Presence Of Fish Research Articles

Mapping endemic freshwater fish richness to identify high-priority areas for conservation: An ecoregion approach.

Freshwater ecosystems are experiencing accelerating global biodiversity loss. Thus, knowing where these unique ecosystems' species richness reaches a peak can facilitate their conservation planning. By hosting more than 290 freshwater fishes, Iran is a major freshwater fish hotspot in the Middle East. Considering the accelerating rate of biodiversity loss, there is an urgent need to identify species-rich areas and understand the mechanisms driving biodiversity distribution. In this study, we gathered distribution records of all endemic freshwater fishes of Iran (85 species) to develop their richness map and determine the most critical drivers of their richness patterns from an ecoregion approach. We performed a generalized linear model (GLM) with quasi-Poisson distribution to identify contemporary and historical determinants of endemic freshwater fish richness. We also quantified endemic fish similarity among the 15 freshwater ecoregions of Iran. Results showed that endemic freshwater fish richness is highest in the Zagros Mountains while a moderate level of richness was observed between Zagros and Alborz Mountains. High, moderate, and low richness of endemic freshwater fish match with Upper Tigris & Euphrates, Namak, and Kavir & Lut Deserts ecoregions respectively. Kura - South Caspian Drainages and Caspian Highlands were the most similar ecoregions and Orumiyeh was the most unique ecoregion according to endemic fish presence. Precipitation and precipitation change velocity since the Last Glacial Maximum were the most important predictors of endemic freshwater fish richness. Areas identified to have the highest species richness have high priority for the conservation of freshwater fish in Iran, therefore, should be considered in future protected areas development.

Fluid–Structure Interactions of Net Cages—Full-Scale Pushing Tests in the Field

Abstract This paper presents field tests on a full-scale cage, with and without fish, being pushed by a boat in Masfjorden at various speeds. The purpose was to imitate the exposure of net cages to different currents. The tests involved measuring cage deformations, fish behaviors, and the corresponding flow upstream, downstream, and inside the cage. The study found that the experimental setup used can achieve predictable and stable upstream flow for a full-scale net cage. Based on pressure tag data, the volume reductions of the cage, both with and without fish, were estimated at different speeds. Both cases show a similar trend of cage volume reduction with respect to flow speeds as the previous studies. Moreover, the presence of fish had limited the influence on the net volume change. The reduction in speed inside and downstream from the cage was within the range reported in previous literature. Notably, when the cage becomes significantly deformed, it not only reduces flow speed but also alters flow directions, as evidenced by the high variability of flow direction inside the empty cage, particularly at high speeds. The measured flow speed inside the stocked cage also exhibited high variability, but the pattern of variation differed significantly from that of the empty cage, indicating the influence of fish. These findings suggest that traditional flow speed models might oversimplify the flow field in and around fish cages, especially in studies concerning the dispersion of particles, pathogens, and dissolved matter in and out of fish cages.

Multiscale analysis predicts native species presence based on habitat and nonnative species abundance

AbstractObjectiveThe loss and degradation of aquatic habitat through fragmentation, water extraction, and climate warming contribute to declining native stream fish diversity. In response to these declines, a large‐scale repatriation program was established in Arizona and New Mexico to expand the distribution and abundance of native fishes. This program has had variable success, with imperiled fish populations establishing and persisting in some streams, while other populations failed to establish.MethodsTo identify factors contributing to the success of repatriation, we conducted a study investigating how biotic and abiotic variables affect native fish presence or absence at differing spatial scales throughout the Gila River basin. We conducted fish and habitat surveys in 29 river reaches at three spatial scales: the 1‐km, 0.1‐km, and mesohabitat scale. We used generalized linear models to identify associations among species presence, habitat characteristics, and nonnative species abundance across spatial scales. Logistic regression models were also used to test associations with heterogeneity of habitat characteristics and species presence.ResultModels indicated strong species‐ and scale‐specific responses to these variables. Nonnative abundance was less influential than other habitat variables in predicting the presence of native fish, although the majority of associations that emerged were negative. Further, we were able to identify that water velocity, depth, and substrate size were the most common variables associated with species' presence across all scales and age‐classes, with most species responding positively to elevated velocities and variable responses for depth and substrate size. Response to variation in habitat was species‐specific, with some associations positive and others negative.ConclusionCollectively, the information from this study will help identify locations with a reasonably high likelihood of supporting native fishes and broaden our understanding of species responses to habitat and nonnative species across multiple scales.

Pengembangan Sistem Kontrol Populasi Ikan Berbasis Arduino Uno dengan Sensor Ultrasonik

Fish populations are one of the important assets in maintaining the balance of aquatic ecosystems. To manage fish populations effectively, an innovative and automated approach is needed. This research aims to develop an Arduino Uno-based fish population control system with ultrasonic sensors as an environmentally friendly and efficient solution. The developed system uses ultrasonic sensors to detect the presence of fish in a pond or water container. The detection data from the ultrasonic sensor is then processed by the Arduino Uno microcontroller. The system can identify the number of fish in aquatic containers and take appropriate action to control fish populations. This research integrates ultrasonic sensor technology with Arduino Uno control capabilities to provide an accurate and automated solution in controlling fish populations. In trials, this system succeeded in identifying and controlling fish populations well, maintaining the balance of aquatic ecosystems without the need for direct human intervention The results of this research have great potential in fish farming applications, environmental research, and natural resource conservation. With the proposed automated approach, it is expected to make a positive contribution in maintaining the balance of aquatic ecosystems and supporting environmental sustainability

Türkiye'nin Batı Akdeniz Havzası'ndaki bir sulak alan sisteminin balık çeşitliliği ve topluluk yapısı: Koca Göl (Dalaman)

Lake Koca (Dalaman), a wetland in the western Mediterranean basin of Türkiye, is an extraordinary lake with salty, fresh, and sulfurous waters and is home to high biodiversity. The present study examines the spatial and seasonal variation in fish communities and assesses the influence of environmental parameters on the community structure of Lake Koca. A total of 1.530 specimens were captured, representing seven families and 11 species (2 non-native, 1 introduced, and 8 native species). Total fish abundance and richness were higher at the littoral than at the limnetic zone, but no seasonal variation was observed. Non-native fish species, Coptodon zillii, was the most abundant in the littoral zone, followed by species of Mugilidae. The abundance of the two endemic fish species (Capoeta aydinensis and Ladigesocypris irideus) was relatively low in both habitats. Shannon-Wiener diversity index and evenness did not vary seasonally and spatially. Fish abundance and richness were significantly and positively correlated with chlorophyll-a and macrophyte coverage while negatively correlated with depth. Spearmen’s Correlation analysis revealed that native fish species show a relationship with the chemical parameters of the water, while C. zillii showed a distribution related to depth and macrophyte density. Both anthropogenic activities and the presence of non-native fish may affect the distribution and abundance of endemic fishes.

Chronic exposure to environmental temperature attenuates the thermal sensitivity of salmonids

Metabolism, the biological processing of energy and materials, scales predictably with temperature and body size. Temperature effects on metabolism are normally studied via acute exposures, which overlooks the capacity for organisms to moderate their metabolism following chronic exposure to warming. Here, we conduct respirometry assays in situ and after transplanting salmonid fish among different streams to disentangle the effects of chronic and acute thermal exposure. We find a clear temperature dependence of metabolism for the transplants, but not the in-situ assays, indicating that chronic exposure to warming can attenuate salmonid thermal sensitivity. A bioenergetic model accurately captures the presence of fish in warmer streams when accounting for chronic exposure, whereas it incorrectly predicts their local extinction with warming when incorporating the acute temperature dependence of metabolism. This highlights the need to incorporate the potential for thermal acclimation or adaptation when forecasting the consequences of global warming on ecosystems.

Persisting in extreme environments: What are the drivers of body conditions of introduced fish in high mountain lakes?

Abstract Salmonids are introduced in various ecosystems, including mountain lakes characterised by extreme environmental constraints. Although these constraints can affect salmonid body condition through direct and indirect pathways, they remain seldom explored despite their importance for understanding salmonid fitness and long‐term establishment. In order to fill this gap, we firstly fitted species‐specific weight–length relationships for three salmonid species in nine mountain lakes, and compared their allometric coefficients with those of 362 salmonid populations worldwide to identify potential differences in growth trajectory of salmonids in the studied lakes. We then investigated how thermal characteristics and lake morphometry could influence salmonid body conditions, both directly and indirectly through salmonid density, the presence of forage fish and resource densities. We calculated salmonid relative body condition Kn and used a structural equation model (SEM) to disentangle these direct and indirect effects. The values of allometric coefficients for the three species did not differ from those of most salmonids worldwide although ontogenetic changes in Salvelinus alpinus weight gain was observed. Kn differed significantly among the populations studied. The strongest effects were related to direct and indirect effects of lake morphometry, while thermal characteristics had mostly indirect effects on Kn. The strength and the sign of the indirect effects of morphometry and temperature were mediated by the direct effects of resource and salmonid densities on Kn. Kn estimates were greater in lakes with shallow basin slopes than those with steep slopes. Shallow basin slopes probably provide habitats that support high prey availability and require lower energy expenditure by salmonids compared to lakes with steep slopes dominated by pelagic habitats. Complementarily, higher winter and summer temperatures favour Kn by supporting higher prey densities and longer periods of feeding activity. Our results may help managers to select lakes that optimise sustainability of salmonid populations based on the joint effects of basin morphometry and the expected thermal modifications induced by global change.

Abundance and composition of invertebrate-feeding leeches in relation to fish status in ponds

Leeches feeding on invertebrates are an important component of freshwater communities, including those dominated by fish, but the effects of fish on their abundance and distribution are not well explored. The relative densities and assemblage structure of two leech families, Erpobdellidae and Glossiphoniidae, were studied from May to August 2014 in ponds stocked with low biomass densities of young common carp Cyprinus carpio, too small to prey on leeches (low-fish ponds), and in ponds containing high biomass densities of large (one- or two-year-old) carp (high-fish ponds), using two types of activity traps (placed either on the bottom or near the water surface). The most common and numerous species were Erpobdella octoculata, Helobdella stagnalis, and Erpobdella nigricollis. The traps near the water surface captured relatively small numbers of leeches, yet the catches showed that in summer some of the leeches moved to the upper layers of the water column, which was free of macrophytes. No differences in leech species richness or diversity were found with respect to fish status of ponds; however, bottom erpobdellids were more abundant in high-fish ponds. Redundancy analysis identified the fish status of the ponds and total nitrogen concentration in water as the only significant variables explaining the distribution of leeches among ponds. Species distribution was nested, but the nestedness pattern was not affected by the fish status of the pond. While fish are generally believed to adversely affect macroinvertebrate diversity and abundance, our study shows that some predatory leech species can persist in the presence of fish and possibly indirectly benefit from it.

Farmed Atlantic salmon (Salmo salar L.) avoid intrusive objects in cages: The influence of object shape, size and colour, and fish length

Underwater vehicles and other mobile platforms are seeing increased use as tools within fish farming, particularly due to current trends towards Precision Farming practices, and more exposed farming sites. Although many of the applications of such tools (e.g., net cleaning and inspection) have become well established industrial practices, it is largely unknown how much such operations disturb the fish and the consequence of this disturbance. In this study, we explored this by exposing Atlantic salmon in commercial net cages to intrusive objects and monitoring the distribution of fish around these using on-board 360-degree sonars. Six different object designs were tested covering variations in size, shape, and colour, which are important static characteristics of underwater vehicles/platforms. The sonar data was first aggregated into images containing the Cumulative Fish Presence over 1-, 5- and 10-min periods to provide a more robust foundation for further analyses. By training a deep learning based method using UNet++ architecture to automatically segment the fish distribution patterns, the mean distance between the inner perimeter of the fish distribution and the object was assessed. Results from the study implied that fish keep greater distances to larger objects. There was, however, no clear impact of the shape. Regarding the effect of colour, fish kept greater distances to yellow than to white objects. When comparing results from tests on fish of different size, data indicate a positive linear relationship between fish weight (age) and distance to an object, that can be expressed as an avoidance distance of an average 3.8 body-lengths. Our findings provide new fundamental knowledge on the dynamics between the fish and objects such as vehicles or other mobile platforms in fish farms, and thus provides valuable insights that can be useful when designing such tools specifically for aquaculture.

Современное состояние кормовой базы участка реки Днепр в пределах Смоленской области

The paper presents materials on the state of aquatic bioresources and their habitat in the Dnieper River within the borders of the Smolensk region, according to 2019 data. The ichthyofauna of the Dnieper River within the surveyed area did not differ in species diversity: 10 species of fish belonging to the families Cyprinidae (Cyprinidae) and perch (Percidae) were identified. Roach (Rutilus rutilus) dominated, the subdominants were chub (Squalius cephalus) and perch (Perca fluviatilis). The average oligochaete index, ranging from 21 to 50%, characterizes the waters of the river as slightly polluted and belonging to class II quality. The composition of phytoplankton was dominated by diatoms and green algae. As part of zooplankton, representatives of the genus Brachionus dominated among rotifers, and crustaceans of the genus Bosmina dominated among branchiformes. The composition of zoobenthos was dominated by larvae of chironomids, subdominants – oligochaetes. The Dnieper River within the borders of the Smolensk region, according to our data, is characterized by the level of development of phytoplankton and zooplankton as a "low-feeding" area for phytophagous fish and zooplanktophages, and by the level of development of zoobenthos as a "high-feeding" area. The ichthyofauna of the studied area is characterized by the presence of predatory and omnivorous fish, the presence of phytophages and zooplanktophages is not characteristic, which may be due to the peculiarities of the state of the natural food supply.

Silver Carp herding: A telemetry evaluation of efficacy and implications for design and application

AbstractObjectiveThe removal of invasive Silver Carp Hypophthalmichthys molitrix is a primary control action in North America. Strong avoidance responses to underwater sound and electricity have been shown to facilitate herding and mass removal of these fish. We conducted a telemetry study on a closed population of Silver Carp (i.e., 10 telemetered fish) to assess fine‐scale movement responses to herding stimuli.MethodsTwo herding boats traveled along bank‐to‐bank transects through the study area (longitudinal progression rate = 0.37 m/s) emitting sound and electricity (“combination technique”) or no added stimuli (“control”).ResultThe combination technique was most effective in terms of increasing fish presence (2.2 × the control) in the refuge zones when herding had concluded and effective range (i.e., fish reaction distance; 1.6 × the control) relative to the herding boats. The median (~1 m/s) and maximum (~2 m/s) swimming velocity was relatively stable across fixed effects, except for the negative influence of water depth on maximum velocity. Water depth also exhibited a negative effect on fish reaction distance.ConclusionOur results suggest that the effective range of the combination technique was conservatively 200 m (~20 dB re 1 μPa > ambient level) when accounting for water depth in the study area. Herding deployments <1 m/s (longitudinal progression) could control fish passing and maintain fish movements toward an intended location. The information provided herein can serve to assist planning, designing, and applying herding efforts to manage, control, and remove these invasive fish.

Bioinspired flatfish detection using electrical impedance measurements

Bottom trawling for flatfish by means of tickler chains has a high ecological impact due to the continuous seabed disturbance, low selectivity and high fuel costs. This issue could be significantly mitigated by using localized startle stimuli, triggered by a detection system that selectively targets flatfishes of landable size. Flatfish, however, constitute a significant challenge for remote detection, due to their low optical and acoustical signatures. Some species of predatory fish feeding on flatfish overcome this issue by using electroreception to localize they prey, even if it is buried in bottom sediments. We take this phenomenon as an inspiration in an attempt to develop a biomimetic remote fish detection technique based on electrical impedance measurements. We constructed a detection system including a set of electrodes and a low-cost analog front-end. The electrodes were mounted on a dedicated frame and dragged above a layer of sand inside a tank with sea water and several common sole (Solea solea). An underwater camera was used to acquire video recordings synchronized with impedance data for reference. We demonstrate that fish presence below the electrodes manifests itself by changes in the measured resistance and reactance values. This phenomenon occurs even if the fish is covered with a layer of sand. The results demonstrate the potential of bioinspired remote flatfish detection, which could be highly useful for monitoring or targeted stimulation.

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.

Connectivity, land use, and fish presence influence smooth newt (Lissotriton vulgaris) occurrence and abundance in an urban landscape

IntroductionUrban areas are challenging environments for wetland species with complex habitat requirements and life cycles. However, even semiaquatic species, representing such complex wetland groups, can be provided with adequate conditions through thorough understanding of their habitat requirements coupled with comprehensive wetland management.MethodsWe studied the occurrence and abundance of the smooth newt (Lissotriton vulgaris), a widely distributed amphibian, in an urban landscape in metropolitan Helsinki, Finland. We classified 50 randomly selected urban wetlands based on their connectivity by applying isolation scores counted using principal component analysis (PCA) and measured the occurrence and abundance of smooth newts in these locations.ResultsOur analyses showed well-connected wetland sites to differ significantly in smooth newt occurrence from both isolated and partially connected sites. Additionally, smooth newt abundance in well-connected wetlands differed from isolated sites. A PCA model with residential buildings (negative effect) and aquatic vegetation (positive effect) best explained smooth newt occurrence and total and male abundance, and female newt occurrence was best explained by a model also incorporating forest and natural open areas. Predation pressure by fish negatively influenced both smooth newt occurrence and abundance.DiscussionTighter networks of constructed wetlands and stricter management guidelines for urban wetland planning and fish community management could increase the suitable habitat for smooth newts in urban landscapes. Managing such areas for the common smooth newt offers potential broad benefits to the conservation of other semiaquatic amphibians and reptiles in urban wetlands and to urban wetland biodiversity in general. Our results show that smooth newt presence may indicate sustained wetland connectivity in an urban landscape and could even be used to signal successful urban planning.

Acute effects of angler’s groundbaits: nutrient flux to water column

Although ground-baiting related nutrient loading has been widely studied, we do not know what proportion of these nutrients release into the water column, affecting primary production directly. We conducted short-term (24-h, 5-day) experiments at wide temperature range, in presence and absence of fish using fish meal-based (FM-GB) and plant-based groundbait (PB-GB), to assess the nitrogen (N) and phosphorus (P) fluxes from GB into the water column. Nitrogen release from unconsumed FM-GB was negligible in the first 3 days, then increased abruptly, releasing 32% of its total N content by the fifth day. In contrast, PB-GB acted as temporary sink for inorganic N forms. Considerable (18–21%) inorganic P release was observed in both GB types in the first twelve hours. Consumed GBs induced considerable inorganic N release and its rate increased with temperature. Particulate forms predominated the released N in PB-GB, suggesting impaired digestion. Phosphorus—dominated by particulate forms—release was similar or lower than in unconsumed GB. Based on our results, excessive use of GB—when high amount of it remains unconsumed—can enhance eutrophication in P-limited ecosystems. Although less digestible GBs may have less abrupt effect on the primary production, undigested nutrients remain unavailable for removal through fish harvest.

Problems of Mangrove Forest Deporestation with the Status of Other User Areas for the Development of Residential Areas and Pond Activities in Kotabaru Regency From A Criminal Perspective

The purpose of carrying out this journal is to find out that deforestation of mangrove forests in Kotabaru Regency carried out by the community is an environmental crime and they want to know the sanctions that can be imposed on perpetrators of mangrove forest deforestation in Kotabaru Regency which cause damage to the mangrove forest ecosystem.
 The results of this writing are that the act of deforestation of mangrove forests in Kotabaru Regency, South Kalimantan Province is caused by the local government's RTRWK inventory process being less than thorough because there are still mangrove forests that are included in residential areas and fisheries cultivation areas. Furthermore, the act of mangrove deforestation is a criminal act of environmental destruction because it pollutes and destroys the surrounding environment, destroying mangrove forests, and destroying the mangrove ecosystem.
 Normative research type, doctrinal legal research type using philosophical thinking by finding a concept, research approach, statutory approach, and conceptual approach. Prescriptive nature of research types and primary secondary and tertiary research.
 There are still mangrove forest plants based on the author's research which are located on the sea coast of Silver Street, Semayap Village, Kotabaru Regency which extends to the Semayap Village housing complex which is a residential area in the RTRWK Kotabaru Regency is located in a residential area, so the author can conclude that the regional government's inventory process in the RTRW process is not thorough enough and the need for the RTRWK to be revised again, as well as the sea coast area, city boundaries, the village of Stagen District. Kotabaru with the presence of fish and shrimp ponds included in the RTRWK for cultivation areas, the writer can conclude that the regional government inventory process in the RTRW process is not thorough enough and the RTRWK needs to be revised again so that the writer concludes that the local regional government is also responsible for the deportation carried out by residential business actors. and pond cultivation on the side of Silver Street, Semayap Village, Kotabaru Regency up to the Semayap housing complex as well as fish pond cultivation on the coast at the city limits of Stagen Village, Kec. North Sea Island District. new city. The current impact is that this location often floods when the sea water is at high tide. The act of deforestation of mangrove forests in Kotabaru Regency, South Kalimantan Province is an environmental crime. Sanctions that can be imposed on the perpetrators are Article 98 paragraph (1) of the Law of the Republic of Indonesia Number 32 of 2009 concerning Protection and Management of the Environment Article 35 Letter e of the Republic of Indonesia Law Indonesia Number 27 of 2007 concerning Management of Coastal Areas and Small Islands and article 73 letter b of Law of the Republic of Indonesia Number 27 of 2007 concerning Management of Coastal Areas and Small Islands and the regional government should be asked for criminal liability in article 112 and article 113 UUPPLH.

Integrating hydrological connectivity and zooplankton composition in Arctic ponds and lakes

Abstract Arctic landscapes are characterised by their numerous ponds and lakes. With increased climate warming and consequent changes in hydrological connectivity, the ecology of many of these waterbodies is expected to change. We sampled 13 ponds and 22 lakes for zooplankton and various limnological and physical environmental variables in the vicinity of Cambridge Bay, Nunavut (69.1169° N, 105.0597° W), with the aim of testing how well the degree of hydrological connectivity explained patterns in species composition and abundance and contributed to crustacean production. Ponds were hydrologically isolated while the lakes were arranged in four lake chains and ranged from the headwaters to highly inter‐connected lakes receiving water from one to 768 upstream lakes. In all sites combined, 77 zooplankton species were found, including 56 rotifers, six copepods, 11 cladocerans, two fairy shrimp species, a mysid, and a tadpole shrimp. We show that the zooplankton communities differed between hydrologically isolated (ponds) and connected (lakes) systems, with 17 species unique to ponds and 20 to lakes. Furthermore, the communities were more similar within lake chains and hence in lakes closer to each other. In ponds, distances between waterbodies had no impact on community similarity. Zooplankton abundance was higher in lakes (255 ind/L) than in ponds (65 ind/L) due to the higher number of rotifers that accounted for nearly 80% of the zooplankton abundance in lakes. In ponds, rotifers, cladocerans, and copepods were equally abundant. In terms of biomass, cladocerans represented 65% of total biomass in all waterbodies except for a chain of deep lakes that had abundant fish communities. In these lakes, cladoceran abundance and biomass were low and probably limited by fish predation. Zooplankton production was higher in ponds (4.6 mgC m−3 day−1) than in lakes (1.7 mgC m−3 day−1), and within lakes was lowest in the chain composed of large lakes (1.3 mgC m−3 day−1). The high production in ponds was closely linked to high zooplankton biomass and further explained by high gross primary production supported by relatively high nutrient concentrations in these shallow systems. Our study emphasises that hydrological connectivity is key to shaping zooplankton communities, although fish presence also appears to affect them. It shows that isolated ponds (that currently account for c83% of all waterbodies on southern Victoria Island) are hotspots of aquatic biological productivity that probably play an essential role in Arctic freshwater landscapes. Finally, our study provides critical baseline information on the current composition of Arctic zooplankton communities important for estimating climate change impacts.

Detection of fish sedimentary DNA in aquatic systems: A review of methodological challenges and future opportunities

AbstractEnvironmental DNA studies have proliferated over the last decade, with promising data describing the diversity of organisms inhabiting aquatic and terrestrial ecosystems. The recovery of DNA present in the sediment of aquatic systems (sedDNA) has provided short‐ and long‐term data on a wide range of biological groups (e.g., photosynthetic organisms, zooplankton species) and has advanced our understanding of how environmental changes have affected aquatic communities. However, substantial challenges remain for recovering the genetic material of macro‐organisms (e.g., fish) from sediments, preventing complete reconstructions of past aquatic ecosystems, and limiting our understanding of historic, higher trophic level interactions. In this review, we outline the biotic and abiotic factors affecting the production, persistence, and transport of fish DNA from the water column to the sediments, and address questions regarding the preservation of fish DNA in sediment. We identify sources of uncertainties around the recovery of fish sedDNA arising during the sedDNA workflow. This includes methodological issues related to experimental design, DNA extraction procedures, and the selected molecular method (quantitative PCR, digital PCR, metabarcoding, metagenomics). By evaluating previous efforts (published and unpublished works) to recover fish sedDNA signals, we provide suggestions for future research and propose troubleshooting workflows for the effective detection and quantification of fish sedDNA. With further research, the use of sedDNA has the potential to be a powerful tool for inferring fish presence over time and reconstructing their population and community dynamics.

Melanocytic tumors with spitzoid morphology: correlation of clinicopathologic features and FISH analysis.

A subset of melanocytic tumors with spitzoid morphology may lead to potential inaccurate diagnosis and lack of assessment of malignancy potential. In this study, we aimed to evaluate melanocytic tumors with spitzoid morphology using conventional melanoma FISH (RREB-1, CCND1, MYB and CEP6) and 9p21 FISH (CDKN2A) probes and compare the probe results with clinical and histopathological features. This study is a multicentric retrospective study including three centers, İstanbul University-Cerrahpaşa, Cerrahpaşa School of Medicine, Department of Pathology, Acıbadem University, School of Medicine, Department of Pathology and ETA Pathology Laboratory. The pathology reports in archives of these three centers between 2015 and 2017 have been reviewed for cases diagnosed as atypical Spitz tumor or melanoma with Spitzoid features. These cases were selected for the study. We analyzed 39 cases of atypical Spitz tumor (AST), 10 cases of melanomas with spitzoid features for clinicopathological data and chromosomal alterations, targeting RREB-1 (6p25), CCND1 (11q13), MYB (6q23), together with 9p21 (CDKN2A), using FISH methodology. Thirty out of total 49 cases showed chromosomal alterations by 4-probe melanoma FISH assay, 22 (56.4%) cases were ASTs, and 8 (80%) cases were melanomas. Eighteen out of 49 cases showed homozygote deletion by 9p21 FISH assay, 12 (30.8%) cases were ASTs, and 6 (60%) cases were melanomas. When histopathological data were compared with FISH results, a statistically significant correlation was found between 9p21 FISH positivity (homozygous deletion) and presence of deep mitosis (p < 0.05). In addition, epidermal consumption (p = 0.07) and increased mitotic activity (p = 0.05) were more frequent in cases with homozygous 9p21 deletion, but these differences did not reach statistical significance. When the clinical features were considered, there was a statistically significant correlation between 9p21 FISH positivity and the diameter (p < 0.05). There was no statistically significant correlation between melanoma FISH assay and any of the histopathological or clinical data. These data suggest that 9p21 FISH positivity correlated with more worrisome histopathologic and clinical features, such as deep mitosis, increased mitotic activity, epidermal consumption, and larger lesion size, so these features are precious, pointing out spitzoid lesions with higher risk. However, there is a need for further studies using FISH or similar techniques in order to provide more accurate prognostic information in lesions Blank morphology.

Numerical modeling and application of the effects of fish movement on flow field in recirculating aquaculture system

Hydrodynamics plays a crucial role in the recirculating aquaculture system (RAS). An efficient flow field is essential for removing residual bait and feces, creating a healthy environment for fish growth, development, and overall welfare. Hydrodynamics not only influences fish growth and development, but the presence and movement of fish also impact the flow dynamics within the culture tank. This article proposes a fluid-solid coupled model based on computational fluid dynamics (CFD) to investigate the interaction between fish movement and the flow field. Firstly, we established a numerical model of a circular tank using tetrahedral meshing. Several bionic fish were introduced into the tank simultaneously, and their movements were defined using UDF (User-Defined Function) files. Secondly, we evaluated the effects of different numbers of fish movements on the velocity and uniformity of the flow field within the tank. To quantitatively analyze the impact of different numbers of bionic fish on the flow field in the culture tank, we calculated the average velocity, velocity uniformity coefficients, and energy-effective utilization coefficients in three different planes (Y = 0.05, Y = 0.1, and Y = 0.15). This study demonstrated that the presence of fish and their tail-swinging motion enhanced the stability of the flow field and reduced low flow velocity zones in the culture tank. As the number of fish increased, the velocity significantly decreased, and the velocity uniformity decreased as well. The results highlight the effectiveness of the numerical modeling method for the fluid-solid coupling of fish interactions with the system's flow field. Furthermore, the model aligns with experimental results and can be utilized to study fish movement and flow fields effectively.