Distribution Of Freshwater Fishes Research Articles

Climate change vulnerability of Arctic char across Scandinavia.

Climate change is anticipated to cause species to shift their ranges upward and poleward, yet space for tracking suitable habitat conditions may be limited for range-restricted species at the highest elevations and latitudes of the globe. Consequently, range-restricted species inhabiting Arctic freshwater ecosystems, where global warming is most pronounced, face the challenge of coping with changing abiotic and biotic conditions or risk extinction. Here, we use an extensive fish community and environmental dataset for 1762 lakes sampled across Scandinavia (mid-1990s) to evaluate the climate vulnerability of Arctic char (Salvelinus alpinus), the world's most cold-adapted and northernly distributed freshwater fish. Machine learning models show that abiotic and biotic factors strongly predict the occurrence of Arctic char across the region with an overall accuracy of 89 percent. Arctic char is less likely to occur in lakes with warm summer temperatures, high dissolved organic carbon levels (i.e., browning), and presence of northern pike (Esox lucius). Importantly, climate warming impacts are moderated by habitat (i.e., lake area) and amplified by the presence of competitors and/or predators (i.e., northern pike). Climate warming projections under the RCP8.5 emission scenario indicate that 81% of extant populations are at high risk of extirpation by 2080. Highly vulnerable populations occur across their range, particularly near the southern range limit and at lower elevations, with potential refugia found in some mountainous and coastal regions. Our findings highlight that range shifts may give way to range contractions for this cold-water specialist, indicating the need for pro-active conservation and mitigation efforts to avoid the loss of Arctic freshwater biodiversity.

European water frame directive ecoregions do not adequately represent freshwater fish biogeography

The quest to understand species' distribution patterns and delineate their limits has led to the establishment of the world's ecoregions, large units of land containing a distinct assemblage of species, both for terrestrial and marine ecosystems. However, freshwaters constitute their own special case within terrestrial ecosystems, and have only recently been divided into freshwater ecoregions, primarily based on watershed limits. Freshwater ecoregions used by the European Water Frame Directive (WFD), which guides freshwater management policies in the European Union, have been criticized for not adequately representing freshwater fish biogeography. This study compares the geographic agreement between WFD ecoregions and freshwater fish distribution at the European scale. Using IUCN Red List distribution maps, we determined the composition of freshwater fish communities in major European basins. Then, we calculated a similarity matrix in order to cluster freshwater basins with more related fish assemblages. We compare our findings with WFD ecoregions and global ecoregions from the Freshwater Ecoregions of the World (FEOW) database. Our results reveal that WFD ecoregions do not sufficiently capture freshwater fish assemblage differences across Europe. Mediterranean basins exhibit high freshwater fish endemism and greater species variation, whereas central European basins harbor more similar fauna. Overall, our results align more with those of FEOW. To enhance the relevance of freshwater ecoregions in Europe for management and conservation, we propose several measures to ensure a comprehensive study involving all stakeholders in the process of defining these ecoregions accurately.

The Influence of Equal Employment Opportunities and Islamic Work Values on The Quality of Work LIfe of Employees CV. Profish International

Nowadays, several companies recognize the value of employee loyalty as one of the tools for their growth. Improving the quality of work life of employees is one approach to maintaining employee loyalty and increasing job satisfaction. The purpose of this study is to find out how the influence of equal employment opportunities and Islamic work values variables on the quality of work life. This research was conducted at CV. Profish Internasional which is a company that has a focus on the world of fisheries from cultivation to the distribution of fresh water fish. The population used in the study were all employees of C.V Profish Internasional, totaling 113 people. By using the Isaac and Michael formula, the sample in this study was 89 people. Data analysis used Patrial Least Square-Structural Equation Model or PLS-SEM analysis using SmartPLS. The results show that equality of employment opportunities and Islamic work values have a significant influence on the quality of work life of CV Profish International employees

Evolution of the ecological niche behind the largest disjunct freshwater fish distribution in the world.

Ecological processes that are behind distributions of species that inhabit isolated localities, complex disjunct distributions, remain poorly understood. Traditionally, vicariance and dispersion have been proposed as explanatory mechanisms that drive such distributions. However, to date, our understanding of the ecological processes driving evolution of ecological niches associated with disjunct distributions remains rudimentary. Here, we propose a framework to deconstruct drivers of such distribution using World's most widespread freshwater fish Galaxias maculatus as a model and integrating marine and freshwater environments where its life cycle may occur. Specifically, we assessed ecological and historical factors (Gondwanan vicariance, marine dispersion) and potential dispersion (niche-tracking) that explain its distribution in the Southern Hemisphere. Estimated distribution was consistent with previously reported distribution and mainly driven by temperature and topography in freshwater environments and by primary productivity and nitrate in marine environments. Niche dynamics of G. maculatus provided evidence of synergy between vicariance and marine dispersion as explanatory mechanisms of its disjunct distribution, suggesting that its ecological niche was conserved since approximately 30 Ma ago. This integrated assessment of ecological niche in marine and freshwater environments serves as a generic framework that may be applied to understand processes underpinning complex distributions of diadromous species.

Downscaling future land cover scenarios for freshwater fish distribution models under climate change

The decreasing freshwater biodiversity trend can be attributed to anthropogenic impacts in terms of climate and land cover change. For targeted conservation efforts, mapping and understanding the distribution of freshwater organisms consists of an important knowledge gap. Spatial modelling approaches offer valuable insights into present-day biodiversity patterns and potential future trajectories, however methodological constraints still hamper the applicability of addressing future climate and land cover change concurrently in one modelling workflow. Compared to climate-only projections, spatially explicit and high-resolution land cover projections have seen less attention, and the lack of such data challenges modelling efforts to predict the possible future effects of land cover change especially on freshwater organisms. Here we demonstrate a workflow where we downscale future land cover projection data from the Shared Socioeconomic Pathway (SSP) scenarios for South America at 1 km2 spatial resolution, to then predict the future habitat suitability patterns of the Colombian fish fauna. Specifically, we show how the land cover data can be converted from plain numbers into a spatially explicit representation for multiple SSP scenarios and at high spatial resolution, employing freshwater-specific downscaling aspects when spatially allocating the land cover category grid cells, and how it can be fitted into an ensemble species distribution modelling approach of 1209 fish species. Our toolbox consists of a suite of open-source tools, including Dinamica EGO, R, GRASS GIS and GDAL, and we provide the code and necessary steps to reproduce the workflow for other study areas. We highlight the feasibility of the downscaling, but also underline the potential challenges regarding the spatial scale and the size of the spatial units of analysis.

Unraveling the complex phylogeographic history of freshwater fishes in Lower Central America: A study of the electric fish Brachyhypopomus occidentalis

Lower Central America (LCA) has a complex biogeographic history shaped by the rise of the Isthmus of Panama and the global climatic oscillations of the Pleistocene. These events have been crucial in structuring biodiversity in LCA, but their consequences for the distribution and partitions of genetic diversity across the region remain to be elucidated. We combined complete mitochondrial genomes and nuclear ultraconserved elements (UCEs) to study the phylogeographic history and population genetic structure of the electric fish Brachyhypopomus occidentalis in LCA. Our results are consistent with the known phylogeographic history of B. occidentalis in LCA, but we update this history in several important ways that help illuminate the phylogeographic history of freshwater fishes in the region. We provide: i) support for three waves of colonization, two of which occurred prior to the final closure of the Panama Isthmus; ii) a more precise understanding of each colonization event, with evidence for a larger footprint of the first event, as well as genetic exchange across the continental divide in subsequent events; and iii) evidence for high levels of previously unrecognized population genetic structure across LCA. This updated model of colonization and diversification of B. occidentalis consists of three waves of dispersal and colonization, which triggered the evolution of geographic breaks in both nuclear and mitochondrial genomes across LCA. These processes are tightly linked to the dynamic uplift of the Isthmus, recent volcanic activity in the region, and the sea-level oscillations of the Pleistocene. These results improve previous phylogeographic inferences regarding the distribution and diversification of freshwater fishes in LCA, and generate testable hypotheses to guide future research exploring the factors shaping biodiversity in the region.

Fish diversity, composition, and guild structure influenced by the environmental drivers in a small temporarily closed tropical estuary from the western coast of India.

Globally, small temporarily closed estuaries are the least considered for fisheries assessment and management due to a low scientific priority and regional importance. However, these ecosystems are highly exposed to anthropogenic pressures and may deteriorate without assessing its aquatic resources. In this study, fish diversity and guild structure of Chettuva-a temporarily closed tropical estuary in the western coast of India-was investigated. A total of 70 fish taxa belonging to 32 families were recorded with the quantitative predominance of families; Mugilidae, Cichlidae, and Leiognathidae. Family Carangidae had the highest species diversity (seven species), followed by Clupeidae and Mugilidae (five species). Ecological guild assessment revealed thatthe immigrating marine fish species (marineestuarine opportunist (34 species) and marineestuarinedependent (13 species)) dominated the guild structure over theestuarine resident species (seven species). The marine species were found all along the saline gradient and throughout the sampling period indicating the salinity ingress towards the estuarine zone throughout the year. Carnivores and omnivores were the major feeding mode functional guilds in terms of diversity, whereas detritivores dominated in numerical abundance throughout the salinity gradient. The major environmental drivers of the fish assemblages in the estuary were salinity and chlorophyll a. The distribution of freshwater fishes and estuarine resident species was connected with the rising primary productivity as the majority of fishes rely on the algae for feeding, whereas marineestuarinedependent and marineestuarine opportunist species occurred in areas with the highest salinity concentrations.

A comparative study of muscle nutrition and intermuscular bone number in improved diploid carp

The common carp (Cyprinus carpio L., COC, 2n = 100) is one of the most widely consumed and distributed freshwater fish in the world. It ranks fourth in total freshwater aquaculture volume in various regions of China, behind Ctenopharyngodon idella, Hypophthalmichthys molitrix, and Aristichthys nobilis. However, in recent years, environmental degradation, inbreeding, disordered breeding, and other adverse effects have caused problems such as low seed quality and poor disease and stress resistance of the carp. In our laboratory, we developed two types of improved diploid carp the hybrid F1 of common carp (♀) × blunt snout bream (Megalobrama amblycephala, BSB, 2n = 48) (♂). To investigate the differences between IDC and IDMC compared to COC, in this study we compared the relevant characteristics of these two types of improved carp with those of COC in terms of muscle nutrient composition, intermuscular bone type, and number. The results showed that among the muscle nutrients, IDC had a higher protein content (18.50%) and lower carbohydrate content (0.70%). In addition, the unsaturated fatty acid content of IDC (3.45%) and IDMC (1.25%) were significantly higher than that of COC (P < 0.05) (0.50%). For monounsaturated fatty acids such as oleic acid (OA, C18:1 n-9) and linoleic acid (PA, C16:1), the content of IDC and IDMC were also abundant. In terms of intermuscular bone morphology, the morphology and type of intermuscular bone in IDC and IDMC medullary arch ossicles were consistent with those of COC. However, the number of intermuscular bones was different, and the average number of intermuscular bones of IDMC decreased by 14.77% (P < 0.05) compared with COC. The advantages of IDC and IDMC are different, with IDC having a higher value of muscle nutrients and IDMC having a lower intermuscular bone content. The distant hybridization of common carp (♀) × blunt snout bream (♂) developed two improved diploid carp varieties with excellent traits, which added carp germplasm resources with high muscle nutrition and lower intermuscular bone, and provided theoretical support for their production application.

Past riverine connectivity effects in population structure and distribution of an endemic freshwater fish from northeastern Brazilian rivers: Phylogeographic, taxonomic, and conservation implications

Abstract The coastal basins of eastern Brazil are influenced by geomorphologic and climatic changes that caused river captures and temporary paleo‐connections due to sea‐level oscillations. These two events can lead to isolation and connection among coastal rivers and have a strong influence on the distribution of freshwater fishes in this region. Characidium bahiense is a small fish species with a wide distribution, ranging from the coastal basins of the North Group of the Northeastern Mata Atlântica ecoregion to São Francisco and Parnaíba ecoregions. The allopatric distribution of C. bahiense associated with the possible morphological and molecular variations among geographically isolated populations stimulated this study. Here, we use an integrative approach, encompassing morphological and mitonuclear data, and paleodrainage reconstruction to better understand the evolutionary history of C. bahiense and to test the putative effects of the current configuration of basins and historical drainage rearrangements on the genetic structuring of the species. Our mitochondrial data show that C. bahiense is not a monophyletic species since the specimens from one locality are more closely related to Characidium cf. lagosantense than to other populations of C. bahiense. Multilocus analyses, however, recovered the monophyly of this species, although the molecular delimitation method considers each mitochondrial DNA lineages as a separated species. Overall, the morphological data revealed some intraspecific overlapping variation, suggesting that all specimens of C. bahiense are conspecific. Molecular analyses combined with geomorphological information suggest that the current distribution of C. bahiense is the result of climate change that directly affected river flow dynamics and recent riverine captures during the Pleistocene. The use of multiple data sources not only provides a more reliable interpretation of the evolutionary history of a species, but can also avoid arbitrary taxonomic decisions. Future phylogeographic studies involving other freshwater fish species with a similar distribution to C. bahiense are necessary to assist in understanding the scenarios presented here.

Accessibility and appeal jointly bias the inventory of Neotropical freshwater fish fauna

Inventorying biodiversity is fundamental to overcoming knowledge shortfalls in species discovery and description (Linnean shortfall), their distributions (Wallacean shortfall) and abiotic niches (Hutchinsonian shortfall). However, inventorying efforts often show spatial biases, and the underlying causes have only been explored at large spatial extents for the most well-known terrestrial taxa. Improving our understanding of these biases and their drivers is particularly crucial in the speciose tropics, where biodiversity knowledge suffers the most from knowledge shortfalls. Using the most complete information available on freshwater fish distributions in three regions in the Neotropics (Orinoco and Trans-Andeans, the Amazon and the La Plata basins), first, we evaluated environmental biases in inventory effort and completeness across sub-basins. Further, we examined three hypotheses (Accessibility, Appeal, and Safety) to explain the differences in contemporary (2000–2018) inventorying efforts. The Accessibility and Appeal hypotheses were well-supported and conjointly explained a moderate proportion of the spatial variation in the inventorying effort. By contrast, the Safety hypothesis predictors showed limited support. The most accessible sub-basins (i.e., lower travel time from cities or closer to fluvial ports) experienced higher inventorying effort regarding the number of unique inventorying locations and years inventoried. Our results suggest that differences in Accessibility alone may be insufficient to explain inventorying biases. Inventorying efforts were also biased against sub-basins with lower biodiversity and habitat diversity, showing preferential sampling driven by sub-basins' Appeal. The imprint driven by Appeal elucidates opportunities to coordinate future efforts to fill the shortfalls of biodiversity knowledge more efficiently for the Neotropical fish fauna.

The Freshwater Biodiversity Information System (FBIS) fish data: a georeferenced dataset of freshwater fishes occurring in South Africa

Freshwater fishes are recognised as South Africa’s most threatened species group. Reliable, long-term data on fish occurrence records are critical for effectively managing and conserving these species. A comprehensive freshwater fish dataset was compiled and uploaded to the Freshwater Biodiversity Information System (FBIS, freshwaterbiodiversity.org), comprising all available records of formally described freshwater fish species occurring in South Africa. An 18-month historic-data collation effort resulted in the accrual of 35 955 new records of freshwater fish from South Africa spanning 194 years (1828–2022), that have since been uploaded to the Global Biodiversity Information Facility (GBIF). Together with pre-existing GBIF records (24 861), a total of 60 837 freshwater fish records are thus now available for South Africa. The data show a marked decline in the number of native fish occurrence records over the last decade. Conversely, the number of occurrences for non-native fishes increased over the past three decades. A data breakdown is provided for each of South Africa’s nine provinces including total number of records, and the numbers of native, non-native, endemic and threatened species. These data provide a much-needed update of the known status and distribution of freshwater fishes in the country.

Distribution of diversity of fishes in an Andean fluvial network

Introduction: The distribution of freshwater fishes in the Colombian Andes results from the interaction between historical and recent factors. Currently, the Andean landscape is facing rapid transformation processes. However, the knowledge regarding species distribution and environmental requirements is advancing slower than the transformations underway in the fluvial networks. Objective: To understand the conformation of the fish assemblage in the middle and lower Cauca River basin, considering the local environmental context before the construction of the Ituango Dam, and quantifying β diversity and its two components (turnover and nestedness) amongst local fish communities. Methods: 58 localities were monitored during nine years (between February 2010 and November 2018), the period before the dam's operation. The species richness (α-diversity), species turnover (β-diversity), and assemblage composition were estimated for the given localities. Results: 114 species were recorded, representing ~ 49 % of the total richness of known species for the Magdalena basin. The richness distribution showed that the number of species varies among the aquatic environments. Swamps presented the most significant number of species, followed by the Cauca River, while streams had the lowest values of richness. The spatial analyses of β-diversity revealed a high variation component in the study area due to species replacement between the aquatic environments. Conclusions: The implementation of long-term monitoring allowed us to recognize that the Cauca River basin conserves a great variety of species-rich environments. The species turnover indicates a high proportion of endemism or multiple sites with unique species. Finally, our study will serve as a baseline to verify, over time, whether the dam's construction is associated with essential changes in the structure of fish communities.

Boosting freshwater fish conservation with high-resolution distribution mapping across a large territory.

The lack of high-resolution distribution maps for freshwater species across large extents fundamentally challenges biodiversity conservation worldwide. We devised a simple framework to delineate the distributions of freshwater fishes in a high-resolution drainage map based on stacked species distribution models and expert information. We applied this framework to the entire Chinese freshwater fish fauna (>1600 species) to examine high-resolution biodiversity patterns and reveal potential conflicts between freshwater biodiversity and anthropogenic disturbances. The correlations between spatial patterns of biodiversity facets (species richness, endemicity, and phylogenetic diversity) were all significant (r=0.43-0.98, p<0.001). Areas with high values of different biodiversity facets overlapped with anthropogenic disturbances. Existing protected areas (PAs), covering 22% of China's territory, protected 25-29% of fish habitats, 16-23% of species, and 30-31% of priority conservation areas. Moreover, 6-21% of the species were completely unprotected. These results suggest the need for extending the network of PAs to ensure the conservation of China's freshwater fishes and the goods and services they provide. Specifically, middle to low reaches of large rivers and their associated lakes from northeast to southwest China hosted the most diverse species assemblages and thus should be the target of future expansions of the network of PAs. More generally, our framework, which can be used to draw high-resolution freshwater biodiversity maps combining species occurrence data and expert knowledge on species distribution, provides an efficient way to design PAs regardless of the ecosystem, taxonomic group, or region considered.

The freshwater fishes from the Costa Verde Fluminense region of southeastern Brazil

Abstract The region between the Brazilian Shield and the Atlantic Ocean is characterized by the presence of numerous hydrographic basins isolated by mountainous terrain that flow directly into the ocean without forming wide coastal plains. However, knowledge about the diversity and distribution of freshwater fish in several coastal areas is still incipient. One of these areas is the Costa Verde Fluminense region, situated between the municipalities of Mangaratiba and Paraty in the Brazilian State of Rio de Janeiro. In order to eliminate the gap of knowledge about the freshwater fish fauna of this region, we prepared a list of the species, and dichotomous identification keys and illustrations of all species. We examined material from expeditions carried out between 1942 and 2019, deposited in the Ichthyological Collection of the Museu Nacional, Universidade Federal do Rio de Janeiro, Brazil. The material comes from 29 continental coastal rivers and four drainages on Ilha Grande island. We recognized 54 fish species belonging to 16 families and 9 orders. The order Siluriformes was the most diverse with 18 species, followed by Characiformes with 14 species, Cyprinodontiformes with 10 species, Cichliformes with four species, Gobiiformes with three species, Syngnathiformes with two species, and Gymnotiformes, Salmoniformes and Synbranchiformes with one species each. These records include two putative undescribed species and four introduced species. Phalloceros anisophallos was the most widely distributed species, recorded in 24 drainages. More than a half (52 %) of the native species occur exclusively in coastal streams, demonstrating the importance of the area for biogeographic and conservation studies.

Exploring the Ichthyofauna of District Mardan, Khyber Pakhtunkhwa, Pakistan

The current study aimed to investigate the diversity and distribution of freshwater fish in the districts of Mardan, located in the northwest of Khyber Pakhtunkhwa province, Pakistan. Mardan is home to numerous streams and rivers between the Indus and Kabul rivers, making it an important area for fishing and farming. A total of 250 fish samples were collected from February to November 2021. Eight species were identified in Mardan, including Mastacembelus armatus, Gara gotyla, Cyprinus carpio, Puntius ticto, Caraccius auratus, Oreochromis mosambicus, Puntius sophore, and Tor putitora. The results suggest that overfishing and water pollution are major factors affecting the survival and expansion of fish species in the area. To improve the fish populations in the rivers and streams, proper stocking and regulations to control overfishing and pollution are needed. The study found that the Cyprinidae family was the most dominant, with eight species identified in the experimental area. However, the number of Mastacembelidae and Cichlidae was found to be low due to pollution, toxic heavy metals, and other environmental factors that affect breeding and other activities of fish.

The past and current distribution of native and non-native fish in the Kowie River catchment, Makhanda, Eastern Cape

Freshwater ecosystems show substantial loss of biodiversity as a result of anthropogenic induced stressors. In this study, we evaluated the distribution of freshwater fishes in the Kowie River catchment using historic fish distribution records supplemented by field survey data. Fishes were collected using a multi-method approach: seine nets, fyke nets and gill nets. Historic fish distribution data showed that 22 freshwater fishes from 11 families historically occurred, while in this study, we recorded a total of 16 freshwater fish species from 9 families. Overall, a decrease in the number of native species was recorded with a total of five species absent and two new non-native species recorded during the current survey. Coptodon rendalli constituted a new record in the Kowie River catchment while Clarias gariepinus was recorded for the first time in the mainstem of the Kowie River. The presence of these two non-native species in the Kowie River catchment may have implications for the conservation and management of the freshwater diversity in the catchment.

Population level genetic divergence and phylogenetic placement of Mexican shortfin mollies (Mollienesia: Poecilia: Poeciliidae)

Abstract Mexico is a megadiverse region with a complex geological history, but it remains unclear to what extent the distribution of freshwater fish has been influenced by geographic barriers. This study examines the population level genetic divergence and phylogenetic relationships of species in the shortfin group of the subgenus Mollienesia (genus Poecilia), a group of live-bearing fishes that are widely distributed across Mexico, with sampling at a small geographic scale. Samples from over 50 locations were analyzed for six species by using phylogenetic and haplotype network approaches to assess genetic diversity across geographic ranges and to refine the distributions of species in this group. The results indicate that Mexican species have diversified following multiple, independent invasions from Middle America. Two species found north of the Trans-Mexican Volcanic Belt (TMVB) and one transversal species exhibited weak phylogenetic structure, likely due to the lack of physiographic barriers, recent colonization, and high dispersal rates among regions. In contrast, three species found south of the TMVB exhibited strong phylogenetic structure, reflecting a longer presence in the area and multiple physiographic barriers that isolated populations. This study identified mechanisms driving divergence and speciation, expanded the known range of several species, and resolved taxonomic uncertainties of populations.

Transcriptome analysis of the muscle of fast- and slow-growing phoenix barb (Spinibarbus denticulatus denticulatus).

Growth rate is a commercial trait in aquaculture that is influenced by multiple factors, among which genetic composition plays a fundamental role in the growth rate of species. The phoenix barb (Spinibarbus denticulatus denticulatus) is a widely distributed freshwater fish species in South China. Although S. d. denticulatus is reared in South China, the molecular mechanisms underlying the growth rate of the species remain unclear. Here, the authors performed transcriptome analysis of muscle tissues from fast-growing (FG) and slow-growing (SG) S. d. denticulatus at 90, 150, and 300 days after hatch (DAH) to elucidate its growth mechanism. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that differentially expressed genes (DEGs) between the two groups were enriched in pathways related to muscle growth, glycolysis, and energy and lipid metabolism. Nonetheless, a higher number of DEGs were identified in the FG vs. SG groups at 90 and 300 DAH compared with 150 DAH. DEGs identified at 90 DAH were mainly enriched in the GH/IGF axis, PI3K-Akt signalling pathway, AMPK signalling pathway and lipid metabolism highly expressed in FG individuals. DEGs identified at 300 DAH were mainly enriched in PI3K-Akt signalling pathway, glycolysis/gluconeogenesis, gene translation and lipid metabolism. In addition, some genes were expressed during the early growth stage in FG individuals but expressed during the late stage in SG individuals, indicating considerable variations in the expression profiles of growth-related genes at different developmental stages. Overall, these findings contribute to the understanding of the growth mechanism of S. d. denticulatus, which would be useful for the propagation of fast-growing breeds.

Distribution of freshwater fishes in Annassery pond, Thalakkulathoor Panchayat, Kozhikode Thaluk, Kerala

In the present communication, an attempt has been made to systematically classify freshwater fishes in Annassery pond Kozhikode. The survey was conducted for a period from June 2020 to May 2021 mainly focused on the distribution and diversity of freshwater fishes. The field studies identified about 8 species of fish belonging to 7 genera, 6 families, and 5 orders based on IUCN status. The fishes diversity in aquatic ponds are very limited and the first-ever systematic survey on the fish diversity of this pond. Among the diversified fishes, Siluriformes and Anabantiformes were found most dominant order represented by 7 and 2 genera. Currently, most of the freshwater fishes population are gradually decreasing may due to climatic factors influences, and manmade activities, in this context to assess the diversity of fishes are important to understand the existing native fish stocks and exotic fish population ratio at the pond level.

Freshwater Fishes of Central America: Distribution, Assessment, and Major Threats

Central America contains a rich diversity of freshwater habitats that support more than 600 species of freshwater fishes. However, despite several perceived threats to the integrity of the freshwater habitats throughout the region, a formal analysis of extinction risk for the region’s ichthyofauna is lacking. In this manuscript, we report an updated checklist of species and a novel comprehensive assessment of the conservation status of Central American freshwater fishes by applying the IUCN Red List Categories and Criteria to species at the global level. We also analyze the distribution of freshwater fishes across Central America and generate baseline geospatial data that can be used in multi-species conservation planning processes, which is available through the Red List Website. Our results indicate that between 15 and 28% of freshwater fishes in the region are threatened with extinction, with considerable uncertainty resulting from elevated data deficiency. We identify major and widespread threats in the region, including pollution, agriculture, aquaculture, biological resource use, natural system modifications, invasive species, and land development. This analysis represents an important first step in formulating effective conservation planning and action initiatives for a taxonomic group that historically has received few protections and can be used to inform conservation priorities of freshwater ecosystems at both national and regional scales.