Search

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.)

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]

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 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]

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]

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]

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]

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

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]

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]

Fish scales (except placoid) have been employed for age determination, growth studies and various growth parameters, which are useful in the formulation of various fishery management practices and the optimum exploitation of fishery stocks of commercial fish species. Fish-scale morphology and its morphometrics can be employed for taxonomic purposes and for phylogenetic relationships. The evaluation of populations/ stocks of the fish species having wide zoogeographical distribution and inhibiting distinctly different ecological conditions has been done with the help of molecular markers. An alte rnate technique, i.e. to study the ultrastructural details of the focus region of the regenerated scale has been found to be more reliable and economical. This technique has been tested positively on the regenerated cycloid scale of an exotic fish, Cyprinus carpio communis L. inhabiting five distinctly ecologically different water bodies of northern India. [ABSTRACT FROM AUTHOR]

Thaparocleidus caecus and Thaparocleidus siamensis are parasitic monogeneans found on the gills of striped catfish Pangasianodon hypophthalmus (Pangasiidae), a native species of Southeast Asia. We report T. caecus and T. siamensis, for the first time in India, from the gills of aquarium-kept P. hypophthalmus (prevalence 40 % and 80 % respectively). We also report T. siamensis from the gills of pond-cultured P. hypophthalmus (prevalence 100 %); no specimen of T. caecus was observed on pondcultured P. hypophthalmus (prevalence 0 %). Morphometric data of the studied parasites did not differ significantly from previous descriptions of the two species recovered in other geographic locations. Similarly, no consequential variation was found when 28S rDNA of T. siamensis from the present study was compared with that of T. siamensis from Malaysia available on GenBank. The present investigation adds to growing cases of freshwater monogeneans that have been concomitantly introduced worldwide as a result of aquarium and aquaculture trade. [ABSTRACT FROM AUTHOR]

This study was conducted to determine taxonomic and zoogeographic features of fishes from the Kor and Helleh River basins in southwestern Iran. The specimens were collected from 2004 to 2007. Twenty four species belonging to 20 genera, 9 families, and 6 orders from the Kor River basin and 21 species belonging to 19 genera, 8 families, and 6 orders from Helleh basin were identified. Ichthyofauna of Helleh basin included some species not present in the Kor basin: Luciobarus barbulus, Tor grypus, Carasobarbus luteus, Garra rufa, Mastacembelus mastacembelus, Glyptothorax silviae, and Cyprinion cf. macrostomum. The Helleh basin ichthyofauna is a combination of western (Ethiopian) and eastern (Oriental) fauna. The cyprinid genera, Barbus, Alburnus, Capoeta, and Chondrostoma should be revised using both molecular and morphological data.

A new record of the freshwater jellyfish Craspedacusta sowerbii in northern Chilean Patagonia is reported. The specimens were collected from Laguna Illahuapi, an oligotrophic shallow lake (15 m maximum depth) in early austral autumn, May 2013. This water body is located in the upper zone of the Rio Bueno basin, Province of Ranco, Region de los Ríos, Chile. The region is characterized by a great diversity of freshwater environments with minimal human pressure. This report confirms the presence of C. sowerbii in Chilean Patagonia and represents the southernmost range of distribution of this exotic medusa in South America. This study also contributes additional information on the limnological characterization of this water body. [ABSTRACT FROM AUTHOR]

We present here a comprehensive account of the diversity, distribution, threats, and suggest conservation measures for the fishes of Bharathapuzha, the largest west flowing river in the southern Indian state of Kerala. A total of 117 species under 43 families and 81 genera were recorded from the river, of which 98 were primary freshwater and 19 were secondary freshwater and/or diadromous species. Six species of non-native fish were also recorded, of which three were exotic to the country and three were transplanted from the gangetic plains. Twenty-eight percent (S = 33) of species that occur in the Bharathapuzha are endemic to the Western Ghats, while three species (Balitora jalpalli, Mesonoemacheilus remadevii and Pseudolaguvia austrina) are restricted in their distribution to the river system. A little more than one-tenth (11%; S = 13) of species that occur in the river are listed under various threatened categories on the IUCN Red List. As part of this study, we also extend the distribution range of Osteochilichthys longidorsalis to the Bharathapuzha River system, based on its collection from the Thoothapuzha tributary. Several anthropogenic stressors including deforestation and loss of riparian cover, dams and other impoundments, pollution, sand mining, non-native species and destructive fishing practices are threatening the rich ichthyofaunal diversity and endemism in the Bharathapuzha. There is hence an urgent need to develop and implement conservation plans, some of which are discussed. [ABSTRACT FROM AUTHOR]

The long-fingered bat Myotis capaccinii is a European trawling bat reported to feed on fish in several Mediterranean locations, but the ecological circumstances of this behavior have not yet been studied. To elucidate the importance of fishing in this bat's diet, we evaluated the frequency and seasonal variation of fish remains in 3,000 fecal pellets collected from M. capaccinii at a nursery roost in Dénia (Eastern Iberian Peninsula) in 2008, 2009, and 2010. Fish consumption occurred evenly throughout the year. All otoliths found in feces were identified as belonging to the surface-feeding fish Gambusia holbrooki. Measuring otoliths, we estimated that the mean size of consumed fish was significantly smaller than the mean measured for available fish, suggesting that the long-fingered bat's relatively small body may constrain its handling of larger prey. Of note, one bat had eaten 15 fish, showing that fish may be a locally or seasonally important trophic resource for this species. By capturing 15 bats and radio-tracking the four with the most fish remains in their droppings, we also identified fishing areas, including a single fishing ground comprising several ponds within a golf course. Ponds hold a high density of G. holbrooki, suggesting that the amount of fish at the water surface may be the principal factor triggering fishing. The observed six-fold increase in percentage of consumed fish across the study period may be related to recent pond-building in the area. We discuss whether this quick behavioral response is a novel feature of M. capaccinii or an intrinsic feature that has erupted and faded locally along the species' history. [ABSTRACT FROM AUTHOR]

Exotic fish species has caused several impacts on aquatic biodiversity. The Lago de Pátzcuaro has some well-studied exotic species, except the Lerma livebearer Poeciliopsis infans. This fish species was introduced into the Lago de Pátzcuaro before 1997 and the aspects of its biology are still unknown. In this study we assessed aspects of the trophic ecology of this exotic fish, P. infans, using gut content and stable isotope analysis to understand its capacity to tolerate anthropogenic environmental degradation in the Lago de Pátzcuaro. We also determined its trophic guild position (TP) using the TrophLab Program and stable isotope. Niche breadth was calculated by standardized Levins' Index (Bi). Fish was captured with a seine during wet and dry seasons at six environmentally different sites and gut contents were obtained. We analyzed a total of 239 gut contents of P. infans. The contribution of each food item in the diet was quantified using frequency of occurrence and area percentage. The importance of each prey item was determined according to the index of relative importance (IRI), and the omnivory index (OI) was used to assess the feeding behavior. Fish were categorized by size and the diet was compared between fish sizes and sites. Dorsal muscle tissue and water hyacinth tissue was obtained for nitrogen isotope signature (δ15N) analysis. Additionally, we measured water and habitat quality to evaluate environmental conditions at each site. We concluded that P. infans is an omnivore (OI=0.28) that consumes mainly detritus (44%), epiphytic diatoms (37%), and secondary on terrestrial insects (6%) and zooplankton (10%). The fish can behave as a specialist (Bi=0.39) or generalist (Bi=0.68) and as a primary consumer (TROPH=2.2; TP=2.3) with a feeding strategy that was the same at different sizes, seasons and sites. None of the evaluated sites showed good environmental quality. We argue that P. infans can tolerate changes in water quality and feeding items availability, because it can exploit resources in multiple trophic webs. However, this species could be dependent on habitat complexity, especially in the aquatic vegetation cover. [ABSTRACT FROM AUTHOR]

The introduction of exotic fish can have profound effects on wetland ecosystems, making it important to understand wetland vulnerability to invasion. Recently, African jewelfish (Hemichromis Mourneuxi) have invaded wetlands in a hydrologically altered agricultural landscape at Archbold Biological Station in peninsular Florida. We sampled 45 wetlands using minnow traps to determine the current distribution and relative abundance of African jewelfish and brown hoplo (Hoplosternum littorale), another established exotic fish. We examined whether wetland area, depth, or distance to nearest ditch influenced the distribution or catch-per-unit-effort (CPUE) of these species. We also measured the total length and weight of 864 African jewelfish and examined gut contents to determine the body condition and diet of this newly established population. African jewelfish were found in only 22% of wetlands but were the most frequently captured vertebrate in those wetlands (mean 8.30 ± 0.81 SE individuals/trap-night). Wetland area was the only significant predictor of African jewelfish distribution and was positively correlated with the combined CPUE of African jewelfish and brown hoplo. Distance to nearest ditch and exotic fish CPUE were inversely correlated. None of the factors examined influenced brown hoplo distribution. The African jewelfish were in good condition, and their diet consisted primarily of fish and macroinvertebrates. Additional research is needed to determine the effects of African jewelfish on native freshwater communities. [ABSTRACT FROM AUTHOR]

We assessed the effects of the abundance and biomass of four exotic fishes (common carp, Cyprinus carpio; guppy, Poecilia reticulata; green swordtail, Xiphophorus hellerii; and redbelly tilapia, Tilapia cf. zillii) on the residual somatic condition (Kr) of endangered Baja California killifish (Fundulus lima) in two oasis systems of Baja California Sur, Mexico. We used multiple regressions to analyze relationships between Kr of the killifish and 21 ecological variables. Biomass of redbelly tilapia and common carp were variables that better explained variation in Kr among populations of killifish. In both drainages, redbelly tilapia was the dominant fish, which relegated smaller habitat units to the other coexisting species of fishes, increasing competition among them and decreasing Kr and abundance of the endemic killifish. We concluded that Kr for populations of killifish may be a good indicator of the competitive interactions with exotic fishes in drainages of Baja California peninsula and should be considered when such stocks are subject to recovery plans or any other management program. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia 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 presents a study on the feeding habits of the Neotropical Otter, or Longtra longicaudis in lotic (streamlet) and semilotic (reservoir) environments. It is hypothesized that otters have different diets depending on the environment because of the place's differences in physics and biotic factors from natural conditions. An analysis of the otter's diet in lotic and semilotic environments of Paranapenema Valley in southeaster Brazil was performed between April 2008 and March 2009. Samples of otter feces were gathered and classified into food items including fish, crustacean and insect. Despite similarities in diets in the two environments, the results showed modifications on the fish species that each group consumed and that those in the semilotic environment ate more exotic fish.

The diet composition and feeding strategy of native and exotic fish species were studied from May 2005 to February 2006 in three Patagonian low-order streams. A total of 464 fish were caught, which belonged to the exotic species Oncorhynchus mykiss (270), Salmo trutta (177) and the native species Hatcheria macraei (17). The analysis of 336 stomach contents indicated that at the individual level, the three species had a generalized feeding strategy based on benthic invertebrates (Plecoptera, Trichoptera, Coleoptera and Diptera). In the three streams, the widest population niches were observed in winter. There was, however, also a slight tendency toward an increased between-phenotype contribution to the niche width in same season, indicating that a small proportion of individuals within the fish populations specialized by predominantly feeding on a few specific prey species. Hence, the wide population niche widths observed throughout the year were partly a result of mixed individual feeding strategies within the populations. The higher diet overlaps were registered between exotics O. mykiss–S. trutta at Glyn and Carbón, and O. mykiss and the native H. macraei at Manguera, but it changed markedly through the year, perhaps depending on temporal changes in food availability suggesting a competitive coexistence of these species. This is mainly related to the fact that both species changed their food preferences in spring and foraged almost exclusively on Aubertoperla illiesi. This implies that in order to reduce the predation risk or the inter-specific competition for food, the fish species might partition the feeding habitats. [ABSTRACT FROM AUTHOR]

Background: In Anzali Lagoon, there are some endemic and exotic fishes. The present study was conducted to compare the parasitic fauna of Blicca bjeorkna, as an endemic fish and Hemiculter leucisculus, as an introduced fish to the lagoon. Methods: A parasitological investigation was done on 78 specimens of B. bjoerkna and 114 of H. leucisculus. The fishes were collected from August 2009 to April 2010 by the electro fishing from Anzali Lagoon. Results: Eleven parasites species were found in 192 fish samples. The prevalence and mean intensity of parasites in each host were as follows: Parasites from B. bjorkna were Trichodina perforata (53.85%); Myxobolus musayevi (27.19%, 1±0.79); Dactylogyrus difformis (88.05%, 8±7.24) and D. sphyrna (5.18%, 0.95±0.51), Diplostomum spataceum (98.72%, 9.51±9.01), Posthodiplostomum cuticula (15.38%, 4.25±2.5), Ripidocotyle sp. (1.28%, 2±0.74); Contracaecum osculatum (17.95%, 1.64±0.79), Philometra rischta (12.8%, 1.4±0.54), and Raphidascaris acus (1.04%, 0.03±0.26). The H. leucisculus were infected with T. perforata (27.19%), D. spataceum (7.89%, 1.33±0.54), Ps. tomentosa (7.02%, 1.62±0.49) and R. acus (0.88%, 3±0.28). B. bjoerkna was presented as a new host for M. musayevi and C. osculatum, while H. leucisculus was introduced as a new host for T. perforata and Ps. tomentosa. Conclusion: The prevalence of parasites was significantly more in native fish than that of exotic fish (P<0.05). This reduction in parasitic infection in H. leucisculus may be due to its immune system resistance, well adaptation to the new environment, host-specific limitation for endemic parasites and disability of introduced parasite to complete its life cycle in the new host as well. [ABSTRACT FROM AUTHOR]

Indiscriminate and illegal farming of the African Catfish Clarias gariepinus, in central Kerala has now resulted in the escape and spread of the species into Vembanad Lake, a large brackish water wetland and inland fish diversity hotspot. We collected 17 individuals of C. gariepinus ranging in size from 200 to 750 mm from different locations in the southern sector of the lake during a field survey conducted in 2007. Samples comprised of mature specimens of both sexes indicating their reproductive potential in the study area. The possible impacts of spread of C. gariepinus into natural water bodies of Kerala, especially the Vembanad Lake, and options for their management are discussed. [ABSTRACT FROM AUTHOR]

Abstract: We describe a tolerance classification based on the physicochemical parameters of water and habitat quality indices for native and introduced fish species in northeastern Spain. Although fish are widely used as biological indicators, the tolerance categories currently available for Spanish Mediterranean fish species are uncertain or subjective. We sampled 430 sites covering a wide range of river conditions, allowing us to develop tolerance scores based on a quantitative assessment. We used indirect ordination methods to establish stress gradients between the environmental variables compiled during the monitoring surveys carried out from 2002 to 2008. We then drew up a tolerance classification for the most common species in our dataset using weighted average inference models based on the following gradients: water quality and the state of physical habitat. The results were corroborated by multivariate gradient analysis. The fish scores obtained were applied to an independent dataset and a positive correlation was found between assessment protocols. Our results corroborate the use of fish, including exotic fish species, as biological indicators. Our findings may be used in a regional Index of Biotic Integrity and for the use of fish in bioassessment studies based on scores. [ABSTRACT FROM AUTHOR]

Food web structure is well known to vary widely among ecosystems. Recent research indicates that there can be a high degree of spatial heterogeneity within ecosystems as well. Xochimilco is a small heterogeneous freshwater system that has been transformed into a network of canals, small lakes, and wetlands. Located within Mexico City, this ecosystem has been intensively managed and highly impacted for more than 50 years. This system receives urban and agricultural runoff, with resulting impacts on water quality. The aquatic community is dominated by exotics such as carp ( Cyprinus carpio) and tilapia ( Oreocrhomis niloticus), though the system still supports endemic species such as the aquatic salamander, axolotl ( Ambystoma mexicanum), and crayfish ( Cambarellus montezumae), which are both endangered. In this study, we used carbon and nitrogen stable isotopes for the whole food web and gut content analysis from the exotic fishes to describe food web structure in different canals within Xochimilco. There were significant isotopic differences among canals. These differences may result from isotopic baseline differences as well as differences in actual food web structure: both are related to local spatial variation in water quality driven by nutrient inputs and exotic fishes. Within-ecosystem variability is likely to be seen in other perturbed shallow systems as well, and should be explicitly considered in future food web studies. [ABSTRACT FROM AUTHOR]

Background. The Ganga River (Ganges) is known of its rich fish diversity which is adversely affected by degrading environmental and ecological conditions. There are more than 300 exotic fish species in India. Many of them (particularly Cyprinus carpio) escaped from confinement and are now present in the Ganga River, challenging its ecological equilibrium. The aim of this project was to study the population characteristics of Cyprinus carpio (i.e., the abundance, size range, food and feeding, gonado-somatic index (GSI), gonad maturity stage, maturity and breeding) and the altered fishery dynamics. Materials and Methods. The commercially caught fishes, including the exotic ones, were identified, examined and measured. Important indices such as: the abundance index of exotic fishes, the gonado-somatic index (IG), as well as the gonad maturity stage of the escapee C. carpio were determined. The gut content was also analyzed to identify food items and thereafter the food richness, diet breadth, and gut repletion index (GRI%) were calculated using the Simpson's diversity index. Results. C. carpio introduced about sixty years ago for aquaculture has now been found to invade into the Ganga, the largest river of the country contributing significantly to the fishery. The abundance index of C. carpio ranged from 12.2% to 45.5 % in 250 km long river stretch of the Ganga River flowing along Kanpur to Varanasi in the state of Uttar Pradesh. The gut content analysis revealed the presence of Eichhornia (9.8%), Pistia (11.6%), Nymphaea (8.5%), annelids worms (7.8%), algae (20.2%), mud and detritus (14.8%). The calculated diet breadth ranged from 0.82% to 0.91%; food richness ranged from 12 to 16, and the gut repletion index (GRI%) was 100% at different sampling sites. Mature females represented all the six reproductive stages with varying gonadosomatic index (IG) (0.5 to 30) in different catches. Presence of spent, ripe, and mature females was recorded. Conclusion. Abundance of exotic fish primarily C. carpio and Oreochromis niloticus in the fishery of the Ganga River was observed. The gonado-somatic index (IG) and the presence of all the six gonadal stages confirmed that C. carpio established its breeding population. The dominant catch of exotic fishes negatively impacted on the important indigenous fishes particularly Indian major carps (Catla catla, Labeo rohita, and Cirrhinus mrigala). The change in dynamics of the fishery due to the presence of common carp attracted attention to conserve rich indigenous germplasm facing threats of shifting from their natural habitats. [ABSTRACT FROM AUTHOR]

In the Hawaiian Islands, intentionally introduced exotic fishes have been linked to changes in native biodiversity and community composition. In 1905, the mosquito fish Gambusia affinis was introduced to control mosquitoes. Subsequently, G. affinis spread throughout the Islands and into coastal anchialine ponds. Previous studies suggest that presence of invasive fishes in anchialine ponds may eliminate native species, including the endemic shrimp Halocaridina rubra. We examined effects of G. affinis on H. rubra populations in anchialine ponds on the Kona-Kohala coast of the island of Hawai'i. In the presence of G. affinis, H. rubra exhibited a diel activity pattern that was not seen in fishless ponds. Shrimp in ponds with fish were active only at night. This pattern was evident in anchialine ponds and in laboratory experiments. In laboratory predation experiments, G. affinis preferentially consumed smaller H. rubra, and in the field the H. rubra collected from invaded sites were larger them those from fishless ponds. Analysis of trophic position using stable isotope analyses showed that feeding of H. rubra was not significantly distinct from that of snails, assumed to feed at trophic level 2.0 on epilithic algae, but G. affinis was slightly omnivorous, feeding at tropic level 2.2. The mosquito fish diet was apparently composed primarily of algae when the defensive behavior of H. rubra made them substantially unavailable as prey. The effect of successful establishment of G. affinis on shrimp behavior has the potential to alter abundance of benthic algae and processing and recycling of nutrients in anchialine pond ecosystems. [ABSTRACT FROM AUTHOR]

Introduced plants and animals have been a prominent worldwide environmental issue for decades; however, considerable debate and confusion remain over how to list and otherwise categorize these species. This paper describes a process for categorizing exotic freshwater fishes that have been found in public waters, The basis of this process has been used by the Florida Fish and Wildlife Conservation Commission for nearly 30 years. Reproducing exotic fishes are grouped into three subcategories (established. possibly established, and localized) using species-specific biological and population characteristics resulting in a list that is helpful for prioritizing research and management activities. The purpose of this paper is to stimulate interest in standardizing processes for categorizing introduced species based on how well they adapt to new environments. [ABSTRACT FROM AUTHOR]

An Ecopath model of the southern part of Lake Kivu, a deep African equatorial lake was constructed to quantitatively describe the possible impact of fish introductions in this ecosystem. This study is considered as an initial step in summarizing ecological and biological information, under a coherent framework, on this ecosystem. Fourteen compartments were considered. As a phytoplankton-based food web, it is observed that key food sources are not fully utilized as transfer efficiencies per trophic levels (TL) varies between 4.5 and 9.4%. Zooplankton plays a major role in transferring organic matter from TL1 to higher TLs due to the abundance of zooplanktivores. Shifts in food preferences and distribution of some of the fish functional groups were observed as a response to competition. The majority of fish biomass concentration is in TL3 (55%). The fishery is concentrated at TL3 and can, therefore, be consider as “immature”, sensu Odum. The direct and indirect effects of predation between system components (i.e. fish, invertebrates, phytoplankton and detritus) are quantitatively described and the possible influence and role in the ecosystem''s functioning of introduced fish species are discussed. [Copyright &y& Elsevier]