, Jherat Lanjheng, and Lebak were classified as eutrophic while Pulau Cina and Dekatagung were hyper-eutrophic. Based on %PTV, the Hijau Daun mangrove is the best mangrove ecosystem while other mangroves were classified as moderate and heavily level polluted.
Kevin Odhiambo Obiero, Jimmy Brian Mboya, Kevin Okoth Ouko
et al.
Abstract Indigenous knowledge is critical in the conservation of wild fish genetic resources and consequent development of fish seed for improved aquaculture production. Local fisher communities rely on aquatic resources mainly for livelihood and subsistence and have therefore come up with systems to manage these resources for sustainable use. This study aimed at identifying the role of indigenous people's knowledge in fish conservation as a way of improving aquaculture, with a specific focus on the conservation of aquaculture fish species in Kenya. Data was collected from individual fisherfolk through semi‐structured questionnaires and field observations. Pearson's chi‐square test was performed on variables that were predicted to influence indigenous knowledge. The chi‐square tests revealed a significant relationship between age and indigenous knowledge (χ 2 = 15.153, p = 0.004). Results also revealed a significant relationship between an individual's years of residence in the area and indigenous knowledge (χ 2 = 17.767, p = 0.003). It was found that the indigenous people use various concepts and strategies for fish conservation and fish production. From the findings of the study, it is recommended that scientists and policy actors should adopt the indigenous people's knowledge as a source of baseline information for fisheries and aquaculture research, and as additional or alternative strategies for the management of fish genetic resources.
Santiago J. Fernández, Cynthia Ibarra, Ximena Navoa
et al.
The Argentine anchovy, Engraulis anchoita, plays a vital role as a key prey species for several marine predators in the north Patagonian marine ecosystem of the Atlantic Ocean. Reconstructing the length and weight of each consumed specimen is essential to provide a detailed description of the trophic ecology of top marine predators. Predictive linear regression equations were calculated for the Patagonian stock of Argentine anchovy to estimate parameters of length-weight relationships using measurements of whole individuals and diagnostic elements such as otoliths, head bones and pectoral fin bones. Among the diagnostic elements analyzed, the cleithrum and dentary exhibited the best fit. This study validates the use of head and pectoral girdle bones as reliable indicators for predicting the weight and length of Argentine anchovy across a wide size range, which corresponds to the target range of various predators. These relationships can contribute to the determination of body condition, estimation of consumed biomass, and calculation of energy density, providing valuable insights into the trophic ecology of predators in the southern Atlantic Ocean.
Marine fish farming in Spain, as in most Mediterranean countries, focuses on the production of European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata). The sector has experienced performance problems that affect the industry’s competitiveness, and infectious and parasitic diseases have been described as being among the main causes of losses. Whereas companies are aware of the need to assess the impact and causes of such losses, the analysis of disease occurrence and mortality in seabass and seabream has received scarce attention from the sector and official administrations. Through information obtained from interviews and surveys, it has been possible to carry out an assessment of disease occurrence and mortality in marine fish farming in Spain. The median survival rate data for seabass and seabream was shown to be slightly higher in seabream, although no significant differences were found between species. It was not possible to further differentiate the causes of diseases or losses, as they were generally not standardized into categories and they also varied between companies. Nevertheless, the aim was to prompt producers and health management stakeholders into discussing how to improve the collection and analysis of data for relevant disease outbreaks and mortalities. Moreover, EU Regulation 2016/429 (the ‘Animal Health Law’) calls on Member States to implement disease surveillance programmes to investigate ‘increased mortality’ events in order to be alert for possible emerging diseases. Good knowledge of a disease situation and its impact on production represents a base mechanism for designing health surveillance. Therefore, the standardization of health data collection and its analysis will help countries in the implementation of surveillance programmes and rapid alert mechanisms in order to combat emerging diseases at an early stage.
Current polarimetric 3D reconstruction methods, including those in the well-established shape from polarization literature, are all developed under the orthographic projection assumption. In the case of a large field of view, however, this assumption does not hold and may result in significant reconstruction errors in methods that make this assumption. To address this problem, we present the perspective phase angle (PPA) model that is applicable to perspective cameras. Compared with the orthographic model, the proposed PPA model accurately describes the relationship between polarization phase angle and surface normal under perspective projection. In addition, the PPA model makes it possible to estimate surface normals from only one single-view phase angle map and does not suffer from the so-called $π$-ambiguity problem. Experiments on real data show that the PPA model is more accurate for surface normal estimation with a perspective camera than the orthographic model.