Field and laboratory studies of Ophryoglena sp. (Ciliata: Ophryoglenidae) infection in zebra mussels,Dreissena polymorpha (Bivalvia: Dreissenidae)

This study, conducted in the Dnieper-Bug Canal in Belarus, is the first to monitor the seasonal (June-November) dynamics of infection with the parasitic ciliate Ophryoglena sp. in a zebra mussel (Dreissena polymorpha) population. Mean population prevalence and intensity of infection varied, respectively, from 11 to 62% and from 0.9 to 24.1 ciliates/mussel. Mean prevalence was highly correlated with mussel length in mussels <20 mm (R(2)=0.97) and was lower in larger mussels. Mean infection intensity in mussels 1-25 mm long was similarly correlated with their size (R=0.98), reached a maximum in the 20-25 mm size-class, and then sharply decreased, thus providing evidence, albeit limited, that high intensity of infection might be lethal. Transinfection of zebra mussels by Ophryoglena sp. was achieved in the laboratory-a first for a protozoan parasite of D. polymorpha; from an initial complete lack of infection, mean prevalence and intensity rose, respectively, to 86.7% and 8.3 ciliates/mussel.     

Zebra mussel (Dreissena polymorpha) seasonal colonization patterns in a sub-tropical floodplain river

Zebra mussel (Dreissena polymorpha) seasonal colonization patterns, growth and habitat preferences were determined in a sub-tropical floodplain river at the southern edge of its distribution in North America during 1995–96 (Atchafalaya River Basin, Louisiana). Zebra mussel movement into subtropical areas represents a major frontier for this species worldwide. The onset of adult zebra mussel colonies occurred when the minimum daily temperature dropped below 31 °C and dissolved oxygen levels rose above 6.5 mg l^-1 in the fall. By mid-winter, mussel populations were established at lateral distances >10 km from the main river channel. Mussel growth occurred throughout the winter with an increase in growth in April and May. Adult mortality occurred during May–August as dissolved oxygen levels declined and minimum daily temperature warmed above 29 °C in the floodplain and 32.5 °C in riverine sites. Limiting factors responsible for the seasonal pattern include temperature and dissolved oxygen tolerances experienced during summer months in the ARB. Summer water conditions apparently preclude establishment of resident zebra mussel populations in the Atchafalaya floodplain. Naturally occurring seasonal patterns in temperature and dissolved oxygen in floodplain rivers may have implications for the expansion of this exotic mollusk in warmwater systems with source colonies restricted to mainstem rivers and seasonal sinks in floodplain regions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Horizontal and Vertical Distribution of the Zebra Mussel (Dreissena polymorpha,Pallas) Larvae in the Modrac Reservoir,Bosnia and Herzegovina

In the Modrac Reservoir, loaded with coal separation suspended material, rapid development of the zebra mussel (Dreissena polymorpha) took place from at least 1987. It is probably the first distinguished “infection” for this part of Balkan Peninsula, caused by this organism. Horizontal and vertical distribution of this mussel, at 15 different reservoir profiles, had been investigated.     

Invasion of the Zebra Mussel Dreissena polymorpha (Pallas, 1771) (Dreissenidae) in Lake Ladoga

Biology Bulletin - In May 2019, the invasive mollusk Dreissena polymorpha (Pallas, 1771) was found in Volkhov Bay of Lake Ladoga by means of an unmanned underwater vehicle. The age of some mollusks...     

Zebra mussels (Dreissena polymorpha) in Ireland, AFLP-fingerprinting and boat traffic both indicate an origin from Britain

1. The zebra mussel (Dreissena polymorpha) is an aquatic nuisance species that invaded Ireland around 1994. We studied the invasion of the zebra mussel combining field surveys and genetic studies, to determine the origin of invasion and the vector of introduction. 2. Field surveys showed that live zebra mussels, attached to the hulls of pleasure boats, were transported from Britain to Ireland. These boats were lifted from British waters onto trailers, transported to Ireland by ferry and lifted into Irish waters within a day. Length‐frequency distributions of dead and living mussels on one vessel imported 3 months earlier revealed a traumatic occurrence caused by the overland, air‐exposed transportation. Results show that a large number of individuals survived after re‐immersion in Irish waters and continued to grow. 3. Zebra mussels from populations in Ireland, Great Britain, the Netherlands, France and North America, were analysed using amplified fragment length polymorphisms (AFLP)‐fingerprinting to determine the origin of the Irish invasion. Phylogenetic analysis revealed that Irish and British mussels clustered closely together, suggesting an introduction from Britain. 4. Ireland remained un‐invaded by the zebra mussel for more than 150 year. The introduction of the zebra mussel to Ireland occurred following the abolition of value added tax in January 1993 on imported second‐hand boats from the European Union (UK and continental Europe). This, together with a favourable monetary exchange rate at that time, may have increased the risk of invasion of the zebra mussel.     

Factors influencing the attachment strength of Dreissena polymorpha (Bivalvia)

Abstract

The effects of several factors (shell length, exposure time, substratum orientation in space, illumination, temperature, conspecifics) upon the attachment strength (measured with a digital dynamometer) of the freshwater, gregarious bivalve Dreissena polymorpha were studied under laboratory conditions. A rapid increase in attachment strength was observed on resocart (a thermosetting polymer based on phenol-formaldehyde resin, with paper as filler) substrata during the first 4-d exposure, after which it stabilised at ca 1 N. The attachment strength increased also with mussel size. Mussel adhesion on variously oriented surfaces (vertical, upper horizontal and lower horizontal) was similar. Illumination inhibited attachment strength, as expected for a photophobic species, but only after a 2-d exposure. After 6 d, no effects of light were detected. Thus, illumination seemed to influence the attachment rate, rather than the final strength. The optimum temperature for mussel attachment was 20 – 25°C. At lower and higher temperatures (5 – 15°C and 30°C), their adhesion strength decreased. The presence of conspecifics stimulated mussel attachment strength.     

Genetic variability and phylogeography of the invasive zebra mussel, Dreissena polymorpha (Pallas)

The zebra mussel, Dreissena polymorpha (Pallas), a bivalve species originally native to the Black and Caspian seas, has invaded Ireland in the last decade. Five microsatellite loci were used to investigate genetic diversity and population structure in 10 populations across Europe (Ireland, UK, the Netherlands and Romania) and the Great Lakes (Lake Ontario and Lake St Clair). Levels of allelic diversity and mean expected heterozygosity were high for all populations (mean number of alleles/locus and H(E) were 10-15.2 and 0.79-0.89, respectively). High levels of polymorphism observed in Irish populations suggest that the Irish founder population(s) were large and/or several introductions took place after foundation. Significant deficits of heterozygotes were recorded for all populations, and null alleles were the most probable factor contributing to these deficits. Pairwise comparisons using Fisher exact tests and F(ST) values revealed little genetic differentiation between Irish populations. The UK sample was not significantly differentiated from the Irish samples, most probably reflecting an English origin for Irish zebra mussels. No significant differentiation was detected between the two Great Lakes populations. Our data support a northwest rather than a central or east European source for North American zebra mussels.     

The Effects of Zebra Mussels (Dreissena polymorpha) on the Foraging Success of Eurasian Perch (Perca fluviatilis) and Ruffe (Gymnocephalus cernuus)

Complex habitat structures can influence the foraging success of fish. Competition for food between fish species can therefore depend on the competitors' abilities to cope with structural complexity. In laboratory experiments, we comparatively assessed effects of zebra mussels (Dreissena polymorpha Pall .) on the foraging success of Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus (L.)). In single‐species and mixed‐species experiments, the fish were fed caddisfly larvae (Tinodes waeneri (L.)) over complex (mussel‐covered stones) and less‐complex (bare stones) substrates. With intraspecific competition, food consumption by perch and ruffe decreased significantly when the complex substrate was used. With interspecific competition, food consumption by perch and ruffe did not change with substrate complexity, but perch clearly out‐competed ruffe on both substrates. Zebra mussel beds provide a refuge for macrozoobenthos against predation by ruffe and probably also by perch. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Seasonal Abundances of Naked Amoebae in Biofilms on Shells of Zebra Mussels (Dreissena polymorpha) with Comparative Data from Rock Scrapings

ABSTRACT. In North America, zebra mussels ( Dreissena polymorpha ) are notoriously known as invasive species. The abundance of naked amoebae sampled from the shells of zebra mussels was compared with abundances from rock scrapings at approximately monthly intervals for 1 year. The sites were 2 km apart along the same shoreline. No significant difference in abundance of naked amoebae ( F =1.44; P ≤0.270) was detected for the two sampling sites. The combined data showed a minimum density of naked amoebae in winter, followed by peaks in early spring. The percent encysted increased from a low of 1% in the summer to 80% in early winter.     

Cytogenetic characterization of the Zebra Mussel Dreissena polymorpha (Pallas) from Miedwie Lake, Poland

Cytogenetic characterization of D. polymorpha was carried out using banding techniques such as C-banding, fluorochrome CMA3 and silver nitrate treatment. The diploid chromosome number of both investigated D. polymorpha forms (typical and albinotic) was the same 2n = 32 (NF = 56). The karyotype consisted of 5 pairs of metacentric, 7 pairs of submetacentric and four pairs of subtelo-acrocentric chromosomes. Ag-NORs were located in the telomeric position on the largest subtelo-acrocentric chromosome pair. C banding patterns indicate many sites of constitutive heterochromatin mainly located in the telomeric regions and interstitially in some chromosomes. CMA3-sites were observed in almost all chromosomes; apart from the Ag-NORs sites, they were located terminally on the chromosome arms and interstitially on three chromosome pairs. Sixteen chromosomes could be counted at the diakinesis stage of meiosis. No differences in banding chromosome patterns were found neither between both analyzed forms of D. polymorpha nor between males and females.     

Changes in the distribution and abundance of Dreissena polymorpha within lakes through time

Dreissena polymorpha population densities and biomass were followed in three Belarusian lakes with different trophic status over a 12-year period subsequent to initial colonization. In all three lakes zebra mussel population densities did not change once they reached a maximum. Application of the Ramcharan et al. [1992. Canadian Journal of Fisheries and Aquatic Sciences 49: 2611–2620] model for predicting population dynamics of zebra mussels was accurate for two of the three lakes studied. Population density appears to depend on the time since initial colonization, relative abundance of substrate available for colonization, lake morphometry and trophic type. Zebra mussel distribution within lakes was highly patchy, but the degree of dispersion decreased over time after initial colonization, which may be a result of saturation of suitable substrates by zebra mussels as populations increase and reach carrying capacity. In lakes where submerged macrophytes are the dominant substrate for zebra mussel attachment, populations may be less stable than in lakes with a variety of substrates, which will have a more balanced age distribution, and be less impacted by year to year variation in recruitment. Dreissena polymorpha usually reach maximum population density 7–12 years after initial introduction. However, the timing of initial introduction is often very difficult to determine. Both European and North American data suggest that zebra mussels reach maximum density in about 2–3 years after populations are large enough to be detected.     

Fouling of European freshwater bivalves (Unionidae) by the invasive zebra mussel (Dreissena polymorpha)

1. The zebra mussel (Dreissena polymorpha) is well known for its invasive success and its ecological and economic impacts. Of particular concern has been the regional extinction of North American freshwater mussels (Order Unionoida) on whose exposed shells the zebra mussels settle. Surprisingly, relatively little attention has been given to the fouling of European unionoids. 2. We investigated interspecific patterns in fouling at six United Kingdom localities between 1998 and 2008. To quantify the effect on two pan‐European unionoids (Anodonta anatina and Unio pictorum), we used two measures of physiological status: tissue mass : shell mass and tissue glycogen content. 3. The proportion of fouled mussels increased between 1998 and 2008, reflecting the recent, rapid increase in zebra mussels in the U.K. Anodonta anatina was consistently more heavily fouled than U. pictorum and had a greater surface area of shell exposed in the water column. 4. Fouled mussels had a lower physiological condition than unfouled mussels. Unlike tissue mass : shell mass ratio, tissue glycogen content was independent of mussel size, making it a particularly useful measure of condition. Unio pictorum showed a stronger decline in glycogen with increasing zebra mussel load, but had a broadly higher condition than A. anatina at the time of study (July). 5. Given the high conservation status and important ecological roles of unionoids, the increased spatial distribution and fouling rates by D. polymorpha in Europe should receive more attention.     

Chironomidae (Insecta: Diptera) from four protected areas in the state of Pernambuco,Brazil

New records and distributional notes of Chironomidae (Insecta, Diptera) are provided for four protected areas in the state of Pernambuco, northeastern Brazil. Additionally, we also present new records and update of distributional ranges from Brazil and the Neotropical Region. In total, 810 specimens belonging to 35 genera within the subfamilies Chironominae (22 taxa), Tanypodinae (11 taxa) and Orthocladiinae (2 taxa) were found. The subfamilies Chironominae and Tanypodinae predominated. Axarus Roback, 1980 Roback, S.S. (1980), ‘New name for Anceus Roback nec Anceus Risso’, Entomological News, 91, 32.[Web of Science ®] , [Google Scholar] and the Tanytarsus ortoni-group were recorded for the first time in the state of Pernambuco, while Nanocladius Kieffer, 1913a Kieffer, J.J. (1913b), ‘Nouvelle étude sur les Chironomides de l'Indian Museum de Calcutta’, Records of the Indian Museum, 9, 119–197. [Google Scholar] was recorded for the first time in the Northeast Region of Brazil. Our results make evident how much and where current knowledge of the northeastern Brazil chironomids remains fragmentary.     

In situ survival and growth of zebra mussels (Dreissena polymorpha) under chronic hypoxia in a stratified lake

Experiments and field surveys were conducted in Hargus Lake (Ohio, U.S.) to investigate the effect of lake stratification on the survival, growth and distribution of zebra mussels. During the lake stratification period, relatively stable temperature and dissolved oxygen (DO) gradients persisted across the water column, allowing us to examine the chronic effect of hypoxia on zebra mussels. Zebra mussels were incubated in cages and suspended at different depths in the water column at both pelagic (max. depth = 12 m) and littoral (max. depth = 3.5 m) sites from April 18 to September 28, 1994. No mussel survived to the end of the experiment in cages ≥ 5.5 m, whereas the highest survival rate (76%) occurred at 5 m depth where temperature and DO remained fairly stable for at least 3 months. The threshold oxygen level for survival was between 1.0–1.7 mg l^-1 when water temperature was at about 17–18 °C. While zebra mussels′ survival rate was not affected under the sublethal hypoxic conditions, their growth was greatly retarded by poor water quality. The field survey showed that the zebra mussels and macrophytes had about the same distribution and their biomasses were positively related. The percentage of mussels in aggregates increased towards their maximum distribution depth. The maximum distribution depth of the naturally occurring zebra mussels was only 2.8 m, whereas the adult mussels could survive the entire stratification period when being artificially placed on the 3.5 m bottom, and young mussels could colonize the 3.5 m bottom if solid substrates were provided. We conclude that lack of substrate, rather than hypoxia, was the limiting factor of zebra mussel distribution above 5 m depth in Hargus Lake. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mariambera,a new genus of Orthocladiinae from Brazil (Insecta: Diptera,Chironomidae)

The genus Mariambera is erected based on the males of M. amazonica n. sp. from Amazonas and M. mariae n. sp. from Minas Gerais. The new genus is easily recognized by the distinctive anal point which has a rounded dorsal lobe with microtrichia and a triangular ventral lobe with very strong, marginal setae, in combination with bare eyes and wing membrane, squama with setae, antenna without strong apical seta, and apparently few, short, very weak, hair-like acrostichals in anterior 1/3 of scutum.     

Modelling the local dynamics of the zebra mussel (Dreissena polymorpha)

1. The bivalve Dreissena polymorpha has invaded many freshwater ecosystems worldwide in recent decades. Because of their high fecundity and ability to settle on almost any solid substratum, zebra mussels usually outcompete the resident species and cause severe damage to waterworks. Time series of D. polymorpha densities display a variety of dynamical patterns, including very irregular behaviours. Unfortunately, there is a lack of mathematical modelling that could explain these patterns. 2. Here, we propose a very simple discrete‐time population model with age structure and density dependence that can generate realistic dynamics. Most of the model parameters can be derived from existing data on D. polymorpha. Some of them are quite variable: with respect to these we perform a sensitivity analysis of the model behaviour and verify that non‐equilibrial regimes (either periodic or chaotic) are the rule rather than the exception. 3. Even in circumstances where the model dynamics are aperiodic it is possible to predict total density peaks from previous peaks. This turns out to be true also in the presence of environmental stochasticity. 4. Using the stochastic model we explore the effects of age‐selective predation. Quite surprisingly, larger removal rates of adults do not always result in smaller population densities and mussel biomasses. Moreover, non‐selective predation can result in skewed size‐frequency distributions which, therefore, are not necessarily the footprint of predators’ preference for larger or smaller zebra mussels.     

Assessment of the genotoxic potential of benzo(a)pyrene and pp'-dichlorodiphenyldichloroethylene in Zebra mussel (Dreissena polymorpha)

The single-cell gel electrophoresis (SCGE) assay and the micronucleus (MN) test were carried out with haemocytes of Zebra mussel (Dreissena polymorpha) specimens to evaluate the potential genotoxicity of benzo(a)pyrene (BaP) and pp'-dichlorodiphenyldichloroethylene (pp'-DDE, a metabolite of pp'-DDT). Mussels were exposed to three different concentrations (0.1 microg/L, 2 microg/L, 10 microg/L) of each chemical in water during 168 h (SCGE assay) and 96 h (MN test) of exposure under laboratory conditions. These levels correspond to nominal molar concentrations of 0.4 nM, 7.9 nM and 40 nM for BaP and 0.3 nM, 6.2 nM and 31 nM for pp'-DDE, respectively. Concurrently, the levels of toxicants were measured in soft tissues of the mussels by gas-chromatographic analyses, to evaluate their temporal trends and the dose/response relationships. Significant increases of the ratio between the comet length and the diameter of the comet head (LDR) and of micronucleus frequencies in comparison with baseline levels were observed not only for all concentrations of BaP, but also for pp'-DDE (except 0.3 nM). The concentration above which DNA damage starts to be significantly increased was 0.8 nmol/g lipids for BaP and 1.6 nmol/g lipids for pp'-DDE, respectively. The results of these experiments show a clear genotoxic effect on this non-target organism not only for the well-known genotoxicant BaP, but also for the final metabolite of pp'-DDT at soft-tissue concentrations that have been found in several aquatic ecosystems worldwide.     

Six new and two newly recorded species of Chironomidae (Insecta: Diptera) in Korea

Adult chironomids were collected by light trap operations, sweeping grasses with insect nets, and aspiration of light‐attracted adults at various localities. All collected specimens were slide‐mounted and identified. Six species new to science were found and named: Rheotanytarsus pseudopentapoda n. sp., Cricotopus byeonsanensis n. sp., Cricotopus parajogantertius n. sp., Limnophyes bukhandecimus n. sp., Limnophyes simensis n. sp. and Orthocladius jeongnungensis. Two species, Ainuyusuroka tuberculatum (Tokunaga) and Pseudosmittia nishiharaensis Sasa and Hasegawa, are found for the first time in Korea. All species are fully described with illustrations. This is the first report of the genus Ainugusurika in Korea.     

Distribution and aspects of population dynamics of the zebra mussel,Dreissena polymorpha (Pallas, 1771), in the lake IJsselmeer area (The Netherlands)

Summary The distribution, settling and growth of the zebra mussel, Dreissena polymorpha Pallas, in Lake IJsselmeer and Lake Markermeer in The Netherlands were studied from 1980 to 1985. In these lakes D. polymorpha is the most important food source for wintering diving ducks. The study was part of an investigation into the carrying capacity of the lakes for these birds.