Conservation Of Fish Biodiversity Research Articles

Mitochondrial Fission Is Involved in Heat Resistance in Zebrafish.

Global warming and extreme weather events pose a significant threat to global biodiversity, with rising water temperatures exerting a profound influence on fish conservation and fishery development. In this study, we used zebrafish as a model organism to explore the impact of a heat acclimation period on their survival rates. The results demonstrated that a 2-month heat acclimation period almost completely mitigated heat stress-induced mortality in zebrafish. Subsequent analysis of the surviving zebrafish revealed a predominance of hepatic mitochondria in a fission state. Remarkably, a short-term fasting regimen, which induced hepatic mitochondrial fission, mirrored the outcomes of the protective effect of heat acclimation and augmented animal survival under heat stress. Conversely, treatment with a mitochondrial fission inhibitor within the fasting group attenuated the elevated survival rate. Furthermore, zebrafish embryos subjected to brief heat acclimation also exhibited increased heat resistance, a trait diminished by a chemical intervention inhibiting mitochondrial fission. This suggests a shared mechanism for heat resistance between embryos and adult zebrafish. These findings underscore the potential use of inducing mitochondrial fission to enhance heat resistance in zebrafish, offering promise for fish biodiversity conservation in the face of global warming.

Examination of the Utility of Environmental DNA Metabarcoding for Monitoring Fish Species in Han Rivr, Korea

Han River in Korea is a crucial water resource and fish habitat. Nonetheless, its biodiversity is declining because of anthropogenic activities, particularly pollution. Fish species sensitive to environmental changes are monitored to conserve biodiversity and pollution monitoring. Fish species can be monitored based on environmental DNA (eDNA) which is released by organisms into the environment eDNA metabarcoding can compensate for the difficulties of collection-based fish monitoring and can be used for efficient monitoring. This study aimed to examine the utility of eDNA metabarcoding for monitoring fish species by performing eDNA metabarcoding of fish 12S rRNA from water samples collected from three locations in the Han River. The results were compared with collection-based survey data from the Water Environment Information System (Ministry of Environment of Korea) from the last three years. The results revealed 32 species that were identified in three locations through eDNA metabarcoding analysis. At all locations, eDNA metabarcoding detected 74.4% of the 43 fish species compared with the collection-based survey data, confirming as a valuable tool for monitoring fish species in Han River. Additionally, eDNA metabarcoding can be used as a tool to compensate for the limitations of collection-based surveys by detecting species with hiding characteristics and nocturnal species that are difficult to detect in collection-based surveys. The results of this study can be used as primary data to contribute to the conservation of fish biodiversity in Han River in the future.

Determination of Growth Indicators of Tilapia sparrmanii (Smith, 1840) in Molepo Dam, South Africa.

<b>Background and Objective:</b> The sustainable management and conservation of fish biodiversity depends on studying fish biology. In this study, the length-weight relationships and condition factors of <i>Tilapia sparrmanii</i> were observed to gain a better understanding of their ecological and nutritional conditions. This information is crucial for the effective management of fisheries. <b>Materials and Methods:</b> During the study, 100 <i>T. sparrmanii</i> were collected from the Molepo Dam from October, 2022 to March, 2023. This fish's condition factor (CF) and length-weight relationship (LWR) were studied. To determine the size of each fish, the total length was measured using a caliper with a precision of 0.1 mm and the weight using a balance with an accuracy of 0.1 g. Differences were analyzed using ANOVA with the Tukey's <i>post hoc</i> test. A non-parametric Chi-square test was employed to evaluate the differences in sexes each month. <b>Results:</b> Their total length and body weight ranged from 4-15 cm and 0.96-57.96 g, respectively. The study found a strong positive relationship between the length and weight of the fish (r = 0.96). The regression coefficient (b) was more than 3.0, indicating a positive allometric growing rate. The condition factors (K) of males and females were not significantly different (p>0.05). The lowest CF value was observed in March (K = 1.01±0.03) and the highest in December (K = 1.73±0.12). The sex ratio of 1.0 male to 1.15 female was observed, which was significantly different from the theoretical ratio of one male to one female. This suggests that males were not significantly more than females (p>0.05). <b>Conclusion:</b> The study found that <i>T. sparrmanii</i> in Molepo Dam exhibited allometric growth, as evidenced by a strong correlation between length and weight represented by a high "r" value. This fish is in good condition because it has no competition for food due to ecological factors.

Fishes of the Alitash National Park: Taxonomic Accounts with Identification Keys of Fish in Floodplain Rivers of Abbay and Tekeze Basins, Ethiopia

Ethiopia has considerable freshwater potential. Currently, the recognized fish diversity in the country’s freshwater ecosystem is more than 200. Despite the presence of such high fish diversity with considerable economic returns, ichthyofaunal studies on Ethiopian rivers are scarce. Thus, this study aimed to identify and compare ichthyofaunal diversity and distribution in floodplain rivers of the Abbay and Tekeze Basins, Ethiopia. Fish were collected using gillnets, cast nets, hooks, electrofishing, and mosquito nets and identified to the species level. Gillnets had stretched mesh sizes of 4–14 cm with a panel length of 25–75 m and a width of 1.5–2 m per mesh size. They were set in the afternoon (5:00 p.m.) and lifted the following morning (7:30 a.m.). Immediately after capture, fish were preliminary identified in the field and tagged with proper information (e.g., sampling locality and date of collection). Similar fishing efforts were applied at all sampling sites for two dry and two wet months over a period of two years (2018-2019). In the present study, both alpha and beta diversity indices were also examined. Identification keys and an annotated checklist of species were generated for easy naming of the entire fish species in the basins. In the ichthyological collection, 43 fish species with 11 new records from the Ayima, Gelegu, and Shinfa Rivers were identified. The first two rivers in the Abbay Basin were the richest in species and number of individuals. Gelegu River had the highest abundance as well. Generally, this study was conducted in areas where no fish biodiversity studies have been undertaken, and the results obtained from this study could be important for fish biodiversity conservation.

Considering species functional and phylogenetic rarity in the conservation of fish biodiversity

AbstractAimRare species make substantial contributions to coastal ecosystem functions. Functional rarity (FR) and phylogenetic rarity (PR) are important features for biodiversity conservation. This work aimed to discuss the necessity and reasonableness of conserving fish FR and PR in coastal seas.LocationChina.MethodsBy compiling historical fish investigation data, joint species distribution modelling (JSDM) was applied to model fish communities in coastal China Seas. Biogeographic patterns of FR and PR were explored, and the effectiveness of current MPA networks in terms of match/mismatch with the hotspots of rarity was assessed.ResultsA total of 44 functionally rare species and 22 phylogenetically rare species were identified. Six of these species were both functionally and phylogenetically rare, and only one was listed as endangered on the Red List of the International Union for Conservation of Nature (IUCN). Functional rarity hotspots covered 10.27% of the coastal areas, which geographically converged in the southern and eastern coast of Taiwan, the Yangtze River Estuary and the Yellow River Estuary. Phylogenetic rarity hotspots only covered 3.06% of the coastal areas, which were sporadically distributed in the coastal East China Sea, the Bohai Sea and the northern Yellow Sea. Current marine‐protected areas (MPAs) only represented 16.16% of the FR hotspots and 20.48% of the PR hotspots, indicating substantial mismatched areas between the MPAs and the hotspots of FR and PR.Main ConclusionsOnly considering threatened species in conservation practices will omit functionally and phylogenetically rare species because FR and PR are not necessarily correlated with species threat status on the IUCN Red List. Functional rarity hotspots do not necessarily overlap with PR hotspots, and current MPAs mismatch the majority of these areas. We therefore advocate that conservation prioritization and expansion of MPA networks should account for FR and PR both at the species and site levels.

Importance of fish biodiversity conservation and management

One of the key concerns for enabling the sustainable use of natural resources is biodiversity and its conservation. Fish make up the most varied group of vertebrates and they are considered to be a reliable indication of water pollution. Humans are causing an increasing loss of biodiversity in aquatic ecosystems, which is likely to have a detrimental impact on ecosystem functioning, services, and resistance to future environmental change. Overfising from different water bodies is one of the major issues which could affect the aquatic ecosystems. These fishing pressures may alter the development and behaviour of fish, alter the life cycles and productivity of fish, and reduce availability of fish stocks. All ecosystems undergo change, and both the existence and number of species will fluctuate with or without human intervention and this should be taken into account for safeguarding biodiversity. In some of the most biodiverse areas in the globe, patterns and causes of aquatic biodiversity loss are poorly understood. This is concerning because a growing number of development projects, like hydropower dams, could have significant effects on the fish fauna of the associated river systems. Many of these areas are also among the most threatened aquatic system on Earth and have human populations that are heavily dependent on the ecosystem services they provide.

Fish biodiversity and their conservation measures in the Mathabhanga river, Chuadanga, Bangladesh

The study was concerned to determine the present status of the fish biodiversity in the Mathabhanga river, Chuadanga and its conversation measures based on the questionnaire interview with 40 fishers, focus group discussion with river bank community members and cross check interview with key informants. A field study was conducted for a period of four months from December, 2021 to March, 2022 to assess the fish biodiversity in the Mathabhanga river, investigate the existing fishing practices and also to identify proper management strategies for the conservation of fish biodiversity in the river. The results revealed that three categories of fishers were engaged in the Mathabhanga river namely, professional fishers (45.0%), seasonal fishers (37.5%) and subsistence fishers (17.5%). Shannon-Weaver diversity (H) and Margalef’s richness (D) values revealed that diversity and richness of fish species were the highest in March (H = 2.99, D = 4.45), followed by February (H = 2.96, D = 3.69) and January (H = 2.63, D = 3.15), while the lowest values were obtained in December (H = 2.60, D = 2.80). The Pielou’s evenness (e) values were found to be slightly varied with the variations of total number of species, being the highest in December (e = 0.94) and the lowest in January (e = 0.91). Different types of fishing gears like seine net, gill net, cast net, hook and line, and traps were found to be operated to catch fish by the fishers during this survey. A total of 26 fish species were identified in the catches of the Mathabhanga river. According to the survey, indiscriminate and overexploitation were found to be responsible for almost 40% loss, and pollution and siltation caused about 25% loss of ecosystem. Around 20% and 15% loss of ecosystem were caused by habitat destruction and changes of river course, respectively. As a result, the water quality was deteriorating day by day, and the availability of fish species and other aquatic biodiversity were decreasing gradually. During the survey, almost 16 fish species was found at a risk to be endangered. The specific conservation measures including community based fisheries management, establishment of sanctuary, control of pollution, maintenance of fishing gears and the implementation of fisheries act should need to be made for the sustainable utilization and conversation of fish biodiversity in the Mathabhanga river.

Biotic resistance to fish invasions in southern China: Evidence from biomass, habitat, and fertility limitation.

Understanding the mechanisms underlying the invasion success or failure of alien species can help to predict future invasions and cope with the invaders. The biotic resistance hypothesis posits that diverse communities are more resistant to invasion. While many studies have examined this hypothesis, the majority of them have focused on the relationship between alien and native species richness in plant communities, and results have often been inconsistent. In southern China, many rivers have been invaded by alien fish species, providing an opportunity to test the resistance of native fish communities to alien fish invasions. Using survey data for 60,155 freshwater fish collected from five main rivers of southern China for 3 years, we assessed the relationships between native fish richness and the richness and biomass of alien fishes at river and reach spatial scales, respectively. Based on two manipulative experiments, we further examined the impact of native fish richness on habitat selection and the reproductive ability of an exotic model species Coptodon zillii. We found no apparent relationship between alien and native fish richness, whereas the biomass of alien fish significantly decreased with increasing native fish richness. In experiments, C. zillii preferred to invade those habitats that had low native fish richness, given evenly distributed food resources; reproduction of C. zillii was strongly depressed by a native carnivorous fish Channa maculata. Together, our results indicate that native fish diversity can continue to provide biotic resistance to alien fish species in terms of limiting their growth, habitat selection, and reproduction when these aliens have successfully invaded southern China. We thus advocate for fish biodiversity conservation, especially for key species, to mitigate against the population development and ecological impact of alien fish species.

Effectiveness of the Natura 2000 network for freshwater fish conservation in a Mediterranean region

Protected areas (PAs) are the cornerstones of global biodiversity conservation efforts, but to fulfil this role they must be effective at conserving both habitat and species. Among protected taxa, freshwater fish are exposed to multiple disturbances and are considered one of the most endangered. The Natura 2000 reserves network was established with the aim of preserving biodiversity across Europe, but few assessments have been made on its effectiveness on the conservation of freshwater fish species. We tested the hypothesis that fish community is exposed to less anthropogenic pressures within the Natura 2000 sites than outside, hosting a higher number of native species and maintain lower number of non-native species. We tested these hypotheses considering 3,777 sampling sites, found across the entire Italian territory. Results showed that PAs did not guarantee less anthropogenic impacts and higher fish species richness than outside PAs, suggesting that PAs are not a panacea for anthropogenic pressures and safeguarding fish diversity. Nevertheless, more caution should be applied to the management measures and the design of new PAs due to the limitations of the protection of a single stretch within a whole river ecosystem. Moreover, the impossibility to operate any management of invasive fish species on the broad scale of a whole river basin is likely the most limiting factor to fish biodiversity conservation in Italy. Finally, it is also necessary to extend the analysis to other basins and Natura 2000 sites in Europe.

Freshwater Fish Biodiversity in a Large Mediterranean Basin (Guadalquivir River, S Spain): Patterns, Threats, Status and Conservation

The Guadalquivir River Basin is one of the largest in the Iberian Peninsula and has a remarkable freshwater biodiversity. Although many studies on hydrological regimes or water quality have been conducted in this basin the biodiversity of freshwater fish, as well as their distribution and conservation status, has never been globally addressed as in other Iberian basins. In this context, we synthesized information on freshwater fish using field procedures and a bibliographic search. Fish distribution patterns at different spatial scales and general environmental conditions were analyzed as well as the conservation status of the fish community. We documented the presence of 40 species (20 native and 20 exotic) in the basin during the 20th century until today. However, we only captured 18 species during the field sampling, with a prevalence for any native species of less than 23% (except Luciobarbus sclateri). The highest species richness was found in mid reaches, while the lower reaches had very low diversity values. Around 50% of species are threatened; according to the IUCN, several species are declining at an alarming rate and others are probably extinct and/or their current status is unknown. Human disturbances during the last few decades have caused serious changes in fish distribution and consequently to their conservation status. Hydrological alterations, intensive agriculture and introduced species are probably the principal reasons for Guadalquivir’s ichthyofauna imperilment. Our study indicates an urgent and real need to identify important areas for fish conservation to guarantee a minimum fish biodiversity conservation over the long term, as well as effective strategies for fish recovery where it still is possible.

Condition Factor and Length-Weight Relationship of Scardinius erythrophthalmus (Linnaeus, 1758) in Anzali Lagoon.

<b>Background and Objective:</b> Studies on fish biology are essential for the sustainable management and conservation of fish biodiversity. This study observed the length-weight relationships and condition factors of common rudd fish, which give us some information about the ecological and nutritional conditions of fish. This information is crucial to fishery management. <b>Materials and Methods:</b> The length-weight relationship (LWR) and condition factors (K) of 270 <i>Scardinius erythrophthalmus</i> caught in Anzali Lagoon from April to August, 2015. <b>Results:</b> The total length and body weight of <i>S. erythrophthalmus</i> ranged from 94-179 mm and 11.98-98.5 g, respectively. A strong positive relationship was observed between length and weight (r = 0.96). There were no significant differences in the condition factors of males and females (p>0.05). The lowest K value was observed in April (K = 1.5±0.04) and the highest in July (K = 2.25±0.34). The sex ratio of 1.0 male: 1.15 female was observed, with no significant difference between males and females (p>0.05). <b>Conclusion:</b> In this study, the regression coefficient (b) in males and females was 3.35 and 3.29, respectively, more than 3.0, which means they have positive allometry growth in both sexes.

Global water consumption impacts on riverine fish species richness in Life Cycle Assessment

Reduced river discharge and flow regulation are significant threats to freshwater biodiversity. An accurate representation of potential damage of water consumption on freshwater biodiversity is required to quantify and compare the environmental impacts of global value chains. The effect of discharge reduction on fish species richness was previously modeled in life cycle impact assessment, but models were limited by the restricted geographical scope of underlying species-discharge relationships and the small number of species data. Here, we propose a model based on a novel regionalized species-discharge relationship (SDR). Our SDR-based model covers 88 % of the global landmass (2320 river basins worldwide excluding deserts and permanently frozen areas) and is based on a global dataset of 11,450 riverine fish species, simulated river discharge, elevation, and climate zones. We performed 10-fold cross-validation to select the best set of predictors and validated the obtained SDRs based on observed discharge data. Our model performed better than previous SDRs employed in life cycle impact assessment (Kling-Gupta efficiency coefficient about 4 times larger). We provide both marginal and average models with their uncertainty ranges for assessing scenarios of small and large-scale water consumption, respectively, and include regional and global species loss. We conducted an illustrative case study to showcase the method's applicability and highlight the differences with the currently used approach. Our models are useful for supporting sustainable water consumption and riverine fish biodiversity conservation decisions. They enable a more specific, reliable, and complete impact assessment by differentiating impacts on regional riverine fish species richness and irreversible global losses, including up-to-date species data, and providing spatially explicit values with high geographical coverage.

Nanotechnology in reproduction, breeding and conservation of fish biodiversity: Current status and future potential

AbstractThe reproductive capability of an organism is the main factor to determine the stability of the population. Till now, numerous reproductive strategies have been used, to successfully breed the fish in captivity but the desired performance is yet to be achieved. Nanotechnology has transformed the reproductive capacity of higher animals to a greater extent and has a huge potential in the aquaculture sector too. The use of nanotechnology in fish reproduction and breeding is limited to the delivery of drugs, hormones, vaccines, or genes and still, an immense scope is left in the area that needs to be explored. Here, the recent progress of nanotechnology in fish reproduction, breeding and conservation of germplasm is reviewed. Further, the key successes in the development of cryopreservation, semen imaging, sperm sorting, germplasm preservation, prototypes of smart nanobiosensors and drug delivery systems in animals including fish are highlighted. The potential future opportunities for nanotechnology to enhance reproductive output and conservative management of fish have been presented. In general, the current review summarises some of the applications of nanotechnology that are performing well in higher animals and could be a game‐changer in manipulating the reproductive potential or conserving the fish germplasm.

Hydrologic variation influences stream fish assemblage dynamics through flow regime and drought

Hydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable flow regimes. We sampled habitats (pool, run, and riffle) in three Runoff/Intermittent Flashy streams (highly variable flow regime) and three Groundwater Flashy streams (less variable flow regime) seasonally (spring, early summer, summer and autumn) in 2002 (drought year) and 2003 (wet year). We used backpack electrofishing and three-pass removal techniques to estimate fish species richness, abundance and density. Fish species richness and abundance remained relatively stable within streams and across seasons, but densities changed substantially as a result of decreased habitat volume. Mixed model analysis showed weak response variable-habitat relationships with strong season effects in 2002, and stronger habitat relationships and no season effect in 2003, and flow regime was not important in structuring these relationships. Seasonal fish species turnover was significantly greater in 2002 than 2003, but did not differ between flow regimes. Fish assemblage stability was significantly lower in Runoff/Intermittent Flashy than Groundwater Flashy streams in 2002, but did not differ between flow regimes in 2003. Redundancy analysis showed fish species densities were well separated by flow regime in both years. Periodic and opportunistic species were characteristic of Runoff/Intermittent Flashy streams, whereas mainly equilibrium species were characteristic of Groundwater Flashy streams. We found that spatial and temporal variation in hydrology had a strong influence on fish assemblage dynamics in Ozark streams with lower assemblage stability and greater fluctuations in density in more hydrologically variable streams and years. Understanding relationships between fish assemblage structure and hydrologic variation is vital for conservation of fish biodiversity. Future work should consider addressing how alteration of hydrologic variation will affect biotic assemblages.

Mesophotic fish communities of the ancient coastline in Western Australia.

Marine diversity across the Australian continental shelf is shaped by characteristic benthic habitats which are determined by geomorphic features such as paleoshorelines. In north-western Australia there has been little attention on the fish communities that inhabit an ancient coastline at ~125 m depth (the designated AC125), which is specified as a key ecological feature (KEF) of the region and is thought to comprise hard substrate and support enhanced diversity. We investigated drivers of fish species richness and assemblage composition spanning six degrees of latitude along sections of the ancient coastline, categorised as ‘on’ and ‘off’ the AC125 based on depth, across a range of habitats and seafloor complexity (~60–180 m depth). While some surveyed sections of the AC125 had hard bottom substrate and supported enhanced fish diversity, including over half of the total species observed, species richness and abundance overall were not greater on the AC125 than immediately adjacent to the AC125. Instead, depth, seafloor complexity and habitat type explained patterns in richness and abundance, and structured fish assemblages at both local and broad spatial scales. Fewer fishes were associated with deep sites characterized by negligible complexity and soft-bottom habitats, in contrast to shallower depths that featured benthic biota and pockets of complex substrate. Drivers of abundance of common species were species-specific and primarily related to sampling Areas, depth and substrate. Fishes of the ancient coastline and adjacent habitats are representative of mesophotic fish communities of the region, included species important to fisheries and conservation, and several species were observed deeper than their currently known distribution. This study provides the first assessment of fish biodiversity associated with an ancient coastline feature, improving our understanding of the function it plays in regional spatial patterns in abundance of mesophotic fishes. Management decisions that incorporate the broader variety of depths and habitats surrounding the designated AC125 could enhance the ecological role of this KEF, contributing to effective conservation of fish biodiversity on Australia’s north west shelf.

Characterization of fish assemblages in mesophotic reefs of Cuba

Although mesophotic coral reef ecosystems (MCEs) are widespread and diverse, they remain largely unexplored. The Caribbean MCEs are among the most studied in the world, but detailed information regarding Cuban MCEs is limited. In this study we present the first analyses of the ichthyofauna of the Cuban MCEs based on data from a research cruise in June 2017. Forty-two sites were sampled around the Archipelago of Cuba using a Remotely Operated Vehicle at depths between 30 and 180 m. Overall, 151 species were observed, including 13 threatened species. Differences in ichthyofauna were observed between marine protected areas (MPAs) and unprotected areas, with greater abundances and species richness inside national parks. Invasive lionfish had greater abundances on the north coast, while the south coast had greater abundances and richness of threatened and commercially valuable species. A detailed analysis (Generalized Lineal Model) showed effects of depth, protection level, reef type (seamount or fringing reef), and region on abundance (as fish observed per minute), but no interaction between them. A transition was observed in the fish assemblages between the 30–60 m and 60–100 m depth ranges. Species abundance and richness decreased with increasing depth. The most represented families of commercial importance (Serranidae, Lutjanidae, and Carangidae) were well represented in the upper, middle, and lower areas of the MCEs, but dominated in deeper areas. The percentage of herbivores in the fish assemblage decreased with increasing depth, contrary to what was observed with piscivores and invertebrate feeders/piscivores. Twenty-seven functional groups were identified, with cryptic micro-invertivores and cryptic planktivores being the most abundant, while roving macro-invertivores and roving piscivores were the most functionally redundant. This research constitutes a valuable contribution to the study and management of ichthyofauna in Cuba and highlights the effectiveness of MPAs in the conservation of fish biodiversity.

Freshwater conservation planning in the far north of Ontario, Canada: identifying priority watersheds for the conservation of fish biodiversity in an intact boreal landscape

Freshwater ecosystems show more biodiversity loss than terrestrial or marine systems. We present a systematic conservation planning analysis in the Arctic Ocean drainage basin in Ontario, Canada, to identify key watersheds for the conservation of 30 native freshwater fish, including four focal species: lake sturgeon, lake whitefish, brook trout, and walleye. We created species distribution models for 30 native fish species and accounted for anthropogenic impacts. We used the “prioritizr” package in R to select watersheds that maximize species targets, minimize impacts, and meet area-based targets based on the Convention on Biological Diversity commitment to protect 17% of terrestrial and freshwater areas by 2020 and the proposed target to protect 30% by 2030. We found that, on average, 17.4% and 29.8% of predicted species distributions were represented for each of the 30 species in the 17% and 30% area-based solutions, respectively. The outcomes were more efficient when we prioritized for individual species, particularly brook trout, where 24% and 36% of its predicted distribution was represented in the 17% and 30% solutions, respectively. Future conservation planning should consider climate change, culturally significant species and areas, and the importance of First Nations as guardians and stewards of the land in northern Ontario.

Fish Biodiversity Conservation and Restoration, Yangtze River Basin, China, Urgently Needs ‘Scientific’ and ‘Ecological’ Action

Although many significant policies and legislation have been put forth by the Chinese government aiming toward “ecological civilization” for the aquatic environment, in practice, the situation is still undesirable. A pioneering multi-year study has since been conducted on the East Tiaoxi River (a major tributary of the renowned Yangtze River), focusing on fish distribution, influencing factors and habitat requirements, and river health as well. This revealed certain key species, hotspot protection areas, negative impacts of local anthropogenic activities, and inappropriate perceptions and practices of conservation and restoration. We found that not all fish species were equally conserved and that the supposedly ecological engineering measures were initiated without regard for ecological integrity. Our exemplary study appreciates scientific basis and truly ecological notion, and urgently advocates comprehensive and continuous basin-scale scientific investigation of fish biodiversity, and “ecological river”-oriented conservation and restoration action for the Yangtze River Basin and broader areas of China.

Special features of neuroendocrine interactions between stress and reproduction in teleosts

Stress and reproduction are both essential functions for vertebrate survival, ensuring on one side adaptative responses to environmental changes and potential life threats, and on the other side production of progeny. With more than 25,000 species, teleosts constitute the largest group of extant vertebrates, and exhibit a large diversity of life cycles, environmental conditions and regulatory processes. Interactions between stress and reproduction are a growing concern both for conservation of fish biodiversity in the frame of global changes and for the development of sustainability of aquaculture including fish welfare. In teleosts, as in other vertebrates, adverse effects of stress on reproduction have been largely documented and will be shortly overviewed. Unexpectedly, stress notably via cortisol, may also facilitate reproductive function in some teleost species in relation to their peculiar life cyles and this review will provide some examples. Our review will then mainly address the neuroendocrine axes involved in the control of stress and reproduction, namely the corticotropic and gonadotropic axes, as well as their interactions. After reporting some anatomo-functional specificities of the neuroendocrine systems in teleosts, we will describe the major actors of the corticotropic and gonadotropic axes at the brain-pituitary-peripheral glands (interrenals and gonads) levels, with a special focus on the impact of teleost-specific whole genome duplication (3R) on the number of paralogs and their potential differential functions. We will finally review the current knowledge on the neuroendocrine mechanisms of the various interactions between stress and reproduction at different levels of the two axes in teleosts in a comparative and evolutionary perspective.

Genetic Evidence for a Mixed Composition of the Genus Myoxocephalus (Cottoidei: Cottidae) Necessitates Generic Realignment.

Sculpin fishes belonging to the family Cottidae represent a large and complex group, inhabiting a wide range of freshwater, brackish-water, and marine environments. Numerous studies based on analysis of their morphology and genetic makeup frequently provided controversial results. In the present work, we sequenced complete mitochondrial (mt) genomes and fragments of nuclear ribosomal DNA (rDNA) of the fourhorn sculpin Myoxocephalus quadricornis and some related cottids to increase the power of phylogenetic and taxonomic analyses of this complex fish group. A comparison of the My. quadricornis mt genomes obtained by us with other complete mt genomes available in GenBank has revealed a surprisingly low divergence (3.06 ± 0.12%) with Megalocottus platycephalus and, at the same time, a significantly higher divergence (7.89 ± 0.16%) with the species of the genus Myoxocephalus. Correspondingly, phylogenetic analyses have shown that My. quadricornis is clustered with Me. platycephalus but not with the Myoxocephalus species. Completely consistent patterns of divergence and tree topologies have been obtained based on nuclear rDNA. Thus, the multi-gene data in the present work indicates obvious contradictions in the relationships between the Myoxocephalus and Megalocottus species studied. An extensive phylogenetic analysis has provided evidence for a closer affinity of My. quadricornis with the species of the genus Megalocottus than with the species of the genus Myoxocephalus. A recombination analysis, along with the additional GenBank data, excludes introgression and/or incorrect taxonomic identification as the possible causative factors responsible for the observed closer affinity between the two species from different genera. The above facts necessitate realignment of the genera Myoxocephalus and Megalocottus. The genetic data supports the two recognized genera, Myoxocephalus and Megalocottus, but suggests changing their compositions through transferring My. quadricornis to the genus Megalocottus. The results of the present study resolve the relationships within a complex group of sculpin fishes and show a promising approach to phylogenetic systematics (as a key organizing principle in biodiversity research) for a better understanding of the taxonomy and evolution of fishes and for supplying relevant information to address various fish biodiversity conservation and management issues.