Freshwater Fish Fauna Research Articles

Detection of invasive freshwater fish species using environmental DNA survey

Invasive species are one of the most significant problem in freshwater ecosystems. Most common non-native freshwater species in Turkish freshwater fish fauna are Prussian Carp (Carassius gibelio), North African Catfish (Clarias gariepinus), Nile Tilapia (Oreochromis niloticus) and Topmouth Gudgeon (Pseudorasbora parva).Recent studies showed that environmental DNA could be used to detect target species inhabiting the ecosystem with higher precision and less effort compared to traditional field surveys. In this study, eDNA approach was used to investigate non-native freshwater fish species from fifteen different locations of Upper Sakarya Basin. eDNA was successfully extracted from the water samples of locations where the species were visually observed. Mean amplification rate of eDNA was calculated as 77.03%.This study is the first environmental DNA study used in detection of four of the most common invasive freshwater fish species. Results clearly indicating that eDNA surveys could be used as an important molecular tool to monitor invasive fish species in freshwater ecosystems.

Species and shape diversification are inversely correlated among gobies and cardinalfishes (Teleostei: Gobiiformes)

Gobies and their relatives are significant components of nearshore marine, estuarine, and freshwater fish faunas in both tropical and temperate habitats worldwide. They are remarkable for their ability to adapt to and diversify in a wide range of environments. Among gobiiform clades, species diversities vary widely, ranging from two species in Kurtidae to more than 1,000 species in Gobiidae. There is also great variation in head and body shape and in environmental preferences (fresh, brackish, or marine habitats). In this study, I used a time-calibrated molecular phylogeny, coupled with morphometric and comparative analyses, to examine evolutionary rates of both speciation and morphological diversification among gobiiform lineages. Projection of the phylogeny onto a shape-derived morphospace shows that Gobioidei is morphometrically distinct from its sister taxon Apogonoidei, but that families within Gobioidei overlap in morphospace. Analysis of species diversification rates indicates that three rate shifts have occurred over the evolutionary history of Gobiiformes. Relative to the other lineages, Kurtidae has exhibited a slowdown in speciation, whereas both Apogonidae and Gobiidae + Gobionellidae have experienced an increase in diversification. Comparative analyses show that in Apogonidae and Gobiidae + Gobionellidae, increased speciation is correlated with diminished rates of morphological diversification, differently manifested in either clade and among the various sublineages. The elevation in speciation rates and diminishment in rates of morphological change in both Apogonidae and the clade Gobiidae + Gobionellidae are correlated with shifts to oceanic habitats from freshwater. This pattern is the complement to that seen across the global radiation of acanthomorph fishes in which a decrease in species diversification is associated with an increase in morphological disparity.

Impacto ecológico de los peces continentales introducidos en la península ibérica

Garcia-Berthou, E., Almeida, D., Benejam, Ll., Magellan, K., Bae, M.-J., Casals, F., Merciai, R. 2015. Ecological impact of inland fish introduced to the Iberian Peninsula. Ecosistemas 24(1): 36-42. Doi.: 10.7818/ECOS.2015.24-1.07 The Iberian Peninsula has a rich fauna of freshwater fish, with many endemics that are threatened. One of the threat causes is the introduction of exotic species or translocation of natives to new basins. In this paper, we review the ecological impacts of these introductions, from the genetic and individual to the community and global levels, primarily using studies from the Peninsula. Although the accumulated evidence is considerable, the ecological impact of most species and introductions has barely been studied and is probably much greater than is known.

Spatial heterogeneity in the Mediterranean Biodiversity Hotspot affects barcoding accuracy of its freshwater fishes

Incomplete knowledge of biodiversity remains a stumbling block for conservation planning and even occurs within globally important Biodiversity Hotspots (BH). Although technical advances have boosted the power of molecular biodiversity assessments, the link between DNA sequences and species and the analytics to discriminate entities remain crucial. Here, we present an analysis of the first DNA barcode library for the freshwater fish fauna of the Mediterranean BH (526 spp.), with virtually complete species coverage (498 spp., 98% extant species). In order to build an identification system supporting conservation, we compared species determination by taxonomists to multiple clustering analyses of DNA barcodes for 3165 specimens. The congruence of barcode clusters with morphological determination was strongly dependent on the method of cluster delineation, but was highest with the general mixed Yule-coalescent (GMYC) model-based approach (83% of all species recovered as GMYC entity). Overall, genetic morphological discontinuities suggest the existence of up to 64 previously unrecognized candidate species. We found reduced identification accuracy when using the entire DNA-barcode database, compared with analyses on databases for individual river catchments. This scale effect has important implications for barcoding assessments and suggests that fairly simple identification pipelines provide sufficient resolution in local applications. We calculated Evolutionarily Distinct and Globally Endangered scores in order to identify candidate species for conservation priority and argue that the evolutionary content of barcode data can be used to detect priority species for future IUCN assessments. We show that large-scale barcoding inventories of complex biotas are feasible and contribute directly to the evaluation of conservation priorities.

Fish Functional Traits Correlated with Environmental Variables in a Temperate Biodiversity Hotspot

The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases and fourth corner analysis, our results support the broad application potential for trait-based methods and indicate trait-based methods can detect environmental filtering by riparian zone land cover.

The ichthyofauna of the Beshar River in Kohkiluyeh and Boyer-Ahmad Province, southwest of Iran

In the present study, we reported the results of the monitoring and investigations of the ichthyofauna of the Beshar River, one of the tributaries of the Tigris−Euphrates basin in Kohkiluyeh and Boyer-Ahmad Province, southwest of Iran. The results showed that during a period from 2010 to 2011, a total of 13 fish species belonging to 4 families and 3 orders were recorded in the Beshar River. The results indicated that among families of ichthyofauna identified the largest family was Cyprinidae with 9 species and 69.23 percent abundance and the dominated species was the Garra rufa with 30.28 percent abundance. The Beshar River ichthyofauna is a combination of fauna and includes 6.5, 14.3 and 17.7 % of species, family and order of Iran freshwater fish fauna respectively.

PARASITOFAUNA OF FIVE FRESHWATER FISHES IN A NIGERIAN FRESHWATER ECOSYSTEM

The parasitic fauna of freshwater fishes of the Warri River, Delta State, Nigeria, with reference to their prevalence, intensity and differences in metazoan parasites between fish sexes, was investigated. A total of 85 fish samples comprising of 21 Tilapia zillii (Cichlidae: Perciformes), 23 Synodontis clarias (Mochokidae: Siluriformes), 23 Chrysichthys nigrodigitatus (Claroteidae: Siluriformes), 16 Hepsetus odoe (Hepsetidae: Characiformes) and 2 Clarias anguillaris (Clariidae: Siluriformes) collected from the Warri River, Delta State, Nigeria, were subjected to parasitological examination. The overall metazoan parasite prevalence was 32.9%. The metazoan parasites recovered were mainly the acanthocephalans: Neoechinorhynchus prolixum , Pomphorhynchus spp., Acanthocephalus spp. and unidentified acanthocephalan, and nematodes: Camallanus polypteri, Capillaria pterophylli, C. cichlasomae, Procamallanus laeviconchus, Philometroides africanus and Railletnema synodontis. Although the acanthocephalans constituted 75.6% and nematodes 22.2% of the parasites recovered, the nematodes had the highest prevalence (23.5%) compared to the acanthocephalans (9.4%). Similarly, variable prevalences were observed for the other metazoan parasite taxa recovered, namely trematoda; Clinostomum complanatum (1.2%), Leech; Pisciola geometra (2.4%) and Crustaceans (1.2%). The highest parasite prevalence (39.1%) was observed in S. clarias, while the least (23.8%) was observed in T. zillii . Generally, the prevalence of parasites was higher in female (35.7%) than in the males (31.6%), although statistically no significant difference was observed in the prevalence by sex (X 2 = 0.145, P = 0.807). The relatively high overall parasite prevalence in fishes inhabiting the Warri River may be attributed to the relatively high level of pollution.

Diversity and Conservation Status of Fish Fauna in Freshwater Lake of Kamalapur, Karimnagar District, Telangana, India

The present paper deals with the diversity, abundance and IUCN status of fresh water fish fauna in freshwater Lake of Kamalapur, Dist Karimnagar. Samples were collected monthly with help of local fishermen by using fishing nets. Total of 25 fishes are belonging to 7 orders, 11 families and 18 genera. Among fishes order Cypriniformes was most dominant with 11 fish species followed by order Siluriformes with six species, the order Perciformes with three species, Symbranchiformes with two species and Ostoeoglossiformes, Beloiniformes and Anguilliformes one species each. Of these, 13 species of fish are least concerned, 4 are data deficient (DD), 6 are not evaluate (NE), 1 species of fish is vulnerable and one species of fish is near threatened. Shannon-Weiner diversity (H - ) and Evenness (J) for different months were calculated.

Ichthyological Overview and Remarks on Freshwater Fishes from Capim River, Lower Amazon Basin, Brazil

The Capim River drainage should be considered small and thin by comparison with large Amazonian rivers. It rises by confluence of the Surubiú and Ararandeua rivers near 400 m high and their headwaters would be comfortably included in the Dry Emerged Lowland (terra firme) forest area of Sternberg’s Amazonian concept. Because of this reason the freshwater fish fauna of Capim River is comprised mainly by Amazonian fish families found in tributaries also with origin in terra firme areas. The ichthyofauna from the main channel of the poorly sampled Capim River, in the stretch between its confluence with Tauarí River and its mouth at Guamá River, is herein reported by way of rapid assessment. Also broad comparisons were made among freshwater fishes of the Capim with that from Tocantins and Guamá rivers. Two rapid access research surveys of collecting ichthyological material were performed in dry and humid periods of the year 1998 comprising the regional hydrologic cycle. The ichthyological diversity showed by the 461 studied specimens includes 79 species probably derived from Guamá and Tocantins rivers. These species are distributed between two situations: 1) downstream Capim River, at confluence with Guamá River, where is under tidal waters influence and periodically flooded, and 2) upriver Capim that is less humid and with water rapids, independent from sea hydrologic influence. This fish fauna includes local species common at high areas of the Amazonian Dry Emerged Lowland that are in part shared with that from Tocantins River. In view of these observations, we assume that the Capim River freshwater ichthyofauna may reflect diverse origin from the simple transfer of populations from Guamá River, but originate through a more complex process including the past ichthyofauna of the earlier drainages of terra firme forest and their reorganization.

Tidal, diel and seasonal effects on intertidal mangrove fish in a high-rainfall area of the Tropical Eastern Pacific

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 494:249-265 (2013) - DOI: https://doi.org/10.3354/meps10512 Tidal, diel and seasonal effects on intertidal mangrove fish in a high-rainfall area of the Tropical Eastern Pacific G. A. Castellanos-Galindo1,2,3,*, U. Krumme1,2,4 1Leibniz Center for Tropical Marine Ecology (ZMT), Fahrenheitstrasse 6, 28359 Bremen, Germany 2Centre of Excellence in Marine Sciences (CEMarin), Cra. 2 No. 11-68, 47004 Santa Marta, Colombia 3Grupo de Investigación en Ecología de Estuarios y Manglares, Departmento de Biología, Universidad del Valle, A. A. 25360, Cali, Colombia 4Thünen Institute of Baltic Sea Fisheries (TI-OF), Alter Hafen Süd 2, 18069 Rostock, Germany *Email: gustavoa80@yahoo.com ABSTRACT: Mangroves are recognized as nursery areas for a large number of marine organisms. Yet many properties of this nursery function and its equivalence between geographical areas remain poorly understood, especially in macrotidal estuarine systems. In this study, we investigated the influence of tides, diel and seasonal variation on intertidal mangrove fish assemblages in a high-rainfall area of the Tropical Eastern Pacific region. Over one year, block net sampling was undertaken during spring and neap tides during both night and day. Four sites along the length of a subtidal channel were sampled to account for salinity gradients. Clupeidae dominated catch abundances of a 50 species-rich assemblage. Catch weights, however, were dominated by Lutjanidae, Tetraodontidae and Ariidae. Fish biomass was low, likely as a result of a poor benthic in- and epi-faunal biomass in a mangrove system of low nutrient status and extremely rainy conditions. Higher salinity creeks yielded significantly greater catches and higher number of species than low salinity creeks. A depauperate freshwater fish fauna in this beogeographical region, unable to compensate for the lack of marine-estuarine species in a low salinity environment, may explain this pattern. A notable increase in rainfall at the end of the year correlated to a decrease in mangrove fish biomass. Partially in agreement with studies from other macrotidal areas, specific combinations of tidal magnitude and diel cycle explained recurring changes in fish assemblage structures, clearly observed at the species level, but not in the number of species or biomass. These results indicate not only how important tidal and diel cycles can be for fish habitat use in macrotidal mangroves, but also highlight how regional (biogeography) and local (geomorphology, precipitation) factors should be incorporated into further investigations of mangrove ecosystem equivalence over large geographical scales. KEY WORDS: Intertidal mangrove creeks · Fish community · Block nets · Macrotides · Tropical Eastern Pacific · Panama Bight mangroves · Colombia · Bahía Málaga Full text in pdf format Supplementary material PreviousNextCite this article as: Castellanos-Galindo GA, Krumme U (2013) Tidal, diel and seasonal effects on intertidal mangrove fish in a high-rainfall area of the Tropical Eastern Pacific. Mar Ecol Prog Ser 494:249-265. https://doi.org/10.3354/meps10512 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 494. Online publication date: December 04, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Annotated checklist of the freshwater fishes of continental and insular Costa Rica: additions and nomenclatural revisions

Based on a combination of intensive literature review, electronic database searches, re-identification of museum specimens and fieldwork, we hereby provide an updated checklist of the freshwater fishes of continental and insular Costa Rica. This checklist, systematically arranged at the ordinal and familial level, includes nomenclatural revisions, distributional information, and when appropriate, cross-references on the basis of Bussing (1998). According to our results, the native Costa Rican freshwater fish fauna is composed by 250 species, divided into 119 genera, 49 families and 19 orders; increasing in 108 the number of species originally reported by Bussing (1998). By far, the vast majority of these species, according to their supposed tolerance to salinity, are peripheral (63.2%), followed by secondary freshwater fishes (23.6%); only 13.2% are primary freshwater fishes. 24 species in this checklist appear to be endemic to Costa Rica. In addition to the native fauna 8 exotic species are reported.

Introduction history of non-native freshwater fish in Okinawa-jima Island: ornamental aquarium fish pose the greatest risk for future invasions

We examined the introduction history of non-native freshwater fish in Okinawa-jima Island, Japan, to identify the pathway posing the greater risk for future invasions and to measure the strength of ornamental fish introductions as a vector of new invasions using all available records of freshwater fish introductions to date. At least 45 non-native freshwater fish have been introduced to Okinawa-jima Island. Of those, 22 species have successfully established in natural waters and, consequently, non-native fish species represent 76 % of the total freshwater fish fauna. The most important pathway was via the dumping of unwanted ornamental aquarium fish, which accounted for 71 % of the total introductions. The introduction of ornamental fish has occurred extensively in recent decades, and all fish introduced since the 1980s have been ornamental aquarium fish. The overall rate of establishment success was estimated at 51 %, although this is undoubtedly an overestimate because of unreported failed introductions. Establishment rates varied between stocked fish (100 %) and dumped ornamental fish (39 %), which may reflect the low propagule pressure of ornamental fish. From the observed trends in freshwater fish introductions, the dumping of ornamental fish into natural waters is expected to continue if no action is taken to reduce this most important pathway. We recommend regulations against the release of unwanted pet fish into natural waters, better programs for returning unwanted pet fish to stores or local zoos, educational programs for aquarists and retailers, and regulations against selling and trading ornamental fish that are judged to pose a high risk of causing economic or ecological harm.

A “lost biodiversity” approach to revealing major anthropogenic threats to regional freshwater ecosystems

We proposed a method for evaluating the quantitative contributions of hypothesized focal pressures to biodiversity loss from freshwater ecosystems at regional or local scales. The method, called the “lost biodiversity approach” (abbreviated as “LBA”) focuses on local biodiversity losses caused by focal pressures. Lost biodiversity is explicitly estimated by statistically modeling the relationships between factors or focal pressures and “differential biodiversity,” defined as the difference between local biodiversity at a sampled site and regional species pool(s).We applied LBA to two cases in Japan: (1) the damselfly fauna of 56 agricultural ponds in a rural region sharing the same regional species pool and (2) freshwater fish fauna in the 13 largest river systems in Hokkaido, which includes multiple species pools. In the former, where nestedness of sampled damselfly assemblages was detected, and thus the difference between local species richness and species pool size was used as a simple indicator of differential biodiversity, biodiversity lost to invasive alien species was successfully quantified. In the latter case, where no nestedness of fish assemblages was detected, and differential biodiversity was analyzed based on an index weighting rare species, biodiversity lost to dams and eutrophication were quantified.The advantages of LBA supported by the case studies were its (1) feasibility, using species snapshot presence–absence data, (2) ability to quantify a baseline for each local community when focal pressures were removed, and (3) ability to evaluate impacts of focal pressures even if each local community belonged to a different species pool. This method will be effective in biodiversity hotspot areas.

On the origin and diversification of Venezuelan freshwater fishes: the genus Gephyrocharax (Ostariophysi: Characidae) a case study

We conducted a phylogeographic analysis of the genus Gephyrocharaxin Venezuela to evaluate geomorphologic evidence for the formation of the country's main watersheds and to establish a biogeographical hypothesis of possible diversification mechanisms of the Neotropical freshwater fish fauna. We assayed eight enzyme systems and general proteins to estimate genetic variability (H, P), intraspecific structuring in several Gephyrocharax valencia and G. venezuelae populations (FIS, FIT, and FST), and a phylogenetic approach for the three species of Gephyrocharax in Venezuela, using Corynopoma riisei as the external group. Fourteen presumptive lociindicate that populations of the three species of Gephyrocharaxanalyzed show a clear genetic inter-specific differentiation, determined by four loci with fixed alleles (GPI-B*,IDH*, ME-1*, and ME-2*). The resulting cladogram shows two major clades: a monophyletic group consisting of Gephyrocharax n. sp. and G. venezuelae(restricted to the northwest of the country) and a group formed exclusively by G. valencia (distributed along the largest geographic range). Speciation of the Venezuelan lineages of the genus Gephyrocharaxcould be explained by the origin and course movements of the present Orinoco River together with geomorphologic processes that have occurred in northern Venezuela since the Miocene.

Introduced freshwater fishes in a global endemic hotspot and implications of habitat and climatic change

Introductions of alien freshwater fish species into the Mediterranean-climatic South-west Coast Drainage Division of Australia have impacted a highly endemic (≈82%) yet depauperate (11 species) native freshwater fish fauna. This study updates the current known introduced freshwater fishes in Western Australia, assesses the historic rate of introductions and how habitat, water quality and climatic changes have facilitated those introductions. South-western Australia has undergone a ≈63% increase in alien freshwater fish introductions since 1970 (44% increase over the past decade) to 13 species; overtaking the number of native fishes. Aquarium species represent 80% of the latest introductions (46% of total number) and the majority (54%) of introduced fishes in the region are of sub-tropical or tropical origin. As found elsewhere, species with broad environmental tolerances and generalist diets are likely to continue to be the main colonizers in this region. We propose that past and future climatic and habitat changes in the Mediterranean-climatic south-west region will facilitate continued invasion of tropical and sub-tropical aquarium fishes and that strategic monitoring, control and public education programs are required to halt future introductions.

Patterns of Distribution of the Helminth Parasites of Freshwater Fishes of Mexico

In order to draw patterns in helminth parasite composition and species richness in Mexican freshwater fishes we analyse a presence-absence matrix representing every species of adult helminth parasites of freshwater fishes from 23 Mexican hydrological basins. We examine the distributional patterns of the helminth parasites with regard to the main hydrological basins of the country, and in doing so we identify areas of high diversity and point out the biotic similarities and differences among drainage basins. Our dataset allows us to evaluate the relationships among drainage basins in terms of helminth diversity. This paper shows that the helminth fauna of freshwater fishes of Mexico can characterise hydrological basins the same way as fish families do, and that the basins of south-eastern Mexico are home to a rich, predominantly Neotropical, helminth fauna whereas the basins of the Mexican Highland Plateau and the Nearctic area of Mexico harbour a less diverse Nearctic fauna, following the same pattern of distribution of their fish host families. The composition of the helminth fauna of each particular basin depends on the structure of the fish community rather than on the limnological characteristics and geographical position of the basin itself. This work shows distance decay of similarity and a clear linkage between host and parasite distributions.

Checklist of the Inland Fishes of El Salvador

The inland fish fauna of El Salvador and its distribution was originally described in 1925 by Samuel Hildebrand. That work has been the main source of information for freshwater fishes of El Salvador up to today. Based on the combination of an intensive literature review, electronic database searches, re-identification of museum specimens, and fieldwork, we hereby provide an updated checklist of the inland fishes of El Salvador. This checklist provides distributional data at the Salvadoran hydrographical and political (by department) levels. The checklist is systematically arranged at the ordinal and familial level and then alphabetically therein. The freshwater fish fauna of El Salvador includes 101 species divided into 64 genera, 29 families, and 14 orders. According to their supposed tolerance to salinity, 73% of these species are peripheral, 23% secondary, and only 4% are primary freshwater fishes. One species is endemic to the country, Amatitlania coatepeque. The low number of primary freshwater fishes and endemics is comparable to the Central American Pacific slope in particular, as well as northern Central America in general.

Can DNA barcoding accurately discriminate megadiverse Neotropical freshwater fish fauna?

BackgroundThe megadiverse Neotropical freshwater ichthyofauna is the richest in the world with approximately 6,000 recognized species. Interestingly, they are distributed among only 17 orders, and almost 80% of them belong to only three orders: Characiformes, Siluriformes and Perciformes. Moreover, evidence based on molecular data has shown that most of the diversification of the Neotropical ichthyofauna occurred recently. These characteristics make the taxonomy and identification of this fauna a great challenge, even when using molecular approaches. In this context, the present study aimed to test the effectiveness of the barcoding methodology (COI gene) to identify the mega diverse freshwater fish fauna from the Neotropical region. For this purpose, 254 species of fishes were analyzed from the Upper Parana River basin, an area representative of the larger Neotropical region.ResultsOf the 254 species analyzed, 252 were correctly identified by their barcode sequences (99.2%). The main K2P intra- and inter-specific genetic divergence values (0.3% and 6.8%, respectively) were relatively low compared with similar values reported in the literature, reflecting the higher number of closely related species belonging to a few higher taxa and their recent radiation. Moreover, for 84 pairs of species that showed low levels of genetic divergence (<2%), application of a complementary character-based nucleotide diagnostic approach proved useful in discriminating them. Additionally, 14 species displayed high intra-specific genetic divergence (>2%), pointing to at least 23 strong candidates for new species.ConclusionsOur study is the first to examine a large number of freshwater fish species from the Neotropical area, including a large number of closely related species. The results confirmed the efficacy of the barcoding methodology to identify a recently radiated, megadiverse fauna, discriminating 99.2% of the analyzed species. The power of the barcode sequences to identify species, even with low interspecific divergence, gives us an idea of the distribution of inter-specific genetic divergence in these megadiverse fauna. The results also revealed hidden genetic divergences suggestive of reproductive isolation and putative cryptic speciation in some species (23 candidates for new species). Finally, our study constituted an important contribution to the international Barcoding of Life (iBOL.org) project, providing barcode sequences for use in identification of these species by experts and non-experts, and allowing them to be available for use in other applications.

A molecular assessment of species boundaries and phylogenetic affinities in Mogurnda (Eleotridae): a case study of cryptic biodiversity in the Australian freshwater fishes

As the driest inhabitable continent, it comes as no surprise that Australia has comparatively few species of freshwater-dependent fishes compared with land masses of similar size and latitudinal coverage. In addition to relatively low rainfall and few permanent waterbodies, a range of other climatic, geological, physical, and biogeographical factors are generally offered up, to account for the low species count in a country otherwise regarded as mega-biodiverse. Here, we challenge this traditional view by hypothesising that Australia’s lack of freshwater fishes largely reflects a dearth of detailed taxonomic activity. Using both allozyme and mtDNA markers, we undertook a molecular assessment on the Australian purple-spotted gudgeons (Mogurnda), recently subjected to a taxonomic revision that saw a three-fold increase in the number of described species. In addition to demonstrating additional, species-level biodiversity within M. adspersa, our genetic data revealed discordant patterns of mitochondrial and nuclear genetic affinities among populations in several species, plus a sister relationship between the two central Australian species. We discuss the broader implications of such cryptic biodiversity for the Australian freshwater fish fauna; most notable among these is our prediction that only 50% of species have been described.

Conserving the freshwater fishes of South America

South America harbours the most diverse freshwater fish fauna in the world, and recent estimates point to between 6000 and 8000 species in the Neotropical region. Such fauna has diverse historical origins, either having invaded and diversified in fresh water from marine ancestors during the Palaeogene or being isolated on the continent since the end of the break‐up of Gondwana in the Cretaceous. Taxonomic, morphological and ecological diversity of South American freshwater fishes is dramatic, as are the myriad freshwater habitats they inhabit. Unfortunately, many of these habitats are severely threatened by deforestation, water divergence for irrigation, industry and other uses by humans, hydroelectric damming, mining, pollution and invasive species. Despite these multiple threats, there are very few on‐the‐ground conservation initiatives in South America, although assessments of species‐extinction risks have been produced at regional and subregional levels in different countries.