Invasive Freshwater Fish Research Articles

Comparing the ecological consequences of globally invasive fishes versus their F1 hybrids in recreational fisheries

Recreational angling is a major introduction pathway for non-native fish into freshwaters, where multiple non-native fishes are often released into waterbodies to diversify the angling opportunities. When these non-native fishes are taxonomically similar, then there is concern that their hybridisation will result in F1 generations comprising of novel phenotypes that outperform their parental species, resulting in the impacts of these ecological engineering species being accelerated. Across two water temperatures (18 °C, 26 °C), comparative functional response analyses (CFR) quantified the consumption patterns of the globally invasive freshwater fish common carp Cyprinus carpio and goldfish Carassius auratus, plus their F1 hybrids, before testing differences in their specific growth rates (SGRs). In CFRs, carp consumed significantly more prey at 18 °C than the other fishes, and with no differences between any of the fishes at 26 °C. SGRs also did not differ substantially between the fishes at either temperature. These results suggest that hybridisation between the high impacting parental species did not produce novel phenotypes of high ecological performance that could accelerate their ecological impacts in invaded ecosystems. Accordingly, the ecological risks of their use in recreational angling remain an issue that is primarily associated with the parent populations, and this can be reflected in their invasion management.

River hydrology mediates fish invasions in Addo Elephant National Park, South Africa

Invasive freshwater fish can often have severe negative effects on native fishes in river systems. The interactions between hydrology and habitat variability can mediate the speed and success of individual invasions and the consequent impact on biodiversity. The rivers within Addo Elephant National Park (AENP) in the Eastern Cape, South Africa experience cyclical droughts and wet periods and as a result are naturally episodic. These rivers were recently invaded by three non-native species, the invasive largemouth bass (Micropterus salmoides) as well as the extralimital sharptooth catfish (Clarias gariepinus) and Mozambique tilapia (Oreochromis mossambicus). Monitoring of key sampling sites along two rivers over a 12-year period that included two major droughts revealed unexpected patterns in the spread of these species and their interactions with native fishes. On the Coerney River, C. gariepinus repeatedly invaded and was extirpated from a seasonal reach of the river, wherein O. mossambicus was only occasionally captured. On the Wit River, two apparently independent introductions of M. salmoides in the lower and upper reaches of the river resulted in patchy habitat occupancy over the course of 12 years. While C. gariepinus regularly co-occurred with native species, M. salmoides appeared to locally extirpate the endangered Eastern Cape redfin (Pseudobarbus afer). During drought, both species persisted in close but disconnected pools, suggesting that the episodic hydrology and geomorphology of these rivers may offer temporary predation refugia for native species during drought.Conservation implications: Drought in episodic rivers can mitigate against the impact and spread of freshwater invasions within protected areas. Effects of drying on invasion corridors and spatial interactions with native species should be taken into consideration when managing such invasions. Severe droughts also offer an opportunity to actively control invasive species when they are confined to accessible drought refugia within the protected area.

An ichthyofaunal amendment with the length-weight relations and condition factors of some endemic and invasive freshwater fishes from Western Anatolia

In the scope of this study, fish fauna of Küçük Menderes River and its tributaries, updated with the comparison of the recent ichthyofaunal studies, as well as the length-weight relations (LWR) and condition factors (CF) were estimated for 7 freshwater fish species belonging to six families from the river basin: endemic Oxynoemacheilus eliasi, Cobitis fahireae; invasive, Carassius gibelio, Atherina boyeri, transloce Perca fluviatilis and the native Squalius fellowesii, Cyprinus carpio. The fish samples were collected with various fishnets and DC electro-fishing devices from six stations in 2018 and 2019. The LWR of the fishes was studied based on 379 specimens. The estimated values of parameter b ranged from 2.884 (A. boyeri) to 3.176 (C. fahireae). The coefficient of determination (R2) was changed between 0.792 to 0.980 for all sampling localities. In the study, Fulton’s condition factor ranged between 0.391 (S. fellowesii) to 3.080 (S. fellowesii); the relative condition factor ranged between 0.346 (O. eliasi) to 2.746 (S. fellowesii), respectively. This research is anticipated to contribute valuable insights for the conservation of the species, while also furnishing essential data to inform future fisheries management studies in the region.

Insights into Ontogenetic Niche Changes in Bluegill, Lepomis macrochirus, Applying Combined Analyses of Stomach Content and Stable Isotopes

We integrated stomach content analysis (SCA) and stable isotope analysis (SIA) to understand ontogenetic niche shifts in the invasive freshwater fish, bluegill, Lepomis macrochirus, inhabiting the Yedang Reservoir in Korea. Based on the total length (TL), we classified L. macrochirus as small (23–57 mm), medium (61–99 mm), or large (100–163 mm). Across all study sites, the index of relative importance (IRI) of zooplankton was high for small individuals, whereas those of benthic macroinvertebrates were high for the medium and large groups. Isotopic niche width estimates based on carbon and nitrogen isotope ratios (δ space) also increased with growth, indicating an ontogenetic niche shift in L. macrochirus. In particular, the δ space and diet plasticity of large fish was higher in the littoral population, implying L. macrochirus are generalist feeders as adults. Individuals classified as small showed confined and constant δ space, regardless of habitat condition. Thus, together with the results on the significantly high IRI of zooplankton, these individuals seem to have strong specialistic feeding ecology. Our study demonstrates the applicability strength of combining SCA and SIA for ecological niche research by providing clear evidence of an ontogenetic niche shift in L. macrochirus and elucidates their feeding ecology.

Species range shifts of notorious invasive fish species in China under global changes: Insights and implications for management

Due to global changes, e.g., climate change and trade globalization, China is facing an increasingly severe threat from invasive freshwater fish species, which have the potential to cause negative impacts across various aspects and pose significant challenges for their eradication once established. Therefore, prioritizing the understanding of invasive species’ potential ranges and their determinants is vital for developing more targeted management strategies. Moreover, it is equally essential to consider the transitory range dynamics of invasive species that reflect changes in habitat availability and accessibility. Here, we used species distribution models (the maximum entropy algorithm) to assess the potential distributions of six notorious invasive fish species (i.e., Coptodon zillii, Cyprinus carpio, Gambusia affinis, Hemiculter leucisculus, Oreochromis mossambicus, and Oreochromis niloticus) in current and future (i.e., the 2030s, 2050s, and 2070s) periods along with their determinants, under two Shared Socio-economic Pathways scenarios (SSP1-2.6 and SSP5-8.5; global climate model: MRI-ESM2-0). Our results showed that the habitat suitability for the six species substantially benefited from temperature conditions (i.e., annual mean temperature or maximum temperature of warmest month). Throughout the given time periods, dramatic range expansions would occur for C. zillii, G. affinis, O. mossambicus, and O. niloticus, ranging from 38.61% to 291.90%. In contrast, the range of C. carpio would change slightly and irregularly, while H. leucisculus would contract marginally, with losses ranging from 1.06% to 12.60%. By the 2070s, species richness of these species would be relatively high in South, Central, and East China and parts of Southwest China. Furthermore, transitory fluctuations in the species ranges for all six species were observed throughout the entire time period (the 2030s–2070s). Given the range shifts for each species during different time periods, as well as time costs and budgets, adaptation strategies should be developed and implemented in the areas where they are most needed in each time period.

Synergistic Effects of Climate Change and Alien Fish Invasions in Freshwater Ecosystems: A Review

The interaction between climate warming and alien fish invasions could have severe consequences in inland waters, which represent isolated environments with high biodiversity richness. Due to the current climatic trend, increasing water temperatures and salinization, shorter ice cover period, and altered flow regimes are predicted for these environments. The aim of this review is to offer a comprehensive analysis at a global scale of the recent studies available in the literature, focused on the responses of invasive freshwater fish to the effects of climate change in both lotic and lentic environments. To achieve this purpose, we selected 34 relevant papers, using the Scopus and Google Scholar database. New alien species establishment, distribution range expansion of species already introduced, and exacerbating impacts on freshwater ecosystems and the native fish communities they host were included in the topics covered by the analyzed papers. Despite the uncertainties related to the unpredictability with which the effects of global warming will occur, the findings of the selected studies served as a support to evaluate conservation and management implications, with particular reference to possible mitigation strategies.

New Australian frontier in freshwater fish invasion via Torres Strait Islands

AbstractAll continents, excluding Antarctica and the Artic, have been affected by incursion from alien freshwater fish species. Australia has not been spared. Four hundred and fifty species have now been declared on the ornamental importation list, making management a real challenge. With approximately 25 non-native species documented, Papua New Guinea (PNG) has likely some problems with invasive freshwater fish. Many of these species have been intentionally introduced to increase access to food as a protein source for remote communities or have spread naturally from western parts of Java and Indonesia, and now constitute a large biomass on some floodplain areas in PNG. The Torres Strait is located between PNG and northern Queensland and was previously a land bridge, though now under higher sea levels the region exists as a series of approximately 300 islands. The threat of further range extension of freshwater fish from PNG into northern Queensland via the Torres Strait Islands is significant, with two invasive fish species already recorded on northern islands of the Torres Strait (climbing perch, Anabas testudineus which has been continually recorded for the past decade; and recently the GIFT tilapia, Oreochromis niloticus). Here we present a case to control further spread of invasive freshwater fish species towards Australia, using a Land and Sea Ranger program, where Rangers are trained to be confident in the identification of pest fish species and to implement strategies to protect their borders from potential future incursions. The success of this program relies on Rangers to continue partaking in surveillance monitoring of coastal waters, checking and controlling for any new invasive species moving from PNG into Australian waters. We outline the biosecurity obligation under Article 14 of the Treaty between the two nations, which identifies the importance of conservation and protection of coastal floodplains from invasive species, and the spread between both nations.

Effects of elevated temperature and microplastic exposure on growth and predatory performance of a freshwater fish

AbstractFreshwater ecosystems are increasingly exposed to co‐occurring anthropogenic stressors that can alter food web interactions and organismal life histories. We examined the individual and combined effects of climate warming and microplastic pollution on the growth rate and predatory performance of an invasive freshwater fish, the round goby (Neogobius melanostomus). In temperature‐controlled chambers, we exposed 160 juvenile gobies to one of six scenarios over 37 d, combining three environmentally relevant concentrations of microplastics (63–75 μm polyethylene microbeads) with two temperature regimes representing contemporary (18°C) and projected mean summer maxima (26°C) in their current range in the Great Lakes–St. Lawrence River basin. Exposure to elevated temperature reduced the growth and predatory performance of round gobies. Their decline in predatory performance was greatest at the highest microplastic concentration, regardless of temperature. The effects of environmentally relevant microplastic concentrations on the growth and performance of gobies were weaker than the effects of thermal stress. Given that the round goby is an abundant and widely distributed bottom‐dwelling fish in nearshore areas of the Great Lakes–St. Lawrence River basin, its responses to these co‐occurring stressors could have cascading effects on food webs.

Correction: Adding insult to injury: anthropogenic noise intensifies predation risk by an invasive freshwater fish species

Correction: Adding insult to injury: anthropogenic noise intensifies predation risk by an invasive freshwater fish species

Prediction of Current and Future Suitable Habitats for Three Invasive Freshwater Fish Species in Europe

Climate change can have a significant impact on the Earth’s ecosystems. Invasive species will respond to climate change, and their responses will have ecological and economic implications. Habitat suitability models (HSMs) are some of the most important tools currently available for assessing the potential impacts of climate change on species. The projections of a model of suitable conditions for three invasive fish species in Europe, Lepomis gibbosus, Perccottus glenii and Pseudorasbora parva, built using Maxent and based on the occurrence throughout the range (native and invasive), on the current climate of Europe and on the forecast climate data for the 2050s and 2070s in the SSP2 and SSP5 scenarios are presented herein. For Lepomis gibbosus and Pseudorasbora parva, climate change will lead to a significant expansion of their zones, with suitable conditions to the north and east, while the change in suitability in their existing ranges will be moderate. For Perccottus glenii, the zone with suitable conditions will shift northward, with a gradual deterioration in the southern and central parts of its current range and an improvement in the northern part. Thus, at present and until the 2070s, Lepomis gibbosus and Pseudorasbora parva can be considered potentially dangerous invasive species in most parts of Europe, while Perccottus glenii can be considered as such only in the northern part of Europe.

Adding insult to injury: anthropogenic noise intensifies predation risk by an invasive freshwater fish species

The ecological impact of invasive species is likely to be modulated by human-induced alterations in habitats, which represents another driver of biodiversity loss. We tested the effect of soundscape degradation on predation by the round goby Neogobius melanostomus, one of Europe’s “worst invasive species”. For this, we compared the relationship between per capita predation rate and prey density (i.e., the functional response) in the presence or absence of motorboat sounds. Unexpectedly, fish displayed a stronger functional response with additional noise, which could be explained by a higher mobility promoting encounters with prey. Our results suggest that anthropogenic noise is likely to exacerbate the impact of invasive species.

The occurrence of Ichthyophthirius multifiliis infection on invasive freshwater fish, the Peacock Bass (Cichla spp.) from Tasik Telabak, Malaysia.

Peacock bass (Cichla spp.) is an invasive fish that has established feral population in many freshwater water bodies in Malaysia. Among the negative impact of invasive species are the co-introduction of new parasites, and they also may act as vector to various disease causal agents. The aim of this study was to identify and to measure the prevalence of parasites of Peacock bass from Tasik Telabak, Terengganu, Malaysia. A total of 28 fishes were sampled by line fishing with the help of anglers and examined for parasites by using general parasitological method and microscopic technique. 3 groups of parasites (Protozoa, Digenea and Nematoda) were found infecting Peacock Bass from the lake. 46% of the samples were infected by Ichthyophthirius multifiliis, a common protozoan parasite that known as the causal agent for White Spot Disease (WSD) in fishes. However, I. multifiliis is not a common parasite for wild Peacock Bass in their native area, this finding could indicate the potential of parasite spillback phenomena from the freshwater fish cages from aquaculture activities in the same lake.

Resistance from a resident heterospecific affects establishment success of a globally invasive freshwater fish

Abstract The role of biotic resistance is a subject of debate in our understanding of invasions. We used a well‐known system in the Northern Range of Trinidad, where ephemeral conditions in small pool habitats lead to repeated colonisation by two native species (guppies, Poecilia reticulata, and killifish, Anablepsoides hartii), to ask questions about the role of biotic resistance and intraguild predation in natural, small‐water habitats. Using horticultural containers under forest cover, alongside constructed bankside mesocosms, we established populations of each species to test hypotheses concerning the conditions under which the guppy, a globally successful invasive species with the potential to establish populations from a single female, could be excluded by a resident intraguild predator, the killifish. Recruitment success of the guppy depended on founder numbers (propagule size) and introduction order (whether first or last to arrive in the habitat). Single founder guppies always failed to recruit in pools with resident killifish, which we posit is directly attributable to biotic resistance from the resident. However, increased propagule pressure (introduction attempts and propagule number) greatly increased the probability of successful invasion. Our results have two main implications. The first is that guppies are capable of being successful colonisers even in the presence of a resident intraguild predator. The second is to highlight the role that biotic resistance can play in preventing establishment in small‐water habitats, especially under circumstances of low propagule pressure. While previous studies have shown that guppies are strong colonisers outside of their native range, our findings suggest that this may not always be the case when there are other small‐bodied fish present. Accordingly, we argue that in small‐water habitats, biotic resistance and intraguild predation relationships should be important considerations when the ability to establish is being assessed for a taxon.

Effect of a temperature gradient on the behaviour of an endangered Mexican topminnow and an invasive freshwater fish

Climate change and biological invasions are two of the major threats to biodiversity. They could act synergistically to the detriment of natives as non-native species may be more plastic and resilient when facing changing environments. The twoline skiffia (Skiffia bilineata) is an endangered Mexican topminnow that cohabits with invasive guppies (Poecilia reticulata) in some areas in central Mexico. Guppies have been found to take advantage from associating with the twoline skiffia and are considered partially responsible for the decline of its populations. Refuge use and exploratory behaviours are trade-offs between being safe from the unknown and the opportunity to explore novel areas in search for better resources or to disperse. The aim of this study is to investigate how a change in temperature affects the refuge use and exploratory behaviours for both species. We found that temperature affects the refuge use of twoline skiffias, and the swimming activity of both species. Skiffias explored the rock more than guppies regardless of the temperature scenario. Also, smaller fish spent more time performing exploratory behaviours than bigger ones. Our study is the first to test the effect of temperature on the refuge use and exploratory behaviour of a goodeid species, and our results contribute to the idea that some natives could be more affected by climate change than some invaders.

Contrasting population genetic responses to migration barriers in two native and an invasive freshwater fish.

Habitat fragmentation impacts the distribution of genetic diversity and population genetic structure. Therefore, protecting the evolutionary potential of species, especially in the context of the current rate of human-induced environmental change, is an important goal. In riverine ecosystems, migration barriers affect the genetic structure of native species, while also influencing the spread of invasive species. In this study, we compare genetic patterns of two native and one highly invasive riverine fish species in a Belgian river basin, namely the native three-spined stickleback (Gasterosteus aculeatus) and stone loach (Barbatula barbatula), and the non-native and invasive topmouth gudgeon (Pseudorasbora parva). We aimed to characterize both natural and anthropogenic determinants of genetic diversity and population genetic connectivity. Genetic diversity was highest in topmouth gudgeon, followed by stone loach and three-spined stickleback. The correlation between downstream distance and genetic diversity, a pattern often observed in riverine systems, was only marginally significant in stone loach and three-spined stickleback, while genetic diversity strongly declined with increasing number of barriers in topmouth gudgeon. An Isolation-By-Distance pattern characterizes the population genetic structure of each species. Population differentiation was only associated with migration barriers in the invasive topmouth gudgeon, while genetic composition of all species seemed at least partially determined by the presence of migration barriers. Among the six barrier types considered (watermills, sluices, tunnels, weirs, riverbed obstructions, and others), the presence of watermills was the strongest driver of genetic structure and composition. Our results indicate that conservation and restoration actions, focusing on conserving genetic patterns, cannot be generalized across species. Moreover, measures might target either on restoring connectivity, while risking a rapid spread of the invasive topmouth gudgeon, or not restoring connectivity, while risking native species extinction in upstream populations.

Contemporary perspectives on the ecological impacts of invasive freshwater fishes.

Introductions of non-native freshwater fish continue to increase globally, although only a small proportion of these introductions will result in an invasion. These invasive populations can cause ecological impacts in the receiving ecosystem through processes including increased competition and predation pressure, genetic introgression and the transmission of non-native pathogens. Definitions of ecological impact emphasize that shifts in the strength of these processes are insufficient for characterizing impact alone and, instead, must be associated with a quantifiable decline of biological and/or genetic diversity and lead to a measurable loss of diversity or change in ecosystem functioning. Assessments of ecological impact should thus consider the multiple processes and effects that potentially occur from invasive fish populations where, for example, impacts of invasive common carp Cyprinus carpio populations are through a combination of bottom-up and top-down processes that, in entirety, cause shifts in lake stable states and decreased species richness and/or abundances in the biotic communities. Such far-reaching ecological impacts also align to contemporary definitions of ecosystem collapse, given they involve substantial and persistent declines in biodiversity and ecosystem functions that cannot be recovered unaided. Thus, while not all introduced freshwater fishes will become invasive, those species that do develop invasive populations can cause substantial ecological impacts, where some of the impacts on biodiversity and ecosystem functioning might be sufficiently harmful to be considered as contributing to ecosystem collapse.

Integrating conventional risk management and population models to assess risks from an established invasive freshwater fish

• Risk assessments are vital to invasive species control but not always suitable for natural resource managers. • Integrating ISO likelihood and consequence risk assessments with population models provide a new approach. • We apply and test this new method on the highly invasive common carp in Australia. • This approach is widely applicable to invasive species globally.

The influence of native populations’ genetic history on the reconstruction of invasion routes: the case of a highly invasive aquatic species

Insufficient data on the origins of the first introduced propagule and the initial stages of invasion complicate the reconstruction of a species’ invasion history. Phylogeography of the native area profoundly shapes the genomic patterns of the propagules on which subsequent demographic processes of the invasion are based. Thus, a better understanding of this aspect helps to disentangle native and invasive histories. Here, we used genomic data together with clustering methods, explicit admixture tests combined with ABC models and Machine Learning algorithms, to compare patterns of genetic structure and gene flow of native and introduced populations, and infer the most likely invasion pathways of the highly invasive freshwater fish Pseudorasbora parva. This species is the vector of a novel lethal fungal-like pathogen (Sphaerothecum destruens) that is responsible for the decline of several fish species in Europe. We found that the current genetic structuring in the native range of P. parva has been shaped by waves of gene flow from populations in southern and northern China. Furthermore, our results strongly suggest that the genetic diversity of invasive populations results from recurrent global invasion pathways of admixed native populations. Our study also illustrates how the combination of admixture tests, ABC and Machine Learning can be used to detect high-resolution demographic signatures and reconstruct an integrative biological invasion history.

Social associations in common carp (Cyprinus carpio): Insights from induced feeding aggregations for targeted management strategies.

Heterogeneity in social interactions can have important consequences for the spread of information and diseases and consequently conservation and invasive species management. Common carp (Cyprinus carpio) are a highly social, ubiquitous, and invasive freshwater fish. Management strategies targeting foraging carp may be ideal because laboratory studies have suggested that carp can learn, have individual personalities, a unique diet, and often form large social groups. To examine social feeding behaviors of wild carp, we injected 344 carp with passive integrated transponder (PIT) tags and continuously monitored their feeding behaviors at multiple sites in a natural lake in Minnesota, USA. The high‐resolution, spatio‐temporal data were analyzed using a Gaussian mixture model (GMM). Based on these associations, we analyzed group size, feeding bout duration, and the heterogeneity and connectivity of carp social networks at foraging sites. Wild carp responded quickly to bait, forming aggregations most active from dusk to dawn. During the 2020 baiting period (20 days), 133 unique carp were detected 616,593 times. There was some evidence that feeding at multiple sites was constrained by basin geography, but not distance alone. GMM results suggested that feeding bouts were short, with frequent turnover of small groups. Individual foraging behavior was highly heterogeneous with Gini coefficients of 0.79 in 2020 and 0.66 in 2019. “Superfeeders”—those contributing to 80% of total cumulative detections (top 18% and top 29% of foragers in 2020 and 2019 respectively)—were more likely to be detected earlier at feeding stations, had larger body sizes, and had higher network measures of degree, weighted degree, and betweenness than non‐superfeeders. Overall, our results indicate that wild carp foraging is social, easily induced by bait, dominated by large‐bodied individuals, and potentially predictable, which suggests social behaviors could be leveraged in management of carp, one of the world's most recognizable and invasive fish.

Integrating Conventional Risk Management and Population Models to Assess Risks from an Established Invasive Freshwater Fish

Integrating Conventional Risk Management and Population Models to Assess Risks from an Established Invasive Freshwater Fish