Fish Invasions

The commonplace, quantitative assertion that ‘invasions’ of exotic (introduced) organisms constitute the ‘second greatest threat’ of species extinction debuted in Edward O. Wilson’s 1992 book, The Diversity of Life. Based only on three interrelated publications summarising concerns about the conservation status of North American freshwater fishes, Wilson laconically extended the claim to planetary significance. This inspired the most-cited article ever published in the American journal BioScience, subsequently underpinning thousands of peer-reviewed publications, government reports, academic and popular books, commentaries, and news stories. While carefully recounting the origin, promotion, and deployment of the ‘second greatest threat’, I argue that its uncritical acceptance exemplifies confirmation bias in scientific advocacy: an overextended claim reflexively embraced by conservation practitioners and lay environmentalists because it apparently corroborated one particular, widely shared dismay about modern society’s regrettable effects on nature.

ABSTRAK
Interaksi trofik pasca masuknya ikan introduksi ataupun ikan asing invasif merupakan dasar
untuk mengkaji tekanan ekologis terhadap ikan asli. Penelitian ini bertujuan untuk menganalisis interaksi trofik komunitas ikan pasca berkembangnya jenis-jenis ikan asing invasif di Danau Matano, Sulawesi Selatan. Ikan contoh diperoleh dari hasil tangkapan jaring insang percobaan, jala lempar, dan seser pada Mei, Oktober, dan November 2015 serta Februari, Juli, dan September 2016. Analisis ekologi trofik yang dilakukan meliputi indeks bagian terbesar, tingkat trofik, luas relung dan tumpang tindih relung makanan, serta pola strategi makan. Hasil penelitian menunjukkan komunitas ikan yang tertangkap di Danau Matano terdiri atas 9 famili, 11 genera, dan 17 spesies. Ikan louhan mendominasi komunitas ikan di Danau Matano sebesar 53,62%. Makanan alami yang banyak dimanfaatkan oleh sejumlah ikan dalam komunitas adalah insekta (Diptera), Gastropoda (Tylomelania sp.), dan larva insekta (Chironomidae). Kelompok trofik komunitas ikan di Danau Matano terdiri atas detritivora, herbivora, insektivora, zoobentivora, dan
piscivora. Masuknya ikan introduksi memunculkan kelompok trofik baru (detritivora dan herbivora). Ikan introduksi cenderung memiliki luas relung makanan yang lebih bervariasi. Kompetisi terhadap makanan alami kategori moderat banyak terjadi antara ikan asli dengan louhan. Strategi pola makan ikan asli di Danau Matano cenderung bersifat spesialis, sedangkan ikan introduksi memiliki strategi pola makan yang lebih bervariasi dan oportunistik. Ikan louhan sebagai ikan introduksi dominan yang bersifat invasif mampu memanfaatkan seluruh sumber daya makanan alami yang tersedia dan menempati tingkat trofik tertinggi di Danau Matano. Tekanan ekologi terhadap ikan asli oleh ikan asing invasif di Danau Matano terjadi karena adanya kompetisi terhadap makanan alami.

Kata Kunci: Danau Matano; ikan asing invasif; ikan louhan; interaksi trofik; strategi pola makan

ABSTRACT
Trophic interactions post-develpment of non-native fish or invasive alien fish species are the basis knowledge for assessing and preventing the ecological pressure on native fish. This research aims to analyze the trophic interactions of fish community post-development of invasive alien fish species in Lake Matano, South Sulawesi. Fish samples were obtained from the catch of experimental gill nets, cast nets, and push nets in May, October, and November 2015 along with February, July, and September 2016. Trophic ecological analysis carried out included index of preponderance, trophic level, niche breadth and niche overlap of natural food, and feeding strategy. The fish
community caught in Lake Matano consists of 9 families, 11 genera, and 17 species. Flowerhorn cichlid dominates the fish community in Lake Matano by 53.62%. Natural foods that are widely used by a number of fish in the community are Insecta (Diptera), Gastropods (Tylomelania sp.), and larvae of Insecta (Chironomidae). The guild trophic of fish community in Lake Matano consists of detritivores, herbivores, insectivores, zoobentivores, and piscivores. The introduction of non-native species bring up to new guilds (detritivores and herbivores). Non-native fishes tends to have a variety niche breadth. Moderate competition for natural food resources between native fish and flowerhorn cichlid is quite high. Feeding strategy of native species in Lake Matano tend to be specialist, while non-natives species have more variety and opportunistic. Flowerhorn cichlid as dominant invasive alien fish species is able to utilize all natural food resources and occupies the highest trophic level in Lake Matano. Ecological pressure on native fish by invasive alien fish species in Lake Matano occurs due to competition in obtaining natural food resources.

Keywords: Lake Matano; invasive alien species; flowerhorn cichlid; trophic interactions; feeding strategy

Sejak ikan bilih (Mystacoleucus padangensis) diintroduksi ke Danau Toba tahun 2003, produksi tangkapan ikan bilih meningkat tajam dari 8.500 ton pada tahun 2007 menjadi 45.000 ton pada tahun 2012. Produksi tangkapan tersebut telah berdampak positif terhadap peningkatan pendapatan nelayan dan kesejahteraannya di sekitar Danau Toba. Namun mulai tahun 2013, produksi ikan bilih menunjukkan penurunan yang disebabkan oleh berbagai faktor, seperti tekanan penangkapan yang menggunakan alat tangkap tidak ramah lingkungan, kawasan suaka ikan bilih belum ditetapkan dan dilindungi, permainan harga ikan bilih berukuran kecil dengan permintaan yang tinggi dan masuknya ikan asing invasif (ikan kaca, Parambassis siamensis). Makalah ini membahas strategi pemulihan sumberdaya ikan bilih dan upaya pengendalian ikan kaca di Danau Toba, Sumatera Utara.
KATA KUNCI: pemulihan sumber daya ikan, suaka, penangkapan, ikan asing invasif.

Since bilih fish (Mystacoleucus padangensis) introduced to Lake Toba in 2003, the catch production of the fish increased sharply from 8,500 tons in 2007 to 45,000 tons in 2012. The catch production has a positive impact on increasing income and welfare of the fishermen around the Lake Toba. However, beginning in 2013, the production of bilih fish showed a decline caused by various factors, such as fishing pressure of the destructive gear, bilih fish reserve areas has not been established and protected, bilih fish of small size intensively catch due to more demanding with high price and the influx of invasive alien fish species of glass fish, Parambassis siamensis. This paper discusses the enhancement and management strategy of the bilih fish resources and efforts to control of glass fish in the Lake Toba, North Sumatra.
KEYWORDS: fish enhancement, reserve area, fish capture, invasive alien fish species

This study presents a detailed comparative analysis of external morphology of four of the most invasive goby species in Europe (round goby Neogobius melanostomus, bighead goby Ponticola kessleri, monkey goby Neogobius fluviatilis and racer goby Ponticola gymnotrachelus) and interprets some ecological requirements of these species based on their morphological attributes. The results are evaluated within an ontogenetic context, and the morphological differences between the species are discussed in terms of the question: can special external shape adaptations help to assess the invasive potential of each species? The morphometric analyses demonstrate important differences between the four invasive gobies. Neogobius melanostomus appears to have the least specialized external morphology that may favour its invasive success: little specialization to habitat or diet means reduced restraints on overall ecological requirements. The other three species were found to possess some morphological specializations (P. kessleri to large prey, N. fluviatilis to sandy habitats and P. gymnotrachelus to macrophytes), but none of these gobies have managed to colonize such large areas or to reach such overall abundances as N. melanostomus.

The cichlids of Africa present many challenges to the taxonomist. Diverse systematic problems at three levels in cichlid phylogeny form the subject matter of this dissertation. At the most general level, I summarize current morphological evidence that supports cichlid monophyly and the most-inclusive groups of cichlids. With this review as a framework, I argue that the most phylogenetically primitive African cichlid is Heterochromis multidens, a little-known large cichlid from the Zaire River basin. I redescribe this monotypic genus and species and illustrate much of its osteology. It possesses a distinctive suite of derived characters, but is uniquely primitive among African cichlids in infraorbital morphology and other features.

At a less inclusive phylogenetic level, I examine the controversy over the monophyletic status of the "species flock" of haplochromine cichlids in Lake Malawi. A derived type of anal-fin markings present in a subset of the Malawian fauna is shared with many non-Malawian haplochromines, indicating that the species flock of Lake Malawi is not monophyletic. The two (or more) faunal components of Lake Malawi are ecologically distinct.

The remaining major parts of the study are concerned with particular assemblages of haplochromine cichlids in Lake Malawi. I present a detailed phylogenetic analysis of the Cyrtocara livingstonii species-group of ambush predators, and characterize a new species in the group. I also describe three new species of haplochromines with three lateral spots and present a key to the three-spot assemblage. Intralacustrine dispersion of Malawi cichlids is briefly addressed in appended material.

"1. Human activities affect fish assemblages in a variety of ways. Large-scale and long-term disturbances such as in-stream dredging and mining alter habitat and hydrodynamic characteristics within rivers which can, in turn, alter fish distribution. Habitat heterogeneity is decreased as the natural riffle–pool–run sequences are lost to continuous pools and, as a consequence, lotic species are displaced by lentic species, while generalist and invasive species displace native habitat specialists. Sediment and organic detritus accumulate in deep, dredged reaches and behind dams, disrupting nutrient flow and destroying critical habitat for habitat specialist species.

2. We used standard ecological metrics such as species richness and diversity, as well as stable isotope analysis of δ13C and δ15N, to quantify the differences in fish assemblages sampled by benthic trawls among dredged and undredged sites in the Allegheny River, Pennsylvania, U.S.A.

3. Using mixed-effects models, we found that total catch, species richness and diversity were negatively correlated with depth (P < 0.05), while species richness, diversity and proportion of species in lithophilic (‘rock-loving’) reproductive guilds were lower at dredged than at undredged sites (P < 0.05).

4. Principal components analysis and manova revealed that taxa such as darters in brood hider and substratum chooser reproductive guilds were predominantly associated with undredged sites along principal component axis 1 (PC1 and manovaP < 0.05), while nest spawners such as catfish and open substratum spawners including suckers were more associated with dredged sites along PC2 (P < 0.05).

5. Stable isotope analysis of δ13C and δ15N revealed shifts from reliance on shallow water and benthic-derived nutrients at undredged sites to reliance on phytoplankton and terrestrial detritus at deep-water dredged sites. Relative trophic positions were also lower at dredged sites for many species; loss of benthic nutrient pathways associated with depth and dredging history is hypothesised.

6. The combination of ecological metrics and stable isotope analysis thus shows how anthropogenic habitat loss caused by gravel dredging can decrease benthic fish abundance and diversity, and that species in substratum-specific reproductive guilds are at particular risk. The effects of dredging also manifest by altering resource use and nutrient pathways within food webs. Management and conservation decisions should therefore consider the protection of relatively shallow areas with suitable substratum for spawning for the protection of native fishes."

We studied the diet of the eastern mosquitofish Gambusia holbrooki with in situ experimental mesocosms located in a shallow lake. Different nutrient concentrations (phosphorus and nitrogen) and fish population densities were tested. Our results confirm that it is a planktivorous species, with also a great ingestion of algae and detritus. Nutrient fertilization caused almost no changes in this species feeding behavior, but larger mosquitofish stocks induced a shift to zooplanktivory and a decline in detritivory. When macrophytes were present, the predation effect focused on zooplankton and plant-associated animals, otherwise predation on bottom macroinvertebrates increased. Females preyed upon almost all groups more intensely, including detritus. Males and juveniles did not overlap diet, the former being more selective on ostracods, while juveniles consumed detritus, rotifers and cladoceran. Our data support the idea that mosquitofish can cause important top-down effects in shallow lakes under a wide variety of ecological conditions, being an important zooplanktivore in both turbid and plant-dominated shallow lakes especially in the Mediterranean zone, where high temperatures and absence of piscivores promote maintenance of its populations during the whole year.

In order to analyse the intraand interpopulation homogeneity/heterogeneity of the pikeperch (Stizostedion lucioperca), the phenotypic variability of morphological characters was estimated on the basis of a biometric analysis of 31 morphometric and 10 meristic characters in 284 specimens collected at four different sections along the Yugoslav sector of the Danube, during 1986–1989. An ANCOVA of morphological characters, with fish size as a covariate, was performed for analysed samples and between males/females and adults/juveniles respectively. Comparison was also made with the pikeperch samples from the Dnepr and the West Dvina (Zhukov 1965). The results were tested with a GT2-method for multiple unplanned comparison of means, or with a t-test where appropriate. The differentiation between populations from three geographically distinct and isolated areas (Danube–Dnepr–Dvina) is much greater than between the four samples from the Danube. The results of the variability analysis of mor...

Analizamos las amenazas y acciones de manejo y conservación de los peces de las familias Poeciliidae, Goodeidae y Cyprinidae enlistados en la NOM-059-SEMARNAT-2010. Para ello se elaboraron 39 fichas de información con base en la consulta y análisis de 160 publicaciones científicas, 10 libros especializados, 10 tesis y la base de datos de CONABIO. Se obtuvo el porcentaje de especies por cada categoría de riesgo y la cantidad de éstas evaluadas mediante el Método de Evaluación del Riesgo de Extinción (MER). Las amenazas, tanto antropogénicas como naturales, se determinaron a partir de las clasificaciones propuestas por Contreras-Balderas et al. (2003) y la UICN (2011). De las 92 especies en la Norma, el 45% se encuentra en peligro de extinción, el 37% amenazado, el 9% en protección especial y el 10% restante se reporta como extinto en el medio silvestre (8) (casi todas ciprínidos). Sólo 30 especies se evaluaron con el MER, siendo la familia Goodeidae la más evaluada con 17 especies, seguida por Poeciliidae (5) y Cyprinidae (8). De las amenazas contabilizadas, el 87.3% fueron de origen antropogénico y el resto naturales. Las amenazas antrópicas más frecuentes fueron el agotamiento del agua, la modificación del hábitat, la contaminación y la introducción de especies exóticas. Las amenazas naturales más comunes fueron la distribución restringida de los organismos y los disturbios relacionados con el clima y los fenómenos meteorológicos. Sólo una especie (Algansea popoche) se encuentra sujeta a manejo (veda). Entre las acciones de conservación destacan el mantenimiento de poblaciones ex situ (principalmente goodeidos), la reintroducción y los programas de erradicación de especies exóticas. Utilizando la información generada, CONABIO llevará a cabo un taller con expertos para realizar el MER para el resto de las especies y discutir cuáles medidas de protección serían las más eficientes para proteger a las más vulnerables.

To examine the effects of climate and anthropogenic impacts on fish growth, we compared growth rates of rainbow trout (Oncorhynchus mykiss) in nine closely located warm-temperate lakes of contrasting morphometry, stratification and mixing regime, and trophic state. Analyses of long-term mark-recapture data showed that in deep oligotrophic and mesotrophic lakes, trout growth rates increased with increasing indices of lake productivity. In contrast, in shallow eutrophic lakes, where fish habitat volume is constrained by temperature and dissolved oxygen, trout growth rates declined with increasing productivity. Growth rates were higher in lakes with greater volumes of favourable habitat (i.e. dissolved oxygen >6.0 mg L-1 and temperature <21°C), and lower in lakes with increased turbidity, chlorophyll a, and nitrogen concentrations. Our findings suggest that lake increases in lake productivity and temperatures as a result of global climatic change are likely to be more detrimental to salmonid habitat quality and volume in shallower, productive lakes, while salmonids will better endure such changes in deeper, oligotrophic lakes. Fishery managers can use this information to aid future stocking decisions for salmonid fisheries in warm-temperate climates.

Clarias gariepinus is an invasive species worldwide, which has been introduced mainly by aquaculture,
and its impact on native fauna is well documented. Three individuals of C. gariepinus were captured by an
artisanal isherman in the D’Una River Basin in Santa Catarina State, Brazil. This paper documents the irst
record of C. gariepinus in this area, indicating an additional spot of occurrence in Brazilian inland waters, and
discusses the potential impacts of this introduction.

The lionfish, after its invasion to the Caribbean, was reported in the Colombian continental Caribbean, thereafter and to measure its impact there have been numerous strategies. Size structure and substrate preference were studied for a year between December 2011 and December 2012 in five locations in Santa Marta, through visual censuses in 30x5 m transects. Size were grouped according to the frequency distribution into four categories (one: between 8 and 14 cm, two: between 15 and 21 cm, three: from 22 to 28 cm and four: between 29 and 35 cm). We observed 92 specimens with a mean of 18.0±5.3 cm. Category two, the most abundant (n=48), predominated in Morro Grande and Isla Aguja, from June to August, followed by categories three (n = 21) and one (n = 20). Category four (n=3) was the less abundant, being found at Morro Grande and Isla Aguja. Variables explaining better the correlation between lionfish densities and type of substrate were sponges (0.6303), coral coverage (0.6111) and abiotic components (-0.9443). Lionfish abundance was marked by the kind of structure available for recruitment; this indicates that the species does not show any substrate preference, adapting to any kind of reef conditions.

With around 15% of all described freshwater fish species in the world, the Amazon Basin is by far the most fish species-rich freshwater ecosystem on the planet. In this opinion paper, a rough evaluation is given on just how vulnerable Amazonian freshwater fishes are to ongoing climate change. And to argue that current anthropogenic threats through rapid expansion of human infrastructure and economic activities in the basin could be a far greater threat to fish communities than those anticipated by any future climate change. Conservation actions in the Amazon Basin should focus preferentially on reducing the impacts of present-day anthro-pogenic threats.

Определен и описан новый для ихтиофауны России аллохтонный вид – восьмиполосая цихлазома Rocio octofasciata (Regan, 1903), населяющий оз. Старая Кубань, г. Краснодар. Проведено сравнение условий жизни данного вида в различных регионах: в историческом ареале, в водоемах юга США и в оз. Старая Кубань. Сформулировано предположение, согласно которому вид образовал в озере самовоспроизводящуюся популяцию и полностью натурализовался. Предложены дальнейшие направления исследования популяции этого вида в Старой Кубани.

An annotated checklist of non-native benthic macroinvertebrates and fish in 6 sub-basins (assessment units) of the Dnieper River is presented (based on a literature survey and the author's unpublished data). In total, the checklist includes 92 non-native aquatic species (invertebrates – 57, fish – 35), primarily of Ponto-Caspian origin. This background information provides support for possible future development of relevant management options towards control of invasive species in the studied area, which is an important part of the European network of inland waterways and the European inland water " central invasion corridor " .

This study aims to identify large-scale environmental variables that explain the distribution of continental exotic fish across five bioclimatic regions in east Algeria (160,000 km²), North Africa. Fish communities were sampled at 39 sites from 2007 to 2010. Seven environmental variables were investigated: habitat type, altitude, latitude, longitude, bioclimatic region, minimum and maximum air temperatures and human pressure. The common carp (Cyprinus carpio Linnaeus, 1758) and the silver carp (Hypophtalmichthys molitrix Valenciennes, 1844) were the most widespread exotic species. Almost all exotic fishes were distributed over desert and sub-humid bioclimatic scales. Reservoirs represent the type of habitat that houses the greatest exotic species richness. The distribution pattern of exotic fishes was mainly predetermined by the type of habitat. Alien ichtyofauna colonizes primarily man-made hydrosystems regardless of environmental variables or the degree of human pressure, making these habitats more vulnerable to invasion.

ABSTRAK
Interaksi trofik pasca masuknya ikan introduksi ataupun ikan asing invasif merupakan dasar
untuk mengkaji tekanan ekologis terhadap ikan asli. Penelitian ini bertujuan untuk menganalisis interaksi trofik komunitas ikan pasca berkembangnya jenis-jenis ikan asing invasif di Danau Matano, Sulawesi Selatan. Ikan contoh diperoleh dari hasil tangkapan jaring insang percobaan, jala lempar, dan seser pada Mei, Oktober, dan November 2015 serta Februari, Juli, dan September 2016. Analisis ekologi trofik yang dilakukan meliputi indeks bagian terbesar, tingkat trofik, luas relung dan tumpang tindih relung makanan, serta pola strategi makan. Hasil penelitian menunjukkan komunitas ikan yang tertangkap di Danau Matano terdiri atas 9 famili, 11 genera, dan 17 spesies. Ikan louhan mendominasi komunitas ikan di Danau Matano sebesar 53,62%. Makanan alami yang banyak dimanfaatkan oleh sejumlah ikan dalam komunitas adalah insekta (Diptera), Gastropoda (Tylomelania sp.), dan larva insekta (Chironomidae). Kelompok trofik komunitas ikan di Danau Matano terdiri atas detritivora, herbivora, insektivora, zoobentivora, dan
piscivora. Masuknya ikan introduksi memunculkan kelompok trofik baru (detritivora dan herbivora). Ikan introduksi cenderung memiliki luas relung makanan yang lebih bervariasi. Kompetisi terhadap makanan alami kategori moderat banyak terjadi antara ikan asli dengan louhan. Strategi pola makan ikan asli di Danau Matano cenderung bersifat spesialis, sedangkan ikan introduksi memiliki strategi pola makan yang lebih bervariasi dan oportunistik. Ikan louhan sebagai ikan introduksi dominan yang bersifat invasif mampu memanfaatkan seluruh sumber daya makanan alami yang tersedia dan menempati tingkat trofik tertinggi di Danau Matano. Tekanan ekologi terhadap ikan asli oleh ikan asing invasif di Danau Matano terjadi karena adanya kompetisi terhadap makanan alami.

Kata Kunci: Danau Matano; ikan asing invasif; ikan louhan; interaksi trofik; strategi pola makan

ABSTRACT
Trophic interactions post-develpment of non-native fish or invasive alien fish species are the basis knowledge for assessing and preventing the ecological pressure on native fish. This research aims to analyze the trophic interactions of fish community post-development of invasive alien fish species in Lake Matano, South Sulawesi. Fish samples were obtained from the catch of experimental gill nets, cast nets, and push nets in May, October, and November 2015 along with February, July, and September 2016. Trophic ecological analysis carried out included index of preponderance, trophic level, niche breadth and niche overlap of natural food, and feeding strategy. The fish
community caught in Lake Matano consists of 9 families, 11 genera, and 17 species. Flowerhorn cichlid dominates the fish community in Lake Matano by 53.62%. Natural foods that are widely used by a number of fish in the community are Insecta (Diptera), Gastropods (Tylomelania sp.), and larvae of Insecta (Chironomidae). The guild trophic of fish community in Lake Matano consists of detritivores, herbivores, insectivores, zoobentivores, and piscivores. The introduction of non-native species bring up to new guilds (detritivores and herbivores). Non-native fishes tends to have a variety niche breadth. Moderate competition for natural food resources between native fish and flowerhorn cichlid is quite high. Feeding strategy of native species in Lake Matano tend to be specialist, while non-natives species have more variety and opportunistic. Flowerhorn cichlid as dominant invasive alien fish species is able to utilize all natural food resources and occupies the highest trophic level in Lake Matano. Ecological pressure on native fish by invasive alien fish species in Lake Matano occurs due to competition in obtaining natural food resources.

Keywords: Lake Matano; invasive alien species; flowerhorn cichlid; trophic interactions; feeding strategy

In the result of the carried out study since 2004, Perccottus glenii was found in 5 basins in Latvia, inhabited by Bombina bombina, situated in Daugavpils district and belonging to three populations: Ilgas, Demene, and Medumi. All the localities are situated on the south-eastern part of Latvia, at a distance of no more than 1-2 km from the borders with Lithuania and Belarus. The long-term (no less than 2 seasons) presence of Perccottus glenii in a small reservoir causes the disappearance of Bombina bombina tadpoles, as well as larvae of other amphibians.

Invasive introduced fish species are well known for their deleterious impacts on aquatic biodiversity and environment. This study provides the first report on the occurrence of introduced Amazon sailfin catfish, Pterygoplichthys pardalis from the Gombak basin, Selangor, Malaysia, where the suckermouth catfish, Hypostomus plecostomus and vermiculated sailfin catfish, Pterygoplichthys disjunctivus had been previously reported. Besides, selected morphometric and meristic measurements between P. pardalis and P. disjunctivus from the Pusu River, Gombak basin were compared. Moreover, we also described two body patterns of the P. pardalis collected from the river. The body pattern which does not fit entirely with the known characteristics of P. pardalis or P. disjunctivus is suspected to be a result of hybridization between