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The introduction of exotic fishes into India began in 1863 with the introduction of trout eggs in the Nilgiri Hills and still continued for various purposes. India has abundant aquatic resources for aquaculture practices and trying to produce more fish in a shorter span of time. This has resulted in overexploitation of enormous quantities of alien invasive fishes which adversely affecting the native aquatic diversity. It is adversely affecting the ecosystem and economy of the communities dependent on it. Once the exotic fish species establishes itself, complete eradication is difficult and more expensive. The aim of this review is to collate the possible impact of exotic fishes in Indian aquatic systems and draw attention to the regulation of such alien fishes. [ABSTRACT FROM AUTHOR]

Copyright of Caldasia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses methods to control the invasion of exotic fish species in Spanish rivers, particularly focusing on techniques like electric fishing, mobile dikes, and electric barriers. It highlights recent applications in rivers like the Ubagua in Navarra to manage species such as the European perch, while balancing ecological needs to protect native species like the common trout.

In the present study, we examined 30 individuals of introduced African cichlids, Oreochromis niloticus and Coptodon rendalli, collected in a river spring of the Pardo River, Paranapanema River basin, southeastern Brazil. Based on morphological and molecular analyses of the partial LSU rDNA gene, we identified four species of monogeneans, Cichlidogyrus tilapiae, C. thurstonae, C. mbirizei, and Scutogyrus longicornis on the gills of O. niloticus, whereas individuals of C. rendalli were infested only with C. papernastrema. This is the first record of C. mbirizei and C. papernastrema in tilapias from Brazil. The ecological consequences of the introduction of exotic species of tilapia such as O. niloticus and C. rendalli along with their monogenean parasites in a wild environment represented by a river spring are discussed. Our new molecular data on Cichlidogyrus and Scutogyrus contribute to the investigation of the phylogenetic interrelationships of these widely distributed genera of monogeneans since their species composition is still unsettled.

Abstract Investigating the determinants of the reproductive biology of fishes is an essential component of fisheries research. Tilapia breeding patterns were investigated to determine the impact of non‐native Oreochromis niloticus on the native congeneric Oreochromis macrochir in the upper Kabompo River in the Northwest of Zambia using the gonadosomatic index and the sex ratios. Oreochromis niloticus was the most abundant fish caught (221, 63.5%) than O. macrochir (127, 36.5%). Results showed that the overall gonadosomatic index means of O. macrochir in both sections were similar. Oreochromis macrochir bred in December and February–March, with no reproduction in June. However, O. niloticus in the invaded section indicated all year reproduction through reduced spawning in May–June, with increased spawning activity in February–March. The sex ratio (females: males) was 1:1.3 and 1:1.7 for O. niloticus and O. macrochir, respectively, and both significantly deviated from the sex ratio of 1:1 (ꭓ2 = 8.42 and 9.37, p

Chira River is located on the north coast of Peru. The lack of knowledge of the ichthyofauna from coastal drainages from Peru is noteworthy. The aim of this study is to characterize the ichthyofauna along the Chira River basin in terms of diversity and altitudinal range distribution. The material examined belongs to the Ichthyological collection of the Natural History Museum (MUSM). The diversity of fishes is composed of 27 species belonging to 19 families and ten orders. Siluriformes and Characiformes were the most diverse, consisting of 22% (six species) for each one. Five species are new records for the Chira River (three natives and two non-natives). Six marine species and seven exotic species were recorded as well. The altitudinal distribution patterns for all species were registered. This study increases the known diversity of freshwater fishes from Pacific Drainage Rivers in Peru, and it could be used for management and conservation plans.

Investigating the determinants of the reproductive biology of fishes is an essential component of fisheries research. Tilapia breeding patterns were investigated to determine the impact of non‐native Oreochromis niloticus on the native congeneric Oreochromis macrochir in the upper Kabompo River in the Northwest of Zambia using the gonadosomatic index and the sex ratios. Oreochromis niloticus was the most abundant fish caught (221, 63.5%) than O. macrochir (127, 36.5%). Results showed that the overall gonadosomatic index means of O. macrochir in both sections were similar. Oreochromis macrochir bred in December and February–March, with no reproduction in June. However, O. niloticus in the invaded section indicated all year reproduction through reduced spawning in May–June, with increased spawning activity in February–March. The sex ratio (females: males) was 1:1.3 and 1:1.7 for O. niloticus and O. macrochir, respectively, and both significantly deviated from the sex ratio of 1:1 (ꭓ2 = 8.42 and 9.37, p <.05). Our study has revealed that O. niloticus was able to spawn across all sampled months with a 23% higher breeding population than O. macrochir, which might explain the suppression in the abundance of native O. macrochir. Due to the superior breeding patterns of O. niloticus, fisheries, wildlife, and aquaculture practitioners need to make contingency plans to alleviate its impacts further downstream of the Kabompo River. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to identify the morphological parameters effective insexual dimorphism in Gambusia holbrooki, as a model but invasive livebearer species in Iranian inland waters, using landmark morphometric truss network system. The linear discriminant analysis showed an average percentage of specimens classified of 100% for morphometric characters indicating a high rate of correct classification of individuals into their original populations. The significant differences between two sexes were observed in the head length, head width, body depth, pre-dorsal length, pre-ventral length, pre-anal length, fork length, dorsal fin length, anal fin length, caudal-peduncle depth and caudal-peduncle length.

Length-weight relationships (LWRs), condition factors, and their variation over time were analyzed for four exotic freshwater fish (bleak, common carp, pikeperch, and roach) in the Estany d'Ivars i Vila-sana shallow lake in Catalonia, Northern Spain. Fish samples were collected twice a year (early summer and autumn), between 2008 and 2016, by using between three and five multi-mesh nylon gillnets. This study provides novel information about four common exotic fishes outside of their natural range and within the context of a restored shallow lake, where the ichthyologic community is evolving in concordance with the ecosystem conditions and the fish community dynamics. [ABSTRACT FROM AUTHOR]

The present investigation deals with the documentation of the aquatic macrophytes from Mansar lake- an important subtropical monomictic lake in the Siwalik hills of Jammu region. Macrophytic survey was carried out in the littoral zone of lake Mansar for a period of two years viz. January 2014 to December 2015 and showed the presence of 26 macrophytic species belonging to 19 genera and 14 families. Among various ecological groups, emergent with 15 species showed qualitative dominance over submersed (8 species) and rooted floating-leaved types (3 species). Two macro-algal species (Chara vulgaris and Nitella hyalina) showed their absence during the first year whereas one species (Najas indica) showed its complete absence during the second year. Based on the Importance value index (IVI), Ipomea carnea was the dominated species in Mansar lake during the two years study period. The diversity indices have confirmed the increased species diversity during summer followed by monsoon and winter. In the present study, the collected macrophytic data was classified under different lifeforms classification as given by Raunkiaer (1934) and the biological spectrum was compared with Raunkiaer's normal biological spectrum. Four recorded life form categories showed dominance of Therophytes followed by Cryptophytes (geophytes > helophytes = hydrophytes), Hemicryptophytes and Chamaephytes. Among the recorded life forms, Therophytes and Cryptophytes dominated over the other life forms classes. Therefore, the present lake may be designated as Thero-cryptophytic type of phytoclimate. Comparison of present macrophytic data with the earlier reports from Mansar lake showed considerable decline in macrphytic diversity over a period of time. [ABSTRACT FROM AUTHOR]

The aim of the study is to present a complete and updated fish inventory of inland waters of the Emilia-Romagna region, Northern Italy, and to highlight the presence of fully exotic fish communities. Overall, based on 208 sampling locations, the observed fish fauna consisted of 45 species, 22 native and 23 exotics. A significant element of the inventory is the identification of xenodiversity hotspots (spatially clustered sites, one lowland and one upland region), where a complete substitution of native species by exotic species was observed (in total seven sites in the lowland and two sites in the upland with no native species presence). These xenodiversity hotspots were found to host specific combinations of exotic species, which may be able to constitute balanced exotic communities. The hotspots of the lowland region are located in the northeast lowland part of the territory, hosting exotic species combinations mainly composed by wels catfish (Silurus glanis Linnaeus, 1758, a large predator), common carp (Cyprinus carpio Linnaeus, 1758, a large benthivore), crucian carp (Carassius spp., a small-bodied generalist) and other less dominant exotic species. The hotspots in the upland region were located in the southwest part of the territory and were dominated by only one exotic species (rainbow trout, Oncorhynchus mykiss (Walbaum, 1792)). A difference between these xenodiversity hotspots is that in the lowland the introductions were mostly unintentional and are not continued, while in the upland the introduction of rainbow trout is intentional and currently carried out by local fishermen. [ABSTRACT FROM AUTHOR]

Abstract A survey of the helminth parasites of alien freshwater fishes from Argentinean Patagonia is presented, based on samples taken from 2010 to 2017 and including previous published records. A total of 1129 fishes were collected, belonging to 11 species from 7 families. We surveyed 34 localities in 12 river basins, and found 43 parasite taxa (15 digeneans, 14 monogeneans, 5 cestodes, 5 nematodes, and 4 acanthocephalans), belonging to 22 families. Data are presented as a parasite/host list with information on host species and localities, site of infection, parasite life–history stage, origin, previous records in Patagonia, and accession numbers to vouchers. The most frequently found helminths were monogeneans and digeneans. Our data suggest that invading fish in Patagonia have transmitted fewer parasite species than they have received by spillback. Twenty–three (53%) of the parasites seem to be acquired by the exotic fishes from native hosts, while 15 helminths were co–introduced along with their exotic fish host and continue to parasitize these alien fish but did not invade native hosts; 4 of these species were introduced with carp, 3 with Cheirodon interruptus , 3 with Corydoras paleatus, 3 with Cnesterodon decemmaculatus , 1 with Oncorhynchus tshawytscha , and 1 with Jenynsia multidentata. The majority of these co–introduced parasites came from the Brazilic ichthyogeographic region (10 species). This is the first review of helminth parasites of alien fishes in Argentina; in total 12 new records of parasites for Argentina, 6 new records of parasites for Patagonia, and 29 new host–parasite records are presented here. This list is far from complete, however, given that some basins in southern Patagonia remain unexplored in terms of parasite detection. Graphical abstract Image 1 Highlights • This is the first review of helminth parasites of alien fishes in Argentina. • We found 43 parasite taxa in alien fishes, belonging to 22 families. • We reported 12 new parasite records for Argentina and 6 new records for Patagonia. • Alien fish in Patagonia have transmitted fewer parasites than they have received by spillback. [ABSTRACT FROM AUTHOR]

In Bellatin's Salón de belleza aquariums filled with exotic fish function as the symbolic nexus through which queer bodies and destructive power intersect and become involved in mutational processes. This article brings the novella into dialogue with biopolitical philosophy, queer theory and posthumanism in order to conceptualise the multivalent implications of the text's trans‐species reflections and crossings. My analysis moves beyond existing interpretations of the novella as a mournful account of the HIV/AIDS pandemic or as a text that documents violence more broadly, by calling attention to the more affirmative potentialities that are also latent in Bellatin's aesthetics of impersonality. [ABSTRACT FROM AUTHOR]

Where biodiversity conservation and environmental preservation are significant concerns, rapid assessment and monitoring of the colonization and spread of non-native species are essential for timely decision-making and response. We developed and evaluated the adequacy of a rapid assessment protocol (RAP) for detecting non-native fish species in 74 Eastern Brazilian lakes. The RAP consists of a single field day employing two surveyors to conduct interviews with local sport fishers, visual surveys of fish, angling with lures, and gillnetting. We compared our results with those from separate, intense, large sampling effort (LSE) field surveys. Despite requiring less than 1/100th of the field effort, the RAP was able to detect the presence of most non-native fish species that were reported in the same lakes by LSE surveys. Information from local sport fishers was invaluable, particularly for detecting species that were in low abundance, but was not available for lakes within a forest preserve area. Non-native introductions commonly lead to rapid and widespread invasion and adverse effects on native biota. Our results strongly suggest that the RAP could function as a cost-effective tool for efficiently assessing the presence of non-native fishes in lakes and monitoring their colonization and spread over large geographic areas. [ABSTRACT FROM AUTHOR]

The Neotropical region has the greatest taxonomic and functional diversity of fish in the world. However, this biodiversity has been threatened by the introduction of non-native species. Therefore, we present a systematic review of the literature concerning the introduction of non-native fish species in Neotropical freshwaters. We examine the origins of non-native fish species, as well as the invaded ecoregions and introduction vectors. Oncorhynchus mykiss, Salmo trutta, Cichla kelberi, and Oreochromis niloticus were the most frequent introduced fish species and rivers and reservoirs were the most studied freshwater ecosystems. Impoundments, aquarium trade, sport fishing, and aquaculture were recorded as the main vectors for the introduction of non-native fish species. Most of the studies were conducted in Brazil. The Upper Parana ecoregion exhibited the largest number of non-native fish species, of which the majority originated from the Lower Parana ecoregion. We noticed that the origins of non-native fish species are linked to their introduction vectors, as several non-native fish species arrive from areas near to where they are introduced, mainly by impoundment and sport fishing. On the other hand, species from regions outside the Neotropics are especially introduced by aquarium trade and aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: Aim: We explored the factors between riverscape features and exotic introgression of cultured rainbow trout (Oncorhynchus mykiss) that drive the current genetic structure in the endemic Mexican golden trout (Oncorhynchus chrysogaster) using a riverscape genetics simulator. Location: Sierra Madre Occidental, Northwest Mexico, North America. Methods: We created a system model for Mexican golden trout to test various scenarios for the effect of riverscape resistance and rainbow trout introgression on the native genetic structure of the Mexican golden trout. Individual genotypes were used to initialize the model and were based upon empirical allele frequencies from three genetically and spatially distinct groups in the study area. The geographical location of the simulated populations was defined using a species distribution model. We included hypotheses for movement of riverine distance and riverscape resistance. We evaluated model performance by conducting population and landscape genetics analyses on the simulation outputs. Results: The most plausible scenario included riverscape resistance without introgression, which presented a spatial genetic structure matching the observed riverscape genetic structure and fitting expected general life‐history patterns for high elevation trout streams. In addition, temperature, precipitation, hydrology and topography were the most important variables influencing species occurrence and dispersal. Main conclusion: This work presents one of the first empirically derived simulation studies of introgression. It highlights the importance of considering riverscape resistance (i.e. hydroclimatic and topographical gradient effects) in models of spatial genetic structure and introgression. Moreover, our modelling suggests that what we characterize as riverscape resistance is acting as a boundary against exotic introgression. The results of this study could help to develop management strategies that preserve native gene pools. [ABSTRACT FROM AUTHOR]

While the significance of anthropogenic pressures in shaping species distributions and abundances is undeniable, some ambiguity still remains on their relative magnitude and interplay with natural environmental factors. In our study, we examined 91 late-invasion-stage river locations in Northern Italy using ordination methods and variance partitioning (partial-CCA), as well as an assessment of environmental thresholds (TITAN), to attempt to disentangle the effects of eutrophication and exotic species on native species. We found that exotic species, jointly with water quality (primarily eutrophication) and geomorphology, are the main drivers of the distribution of native species and that native species suffer more joint effects than exotic species. We also found that water temperature clearly separates species distributions and that some native species, like Italian bleak ( Alburnus alborella ) and Italian rudd ( Scardinius hesperidicus ), seem to be the most resilient to exotic fish species. We also analyzed the dataset for nestedness (BINMATNEST) to identify priority targets of conservation. As a result, we confirmed that altitude correlated negatively with eutrophication and nestedness of exotic species and positively with native species. Overall, our analysis was able to detect the effects of species invasions even at a late invasion stage, although reciprocal effects seemed comparable at this stage. Exotic species have pushed most native species on the edge of local extinction in several sites and displaced most of them on the rim of their natural distribution. Any potential site- and species-specific conservation action aimed at improving this situation could benefit from a carefully considered prioritization to yield the highest results-per-effort and success rate. However, we encourage future research to update the information available before singling out specific sites for conservation or outlining conservation actions. [ABSTRACT FROM AUTHOR]

Due to its location and geomorphology, Colombia has a great variety of ecosystems and a high biodiversity; this natural wealth is also observed in its drainage basins where, additionally, a considerable number of endemic plants and animals have been reported. Unfortunately, these bodies of water have undergone major changes made by man; such is the case of the Porce River Drainage. In addition to the use of its water for hydroelectric generation, its channel has been altered and affected by the growth of a great city on its banks, causing the populations of fish that live there to suffer great alterations and disappearances. The ecosystem services provided by fish in this ecosystem have not been adequately determined. Based on functional traits such as size, diet, habitat and distribution in the water column of the fish of the Porce River, the ecosystem services provided by these organisms will be characterized, showing their importance and which types of services they provide direct or indirectly to society. This will allow the formulation of a proposal for more integral management of the biodiversity of this heavily impacted drainage. Sixtytwo species of fish were found in this drainage that can provide regulatory ecosystem services such as: biological control (32 species); water quality improvement (30 spp.); genetic resources (54 spp.); provision services such as food (11 spp.) and ornamental fishes (31 spp.); and cultural services as sources of leisure and recreation (15 spp.). Unfortunately, this drainage has been negatively impacted by modifications of its channel, contamination of its waters and introduction of exotic fish species for the provision of food. All these impacts strongly affect this ecosystem and drastically decrease the surviving native fish populations that have been reported for this river, seriously reducing the ecosystem services that the Porce River species can supply, and which are essential for the functioning of the other ecosystems associated with this drainage and for the human well-being of the region. [ABSTRACT FROM AUTHOR]

Mediterranean shallow lakes support high biodiversity but suffer many anthropogenic threats, including introductions of alien fish. We studied the impact of introduction of common carp ( Cyprinus carpio ) to Medina and Zoñar lakes in SW Spain. Both lakes were protected as Ramsar sites because of their importance for waterbirds, particularly the globally threatened white-headed duck ( Oxyura leucocephala IUCN Endangered) and common pochard ( Aythya ferina IUCN Vulnerable). Two carp introduction events in Medina lake, with total eradication of carp in between, provided a unique opportunity to study the impacts of carp on the waterbird community (counted monthly from 2001 to 2013, with up to 69 species) and submerged macrophyte cover (quantified with satellite images). A comparison of waterbird abundance before and after carp eradication in the smaller Zoñar lake supported the results from Medina lake. Carp consistently led to the destruction of macrophyte beds and a radical change in the waterbird community. After controlling for the influence of depth fluctuations, the numbers and species richness of diving ducks were significantly reduced by carp, whilst the opposite effect was observed for piscivores such as herons. Negative impacts on O. leucocephala , A. ferina , red-crested pochard ( Netta rufina ) and herbivorous coots ( Fulica spp.) were particularly pronounced. A significant negative impact of carp was also recorded on greater flamingos ( Phoenicopterus ruber ), black-necked grebes ( Podiceps nigricollis ), little grebes ( Tachybaptus ruficollis ) and gadwall ( Anas strepera ). In contrast, carp presence had a positive impact on grey herons ( Ardea cinerea ). The ongoing expansion of alien cyprinids in the Mediterranean region constitutes a major threat for waterbirds and particularly for sedentary, threatened taxa such as the white-headed duck and red-knobbed coot ( F. cristata ). Of 22 key sites for the isolated Iberian population of white-headed duck identified in a European action plan in 1996, at least 14 have since suffered carp invasions. Further development of successful control methods for carp populations is urgently required to support the conservation of waterbirds in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Aquatic biodiversity loss can be attributed in part by the presence of invasive species that increase the risk of extinction of native species through competition, predation, transmission of parasites and disease, hybridization and introgression. This study reports the first record of Heterotilapia buttikoferi in the upper Paraná River basin, Brazil. Additionally, the effects of establishment of this invasive species and the lack of an effective political and environmental management in Brazil that hinder exotic species' eradication are herein discussed. [ABSTRACT FROM AUTHOR]

The only species of Cephalopholis currently known from the Mediterranean is Cephalopholis taeniops (Valenciennes, 1828), which was recorded from Libya, Malta, and Lampedusa after having autochthonously extended its original Atlantic range. All records of Cephalopholis substantiated by specimens or images from Malta were evaluated, showing that an individual filmed in August 2009 was misidentified and instead represents the first record of Cephalopholis hemistiktos (Rüppell, 1830) from the Mediterranean. Based on these records, C. taeniops is considered to be established in Maltese waters while C. hemistiktos is regarded as a 'casual' species, most likely transported by shipping or introduced as an aquarium escapee. [ABSTRACT FROM AUTHOR]

Fishless Andean high mountain lakes may be vulnerable to fish invasion because they tend to be small, oligotrophic and contain low zooplankton diversity. During the first decades of the twentieth century, rainbow trout, Oncorhynchus mikiss, was introduced in South America, and stocking of juvenile stages (fry) in lakes continues today. However, their effect on plankton in these lakes has been little studied. We performed a mesocosms experiment to assess effects of trout of different ontogenetic stages on zooplankton and phytoplankton in a tropical-Andean high mountain lake. The presence of trout fry resulted in declines in several large zooplankton taxa, increases in chlorophyll a and dissolved inorganic nitrogen (DIN). Our results showed that small fry consume large copepods (Colombodiaptomus brandorffi) at a faster rate than larger fry, and also consumed medium sized copepods (Tropocyclops prasinus) that are not affected by the larger trout fry. Fish of both sizes consumed Ceriodaphnia quadrangula, a midsize cladoceran. Fish predation had weak effect on the phytoplankton biomass, but we found a correlation between zooplankton biomass and phytoplankton richness, and significantly larger cell of the alga Peridinium in the presence of fish. Our results indicate that trout introduction produces cascading ecological and phenotypic effects on the plankton communities of tropical mountain lakes, similar to those observed in temperate latitudes. [ABSTRACT FROM AUTHOR]

The purpose of this research was to analyze the abundance and distribution of four recently introduced fish species in the Tiber River basin: Gobio gobio, Luciobarbus graellsii, Rutilus rutilus, and Rhodeus sericeus. An additional aim was to evaluate the relationships of these species with environmental factors. The study area comprised 92 watercourses in the Umbrian portion of the Tiber River basin and analyzed data collected during 1990-2014, in 158 sampling sites. The results show that all four species were quickly established, with self-sustaining populations revealing invasive characteristics. In just a few years these species extended their distribution significantly in the study area; they preferentially colonized the lower reaches of rivers characterized by warmer waters and a slow current rate and were also associated with poor environmental quality conditions. The research results provide valuable information useful for risk assessment as well as for the design of proper invasive species management programs. [ABSTRACT FROM AUTHOR]

Little is known about the effect of top predator introduction in historically fishless communities, especially on remote islands. This issue is important because it might strongly affect climate reconstructions derived from biota assemblages such as chironomids. Head capsule larval remains of chironomids have been studied in a 660 years lacustrine sedimentary sequence from Lake Azul (Sao Miguel Island, Azores archipelago) to assess the extent and timescale of the effect of the predator introduction occurring in this historically fishless lake. Analysis of similarity showed that the chironomid assemblage was statistically different before and after predator introduction (R = 0.78; p < 0.001). Abundance of chironomids was about 40% greater in the fishless lake period compared to the period in the presence of predator. Results show major change in chironomid assemblage coinciding with the first time of goldfish introduction (around 1790 CE), followed by carp (1890 CE) and pike (1979 CE) introductions. The composition of feeding group guilds changed following a pattern characterized by a decrease in abundance of detritivorous and predaceous taxa and an increase in abundance of grazing chironomid taxa. This study suggests that predator introduction was the most important factor affecting the chironomid assemblages in this natural, Azorean fishless lake, but predators did not affect all chironomid species. Other external forcings like major climate oscillations, anthropogenic activities in the catchment basin, and volcanic eruptions seem to play an additional role. The latest stage of the warm and arid Medieval Climate Anomaly (1000–1300 CE) favoured the occurrence of some warm-adapted chironomid taxa, which were absent through the Little Ice Age (ca. 1450–1850 CE) cool period. [ABSTRACT FROM AUTHOR]

The Guadiamar River (SW Iberian Peninsula) received a major toxic spill (6 hm3) from a tailing pond in 1998 that defaunated 67 km of the main stem. Following early mud removal works, the fish assemblage was annually monitored at four affected sampling sites and one located in the upstream non-affected reach of the Guadiamar River as reference. Fish abundance and assemblage structure were analysed. Principal response curve was applied to assess the recovery trends and to identify the most influential species. A non-metric multidimensional scaling ordination and permutational multivariate analysis of variance were applied to evaluate changes in fish assemblage structure between sites and years. Overall, the affected reaches harboured fish within 2 years of the spill. Colonists arrived mainly from the upstream and downstream non-affected Guadiamar River reaches and, to a lesser extent, from three lateral tributaries. It is likely that the proximity, connectivity and environmental conditions of non-affected fish sources greatly influenced the recolonization process in each site. The structure of the fish community in the affected sites was initially similar to that in the unaffected reference stretch but changed dramatically with time, and each site followed its own trajectory. Currently, long-term threats such as mining leachates, urban sewage, agricultural pollution and exotic fish species expansion have probably exceeded the initial spill effect. This highlights the large effect of anthropogenic factors on freshwater ecosystem resilience, and the need to significantly reduce both pollution and exotic species if the affected reach of the Guadiamar River is to recover fully. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

India is known for its immense aquatic wealth, in particular freshwater fish resource. But, the ongoing ornamental fish trade and introduction of exotic fishes in the wild pose a serious threat to India's native aquatic diversity. Recent studies from several parts of India have revealed the presence of several ornamental fishes in inland water bodies, including the biologically sensitive areas such as Chalakudy River in the Western Ghats, a biodiversity hotspot which harbours 16 endangered and 4 critically endangered species. So far, 27 ornamental species have been reported in the inland wetlands of India. Among them, 15 have already established a good breeding population and have emerged as a threat to the native species. Awareness among the public, policy makers and researchers about the impacts of ornamental fishes in inland water is the need of the hour. Stringent measures should be taken to monitor the aquarium fish trade and accidental release of exotic species into inland waters. If not, the invasion of ornamental fishes may demolish the inland aquatic diversity of native Indian breeds. [ABSTRACT FROM AUTHOR]

The article presents the discussion on fluorescent aquarium curiosity escaping from fish farms and threatening local biodiversity. Topics include engineered exotic fish threatening the local fauna in one of the most biodiverse spots on the planet; and measuring the animals and the eggs analyzing the stomach content.

We provide an overview of the current status of vertebrate invasive species throughout Chile, updating information on terrestrial exotics and reporting for the first time the situation of exotic freshwater fishes. In addition, we document the legislation and programs that the Chilean government has implemented to limit the entry of exotics to the country or minimize their impact on native wild flora and fauna and on natural ecosystems. We document what is known about the introduction of 26 exotic fish species to continental waters of the country, discussing the distribution and putative effects of those 11 species that may be considered invasive. From a previous list of 24 terrestrial vertebrate invaders, we withdraw the Argentine tortoise (Chelonoidis chilensis), reindeer (Rangifer tarandus) and mouflon (Ovis ammon) because there are no data on their subsistence in the wild. On the other hand, we add three new species: red-eared freshwater turtle (Trachemys scripta), monk parakeet (Myiopsitta monachus), and red-crested cardinal (Paroaria coronata), thus keeping the total number of terrestrial invaders unchanged at 24 species. The chief agency in charge of existing laws and regulations regarding the import of exotic freshwater species is the National Fisheries Service (SERNAPESCA, in Spanish), a dependency of the Ministry of Economy. The main agency in charge of enforcing existing laws and regulations regarding the import of exotic terrestrial species to Chile is the Agriculture and Livestock Service (SAG, in Spanish), a dependency of the Ministry of Agriculture. Currently, SAG is not only controlling major border passes, seaports and airports, but also is funding studies to monitor and control already existing invaders. In addition, the Chilean Forest Service (CONAF, in Spanish) is also concerned about invasive species, but only if they enter national parks and reserves within the National System of Protected Wildlife Areas (SNASPE, in Spanish)Entregamos una revisión del estado actual de las especies de vertebrados invasores en Chile, actualizando información sobre las especies exóticas terrestres y documentando la situación de las especies exóticas de peces dulceacuícolas. Además, revisamos la legislación pertinente y los programas que el gobierno chileno ha implementado para limitar la entrada de especies exóticas al país o para minimizar su impacto sobre la flora y fauna nativas y los ecosistemas naturales. Documentamos lo que se conoce sobre la introducción de 26 especies exóticas de peces a las aguas continentales de Chile, discutiendo la distribución y efectos putativos de 11 especies que pueden considerarse invasivas. De la lista previa de 24 especies invasoras de vertebrados terrestres, nosotros retiramos la tortuga argentina (Chelonoidis chilensis), el reno (Rangifer tarandus) y el muflón (Ovis ammon), porque no hay evidencias de que hayan logrado asilvestrarse. Por otra parte, agregamos la tortuga dulceacuícola de orejas rojas (Trachemys scripta), la cotorra argentina (Myiopsitta monachus) y el cardenal de cresta roja (Paraoria coronata), manteniéndose así el total de invasoras constante en 24 especies. La principal agencia a cargo de implementar las leyes y regulaciones existentes con respecto a la importación de especies exóticas de peces es el Servicio Nacional de Pesca (SERNAPESCA), una dependencia del Ministerio de Economía. La principal agencia a cargo de aplicar las leyes y regulaciones vigentes sobre la importación de especies exóticas terrestres a Chile es el Servicio Agrícola y Ganadero (SAG), una dependencia del Ministerio de Agricultura. Actualmente, el SAG no solo controla los pasos fronterizos, puertos y aeropuertos de Chile, sino también financia estudios para monitorear y controlar los invasores ya presentes en el país. Además, la Corporación Nacional Forestal (CONAF) también se involucra con especies invasoras, pero solo si ellas entran al Sistema Nacional de Áreas Silvestres Protegidas del Estado (SNASPE)

Los sistemas fluviales de la zona central de Chile presentan variaciones estacionales en: caudal, temperatura y conductividad. Esto ha influenciado a la fauna íctica nativa la que ha sido caracterizada como primitiva, representada por un bajo número de géneros y especies. La coexistencia de especies nativas e introducidas en el río Maule, Chile (35°43°S;71°05°W), se remonta a comienzos del siglo XX, sistema en el cual las interacciones ecológicas entre estas especies no han sido suficientemente evaluadas. Para ello, se seleccionaron cuatro estaciones de trabajo en el sector andino del río Maule y sus tributarios, en dos periodos del año 1988. La fauna íctica se obtuvo realizando censo total, con un equipo de pesca eléctrica, analizándose el contenido estomacal de 142 ejemplares de Oncorhynchus mykiss, Basilichthys australis y Salmo trutta. La dieta de la mayoría de los peces analizados estuvo compuesta de organismos bentónicos, donde los taxa predominantes fueron Chironomidae, Ephemeroptera y Trichoptera. Se utilizó el índice de Horn para comparar la sobreposición de nicho trófico entre las diferentes especies, encontrándose un alto grado de sobreposición de nicho trófico en todas las estaciones y localidades. La sobreposición de nicho trófico y la diversidad bentónica se asociaron negativamente, lo que podría indicar cambios en la intensidad de las interacciones ecológicas causadas por cambios en el gradiente de recursos.Fluvial systems of central Chile show seasonal variations in: caudal, temperature and conductivity. This has influenced the ichthic native fauna, which has been characterized as primitive, with a low number of genera and species. The coexistence on native and exotic fishes in the Maule river, Chile (35°43°S;71°05°W), is registered since the beginning of the XX century; system in which the ecological interactions between these species have not been adequately evaluated. For this, in between two different seasons of the year 1988, four different locations were selected in the Andean zone of the Maule river and its tributaries. The ichthic fauna was obtained using total census, with electrofishing equipment, stomach contents of 142 specimens of Oncorhynchus mykiss, Basilichthys australis and Salmo trutta were analized. The principal diet of the fishes analysed was basically benthic organisms, where Chironomidae, Ephemoroptera and Trichoptera were the predominant. Horn°s index was used to compare trophic niche overlap among species, finding a high overlap index in all seasons and locations. Niche overlap and benthic diversity showed a negative relationship, this may indicate changes in the intensity of ecological interactions caused by changes in the gradient of resources

Pacific islands are particularly vulnerable to the effects of invasive species. After habitat destruction or modification, invasive species are responsible for more biological extinctions than any other cause. Further, the rate of extinction of native species has been higher on islands than anywhere else in the world. Invasive species have also degraded native ecosystems. In order to detect exotic intertidal mollusk species, an extensive sampling around Moorea Island, a more or less unspoiled island surrounded by a rich coral reef habitat, has been developed considering that sampled points have different characteristics in wave exposure, algae coverage, type of substrate, distance to ports, distance to freshwater, distance sewage and boat traffic. Samples were DNA barcoded for unequivocal species assignation. The presence of five NIS among 26 species seems an important signal of introduction of alien biota in Moorea Island coast. However they were represented by a total of 38 individuals among 1487 mollusks (2.55%). While the distance to relatively big ports influenced directly species richness, the intensity of maritime traffic measured as boat density near sampling points was significantly associated with the frequency of exotic species. Other environmental factors did not show significant correlation with the frequency of exotics, suggesting that in an environment without big discontinuities, with little habitat modification, local boat traffic is the most influential factor in the spread of exotic species. This could be mitigated relatively easily by reducing boat density in local zones of ecological interest. [ABSTRACT FROM AUTHOR]

The introduction of invasive species represents a major threat to the integrity of stream-dwelling fish populations worldwide, and this issue is receiving increasing attention from scientists, in particular because of potential impact on biodiversity. In this study, we analysed the dispersal of an exotic loricariid fish the red fin dwarf pleco (Parotocinclus maculicauda) in a stream of the Atlantic Forest biome in coastal south-eastern Brazil and evaluated the effects of this invasion on the native loricariid common pleco (Hypostomus punctatus). Specimens were collected at eight sites located along the course of the stream over a 15-year period. The distribution and density of the two species were determined by the Successive Removal Method. The introduction of P. maculicauda occurred in the medium sector of the stream, and during the course of the study, the species dispersed to new sites further upstream. By the end of the study, it was found at all points upstream from the original site. Hypostomus punctatus was registered at all sample sites both before and after the introduction of P. maculicauda, but its density decreased at all upstream sites after the arrival of the exotic species. Our analysis shows that colonisation by P. maculicauda seems to have a negative effect on H. punctatus densities. The maintenance of H. punctatus densities at the sites not colonised by P. maculicauda reinforces the conclusion that the colonisation of the stream by the exotic species had deleterious effects on the density of the resident H. punctatus populations, either by direct or indirect action. [ABSTRACT FROM AUTHOR]

Non-native species are often major drivers of the deterioration of natural ecosystems. The common carp Cyprinus carpio are known to cause major changes in lentic systems, but may not be solely responsible for large scale changes in these ecosystems. We used data from extensive collection efforts to gain insight into the importance of carp as drivers of ecosystem change in Lake Patzcuaro, Mexico. We compared the structure (fish density, biomass, diversity, and evenness) of fish assemblages from six Lake Patzcuaro sites with different habitat characteristics. Intersite comparisons were carried out for both wet and dry seasons. We explored the relationships between non-carp species and carp; and studied multivariate interactions between fish abundance and habitat characteristics. From a biomass perspective, carp was dominant in only four of six sites. In terms of density, carp was not a dominant species in all sites. Further, carp density and biomass were not negatively related to native species density and biomass, even when carp density and biomass were positively correlated to water turbidity levels. Carp dominated fish assemblages in the shallowest sites with the highest water turbidity, plant detritus at the bottom, and floating macrophytes covering the lake surface. These results suggest that the effect of carp on fish assemblages may be highly dependent on habitat characteristics in Lake Patzcuaro. Watershed degradation, pollution, water level loss, and other sources of anthropogenic influence may be more important drivers of Lake Patzcuaro degradation than the abundance of carp. [ABSTRACT FROM AUTHOR]

We examined the interactions of the common carp ( Cyprinus carpio L.) and nutrient additions on water quality, sedimentation rates, and submerged macrophyte biomass in mesocosms in Delta Marsh, Manitoba, Canada. We wanted to determine if carp and nutrients interacted synergistically to increase phytoplankton biomass. A two-by-three duplicated, factorial design had the following treatments: (1) control mesocosms with no carp or nutrient additions; (2) low carp density and no nutrient additions; (3) high carp density and no nutrient additions; (4) no carp and nutrient additions; (5) low carp density and nutrient additions; and (6) high carp density and nutrient additions. The presence of carp increased ammonia concentrations, turbidity, and phytoplankton biomass as expected but did not increase total reactive phosphorus concentrations. The presence of carp did not appear to interact synergistically with nutrient additions to increase phytoplankton as has been suggested by others. In mesocosms with high carp density and receiving nutrient enrichment, phytoplankton appeared to be suppressed relative to mesocosms receiving nutrient enrichment only, and nutrient enrichment and low carp density. Overall, the presence of carp appears to mimic the effects of eutrophication. Our results demonstrate that carp can cause a shift from a clear, macrophyte-dominated state to a turbid phytoplankton-dominated state at a biomass of less than 600 kg ha. [ABSTRACT FROM AUTHOR]

The axolotl ( Ambystoma mexicanum) is a critically endangered and threatened species endemic of the Central Valley of Mexico. The population of this neotenic amphibian has declined in recent years as a result of habitat destruction, polluted waters, and the introduction of exotic species such as tilapia. We evaluated the antipredator response of predator-naïve axolotls to visual and chemical cues of the Nile tilapia ( Oreochromis niloticus) and its foraging consequences. Axolotls decreased their activity and increased their use of refuge in the presence of combined chemical and visual cues from the predator. The axolotls seem to use their vision to confirm the level of risk perceived through chemical signals to modulate their antipredator response accordingly. The axolotls engaged in prey capture at a similar rate independent of the type of predator exposure. However, the efficiency of prey capture decreased in axolotls exposed to the chemical and the combined visual and chemical cues from the tilapia. The foraging costs to the axolotls induced by tilapia can ultimately affect their growth rate and size. The axolotls display antipredator behaviours to reduce the risk of predation by tilapia, which is a primary condition of coexistence with this exotic predator. [ABSTRACT FROM AUTHOR]

Gussevia spiralocirra, a Neotropical parasitic monogenoid (Platyhelminthes), has been recorded from the type host, freshwater angelfish Pterophyllum scalare (Cichlidae), collected from the post-quarantine populations in local aquarium markets of Lucknow and Itanagar, India. The finding establishes India as a geographical distribution record for G. spiralocirra, and more importantly, reveals a potentially serious breach of quarantine regulations of the country. The present communication provides a summary assessment of existing Indian guidelines for importation of exotic aquarium fish and highlights some of its major shortcomings. [ABSTRACT FROM AUTHOR]

Globally, amphibian populations are threatened by a diverse range of factors including habitat destruction and alteration. Forestry practices have been linked with low diversity and abundance of amphibians. The effect of exotic Eucalyptus spp. plantations on amphibian communities has been studied in a number of biodiversity hotspots, but little is known of its impact in the Mediterranean region. Here, we identify the environmental factors influencing the presence of six species of amphibians (the Caudata Pleurodeles waltl, Salamandra salamandra, Lissotriton boscai, Triturus marmoratus and the anurans Pelobates cultripes and Hyla arborea/meridionalis) occupying 88 ponds. The study was conducted in a Mediterranean landscape dominated by eucalypt plantations alternated with traditional use (agricultural, montados and native forest) at three different scales: local (pond), intermediate (400 metres radius buffer) and broad (1000 metres radius buffer). Using the Akaike Information Criterion for small samples (AICc), we selected the top-ranked models for estimating the probability of occurrence of each species at each spatial scale separately and across all three spatial scales, using a combination of covariates from the different magnitudes. Models with a combination of covariates at the different spatial scales had a stronger support than those at individual scales. The presence of predatory fish in a pond had a strong effect on Caudata presence. Permanent ponds were selected by Hyla arborea/meridionalis over temporary ponds. Species occurrence was not increased by a higher density of streams, but the density of ponds impacted negatively on Lissotriton boscai. The proximity of ponds occupied by their conspecifics had a positive effect on the occurrence of Lissotriton boscai and Pleurodeles waltl. Eucalypt plantations had a negative effect on the occurrence of the newt Lissotriton boscai and anurans Hyla arborea/meridionalis, but had a positive effect on the presence of Salamandra salamandra, while no effect on any of the other species was detected. In conclusion, eucalypts had limited effects on the amphibian community at the intermediate and broad scales, but predatory fish had a major impact when considering all the scales combined. The over-riding importance of introduced fish as a negative impact suggests that forest managers should prevent new fish introductions and eradicate fish from already-occupied ponds whenever possible. [ABSTRACT FROM AUTHOR]

This paper presents a list of the exotic fish species introduced in Mexican aquatic systems. This list is the result of the systematized information contained in several databases of ichthyological collections around the world and different publications. A total of 104 species were found, distributed in 19 families and 51 genera. The most species-rich were Cyprinidae with 22 species, Poeciliidae (19 species), Cichlidae (15 species) and Centrarchidae (13 species). A map and an electronic database were created based on the knowledge of the species, showing the known introductions of exotic fishes in the country. The information was obtained from a database stored in the Colección Nacional de Peces IBUNAM, which can be accessed online. This study has a high importance for the knowledge of the exotic fish fauna of Mexico and its current status. [ABSTRACT FROM AUTHOR]

The effects of plerocercoids of the cestode Triaenophorus nodulosus infecting the livers of native Eurasian perch Perca fluviatilis and non-native pumpkinseed Lepomis gibbosus was investigated in 17 sites along the Moselle watershed. With a single exception, infected individuals were not observed in the main channel whether or not northern pike Esox lucius, a final host, was present. In ponds where the pike was present, the prevalence of T. nodulosus averaged 86% in Eurasian perch and 15% in pumpkinseed. The parasite was not present at all in ponds when pike were absent. Parasite load, hepatosomatic index (HSI), gonadosomatic index (GSI) and body condition index (CI) were compared between hosts in one site where parasite prevalence and fish abundance was highest. HSI in infected perch was significantly higher than in uninfected perch, whereas no differences in HSI were detected between infected and uninfected pumpkinseed. While perch were more frequently infected and had a greater average parasite load than pumpkinseed, there were no significant differences in either indicator between the two species. Furthermore, no significant differences in GSI or CI were observed between infected and uninfected fish in either species, by either gender or maturity stage. We hypothesize that pumpkinseed is more resistant to the parasite or less likely to feed upon infected copepods than perch. [ABSTRACT FROM AUTHOR]

During the last decades invasive species became a matter of concern all over the world. Established salmonid populations make sport fishery in Patagonia one of the top in the world, but there is increasing evidence that these populations have negative impacts on native ecosystems. Predation rates and feeding preferences of native catfish Hatcheria macraei and invasive trout Oncorhynchus mykiss were compared by exposing three stream benthic invertebrate species with contrasting ecological roles to direct predation. Secondly, feeding and escaping behaviours of the mayfly Meridialaris chiloeensis belonging to either non-naive or naive populations to predators were investigated in the presence of predation chemical cues, i.e. non direct predator access. Total predation by trout was 2–3 times higher than by native catfish. Trout had clear prey preferences while catfish changed its preferences with shifting prey composition. Invertebrate species showed different responses to predation by native and exotic fish due to the different strategies of fish and invertebrates which resulted from the combination of predator efficiency and prey vulnerability. Feeding activity of non-naive nymphs was significantly lower than that of naive nymphs. In addition, mayfly nymphs from both populations showed higher emigration rates in presence of trout chemical cues than in presence of catfish cues or in fishless treatment. Consequently, the reduced feeding activity observed in non-naive mayflies exposed to rainbow trout cues resulted from their inactivity in channels, as both nymph populations had similar emigration rates. Due to high predation rates, prey preferences (i.e. high potential to exploit prey resources) and induced strong predation avoidance behaviour of prey, invasive trout may have a stronger influence on the abundance and species composition of native macroinvertebrates than native catfish. In just about one century, invertebrate species such as the ubiquitous M. chiloeensis show behavioural adaptations to this exotic predator. [ABSTRACT FROM AUTHOR]

The alteration of aquatic ecosystems and increasing aquarium fish trade with exotic species is promoting the presence and invasion of these species in large river systems, with the consequent loss of native biodiversity and the homogenization of aquatic systems. The Chontalcuatlan-Amacuzac hydrological system belonging to the biogeographical province of the Balsas River is one of the main regions in Mexico devoted to the breeding and rearing of aquarium fish, where the improper handling of these organisms has caused their escape to adjacent hydrological systems and, together with urban and industrial pollution, are changing schemas and levels of regional biodiversity. As a first approximation to determine these effects, we evaluate a segment of 140 km of this hydrological system through surveys in 12 sites during the time of major climatic and flow stability, and relating environmental variables with the distribution and abundance of fish. Also, the structure of fish assemblages was assessed by means of similarity and multivariate statistical methods (correspondence and principal components analysis), and these assemblages were found to be segregated by a thermal gradient. Exotic fish were dominant in conditions of low environmental quality, while native species were restricted to areas with better quality of water and geographic isolation. Exotic taxa such as Amatitlania nigrofasciata, Pterigloplictys disjunctivus, Pterigloplictys pardalis, Poeciliopsis gracilis and Heterandria bimaculata, have achieved the degree of invasive due to the fact that they are distributed of abundant manner in the entire hydrological system. [ABSTRACT FROM AUTHOR]

Aquaculture, the rearing of aquatic organisms under controlled or semi-controlled conditions to produce organisms, mainly for food, ornamental and sporting purposes, is a fastest-growing animal-food-producing sector in the world. The human-mediated introduction of exotic fish has played an important role in the success story of aquaculture. Nonetheless, many exotic fish have been implicated in the loss of native fish biodiversity, largely through the transmission of parasites and diseases amongst others. Whilst the transmission of parasites following the introduction of exotic food fish is well documented, transfer of those carried by exotic ornamental fish has received little attention. This article provides the first summary review of the global translocation of the platyhelminthes class Monogenoidea via the aquarium fish trade to draw attention to the growing parasitological risk factors associated with this form of commerce. By examining the invasive characteristics of both aquarium fish and monogenoids, I review how the monogenoids fit into the different stages that an introduced species goes through when invading the destination environment. For this, I use a theoretical framework, synthesising published reports on the aquarium fish trade with current knowledge on monogenoids to model invasion success. Next, I provide examples of invasive monogenoids on exotic Indian aquarium fish and briefly discuss the vulnerability of India to colonisation by imported aquarium fish and their parasitic monogenoids. I conclude that the aquarium fish trade is a perfect gateway for worldwide translocation of monogenoids. As this trade continues to increase and intensify, global translocation of monogenoids will expand even further. [ABSTRACT FROM AUTHOR]