Umbra Pygmaea Research Articles

Exploring the distribution of the non-native Umbra pygmaea across European freshwater ecoregions through climatic suitability and locally consumed diet

The East American mudminnow Umbra pygmaea was introduced to Europe a century ago and is now established in at least six European countries. Although considered harmless and with low spread potential, this fish species shows potential to colonise a broad range of habitats due to its wide environmental tolerance. Stomach content analyses were conducted over 3 years to obtain a first insight into this species' diet, which could indicate the potential to alter the biotic composition of recipient ecosystems. The results showed that this fish can potentially have a high impact on insects, fish, and even amphibians through predation. Species distribution models further indicated that environmental conditions of Central European ecoregions are currently a limiting factor for the spread of this species which seems, at least for now, to be driven by anthropogenically driven introductions. Considering the species’ potential to be invasive and impact native biota, monitoring of potential spread is recommended.

DNA Transposon Expansion is Associated with Genome Size Increase in Mudminnows.

Genome sizes of eukaryotic organisms vary substantially, with whole-genome duplications (WGD) and transposable element expansion acting as main drivers for rapid genome size increase. The two North American mudminnows, Umbra limi and Umbra pygmaea, feature genomes about twice the size of their sister lineage Esocidae (e.g., pikes and pickerels). However, it is unknown whether all Umbra species share this genome expansion and which causal mechanisms drive this expansion. Using flow cytometry, we find that the genome of the European mudminnow is expanded similarly to both North American species, ranging between 4.5 and 5.4 pg per diploid nucleus. Observed blocks of interstitially located telomeric repeats in U. limi suggest frequent Robertsonian rearrangements in its history. Comparative analyses of transcriptome and genome assemblies show that the genome expansion in Umbra is driven by the expansion of DNA transposon and unclassified repeat sequences without WGD. Furthermore, we find a substantial ongoing expansion of repeat sequences in the Alaska blackfish Dallia pectoralis, the closest relative to the family Umbridae, which might mark the beginning of a similar genome expansion. Our study suggests that the genome expansion in mudminnows, driven mainly by transposon expansion, but not WGD, occurred before the separation into the American and European lineage.

Multiscale Environmental Influences on Fish Assemblage Structure of South Atlantic Coastal Plain Streams

AbstractSouth Atlantic coastal plain streams are unique and understudied freshwater environments that provide crucial habitats for a wide range of aquatic taxa. We investigated patterns in fish assemblages across South Carolina's coastal plain, and developed statistical models to identify the dominant multiscale abiotic environmental factors that influence assemblage structure. Cluster and indicator species analyses of fish assemblage data collected at 208 wadeable streams indicated the presence of four predominant species associations that commonly occur in the South Atlantic coastal plain, which we termed the (1) fluvial, (2) Eastern Mudminnow, (3) centrarchid, and (4) nonfluvial assemblages. A random forest analysis indicated that geographic gradients and instream habitat variables associated with velocity, channel form, stream size, depth, and large wood generally played a greater role in distinguishing fish assemblages than catchment land cover. A follow‐up principal component analysis showed that these instream habitat variables showed weak relationships with current anthropogenic land‐cover conditions. We suggest several possible explanations for our findings, including (1) a sustained dynamic equilibrium among catchment, riparian, and instream conditions over time may encourage assemblage partitioning among differential instream habitats, (2) past landscape conditions may have a greater influence on current instream habitat conditions and fish assemblage structure than current landscape conditions, (3) weak relationships between catchment land cover and instream habitats may be common in low‐elevation regions, and (4) seasonal variation in hydrologic patterns may dominantly influence instream habitat conditions and fish assemblage structure. Our study adds essential information towards a better understanding of how South Atlantic coastal plain fish assemblages respond to environmental factors across multiple spatial scales. Such knowledge will help improve management and conservation strategies, as well as assist in the development of appropriate indicators for standardized evaluations of ecological integrity.

Diet of the Eastern Mudminnow (Umbra pygmaeaDeKay) from Two Geographically Distinct Populations within the North American Native Range

Umbra pygmaea (Eastern Mudminnow) is a freshwater species common in Atlantic slope coastal lowlands from southern New York to northern Florida and is typical of slow-moving, mud-bottomed, and highly vegetated streams, swamps, and small ponds. We examined its seasonal food habits at the Great Swamp National Wildlife Refuge (NWR), NJ and at the Croatan National Forest, NC. A total of 147 Eastern Mudminnow from 35–112 mm TL and 190 Eastern Mudminnow from 22–89 mm TL were examined from these sites, respectively. At both locations, we found it to be a bottom-feeding generalist that consumes cladocerans, ostracods, chironomid larvae, coleopteran larvae, and other insects and crustaceans. Ostracods were most common in the diet at the Great Swamp NWR and occurred in 62% ± 2.5% of the stomachs with food. At Croatan National Forest, chironomid larvae were most common and occurred in 66.7% ± 15.8% of the stomachs. There were no statistically significant differences in diet composition between the sites during the winter, summer, and fall. However, when compared on an annual basis, Jaccard's Index (θJ = 0.636, P = 0.05) suggested that the diet at the two study sites was significantly different. While we identified the same major food groups at both locations, the utilization of these food groups varied seasonally. Detritus was a major stomach content at both locations throughout the year. We also documented cannibalism during the summer season at both locations. The seasonal diet of the Eastern Mudminnow was similar to that of Umbra limi (Central Mudminnow) and Umbra krameri (European Mudminnow). Our findings here are the first quantitative examinations of seasonal differences in the diet of the Eastern Mudminnow within its native North American range.

Genotoxicity testing of samples generated during UV/H2O2 treatment of surface water for the production of drinking water using the Ames test in vitro and the Comet assay and the SCE test in vivo

UV/H2O2 treatment can be part of the process converting surface water to drinking water, but would pose a potential problem when resulting in genotoxicity. This study investigates the genotoxicity of samples collected from the water treatment plant Andijk, applying UV/H2O2 treatment with an electrical energy dose of 0.54 kWh/m(3) and a H2O2 dose of 6 mg/l. Genotoxicity was tested in vitro using the Ames and Comet assay. All samples showed negative results. Samples were also tested in in vivo genotoxicity tests in Eastern mudminnow fish (Umbra pygmaea) by a sister chromatid exchange (SCE) and a Comet assay. No significant increases in SCEs were observed, but gill cells isolated from fish exposed to water obtained immediately after UV/H2O2 treatment and to Lake IJsselmeer water showed significantly increased DNA damage in the Comet assay. All other samples tested negative in this Comet assay. This indicates that DNA damaging compounds may result from the UV/H2O2 treatment, but also that these can be efficiently eliminated upon granular activated carbon (GAC) treatment of the water. It is concluded that when combined with this subsequent GAC treatment, UV/H2O2 treatment for the production of drinking water from surface water is not of concern with respect to genotoxicity.

Genotoxic effects in the Eastern mudminnow (Umbra pygmaea) after prolonged exposure to River Rhine water, as assessed by use of the in vivo SCE and Comet assays

The production of drinking water from river water requires a certain minimal river water quality. The Association of River Rhine Water Works (RIWA), therefore, operates a monitoring network. In vitro mutagenicity studies have shown that the genotoxicity of the River Rhine water steadily decreased from 1981 until 2001. Compared to a study in 1978, a decrease in genotoxicity was also observed in an in vivo genotoxicity study in 2005, in which Eastern mudminnows (Umbra pygmaea) were exposed to River Rhine water, and gill cells were used for the Sister Chromatid Exchange (SCE) test and the Comet assay. In this 2005 study, the in vivo genotoxicity increased upon extending exposure of the fish from 3 to 11 days. Therefore, the objectives of this study were to investigate (i) whether new data corroborate that in vivo genotoxicity of River Rhine water is at present lower than in 1978, (ii) whether the Comet assay is a suitable alternative to the SCE assay, and (iii) whether further prolonged exposure results in a further increase in in vivo genotoxicity. The new data corroborate that in vivo genotoxicity of River Rhine water is at present lower than in 1978. The Comet assay is a useful addition but does not provide a substitute for the SCE endpoint in these in vivo genotoxicity studies. Prolonging the exposure time of Eastern mudminnows to River Rhine water from 11 to 42 days did not give a significant increase in SCEs and DNA damage (Comet assay) in gill cells.

Age, Growth, and Reproduction of the Eastern Mudminnow (Umbra pygmaea) at the Great Swamp National Wildlife Refuge, New Jersey

Abstract Umbra pygmaea DeKay (Eastern Mudminnow) is one of four species of Umbridae in North America. There is little published life-history information on the species within its native range, particularly on age, growth, and reproduction. This study focuses on these aspects of the life history of this fish at the Great Swamp National Wildlife Refuge in Morris County, NJ. A total of 336 fish of seven species was collected from June 1978 through May 1979, with the Eastern Mudminnow comprising 74% of the total. The average annual growth increment in total length for the Eastern Mudminnow was 15.3 ∓ 2.06 mm, with age-1 fish averaging 40 mm total length and age-5 fish, the oldest collected, averaging 107 mm total length. The length-weight relationship was log10W = -5.291 + 3.182 log10TL mm for males and log10W = -4.999 + 3.032 log10TL mm for females. We observed no statistically significant sexually dimorphic differences in length-weight relationships in this population. The ratio of females to males increase...

Present status of the North American Umbra pygmaea (DeKay, 1842) (eastern mudminnow) in Flanders (Belgium) and in Europe

The eastern mudminnow Umbra pygmaea (DeKay, 1842) originates from the eastern part of the United States of America and was transferred to Europe already at the beginning of the 20th century. This paper summarizes the current distribution in Europe and adds an extended dataset of eastern mudminnow records in Flanders (Belgium). The core of the European distribution seems to be the southeast of The Netherlands and the northeast of Flanders. Eastern mudminnow is established in lotic waters in Flanders and was found on 76 locations over the last 15 years. Neutral pH and high oxygen concentrations positively correlate with the presence of eastern mudminnow. The abundance of U. pygmaea decreases significantly with an increase of the number of fish species. The length-frequency distribution shows a peak at 7.0 cm and total length of U. pygmaea specimens varies between 3.4 and 13.7 cm. The overall length-weight relationship for all U. pygmaea specimens in Flanders shows a positive allometric growth. Fulton’s condition factor for all eastern mudminnow specimens caught in Flemish rivers is 1.22. Assessment of U. pygmaea on its potential invasiveness in Flanders results in a low to medium risk.

Genotoxic effects in the Eastern mudminnow ( Umbra pygmaea L.) after exposure to Rhine water using the SCE and comet assay: A comparison between 1978 and 2005

Genotoxic effects in the Eastern mudminnow ( Umbra pygmaea L.) after exposure to Rhine water using the SCE and comet assay: A comparison between 1978 and 2005

Genotoxic effects in the Eastern mudminnow ( Umbra pygmaea L.) after exposure to Rhine water, as assessed by use of the SCE and Comet assays: A comparison between 1978 and 2005

Surface water used for drinking-water preparation requires continuous monitoring for the presence of toxic compounds. For monitoring of genotoxic compounds fish models have been developed, such as the Eastern mudminnow ( Umbra pygmaea L.) because of its clearly visible 22 meta-centric chromosomes. It was demonstrated in the late seventies that Rhine water was able to induce chromosome aberrations and sister chromatid exchange in this fish species. Although in vitro mutagenicity studies of the RIWA (Rhine Water Works, The Netherlands) have shown that the genotoxicity of the river Rhine steadily decreased during the last decades, there is still concern about the presence of some residual mutagenicity. In addition, in most studies the water samples have been tested only in in vitro test systems such as the Salmonella-microsome test. For this reason, and in order to be able to make a comparison with the water quality 27 years ago, a study was performed with the same experimental design as before in order to measure the effect of Rhine water on the induction of SCE in the Eastern mudminnow. As a new test system the single cell gel electrophoresis assay (Comet assay) was performed. Fish were exposed to Rhine water or to groundwater for 3 and 11 days in flow-through aquaria. Fish exposed for 11 days to Rhine water had a significantly higher number of SCE and an increased comet tail-length compared with control fish exposed to groundwater. After exposure for three days to Rhine water there was no difference in SCE and a slightly increased comet tail-length compared with the control. It was concluded that genotoxins are still present in the river Rhine, but that the genotoxic potential has markedly decreased compared with 27 years ago. Furthermore, the Comet assay appears to be a sensitive assay to measure the genotoxic potential of surface waters in fish.

Hybridization in Umbridae in the Hudson River, New York, with Designation of Neotypes for Umbra limi and Umbra pygmaea

We document the occurrence of a natural hybrid between the Eastern Mudminnow, Umbra pygmaea (DeKay 1842) and the Central Mudminnow, U. limi (Kirtland 1840). Hybrid individuals were collected in a supratidal pool in a fresh-tidal marsh in the Hudson River, New York. ANOVA, ANCOVA, principal components analysis, and discriminant function analysis of meristics and morphometrics showed that the hybrids were distinguishable from the parental species and were generally intermediate between them. The tidal Hudson River is the only place these species are sympatric, and hybridization must have occurred within the last several decades. We designate neotypes for Umbra pygmaea and Umbra limi.

LARVAL PERFORMANCE AND OVIPOSITION SITE PREFERENCE ALONG A PREDATION GRADIENT

The ability of females to assess habitat quality for offspring can strongly influence individual reproductive success as well as population dynamics and community assembly. However, the specific relationship between oviposition site selection and larval performance is often unclear. Ovipositing females of several species of treefrogs (Hyla) avoid predatory fish. The fish density required to elicit such avoidance and its relationship to larval performance are central to our understanding of how behavior can drive population dynamics and community assembly in complex landscapes. We conducted experiments investigating both oviposition preference and larval performance in pinewoods treefrogs (Hyla femoralis) along a density gradient of predatory fish (0–6 Umbra pygmaea). Female H. femoralis detected and strongly avoided the nonlethal presence of even a single 2-g fish, ovipositing almost exclusively in predator-free controls. In a separate experiment, larval performance largely matched adult preferences; larvae were totally eliminated in all but the lowest fish density. Given a landscape of breeding sites of varying risks, ovipositing H. femoralis behaviorally partition available habitats into those with and without fish, largely matching the associated fitness consequences.

Chromosomal characteristics of ribosomal DNA in two extant species of North American mudminnows Umbra pygmaea and U. limi (Euteleostei: Umbridae)

The locations and chromosomal characteristics of ribosomal DNA (rDNA) sites in the karyotypes of two extant North American species of mudminnows, Umbra pygmaea and U. limi (2n = 22, NF = 44), were analyzed sequentially by conventional Giemsa staining, Ag staining, CMA₃ fluorescence and fluorescence in situ hybridization (FISH). The nucleolar organizer regions (NORs) were located in the fourth chromosomal pair in both species (pericentromeric region in U. pygmaea and subtelomeric in U. limi). These sites were strongly CMA₃-positive suggesting that the rDNA sites in these species are associated with GC-rich DNA. FISH with a rDNA probe gave consistently positive signals in the same regions detected by Ag-staining and CMA₃-fluorescence. However, both species also had additional CMA₃-positive/Ag-negative heterochromatic blocks at pericentrometric regions of several chromosomal pairs (three in U. pygmaea and five in U. limi). FISH revealed additional rDNA clusters in both species. It is hypothesized that a paracentric inversion of the chromosome arm carrying the NORs might be one of the rearrangements differentiating the karyotypes of two North American species. The presence of additional rDNA sites is indicative of more complex rearrangements. The pericentromeric NOR phenotype of Umbra pygmaea is similar to that seen in U. krameri and in the distantly related genus Esox.

Prolactin cell activity and sodium balance in the acid-tolerant mudminnow Umbra pygmaea in acid and neutral water

In East-American mudminnows, obtained from lakes and bogs of different water pH levels, prolactin cell size and ultrastructure reflect higher secretory activity in neutral water than in water of pH 3.5–6.5. This contrasts with observations on other species in which prolactin cell activity is higher at low water pH. Laboratory experiments involving acute exposure of mudminnows from pH 5.5 for 48 hr to different pH levels showed that prolactin secretion increased in water below pH 3 and above pH 6.5, which could be correlated with losses of blood electrolytes. No osmoregulatory stress was noticeable in the pH range of 3.5 to 5.5. Acclimation of fish for 5 to 6 months to either pH 4.5 or 7.2 confirmed that prolactin cell activity, as estimated with ultrastructural morphometry, was significantly higher in water of neutral pH than of pH 4.5. The growth rate was significantly higher at the lower pH. Determination of whole body sodium fluxes, with 24Na as a tracer, showed that both groups had a positive sodium balance. However, total body Na + influx as well as efflux values were slightly but significantly reduced at pH 7.0 when compared to pH 4.5. The reduction of Na + efflux at pH 7.0 is in line with increased secretion of prolactin since this hormone is known to limit the branchial permeability to water and ions, including Na +. The results show that the mudminnow is extremely acid tolerant, having an optimum water pH range of about 3.5 to 6.0, which is consistent with ecological observations. Prolactin secretion is at a minimum in this range. Exposure to neutral water represents osmoregulatory stress for the mudminnow, in contrast to all other teleost species examined so far.

Impact of acidification and eutrophication on the distribution of fish species in shallow and lentic soft waters of The Netherlands: an historical perspective

The species richness and composition of fish assemblages were examined in lentic soft waters in The Netherlands. The selected bodies of water reflected a large variation in geomorphological and limnological factors. In total, 24 fish species were encountered in Dutch soft waters. During 1983–1984 Esox lucius, Perca fluviatilis, Rutilus rutilus, Scardinius erythrophthalmus, Tinca tinca and Umbra pygmaea were quite common. In slightly acid and alkaline waters (pH≥5) Rutilus rutilus, Scardinius erythrophthalmus, Perca fluviatilis, Ictalurus nebulosus and Cyprinus carpio accounted for about 90% of the total number of specimens in the catches. Strongly acid waters (pH < 5) generally were fishless. If fish were present in these waters, however, the catches mainly consisted of Umbra pygmaea. Only in a few strongly acid systems were other species collected. The lowest pH at which certain fish species occurred varied from 3.1 to 7.0. In particular, Umbra pygmaea was extremely acid‐tolerant. The percentage of waters which harboured fish as well as the average number offish species per water decreased steeply between pH 6 and 4.The sampled waters showed remarkable differences in their fish assemblages. With hierarchical classification, six groups of waters could be distinquished with respect to their fish fauna. The site groups are defined and characterized physico‐chemically and their fish assemblages described. Multivariate analysis showed that the structure of fish communities is strongly related to the pH, the alkalinity, trophic level and the ionic composition of the water. Comparison of historical and recent data on the occurrence of fish strongly indicated that in many sampling sites fish species or even entire fish assemblages had disappeared. Ordination of available data also illustrated recent changes in community structure. At least 67% of the nowadays extremely acid waters formerly harboured fish populations. The impoverishment of fish communities or the total loss of fish were primarily caused by cultural acidification. Limited nutrient enrichment of soft waters only resulted in minor alterations of fish assemblages.

Biology of the acid‐tolerant fish species Umbra pygmaea (De Kay, 1842)

In The Netherlands, the mudminnow Umbra pygmaea mainly occurs in water bodies with a pH ranging from 3–5 to 4–0, an alkalinity less than 0.1 meq 1−1 and a calcium content below 100 μmol 1−1. The abundance of mudminnows is inversely related to the pH and the presence of predatory fish species. Experimental studies show that If. pygmaea is extremely acid‐tolerant. Exposure to media with pH values ranging from 4.0 to 7.0 did not cause mortality or significant changes in blood plasma osmolarity and haematocrit. At pH 3.0 no mortality was recorded although a strong decrease in the plasma osmolarity was observed. Exposure to pH 2.8 and calcium concentrations of 100 or 500 μ mol 1−1 for 10 days caused 70% and 40% mortality respectively. The growth, reproduction and feeding of mudminnows are described. Age‐growth and length‐age relationships were calculated. Gonadal development started between September and January. The highest Gonado Somatic Index was recorded in spring. Spawning occurred from April to May. Fecundity of a sample of females was assessed. Nematocera provided the main item of diet of U. pygmaea; the microfauna ingested was dominated by Cladocera. The adaptations of mudminnows to acid environments are discussed.

Stimulation of sodium efflux in air-breathing fish exposed to low pH

Sodium efflux and survival times at low pHs were measured in two species of facultative air-breathing fish. Mudminnows ( Umbra pygmaea) and gar ( Lepisosteus platyrhincus) were quite tolerant of exposure to acidic waters. This tolerance was associated with a striking capacity for resisting the acceleration in sodium efflux usually characteristic of low pH toxicity. Such a specialization for ionic regulation may have evolved within the context of life in naturally acidic swamps low in sodium concentration. The presence of a very strong degree of resistance to low pH-induced sodium loss in these species affirms the crucial importance of net sodium loss as a mechanism of acid toxicity. Both species showed similar relationships between sodium efflux and low pH. Survival times at low pHs were inversely related to sodium efflux. At death, body sodium concentrations in both species were severely depressed, reflecting large net losses of sodium. An acid resistant salmonid, Salvelinus fontinalis, shows a correlation between sodium efflux and survival time similar to those of the air-breathers studied here. Possession of the capacity for aerial respiration is obviously not the only or perhaps even the primary factor that confers increased resistance to acid toxicity in these two air-breathing fish.

Induction of nuclear anomalies (micronuclei) in the peripheral blood erythrocytes of the eastern mudminnow Umbra pygmaea by ethyl methanesulphonate

In a short feasibility study, we detected the induction of nuclear anomalies in the peripheral blood erythrocytes of fish by the genotoxic compound ethyl methanesulphonate. Exposure of the eastern mudminnow Umbra pygmaea to the compound gave rise to nuclear segments resembling the particles found in mammalian micro-nucleus tests, but also to irregular Feulgen-positive structures in the cytoplasm. Further studies with fish erythrocytes are recommended for investigating whether the monitoring of nuclear anomalies is a suitable and rapid method for the detection of genotoxic compounds in the aquatic environment.

The killifish Nothobranchius rachowi, a new animal in genetic toxicology

Nothobranchius rachowi, a tropical fish that belongs to the family of the Cyprinodontidae, is introduced as a new animal for genetic toxicological studies. The karyotype of N. rachowi consists of 16 large chromosomes. This species can be used for studies on chromosomal aberrations as well as for observations on sisterchromatid exchanges (SCEs). Exposure to 120 mg ethyl methanesulphonate per litre water induced 0.66 SCEs per chromosome, whereas the spontaneous frequency amounted to 0.10 SCEs per chromosome. A comparative study with Umbra pygmaea indicated that the sensitivity for this kind of mutagen is the same in both species. After exposure of N. rachowi to 50 mg cyclophosphamide per litre of water, 0.35 SCEs per chromosome were induced, showing that promutagens could be detected. It is postulated that N. rachowi can be used for screening both pure compounds and surface water for genotoxic potential. An advantage of N. rachowi over Umbra spp. is that the former species is more likely to breed under laboratory conditions.

Cytogenetic effects on the eastern mudminnow, Umbra pygmaea, exposed to ethyl methanesulfonate, benzo[ a]pyrene, and river water

In order to investigate the possibilities of using the eastern mudminnow, Umbra pygmaea, as a test animal for the detection of the genotoxic effects of chemical pollution in the aquatic environment, this fish was exposed to two known genotoxic agents and to water from the Rhine river. The eastern mudminnow was used because of its nearly ideal karyotype for cytogenetic studies. This fish has a relative small number (2 n = 22) of large meta- and submetacentric chromosomes. For sister chromatid exchange studies a modification of the technique of A. D. Kligerman and S. E. Bloom (1977, J. Fish. Res. Bd. Canad. 34, 266–269) was used. To improve the number of metaphases with differential staining, the percentage of these metaphases in gill, fin, and skin tissues were determined after repeated bromodeoxyuridine injections. The best results were obtained with gill tissue after two injections with Brdu. The two mutagens used were ethyl methanesulfonate, a direct acting alkylating agent, and benzo[ a]pyrene, which requires metabolic activation. Both substances induced chromosome aberations. The mutagenicity of water from the Rhine river at Lobith, The Netherlands, was investigated in two experiments. In both experiments an effect was found on the frequency of both sister chromatid exchange and chromosome aberrations. The eastern mudminnow, U. pygmaea, appeared to be a useful test animal for the detection of the cytogenetic effects of chemical pollution in the aquatic environment.