Lake Fish Research Articles

Winter is not coming: evaluating impacts of changing winter conditions on coregonine reproductive phenology

Fishes in northern latitude lakes are at risk from climate-induced warming because the seasonality in water temperature is degrading, which can change ecosystem properties and the phenology of life-history events. Temperature-dependent embryo development models were developed for a group of cold, stenothermic fishes (Salmonidae Coregoninae) to assess the potential impacts of climate-induced changes in water temperature on cisco (Coregonus artedi) from two populations in Lake Superior (Apostle Islands [USA] and Thunder Bay [Canada]) and one in Lake Ontario (USA), vendace (C. albula) in Lake Southern Konnevesi (Finland), and European whitefish (C. lavaretus) in lakes Southern Konnevesi, Constance (Germany), Geneva (France), and Annecy (France). Water temperatures for each study group were simulated and changes in reproductive phenology across historic (1900–2006) and three future climatic-warming scenarios (2007–2099) were investigated. Models predicted that increases in water temperatures are likely to cause delayed spawning, shorter embryo incubation durations, and earlier larval hatching. Relative changes increased as warming scenarios increased in severity and were higher for littoral as compared to pelagic populations. Our simulations demonstrated that slower cooling in the autumn and (or) more rapid warming in spring can translate into substantial changes in the reproductive phenology of coregonines among our study groups. We expect that the changes in reproductive phenology predicted by our models, in the absence of thermal or behavioral adaptation, will have negative implications for population sustainability.

Long-term decline of whitefish (Coregonus lavaretus) population in the boreal lake Pyhäjärvi, southwest Finland, relative to simultaneous abiotic and biotic changes

In recent decades many lake fish populations have faced complex pressures particularly due to climate warming and eutrophication. In Lake Pyhäjärvi, southwest Finland, profound changes have occurred in the commercial winter fisheries targeting the coregonids vendace, Coregonus albula, and whitefish, Coregonus lavaretus. The responses of vendace have been examined earlier, and here the detailed analyses are extended to the whitefish. In the 1970s and 1980s, the coregonid fishery was sustainable, but in 1991–1998, intense exploitation led to recruitment overfishing of vendace. Despite temporarily improved growth and recruitment of whitefish during vendace decline, whitefish population biomass declined throughout the study period, while perch (Perca fluviatilis), roach (Rutilus rutilus) and ruffe (Gymnocephalus cernuus) increased and vendace and smelt (Osmerus eperlanus) maintained their abundance. As many other northern lakes, Pyhäjärvi seems to be changing from coregonid to perch dominance due to climate warming and eutrophication. Whitefish decline was associated with decreases in fecundity, winter survival of embryos, and larval density. The spawning stock was kept small by intensive fishery. The decline of the relative fecundity was likely due to food competition with vendace and especially the perch and roach populations that increased with eutrophication and more frequent hot summers. The winter survival of whitefish embryos decreased when the introduced signal crayfish (Pacifastacus leniusculus) increased. Despite decreasing fishing effort in the 2000s the larval numbers continued to decline. In the prevailing circumstances in Pyhäjärvi, whitefish will with high probability remain as a minor and still declining species of the fish assemblage.

Bacterial Quality and Molecular Detection of Food Poisoning Virulence Genes Isolated from Nasser Lake Fish, Aswan, Egypt.

The microbial analysis of fish is critical for ensuring overall health. Uncooked fish can serve as a conduit for transmitting several types of microbes; the current investigation sought to assess the bacterial levels in various kinds of fish from Nasser Lake, Aswan, Egypt, considered the chief source of potable water in Egypt. Two hundred and fifty fish samples, including 50 of each Oreochromis niloticus, Sander lucioperca, Lates niloticus, Clarias gariepinus, and Mormyrus kannume, from Nasser Lake, Aswan, Egypt, were collected to detect the bacterial load, isolation, and identification of Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio parahaemolyticus and their virulence genes. The findings revealed that Oreochromis niloticus and Clarias gariepinus exhibited higher bacterial loads than other fish species. Incidences of bacterial contamination among examined fishes were 28.8%, 20.4%, and 16% for Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio parahaemolyticus, respectively. Additionally, PCR analysis detected the presence of aerA (60%) and Act (40%) genes in A. hydrophila, rpoB (70%) and LasB (30%) genes in P. aeruginosa, and ToxR (70%) and tdh (50%) genes in V. parahaemolyticus. The study suggested that the bacterial contamination levels in Oreochromis niloticus and Clarias gariepinus could be notably more significant than in other species that could potentially be harmful to the consumers, especially considering the identification of particular bacteria known to cause foodborne illnesses. Further recommendations emphasized that regular monitoring and assessments are required to preserve their quality.

Genetic variability of the endangered fish lake minnow (Eupallasella percnurus) in populations newly established by translocation and those existing long term in Poland.

The lake minnow Eupallasella percnurus is a small leuciscid fish. In Poland, this species has been in a continuous decline since the mid-20th century and is presently considered as a extremely endangered. According to Polish law, E. percnurus is a strictly protected species that requires active conservation measures. In Poland, one the most common and effective measure of active protection E. percnurus is initiation of new populations. For this purpose, in 2004-2012, juvenile individuals originating from aquaculture conditions were translocated to group of isolated water bodies not inhabited by this species. The juveniles were offspring of parental fish belonging to the same local population, which is extinct at present. Five of those attempts were successful. The aim of the present study was to assess the genetic variation in a group new populations and compare genetic variation indicators with 13 old populations that had existed for decades. The polymorphism of 13 microsatellite markers was investigated, significance of differences in the genetic variation indicators between the groups were tested using a one-way analysis of variance (ANOVA). The mean values of all summary statistics under study, i.e. observed heterozygosity, expected heterozygosity and the total number of alleles, were higher in the group of new populations compared to almost all old ones. A similar dependence was found for Garza-Williamson M values, where the mean for the group of new populations was higher than in almost all old populations. Our results indicate that all recently established E. percnurus populations have not yet experienced any extensive founder effects or bottlenecks. They have preserved a large part of the genetic variability typical of their maternal population, which might also have been relatively high. This feature of new populations, may give them a relatively high ability to adapt to changing environments in the future.

Изменение содержания тяжелых металлов в печени Perca fluviatilis

An assessment of the impact of emissions from the activities of coal mines on the morphology and physiology of perch (Perca fluviatilis) of the Bolshoe and Stolbovoye lakes of the Sorokaozerki tract in the Altai region of the Republic of Khakassia was carried out. Common perch, along with silver carp, are the predominant species in most fishing lakes of Khakassia. The catch of fish was carried out in 2019, 2021 and 2022, the absence of common perch in the catches of 2022 led to the need to analyze this phenomenon. 20 specimens from each reservoir were examined. The regularities of the correlative growth of their internal organs of fish were taken into account, since the living conditions of animals closely correlate with some of their morphological features. Morphophysiological indicators were studied, namely the liver index of perch (Perca fluviatilis), a comparison of this indicator by age and time of capture was carried out. The average index for each age group was calculated taking into account the arithmetic mean error. It was found that the value of the liver index tends to increase over the period from 2019 to 2021 for all age groups, which may indicate the problem of accumulation of heavy metals in the liver. Samples of the liver of the common perch were examined for the content of heavy metals (Pb, Cd, Zn, Cu, Fe, Co, Mn, etc.). The content of lead, arsenic, mercury in the liver of fish does not exceed the MPC. For individual metals (zinc, copper, chromium, iron), there is a large significant excess of MPC: 82% zinc, up to 40% copper, more than 90% chromium, exceeding the MPC of iron by more than 2.4 times.

Karadeniz Somonunun Yolculuğu: Havuzdan Sofraya

Black Sea salmon is from the Salmonidae family and is an endemic species distributed in the Black Sea. These fish, which exhibit anadromous behavior, prefer parts of rivers close to their source for reproduction and the Black Sea for feeding. The first cultivation study of this species, which has high consumer preference and economic value, was started by SUMAE in 1998. As a result of 24 years of work, F7 generation broodstock was created. In order to popularize the production of the species, the private sector was supported with broodstock. In this study, the breeding process of Black Sea salmon was examined and the introduction of the species was aimed. Today, 25 private sector enterprises have production licenses and many enterprises carry out commercial production of the species in the form of trial production with 1603 tons in total. Commercial production is concentrated in the Eastern Black Sea Region, which is the natural distribution area of the species. While enterprises that produce portion size in ponds and have restaurants prefer the red-spotted stream ecotype in production, enterprises that produce large-sized fish in dam lakes and the sea prefer the marine ecotype, which reaches sexual maturity late and has a better growth performance than other ecotypes. Since Black Sea salmon is our only endemic trout species showing typical salmon characteristics, its adaptation to the natural environmental conditions of our country for sea net cage and freshwater aquaculture is quite good.

Assessment of motorized commercial gillnet fishery of the three commercially important fishes in Lake Tana, Ethiopia

This study was conducted from July 2010 to June 2011 to assess the status of motorized commercial gillnet fishery of the three commercially most important fishes in Lake TanaLabeobarbusspp., Oreochromisniloticus(Nile tilapia) and Clariasgariepinus (African catfish). Catches were monitored daily and additional information on number of gillnets used, mesh size of gill nets and location of fishing grounds were collected. Data on the Labeobarbus species composition were collected 3 days per month. The total fish yield from the main fishing grounds of the commercial fishery was 238 metric tons/year. The catch of tilapia was 71%, that of catfish 18% and that of Labeobarbus 11% of the total catch. Peak production was from March - May 2011. Most effort (80%) was allocated to the North Eastern Floodplain (NEFP). The total number of gillnets set and boat trips made were 85,943 and 3104, respectively, which is much higher than reported previously. Consequently, the Catch per Unit effort (CpUE; kg/trip) of the 2010/2011 production year was with 64.7 ± 3 (95% CL) kg much lower than reported previously. The CpUE of all three fish taxa was lower than previously reported, but especially the LabeobarbusCpUE was much lower than before (6.1 kg). An integrated management plan and research program for the Lake Tana basin is urgently required to prevent the collapse of an important fishery and the extinction of the only known cyprinid species flock in the world.

Molecular detection of bacteria from fish lakes in Wasit province

Fish products are very susceptible to microbial contamination, rendering them perishable thus challenging the customers health. The goal of this study was to determine the molecular identification and bacterial isolates diversity obtained from infected fish skin, gills, and fins obtained from lakes Alzarkan village in Wasit Province of Iraq during the period (October 2021- May 2022). A total of 50 fish were collected and 100 samples of organ lesions were taken. For bacterial identification, the tissuees of the fish were as cut with a sterile knife and blended in the buffered peptone water. Molecular identification and the obtained PCR product were are subjected to using the primers for Flavobacterium columnare, Edwardsiella ictaluri and Aeromonas salmonicida. Molecular analyseis revealed bacterial strains high proportion of Flavobacterium columnare identification was 20/50 (40%). The higher identification rates of Flavobacterium columnare in skin 10/20 (5%), in gills 7/20 (35%) and in fins 3/20 (15%). Accurate identification of the 20 isolated Flavobacterium columnare were confirmed by PCR. For identifying certain diseases, molecular approaches provided sensitive, rapid, and precise data without the need for time-consuming traditional techniques. The Edwardsiella ictaluri and Aeromonas salmonicida were not identified. While Flavobacterium columnare termed to be first molecular proof as a farmed fish pathogen in Iraq. Keywords: Molecular detection, Bacteria, Fish lakes, Wasit province, Iraq.

Habitat modulates population-level responses of freshwater salmon growth to a century of change in climate and competition.

The impacts of climate change are widespread and threaten natural systems globally. Yet, within regions, heterogeneous physical landscapes can differentially filter climate, leading to local response diversity. For example, it is possible that while freshwater lakes are sensitive to climate change, they may exhibit a diversity of thermal responses owing to their unique morphology, which in turn can differentially affect the growth and survival of vulnerable biota such as fishes. In particular, salmonids are cold-water fishes with complex life histories shaped by diverse freshwater habitats that are sensitive to warming temperatures. Here we examine the influence of habitat on the growth of sockeye salmon (Oncorhynchus nerka) in nursery lakes of Canada's Skeena River watershed over a century of change in regional temperature and intraspecific competition. We found that freshwater growth has generally increased over the last century. While growth tended to be higher in years with relatively higher summer air temperatures (a proxy for lake temperature), long-term increases in growth appear largely influenced by reduced competition. However, habitat played an important role in modulating the effect of high temperature. Specifically, growth was positively associated with rising temperatures in relatively deep (>50 m) nursery lakes, whereas warmer temperatures were not associated with a change in growth for fish among shallow lakes. The influence of temperature on growth also was modulated by glacier extent whereby the growth of fish from lakes situated in watersheds with little (i.e., <5%) glacier cover increased with rising temperatures, but decreased with rising temperatures for fish in lakes within more glaciated watersheds. Maintaining the integrity of an array of freshwater habitats-and the processes that generate and maintain them-will help foster a diverse climate-response portfolio for important fish species, which in turn can ensure that salmon watersheds are resilient to future environmental change.

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.

A comparison of stable isotopes and polychlorinated biphenyls among genetic strains of Lake Ontario lake trout (Salvelinus namaycush)

This study quantified stable carbon (δ13C) and nitrogen (δ15N) isotopes, polychlorinated biphenyl (PCB) concentrations and growth rates among multiple genetic strains of Lake Ontario lake trout (Salvelinus namaycush) to evaluate the potential role of genetics in these parameters. Fish ranging in age from 1 to 31 years (n = 72) and representing nine genetic strains including wild-recruits to hatchery fish derived from Lakes Ontario, Superior and Champlain watersheds, and individuals of unknown hatchery origin. Carbon (δ13C) and nitrogen (δ15N) stable isotope values averaged −22.2 ‰ and 17.4 ‰, respectively, but did not differ significantly among genetic strains. ΣPCB concentrations ranged from 42 to 1820 ng/g and varied significantly among individuals including those of similar age and genetic strain. For example, Sum PCB (ΣPCB) concentrations among 7-year-old fish (n = 16) ranged from 159 to 607 ng/g, which compares to growth rates of 3.5 – 32.9 %/yr for these same fish. Multivariate analysis of stable isotope and PCB profiles, however, provided considerable resolution among the strains. For example, fish of unknown hatchery origin ordinated most similar to Seneca Lake fish, the predominant strain stocked in Lake Ontario. Wild fish had a unique ordination with only Lake Superior Klondike strain fish overlapping into their ordination space. Lakes Champlain and Superior strain individuals had similar ordinations but did not overlap substantially with wild or Klondike strain fish. Combined, these differences agree with the ecologies described for these strains in their native ecosystems suggesting that insight can be gained from strain specific evaluations of ecological tracers and these pollutants among Great Lakes lake trout.

Molecular Identification of 16S rRNA and Some Virulence Genes From Aeromonas spp. in Nasser Lake Fish Species, Aswan, Egypt

Molecular Identification of 16S rRNA and Some Virulence Genes From Aeromonas spp. in Nasser Lake Fish Species, Aswan, Egypt

Seeking Education on Their Terms: The Atikameksheng Anishnawbek [White Fish Lake First Nations] 1880–1930

Abstract This paper offers a historical context and analysis on an under-studied First Nations located within the Huron–Robinson Treaty area of Northeastern Ontario—Atikameksheng Anishnawbek [White Fish Lake First Nations], whose relatively small population dealt with a great many challenges as settler society arrival created pressures on livelihoods, spirituality, physical well-being, lifestyles, and much more. Detailed micro-study of the Whitefish Lake Roman Catholic Day School operations from 1880 to the 1930s reveals a continuing tale of the Band’s efforts at obtaining Indigenous-led education for its children, as well as the often indifferent, sometimes hostile, and at best incompetent role played by Indian Affairs. Often a tale of struggle rather than success, it nevertheless sheds light on First Nations’ determination to provide their children with effective education emerging from Indigenous traditions. (PVK)

Testing countermeasures to reduce 90Sr content in fish products

Activity concentrations of 90Sr in fish in lakes located within the Chornobyl Exclusion Zone (ChEZ) reach 100 kBq kg−1, which is several thousand times higher than the permissible level in Ukraine (35 Bq kg−1). This study was conducted in the natural conditions of the ChEZ to determine the effectiveness of keeping radioactively contaminated fish in “clean” water to reduce the 90Sr content of their muscle tissue, as previously shown in short-term laboratory experiments. It was found that transferring tench (Tinca tinca (Linnaeus, 1758)) from Lake Glubokoye one of the most contaminated lakes in the ChEZ, to a cage in the “clean” Lake Starukha for 45 days did not lead to a significant decrease in 90Sr content in both bone and muscle tissues.Establishing permissible levels of 90Sr concentration only in fish fillet, and not in the whole fish body (with bone tissue), is appropriate for human radiation protection, since the retention factors of 90Sr treatment for boiled bone tissue of crucian carp from the Chornobyl exclusion zone are less than 0.01, and up to 97% of strontium is contained in bone tissue.

Enrichment, bioaccumulation and human health assessment of organochlorine pesticides in sediments and edible fish of a plateau lake.

The organochlorine pesticides (OCPs) are with features of persistence, high toxicity, bioaccumulation and adverse impact on ecosystems and human beings. Although OCPs pollutions have been observed in the plateau lakes, comprehensive understandings in the distribution characteristics and human health risks of OCPs in these valuable but fragile ecosystems are limited. We here investigated the distribution, bioaccumulation process and health risks of OCPs in the Jianhu lake, a representative plateau lake in China. The endrin ketone, endrin aldehyde and heptachlor were the most dominant species in surface and columnar sediments. Their total contents ranged between 0 ~ 1.92 × 103ng·g-1. The distribution of OCPs in sediment cores combined with chronology information indicated that the fast accumulation of OCPs happened during the last decades. Combining the distribution features of OCPs in different sources with mixing model results of carbon isotope (δ13C), farming area was identified as the main source (46%), and the OCPs were transported to lake by inflow-rivers (37%). The enrichment of OCPs in sediments caused considerable bioaccumulation of OCPs in local fish (∑OCPs 0-3199.93ng·g-1, dw) with the bio-sediment accumulation factor (BSAF) ranging from ND to 9.41. Moreover, growing time was another key factor governing the accumulation in specific species (Carassius auratus and Cyprinus carpio). Eventually, the carcinogenic risk index (CRI) and exposure risk index (ERI) of the endrin category and aldrin exceeded the reference value, indicating relatively high health risks through consumption of fish. Overall, this study systematically illustrated the bioaccumulation process and health risks of OCPs in the typical plateau lake, providing theoretical support for the better protection of this kind of lakes.

Short Communication: The biodiversity of aquatic organisms in Anak Laut Lake, Aceh Singkil District, Indonesia

Abstract. Muhtadi A, Leidonald R, Yolanda O, Harahap R, Matondang NP, Putri K, Simamora LFM, Sitompul G. 2023. Short Communication: The biodiversity of aquatic organisms in Anak Laut Lake, Aceh Singkil District, Indonesia. Biodiversitas 24: 4837-4844. Anak Laut Lake is a unique and strategic coastal lake, significantly recognized for its diverse marine biota and the potential to be a spawning, nursery, and feeding ground. Therefore, this research aimed to determine the types of aquatic organisms, including plankton, fish, crustaceans, benthos, seagrasses, and mangroves in Anak Laut Lake. The experiment was conducted in October 2022 in the Anak Laut Lake ecosystem, North Singkil Sub-district, Aceh Singkil District, Aceh Province, Indonesia. The plankton was taken using a plankton net tool, extracted vertically from a depth of 2 m, and pulled to the surface. Fish and crustaceans were observed and caught with purse seines, ring nets, and gill nets. Benthic organisms were directly observed on the edge of the lake, along with the identification of mangroves, while at the bottom, the fishermen dove into the water. The data obtained were analyzed descriptively and compared with similar research. The results showed a rich biodiversity in Anak Laut Lake, with at least 165 species/genera of aquatic biota, 9 species of mangroves, and 2 Seagrass species. The marine nekton found consisted of fish (55 species), shrimp (3 species), and crabs (10 species). The macrozoobenthos found in Anak Laut Lake consisted of 13 species of clams, 12 gastropods, 3 sea cucumbers, 2 sand dollars, 2 horseshoe crabs, and 1 sea urchin. Various species of aquatic biota whose existence was threatened in nature and found in this lake included golden sea cucumber (Stichopus herrmanni), seahorse (Hippocampus comes and Hippocampus kuda) with Vulnerable status (VU), tap ray (Maculabatis gerrardi), and sand cucumber (Holothuria scabra) with Endangered species status (EN). This shows that this coastal lake is an important and crucial habitat for several species that are vulnerable to extinction. For this reason, in the future, further studies are needed regarding the habitat characteristics and spatial and temporal distribution of aquatic organisms in Lake Laut, so that more appropriate management can be implemented for the sustainability of the lake.

Patterns and repeatability of multi‐ecotype assemblages of sympatric salmonids

AbstractAimHigh repeatability among assemblages of closely related but ecologically distinct ecotypes implies predictability in evolution and assembly of communities. The conditions under which ecotype assemblages form predictably, and the reasons, have been little investigated. Here, we test whether repeatability declines as the number of ecotypes builds.LocationPostglacial lakes with a circumboreal distribution.Time PeriodData were extracted from studies published between 1982 and 2019.Major Taxa StudiedEcotype assemblages from two Salmonid genera – Salvelinus and Coregonus. Fish in postglacial lakes commonly occur as pairs of ecotypes, typically with a pelagic and a littoral/benthic form, but in Salvelinus and Coregonus, assemblages commonly contain multiple sympatric ecotypes.MethodsWe used a meta‐analysis of Salvelinus and Coregonus to empirically assess how repeatability varies across assemblages of two to seven ecotypes. We examined repeatability of use of broad niche categories as well as underlying phenotypic traits.ResultsWithin Coregonus, repeatability across multi‐ecotype assemblages did not break down with the addition of a third or fourth ecotype. However, in Salvelinus, repeatability was largely absent and independent of the number of ecotypes. Repeatability of trait frequency distributions was absent in both genera, yet associations between trait means and niche categories were evident, especially in Coregonus.Main ConclusionsThese results show that repeatability can vary greatly between lineages; that repeatability need not break down as the number of ecotypes builds; and that high repeatability of broad niche categories may result despite marked differences in the underlying frequency distribution of trait means. These findings not only affirm the presence of repeatable ecotype assembly and early stages of divergence in postglacial fishes at a global scale, but also highlight variability among taxa and underlying phenotypic traits.

Heavy Metal Levels and Cancer Risk Assessments of the Commercial Denis, Sparus aurata Collected from Bardawil Lake and Private Fish Farm Waters as a Cultured Source, Egypt

Heavy metal pollution of natural and cultivated habitats may be caused by agricultural, industrial, and human activities. Fish living in these habitats easily accumulate metals in their organs; for food safety and human health, the heavy metals in fish flesh are of major concern due to the harmful nature of these pollutants even in low quantities. In this study, metals (Iron, Fe; Lead, Pb; Cadmium, Cd; Nickel, Ni; Copper, Cu and Zinc, Zn) in the muscle, liver, intestine, and gill of gilthead seabream (Sparus aurata, Denis is local name) were monitored to determine the contamination levels and to investigate the protective impact of cooking methods on the reduction or mitigation of metal levels. Although the Denis samples exhibited relatively low Pb and Cd levels, most fish samples had elevated levels of Fe and Zn. The examined metals accumulated at the highest level in the liver and gills compared to the other organs. Results showed that cooking methods had a considerable effect on concentrations of metals. However, the levels of metal in S. aurata from various sources were reduced significantly (P < 0.05) by frying, microwave, and grilling cooking, which was ordered in the following sequence as microwave cooking < grilling < frying. The consumption of Denis fish from different sources (wild and cultured) has no negative effects on health, according to a study of health hazards based on indices of carcinogenic and non-carcinogenic. The metal results indicated that different fish sources (wild and cultured) could be acceptable for human consumption. Data hypothesized a positive impact of awareness among the native community.

Morphological, histological and phylogenetic identification of three species of Myxobolus (Myxosporea: Myxobolidae) infecting different carp lineages in China.

The global cultivation of common carp Cyprinus carpio is developed primarily for either food or recreational purposes and myxosporean infections causing significant economic losses are regularly troublesome for carp farmers. However, most myxosporean species are poorly characterized, making it difficult to correctly elaborate on their parasitism mode and determine pathogenicity. Here, based on an integrative approach, we supplemented fundamental information on three Myxobolus species infecting different carp lineages in China. Myxobolus elliptoides Wu et Chen, 1987; Nine new species of Myxosporida from freshwater fish of Wuhu lake, Hubei, China. Acta Hydrobiologica Sinica, 11, 161 formed yellowish pseudocysts in the anal fin of common carp and were observed with ellipsoidal myxospores and two polar capsules of distinct dimensions. The dermal tissue within the fin ray was regarded as the type site for growing plasmodia of M. elliptoides. Myxobolus basilamellaris Lom et Molnar, 1983; Myxobolus basilamellaris sp. n. (myxozoa, Myxosporea), a parasite of the gills of common carp (Cyprinus carpio L.). Folia Parasitologica, 30, 1 aggregated ellipsoidal myxospores at the base of the gill filaments of koi carp juvenile, causing significant tissue damage. Myxobolus artus Achmerov, 1960, enwrapped in diffuse pseudocysts, was observed throughout the trunk muscle of mirror carp. Its oblate myxospores were asymmetrical and contained two unequal-sized polar capsules. According to the localization of large plasmodia, inter- and intramuscular preferences were displayed by M. artus. For precise species identification, we provided the SSU rDNA sequences for each species of Myxobolus. Among them, M. elliptoides was molecularly characterized for the first time, showing the highest 94.21% identity to Thelohanellus sinensis (KY469292). Phylogenetically, the affinity of both M. artus and M. basilamellaris to their conspecific species derived from different carp lineages was highly supported. Moreover, the intermixed cluster of Myxobolus species, including M. elliptoides, with those of Thelohanellus species provided evidence for querying the monophyletic evolution history of these taxa. This work updates the appreciation of the concerned species and enhances our understanding of the parasite fauna of common carp.

Origin of endemic species in a moderately isolated ancient lake: The case of a snakehead in Inle Lake, Myanmar

AbstractInle Lake is an ancient lake in Myanmar, which is an important area with unique and diverse fauna. Its ichthyofauna is believed to have formed non‐radiatively, but the historical processes are poorly understood. To elucidate the mechanisms that shape species diversity in this moderately isolated biogeographical ‘island’, this study focused on a typical endemic fish of Inle Lake, Channa harcourtbutleri (Channidae, Anabantiformes), with its widely distributed sister species, C. limbata, and estimated the historical distribution and diversification processes of the endemic fish based on genome‐wide polymorphism (MIG‐seq) and mitochondrial DNA data. Channa harcourtbutleri contained two genetically and morphologically distinct groups inhabiting Inle Lake and the surrounding rivers respectively. These two groups were genetically the closest to each other; however, the riverine group showed some similarity to the closely related species, C. limbata from Southeast Asia. The mtDNA haplotypes of the endemic species were not monophyletic; most of the riverine group had haplotypes identical or close to those of C. limbata from the upper Irrawaddy and Salween rivers. The time tree suggested that C. harcourtbutleri diverged from C. limbata in the early Pleistocene and then experienced secondary contact with C. limbata in the late Pleistocene. Genetic and morphological differentiation within C. harcourtbutleri suggests that local adaptation to different environments has played an important role for the coexistence of its two forms with some reproductive isolation. Further, the results highlight the importance of multiple colonization and allopatric speciation in shaping biodiversity in the long‐term, moderately isolated environments.