International Journal of Molecular Ecology and Conservation, 2025, Vol.15 http://ecoevopublisher.com/index.php/ijmec © 2025 EcoEvoPublisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved.
International Journal of Molecular Ecology and Conservation, 2025, Vol.15 http://ecoevopublisher.com/index.php/ijmec © 2025 EcoEvoPublisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved. EcoEvoPublisher is an international Open Access publishing platform that publishes scientific journals in the field of ecology and evolution registered at the publishing platform that is operated by Sophia Publishing Group (SPG), founded in British Columbia of Canada. Publisher EcoEvo Publisher Edited by Editorial Team of International Journal of Molecular Ecology and Conservation Email: edit@ijmec.ecoevopublisher.com Website: http://ecoevopublisher.com/index.php/ijmec Address: 11388 Stevenston Hwy, PO Box 96016, Richmond, V7A 5J5, British Columbia Canada International Journal of Molecular Ecology and Conservation (ISSN 1927-663X) is an open access, peer reviewed journal published online by EcoEvoPublisher. The journal is considering all the latest and outstanding research articles, letters and reviews in all aspects of molecular ecology and conservation, containing the contents of the ranges from the applied to the theoretical in molecular ecology and nature conservation, the policy and management with comprehensive and applicable information; the ecological bases for the conservation of ecosystems, species, genetic diversity, the restoration of ecosystems and habitats; as well as the expands the field of ecology and conservation work. All the articles published in International Journal of Molecular Ecology and Conservation are Open Access, and are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. EcoEvoPublisher uses CrossCheck service to identify academic plagiarism through the world’s leading plagiarism prevention tool, iParadigms, and to protect the original authors’ copyrights.
International Journal of Molecular Ecology and Conservation (online), 2025, Vol. 15, No.4 ISSN 1927-663X https://ecoevopublisher.com/index.php/ijmec © 2025 EcoEvoPublisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved. Latest Content Genetic Differentiation and Invasive Expansion Mechanisms of Global Channa Populations Yue Zhu, Jinni Wu International Journal of Molecular Ecology and Conservation, 2025, Vol. 15, No. 4, 153-162 Ecological Succession and Community Dynamics at Whale Fall Sites Manman Li International Journal of Molecular Ecology and Conservation, 2025, Vol. 15, No. 4, 163-174 Mechanisms and Patterns of Seed Dispersal in Terrestrial Ecosystems Jiong Fu International Journal of Molecular Ecology and Conservation, 2025, Vol. 15, No. 4, 175-186 Impacts of Climate Change on Snake Habitat Selection and Population Dynamics Jing He, Jun Li International Journal of Molecular Ecology and Conservation, 2025, Vol. 15, No. 4, 187-195 African Terrestrial Snails as Emerging Invasive Pests: Assessing Their Ecological and Agricultural Impacts Wenying Hong, Rudi Mai International Journal of Molecular Ecology and Conservation, 2025, Vol. 15, No. 4, 196-205
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 3 Research Insight Open Access Genetic Differentiation and Invasive Expansion Mechanisms of Global Channa Populations Yue Zhu 1, Jinni Wu 2 Aquatic Biology Research Center, Cuixi Academy of Biotechnology, Zhuji, 311800, Zhejiang, China Corresponding email: jinni.wu@cuixi.org International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4 doi: 10.5376/ijmec.2025.15.0016 Received: 10 May, 2025 Accepted: 18 Jun., 2025 Published: 03 Jul., 2025 Copyright © 2025 Zhu and Wu, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhu Y., and Wu J.N., 2025, Genetic differentiation and invasive expansion mechanisms of global channa populations, International Journal of Molecular Ecology and Conservation, 15(4): 153-162 (doi: 10.5376/ijmec.2025.15.0016) Abstract This study reviews the research achievements in molecular ecology in recent years, sorted out the genetic diversity and global population structure of the main species of the Channa spp., revealed the genetic differentiation patterns of the native and invasive populations, as well as the ecological genetic mechanisms behind the successful invasion and rapid spread of acanthus. This study analyzed the population characteristics of the native Asian habitat and invasive regions such as North America and Europe through regional case studies, explored the invasion paths and spread patterns of black fish, and evaluated the possible ecological risks they might bring in new water areas. At the same time, the challenges faced in the management of black fish invasion were also discussed, emphasizing the importance of using population genetic data for risk assessment and traceability management, and looking forward to possible ways to curb the global invasion of black fish in the future by establishing transmission prediction models, developing genetic control technologies and implementing ecological restoration strategies. Studies have shown that the Channa spp exhibits significant genetic differentiation worldwide, as well as an invasion and diffusion ability driven by both biological characteristics and human activities. Strengthening international collaboration and conducting risk monitoring and management based on molecular ecological data are key measures to deal with the invasion of black fish. This research not only holds significance for protecting biodiversity but also provides crucial evidence for the assessment and traceability of intrusion risks. Keywords Channa spp.; Genetic diversity; Invasive species; Population differentiation; Diffusion mechanism 1 Introduction Invasive species have become an important driver of global ecosystem change and biodiversity loss, and the environmental and economic losses they cause have attracted widespread attention from various countries (Early et al., 2016). The Channa spp. belongs to the family Channa of the order Siluriformes. It is a kind of carnivorous freshwater fish native to Asia. It is commonly known as "snakehead fish" because of its wide and flat head resembling a snake. Black fish have unique respiratory organs. They can breathe through gills and also breathe air with the assistance of gills. This enables them to survive in hypoxic environments and stay out of water for several days in moist conditions (Resh et al., 2021). Origin studies have shown that most species of black fish have typical reproductive characteristics combining R-strategy and K-strategy, such as rapid growth, early maturity and high reproductive capacity, and parental protection of young fish (Orrell et al., 2005; Harrington et al., 2022). For example, the northern black fish (Channa argus) can lay tens of thousands of eggs at a time, and the parent fish will guard the fish nest and the young fish, improving the survival rate of the offspring (Resh et al., 2021). These biological advantages enable black fish to rapidly establish populations and spread after being introduced to new environments, exerting intense predation and competitive pressure on native fish in the local waters (Li et al., 2016; Harrington et al., 2022). Since the second half of the 20th century, with the development of global aquaculture, edible and ornamental fish trade, some species of the genus Channa have been artificially introduced to regions outside Asia and gradually evolved into highly invasive alien fish species (Gozlan et al., 2010; Harrington et al., 2022). The appearance of black fish has been reported in local waters of the United States, Russia, the Middle East and even Africa. Among them, northern black fish have formed multiple resident populations in the eastern United States, causing ecological risks and fishery management problems (Wegleitner et al., 2016).
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 4 In view of the possible ecological risks brought by the invasion of black fish, the management departments of various countries have begun to pay attention to its spread dynamics and source tracing. However, there may be differences in the genetic background and invasion mechanism of black fish populations in different regions, and the understanding of their global diffusion patterns is still insufficient (Bock et al., 2016; Resh et al., 2021). The development of molecular ecological methods has provided new tools for revealing the transmission paths of invasive species and their adaptive evolution. For example, population single nucleotide polymorphism (SNP) data obtained by high-throughput sequencing can be used to trace the origin of invasive populations and monitor changes in genetic diversity (Cristescu, 2016; Resh et al., 2021). This study will summarize the research progress on the genetic differentiation and invasion spread of black fish species in recent years, with a focus on the species diversity of the main black fish species and the geographical distribution patterns of their native habitats and invasion sites. Reveal the genetic structure of black fish populations and the genetic differentiation between native and invasive populations by using molecular markers; The ecological and genetic mechanisms of the invasive spread of black fish Typical regional case analysis of the spread patterns and genetic characteristics of black fish, as well as the challenges and future research directions faced by black fish invasion management. This study aims to deepen the understanding of the global invasive biology of black fish and provide a scientific basis for formulating effective prevention, control and management strategies. 2 The Species Diversity and Distribution Overview of the Genus Channa 2.1 Introduction to the main species of the genus Channa The genus Channa contains approximately 30 to 40 valid species in taxonomy and is widely distributed in tropical and temperate regions of Asia. It is an important carnivorous fish group in the inland waters of Asia. Among them, representative species include: Northern black fish (Channa argus), which is native to Northeast China, the Korean Peninsula and the Russian Far East (Figure 1) (Liu et al., 2024); The striped black fish (Channa striata) is widely found in countries in South and Southeast Asia. The red-scaled black fish (Channa micropeltes), also known as the giant black fish, is distributed in places such as the Malay Peninsula, Sumatra and Borneo in Southeast Asia. And other species such as the South Asian eye-spotted black fish (Channa marulius), Fujian black fish (Channa maculata), etc. (Conte-Grand et al., 2017; Harrington et al., 2022). Different black fish species have certain differences in ecological habits and life history strategies, which may affect their invasive ability. For example, the northern black fish ADAPTS to the temperate climate, can tolerate lower water temperatures, and can overwinter and reproduce in areas with lower annual average temperatures (Resh et al., 2021); The striped black fish prefers shallow water environments in tropical and subtropical regions and has the ability to sleep in the mud during the dry season and survive in harsh conditions. In terms of reproductive strategies, black fish generally belong to the multiple spawning type, with a high spawning frequency and a large single spawning quantity each year. The fertilized eggs have oil ball buoyancy and gather into clusters to float on the water surface. The parent fish will carry out the behavior of protecting the young for several weeks (Orrell and Weigt, 2005; Li et al., 2016). These characteristics enable black fish to reproduce efficiently and maintain population growth even in the absence of natural enemies after being introduced into new waters (Harrington et al., 2022). 2.2 Distribution pattern of origin and invasion areas The species of black fish are mainly native to East Asia, South Asia and Southeast Asia, including most parts of China, the Indian subcontinent and the countries of the Indochinese Peninsula, as well as the Indonesian archipelago, etc. (Conte-Grand et al., 2017). Within the original habitat, black fish populations in different geographical regions often form genetic differentiation due to historical geographical isolation. For example, the striped black fish has differentiated into several local populations or lineages in Southeast Asia (Duong et al., 2019; Robert et al., 2019). In recent decades, due to human activities, black fish have been introduced to many countries outside Asia, with the most notable invasion in North America. Since the end of the 20th century, invasive black fish have been
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 5 discovered in the United States many times. Among them, the breeding population was first confirmed in a pond in Maryland in 2002. Since then, northern black fish have successfully colonized in basins such as the Potomac River in the middle Atlantic of the United States and spread to adjacent water systems (Wegleitner et al., 2016; Odenkirk and Isel, 2016). In Europe, there were only sporadic records in the past: for instance, a giant black fish was caught in the hot spring waters of Tuscany, Italy in 2012, and northern black fish were introduced to Slovakia and the Czech Republic in the 20th century but did not form sustained populations (Piazzini et al., 2014). Figure 1 Map of sampling sites for C. argus. The red dot shows the specific sampling locations (Adopted from Liu et al., 2024) In other parts of Asia, the spread of black fish is more manifested as artificial transplantation beyond their original distribution areas. For instance, in China, the northern black fish was once introduced as a farmed species into some waters in the south, resulting in competition between it and the spotted black fish (Channa maculata), which is native to South China. Red-scaled black fish were introduced into reservoirs in Malaysia and proliferated explosively (Simberloff and Vitule, 2014). Reports in the Middle East show traces of invasive black fish found in wetlands in Iran and Iraq, speculated to be caused by aquatic release. In Africa, Madagascar introduced striped black fish from Asia for aquaculture in the 1970s. Later, they escaped into natural water bodies due to floods and spread, affecting the local freshwater fish population. 2.3 The role of human activities in diffusion Human activities are one of the main driving forces for black fish species to break through geographical barriers and achieve transcontinental diffusion (Harrington et al., 2022). The introduction of species in aquaculture is an important way for the large-scale transfer of black fish. The black fish has delicious meat and grows rapidly. It is a popular edible fish in some countries in East and Southeast Asia, and in some regions, it is also believed to have medicinal and nourishing value. Therefore, people have made many attempts to introduce black fish into new areas for aquaculture or restocking fisheries. For instance, in the 1960s, the Soviet Union introduced northern black fish for fishery resources and conducted experiments on stocking them in waters outside the Far East.
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 6 The ornamental fish trade has risen in recent years, driving some small or brightly colored black fish into the global pet market. India is one of the centers of snakehead diversity. Its exports of live snakehead increased sixfold from 2014 to 2019, mainly to mainland China, Taiwan, and Hong Kong (Harrington et al., 2022). Among them are many newly described "rainbow black fish" species. Due to the difficulty in species identification and insufficient trade regulation, once they escape or are abandoned, they may survive and reproduce in non-native environments. Black fish can be carried by humans across natural geographical barriers through live fish transportation and market sales. The fact that northern black fish appeared almost simultaneously in several disconnected river basins in the United States suggests that it is very likely the result of multiple introduction through different channels (Wegleitner et al., 2016). In Asia, the situation where native species are artificially transplanted and spread is more common. For example, the striped black fish has been artificially brought into the Philippines, some islands in Oceania and even areas outside the Korean Peninsula (Duong et al., 2019). In addition, religious release of animals is also a potential approach. In some Asian cultures, there is a tradition of releasing live fish back into nature, which may unintentionally introduce black fish into waters that do not exist originally (Gozlan et al., 2010). 3 The Genetic Structure and Differentiation Pattern of Black Fish Populations 3.1 Research progress in molecular markers and population genetics Molecular genetic markers provide a powerful tool for analyzing the population structure and invasion and spread history of black fish. Early studies mostly employed haplotype analysis of mitochondrial DNA fragments (such as control region D-loop or COI genes) to reveal the phylogenetic geographical patterns of species and potential latent species (Conte-Grand et al., 2017). In recent years, microsatellite (short tandem repeat) and single nucleotide polymorphism (SNP) markers have been widely used in population genetics studies of black fish (Yan et al., 2014; Wegleitner et al., 2016). After the rise of high-throughput sequencing, methods such as restriction enzyme restriction site association sequencing (RAD-seq) have been used for genome scanning of black fish, obtaining thousands of SNP loci and achieving a fine characterization of the population structure (Resh et al., 2018; Resh et al., 2021). In addition, methods such as whole genome sequencing and mitochondrial genome sequencing have also begun to be applied in black fish research: Xu et al. (2023) constructed a chromosomal reference genome of northern black fish, providing valuable resources for understanding the adaptive evolution of black fish; Some scholars have determined the complete mitochondrial genomes of multiple black fish species and conducted phylogenetic analyses, clarifying the evolutionary relationships within the black fish family. 3.2 Genetic diversity and lineage division of native populations The native populations of black fish usually have high genetic diversity and obvious geographical differentiation patterns. This is partly due to the long-term evolution of the black fish species over a vast area of Asia, which has been affected by river basin isolation and climate change, resulting in different local populations. On the other hand, some traditionally classified "widespread species" may actually contain several lineages with significant genetic differences (Conte-Grand et al., 2017). Take the striped black fish (Channa striata) as an example. Studies have shown that this species can be divided into at least two major genetic lineages, east and west, within its distribution area in North Borneo. The divergence between the two corresponds to the river segregation caused by paleogeographic events (Robert et al., 2019). High genetic diversity means that the native black fish has a rich gene pool, which is conducive to its adaptation to the variable environment (Duong et al., 2019). At the same time, the existence of different lineages should be treated with caution when classifying black fish and dividing conservation units. For instance, in recent years, a variety of new black fish species have been discovered in northeastern India and Myanmar. Many individuals that were previously classified as a known population actually belong to undescribed new species (Conte-Grand et al., 2017; Harrington et al., 2022). For invasive ecology, clarifying the genetic background of native populations is helpful for tracing the sources of alien populations.
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 7 3.3 Genetic bottlenecks and founding effects of invasive populations When black fish are introduced to new habitats, a population is usually established by only a small number of individuals, and thus may experience a decline in genetic diversity, namely the "founding effect" and genetic bottleneck. This is a common phenomenon in many invasive species: due to the limited number of initial invasive individuals, genetic variation is lower than that in the original habitat, which theoretically may limit their potential for adaptive evolution (Bock et al., 2016). However, the situation of the northern black fish in the United States indicates that multiple independent introductions and cross-mating may have alleviated the genetic bottleneck to a certain extent. Microsatellite analysis of several invasive populations in the eastern United States by Wegleitner et al. (2016) indicated that the genetic structures of northern blackfish in different rivers were different from each other, and it was inferred that at least two or more independent introduction events occurred. The introduction of multiple sources has led to a relatively high degree of genetic variation, and even cases of "genetic hybridization" due to interbreeding of different source lineages have occurred. Both theory and experience indicate that higher genetic diversity is conducive to the successful adaptation of invasive populations to new environments (Cristescu, 2016). Therefore, the genetic bottleneck effect of the black fish invasion population may be offset by multiple introductions. Conversely, if invasive populations reproduce in isolation for a long time and lack the inflow of new genes, there may be signs of reduced genetic diversity. For example, some interstate isolated pond populations have lower genetic variations and are presumed to be the offspring of a single event (Wegleitner et al., 2016). 4 The Ecological and Genetic Mechanisms of the Invasive Spread of Black Fish 4.1 The promoting effect of biological characteristics on diffusion The biological characteristics of the black fish species themselves are the basis for them to become successful invaders. These fish possess a series of adaptive characteristics that are conducive to diffusion and colonization. In terms of respiration, black fish have both gill respiration and assisted air respiration capabilities. They can survive in water bodies with low dissolved oxygen and crawl out of the water briefly when necessary to search for new ponds or rivers (Resh et al., 2021). In terms of reproduction, a high reproduction rate and parental child-rearing behavior significantly increased the growth rate and stability of invasive populations (Odenkirk and Isel, 2016). In terms of nutritional ecology, black fish, as one of the top predators, possess extremely strong adaptability to food and high hunting efficiency. They feed on a wide variety of species, ranging from fish and shrimp to amphibians, reptiles, and even small mammals (Li et al., 2016). The migration behavior of black fish is also worthy of attention. Although most of the time they inhabit still water environments such as lakes and ponds, they will move long distances along streams or ditches when resources are scarce or their habitats change (Love and Newhard, 2012). 4.2 Human activities and cross-border communication paths The global invasion of black fish largely depends on long-distance transmission routes mediated by humans. Under natural conditions, even if black fish have a certain ability to migrate over land, their spread is mainly confined within connected water systems or short adjacent waters. However, human means of transportation and trade networks have provided "transportation corridors" for black fish to cross continents and oceans (Harrington et al., 2022). Take the northern black fish as an example. Its introduction from East Asia to North America clearly could not be achieved through natural distribution, but was carried there by humans through aircraft, ships, etc. The ornamental fish industry has also formed a global network. Many black fish species are classified as tropical fish and are exported to the aquarium markets in Europe, America, Japan and other places by air. The risk of this path lies in the fact that once ornamental fish enthusiasts or merchants release black fish into the wild, it may trigger colonization. From this, it can be seen that the global spread of black fish is not simply a "spontaneous drift", but more like taking the "express train" of human logistics (Evers et al., 2019; Maia et al., 2025).
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 8 4.3 Genetic adaptation and rapid expansion capacity Whether black fish can successfully expand in the invasive area depends not only on the number of initially introduced individuals and their biological characteristics, but also closely related to their genetic adaptation process (Bock et al., 2016). When an invasive species enters a new environment, it needs to face different climatic, hydrological and biological factor pressures. If its population has sufficient genetic variation, it is more likely to quickly adapt to the new environment through natural selection and thus achieve expansion (Cristescu, 2016). The genomic characteristics of black fish (such as polyploid or gene replication) and abundant natural variations provide potential fitness advantages for them (Conte-Grand et al., 2017). When these fish have established a firm foothold in a new environment, they often prepare for further expansion through the preservation of genetic diversity or even evolution (Tepolt, 2015). In the future, through means such as comparative genomics and common garden experiments, the adaptive evolution mechanism during the invasion of black fish can be understood more deeply (Bock et al., 2016). This is of great significance for predicting its spread trend and formulating control strategies. 5 Regional Case Analysis 5.1 Population differentiation and adaptability in Asian Origin The native habitat of Asia is the region with the highest species diversity and genetic diversity of the genus Hyacinthus. The populations in various regions have formed obvious differentiation patterns during long-term evolution and have shown high adaptability to their respective habitats (Conte-Grand et al., 2017). In China, different species and populations of black fish correspond to diverse ecological environments: northern black fish adapt to the cold rivers and lakes in Northeast China and can survive in frozen water bodies in winter. The spotted black fish in South China can tolerate high temperature and low oxygen, and often inhabits rice fields and swamps where only residual water remains after drying up in summer (Harrington et al., 2022). The black fish populations native to Asia are often isolated from each other due to geographical barriers, but human activities are gradually breaking this isolation. For instance, the black fish in the north and south of China were originally separated from the subtropical population in the Yangtze River Basin and the temperate population north of the Yellow River. However, due to aquaculture and water diversion projects, nowadays in some areas, two different black fish species coexist or even live together. Attention needs to be paid to their ecological competition and genetic hybridization (Yan et al., 2018). In the native Asian environment, black fish populations usually co-evolve with local natural enemies, prey and competitors, and the ecological relationship is relatively balanced (Duong et al., 2019). 5.2 Genetic characteristics and spread patterns of invasive black fish in North America North America, especially the eastern part of the United States, has been a hotspot for black fish invasion in the past two decades. Among them, the spread of northern black fish (Channa argus) is particularly remarkable (Wegleitner et al., 2016). The first record of black fish colonization in the United States occurred in Maryland in 2002. After a failed small-scale clearance, the species rapidly spread along the Potomac River and entered rivers in adjacent states such as Virginia (Odenkirk and Isel, 2016). Since then, breeding populations have also been successively discovered in the Hudson River Basin of New York State, the Delaware River Basin of Pennsylvania and other places, indicating that the northern black fish has blossomed in multiple locations along the east coast of the United States, and there are significant genetic structural differences among the sampled populations (Figure 2) (Wegleitner et al., 2016). The North American black fish diffusion model, in addition to human multi-point distribution, also demonstrates a certain natural diffusion capacity. Taking the Potomac River population as an example, studies have monitored that it migrated approximately 20 kilometers upstream from the tidal freshwater area between 2004 and 2014 and entered multiple tributaries. The population size has grown exponentially and has accounted for a significant proportion in local catches (Odenkirk and Isel, 2016). However, interestingly, some studies have found that the impact of the invasion of northern blackfish on local fish communities may be lower than expected. The analysis of the downstream fishery data of Potomac by Love and Newhard (2012) shows that ten years after the large-scale
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 9 appearance of black fish, the overall decline in the abundance of local native fish was not significant, and the change in fish population structure was limited. This indicates that the ecological impact of black fish is complex and requires long-term observation. Figure 2 Geographic location and genetic structure of Northern snakehead (Channa argus) populations (Adopted from Resh et al., 2018) Image caption: Pie charts represent the average admixture from each geographically distinct putative population (Arkansas, Potomac River Basin, Upper Hudson River Basin, Lower Hudson River basin, Philadelphia) (Adopted from Resh et al., 2018) 5.3 Intrusion risk assessment and early monitoring cases in Europe and Africa Compared with North America, there are no large-scale black fish invasions in Europe and Africa at present, but the potential risks cannot be ignored. The climate on the European continent is generally cold, which is not conducive to the survival of tropical black fish. However, the Mediterranean region in southern Europe and some warm drainage waters may become the foothold of black fish (Piazzini et al., 2014). In Slovakia and the Czech Republic, northern black fish were introduced from the former Soviet Union for aquaculture experiments in history. However, due to the severe cold in winter, they basically did not survive in the wild. However, as global temperatures rise, some waters in Europe may become suitable for black fish breeding in the future. It is necessary to continuously monitor the species distribution model predictions under climate change scenarios. At present, the invasion of black fish in Europe and Africa is still at the individual case stage, but it is necessary to take preventive measures in advance. Drawing on the experience of North America, establishing a complete risk assessment model, public reporting network and rapid response plan can minimize the probability of black fish taking root and multiplying in these areas to the greatest extent (Lapointe et al., 2010; Xu et al., 2017). 6 Management Challenges and Future Research Directions 6.1 Risk assessment and traceability management supported by genetic data The management of the global invasion of black fish urgently requires scientific decision-making in combination with genetic information. Data based on population genetics can be used to construct more accurate intrusion risk assessment models. Traditional risk assessment often relies on the ecological environment fit of species and historical invasion records, while the introduction of genetic diversity and adaptation potential considerations will make the assessment more comprehensive (Cristescu, 2015). Genetic traceability is crucial for intrusion management. Through the analysis of the genetic structure of the invasive black fish, it is possible to trace which native region or even which trade event it originated from (Resh et al., 2021). Genetic monitoring can evaluate the effectiveness of management measures. By continuously collecting DNA samples from invasive populations and
International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 16 0 detecting changes in allele frequencies, it is possible to determine whether control measures have caused population bottlenecks or interrupted gene flow. Furthermore, for invasive populations mixed with multiple sources, genetic data can help identify whether hybrid offspring exist, thereby understanding the evolutionary dynamics of the invasive population (Bock et al., 2016). 6.2 Prediction model of global communication potential In order to prevent the further spread of black fish in a forward-looking manner, it is very necessary to establish a prediction model for the global transmission potential. This type of model usually integrates factors such as species niche, climate matching, human activities and diffusion capacity to simulate the colonization probability and possible diffusion path of black fish in non-invasive areas (Herborg et al., 2007). The climate matching model predicts which regions have the climatic conditions for the survival and reproduction of black fish by correlating the environmental parameters of the original habitat of black fish with the climate data of the target area (Poulos et al., 2012). Human transmission factors need to be incorporated into the model. A simple niche model may underestimate the possibility of invasion, as artificial introduction can break through ecological barriers. The diffusion model should take into account the diffusion ability of black fish, including both natural and artificial channels. In areas connected by river networks, black fish can spread along the water, and it is necessary to simulate the speed of their expansion along the water system (Odenkirk and Isel, 2016). 6.3 Exploration of genetic control and ecological restoration strategies In areas where black fish have invaded and are difficult to eradicate, management strategies need to gradually expand from traditional physical or chemical removal to control and restoration at the genetic and ecological levels. Genetic control technology is highly anticipated. For instance, the idea of "genetic biological control" suggests that the population growth of a target species can be suppressed by manipulating its genes. Ecological restoration is also an important part of the long-term governance of invasive black fish. The invasion of black fish can lead to changes in the food web structure and the decline of native fish populations. The ecosystem will not recover automatically after simple removal of black fish and requires human assistance (Britton et al., 2010). There is also the view that guiding the fishing industry to catch and utilize black fish is one of the methods to control black fish. Scientific research cooperation between the invaded areas and the native habitats should be strengthened. The natural enemies and diseases of black fish in the native ecosystems should be learned, and the introduction of symbiotic pathogens as biological control factors should be attempted (Britton et al., 2011). 7 Concluding Remarks Black fish, as typical representatives of invasive species, have demonstrated astonishing diffusion capabilities and ecological adaptability on a global scale. Black fish have rich genetic diversity and significant lineage differentiation in their native habitats. Different species and populations have evolved unique life history strategies and are highly adapted to their respective environments. This genetic and ecological preparation enables it to quickly establish a population and expand to the surrounding areas once it enters new regions through human activities by taking advantage of its own biological strengths (such as tolerance to harsh environments, strong reproductive capacity and strong predatory ability, etc.). The retention of genetic variations and adaptive evolution during the invasion process further promoted the spread of black fish, enabling them to cope with the challenges of different ecological conditions. This series of discoveries poses challenges to the management of biological invasions: The monitoring and control of black fish require a multidisciplinary integrated strategy. From the perspective of molecular ecology, using population genetics methods for risk assessment and traceability analysis can more accurately locate high-risk areas and the sources of invasion. Model predictions based on global data can help us anticipate possible diffusion trends and prioritize prevention. In the face of already colonized populations, only by comprehensively applying multiple measures such as ecological, genetic and social management can a lasting control effect be achieved. The problem of black fish invasion is also a microcosm of the mutual feedback between human activities and nature. To this end, countries need to enhance collaboration and share experiences in scientific research and management. At the source, supervision over species export should be strengthened. In the input area, a rapid
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International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 163-174 http://ecoevopublisher.com/index.php/ijmec 1 63 Research Insight Open Access Ecological Succession and Community Dynamics at Whale Fall Sites Manman Li Hainan Institute of Biotechnology, Haikou, 570206, Hainan, China Corresponding email: manman.li@hitar.org International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4 doi: 10.5376/ijmec.2025.15.0017 Received: 16 May, 2025 Accepted: 24 Jun., 2025 Published: 18 Jul., 2025 Copyright © 2025 Li, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Li M.M., 2025, Ecological succession and community dynamics at whale fall sites, International Journal of Molecular Ecology and Conservation, 15(4): 163-174 (doi: 10.5376/ijmec.2025.15.0017) Abstract This study reviews the research progress in whale fall ecology in recent years, focusing on the definition and discovery history of whale falls, the division of ecological succession stages, the dynamic driving mechanism of communities, and the connection between whale falls and other deep-sea ecosystems (cold seep, hydrothermal). It also compares the similarities and differences among whale fall communities in different sea areas and whale species. Research shows that whale falls, as unique "nutrient islands" in the deep sea, have nurtured rich and specialized biological communities, and their succession process reflects complex interspecific interactions and energy flow mechanisms. The decomposition process of whale carcasses releases a huge amount of organic matter, triggering continuous ecological succession stages, including the scavenging stage, the eutrophic opportunism stage, the sulfide-driven stage, and the oligotrophic "reef" stage. The species composition and functional dynamics vary in each stage. Whale fall ecosystems play a significant role in maintaining deep-sea biodiversity, promoting the cycle of energy and matter, and connecting scattered chemical energy ecological hotspots. In-depth research on the dynamics of whale fall communities not only helps to understand the evolution and adaptation strategies of deep-sea life, but also facilitates the assessment of the role of whale falls in the carbon cycle and deep-sea ecological functions, providing a scientific basis for the conservation of deep-sea biodiversity and resource management. Keywords Whale fall; Deep-sea ecosystem; Ecological succession; Biodiversity; Chemosynthetic habitat 1 Introduction whale fall refers to the isolated ecosystem formed when large cetaceans die and sink to the bottom of the sea. The deep-sea environment is characterized by a scarcity of energy and food, and has long been referred to as the "Marine desert". However, when a huge whale carcass falls into the deep sea, it is like an oasis emerging in the desert, suddenly providing rich nutrient supply and habitat for deep-sea creatures (Yin et al., 2023). The large amount of organic matter carried by whale falls can be decomposed and utilized for decades to hundreds of years, and is hailed as the "gift" of deep-sea life (Silva et al., 2021; Li et al., 2022). Research shows that a 30-ton whale carcass contains approximately 1.2×10 3 kilograms of organic carbon, equivalent to the amount of carbon received by a 100-square-meter deep-sea bed over 1,000 years. Such concentrated organic matter input has broken the normal oligotrophic state in the deep sea, significantly increased local biomass and biological activity, and made whales an important hotspot for deep-sea biodiversity (Martin et al., 2021). For instance, at least 43 species, totaling approximately 12,490 biological individuals, were recorded on a whale fall on the seabed of the North Pacific Ocean, far exceeding the biological abundance of the surrounding background environment (Li et al., 2022). Whale falls not only provide a food source, but also the sulfides released from the decomposition of lipid in their bones can support chemoautotrophic biomes, similar to chemoautotrophic ecosystems such as cold seep and black chimney (Silva et al., 2021; Pearson et al., 2023). Meanwhile, whale falls may act as "stepping stones" to promote the diffusion of deep-sea sulfide-dependent organisms among dispersed geochemical habitats (Pereira et al., 2020; Silva et al., 2021). Due to the contingency and spatial limitations of whale fall formation, there have been relatively few related studies in the past (Li et al., 2022). However, in recent years, with the development of deep-sea technology and the rise of interdisciplinary research, whale fall ecology has received increasing attention (Yin et al., 2023).
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