Article

Invasion of Freshwater Molluscs in the Czech Republic: Time Course and Environmental Predictors

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Abstract

The number of non-native species has dramatically increased over the last decades in many aquatic habitats of central Europe. Although the spreading of alien mollusc species can poses a serious threat to many native species, no attempt has been made to assemble and analyse an extensive dataset collected over a long time span. So far, eight non-native species of aquatic molluscs - five gastropods and three bivalves - have been recorded in the wild in the Czech Republic in central Europe. We assembled a dataset consisting of 1,783 sites with the presence of these non-native species recorded between 1891 and 2014. We aimed to explore the time course and spatial pattern of the invasions and to define some of the gross predictors of the occurrence of these species by categorizing their sites based on habitat type, elevation and distance from the nearest large river. We found that most of these species expressed affinities to non-natural standing waters and large rivers. The most invaded parts of the Czech Republic were large lowlands, especially the Elbe River basin. In contrast, hilly and mountain areas were notably less invaded as the number of records sharply decreased towards higher elevations for all studied species except Gyraulus parvus. The highest invasion rate was documented for Physella acuta and Potamopyrgus antipodarum, in contrast to two modern invaders (Menetus dilatatus and Corbicula fluminea) that had a much lower rate of colonisation. However, the other four species showing an intermediate rate of spreading were recorded for the first time both 70 years ago (Dreissena polymorpha and Ferrissia fragilis) and less than 20 years ago (Gyraulus parvus and Sinanodonta woodiana). Large rivers serve as the most important corridors for the spreading of non-native species, with a significant association between the number of non-native species recorded and the distance from the 8th- and 9th-order rivers.

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... Three non-native bivalves have been known from the Czech Republic (Beran, 2002;Lorencová et al., 2015). While originally ponto-caspian Dreissena polymorpha (Pallas, 1771) was recorded for the first time more than 120 years ago in the Labe River near Ustí nad Labem (Blažka, 1893), first record about the occurrence of S. woodiana exists from 1996 from South Moravia (Beran, 1997) and Corbicula fluminea (O. ...
... F. Müller, 1774) was first recorded in 1999 from the Labe River near the Czech-German boundaries (Beran, 2000). Recently the first mentioned species occurs mostly in the lowlands of the largest rivers (Labe, Vltava, Morava and Dyje) and their surroundings (Lorencová et al., 2015). In natural habitats such as rivers D. polymorpha usually does not occur in densities that could significantly affect other organisms including unionids. ...
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... Additionally, S. woodiana invasion threatens the endangered European bitterling Rhodeus amarus 16 , and its massive die-offs negatively impact water quality and reverberate to terrestrial ecosystems 41,42 . The increasing prevalence of S. woodiana in invaded areas 17,23,43,44 supports its predicted ability to effectively compete with native mussels. Our present study shows that demographic profiles of co-occurring mussel populations can indicate future dominance shifts already at initial invasion stages. ...
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... Since we have material of N. islandicus from the type-locality, we assume the correct identification of the snail host is G. cf. parvus, which is a species widely distributed in North America, and which was also found in south Greenland; currently it is spreading in Europe [50,90,135]. Adults and cercariae of N. islandicus were also found in North America in the western grebe Aechmophorus occidentalis (Lawrence, 1858), and the snail Planorbula armigera (Say, 1821), respectively [52,126], indicating that the species is not restricted to Iceland, and it can be expected to occur throughout North America, as A. occidentalis occurs from British Columbia to California [30], and the snail G. parvus is common [15]. ...
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... The occurrence of only two non-native species in the newly created lake is rather surprising and very low in comparison with e.g. Lake Most (beran 2013) but the probable reason is that other non-native species are not known from this area (Lorencová et al. 2015) so it will be interesting if (and when) other non-native species inhabit this lake. ...
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1. Introduction of alien species is one of the major threats to aquatic biota and knowledge of the major correlates of their occurrence is pivotal in planning reliable conservation strategies. 2. To understand whether specific freshwater habitats are more likely to be invaded than others, a dataset on the occurrence of 1604 species in 54 taxonomic groups from 181 sites across the Italian peninsula was gathered. 3. The EUNIS habitat classification was used, selecting for the study's seven habitat types at the second EUNIS level, including lentic (EUNIS C1; 64 sites), lotic (EUNIS C2; 99 sites) and highly artificial (EUNIS J5; 18 sites) habitats. 4. The aim of the study was to test whether the overall number of alien species and the proportion of alien species for each taxonomic group differed between habitat types and could be explained by environmental, human-mediated, or climatic factors. 5. Using generalized linear mixed effect models to account for potential confounding factors, only average air temperature of the site was a significant positive predictor of the occurrence of alien species, regardless of habitat type, species richness, and other climatic variables. 6. A direct effect of temperature could be excluded given the origin of alien species, mostly from colder areas than Italy. Thus, an indirect effect could be hypothesized at the Italian latitudes, with warmer areas potentially more likely to be visited by tourists than colder areas. If this hypothesis is confirmed, the results of the analyses call for a compromise between the maintenance of recreational activities in the wild and the preservation of a natural environment to prevent the arrival and spread of alien species. On the other hand, no further recommendations can be implemented regarding habitat susceptibility to alien species.
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The Asian clam Corbicula fluminea has been observed,from 14 different sites on the River Elbe from the Czech-German border
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1. How species reach and persist in isolated habitats remains an open question in many cases, especially for rapidly spreading invasive species. This is particularly true for temporary freshwater ponds, which can be remote and may dry out annually, but may still harbour high biodiversity. Persistence in such habitats depends on recurrent colonisation or species survival capacity, and ponds therefore provide an ideal system to investigate dispersal and connectivity. 2. Here, we test the hypothesis that the wide distributions and invasive potential of aquatic snails is due to their ability to exploit several dispersal vectors in different landscapes. We explored the population structure of Physa acuta (recent synonyms: Haitia acuta, Physella acuta, Pulmonata: Gastropoda), an invasive aquatic snail originating from North America, but established in temporary ponds in Doñana National Park, southern Spain. In this area, snails face land barriers when attempting to colonise other suitable habitat. 3. Genetic analyses using six microsatellite loci from 271 snails in 21 sites indicated that (i) geographically and hydrologically isolated snail populations in the park were genetically similar to a large snail population in rice fields more than 15 km away; (ii) these isolated ponds showed an isolation-by-distance pattern. This pattern broke down, however, for those ponds visited frequently by large mammals such as cattle, deer and wild boar; (iii) snail populations were panmictic in flooded and hydrologically connected rice fields. 4. These results support the notion that aquatic snails disperse readily by direct water connections in the flooded rice fields, can be carried by waterbirds flying between the rice fields and the park and may disperse between ponds within the park by attaching to large mammals. 5. The potential for aquatic snails such as Physa acuta to exploit several dispersal vectors may contribute to their wide distribution on various continents and their success as invasive species. We suggest that the interaction between different dispersal vectors, their relation to specific habitats and consequences at different geographic scales should be considered both when attempting to control invasive freshwater species and when protecting endangered species.
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The River Danube, connected to the Rhine catchment via the Rhine-Main-Danube Canal, is part of a significant aquatic invasion corridor in Europe between the North Sea and the Black Sea. Among its aquatic fauna molluscs, crustaceans and fishes represent the most prominent groups of invaders in terms of species number and biomass. The listed reptile species is in the list of the 100 worst invasive species in the world. This paper reviews available information about the arrival time, way of introduction, distribution area, dominance in communities, ecosystem functions, and impact on the native fauna along the Hungarian stretch of the Danube of 43 non-indigenous species having arrived from several continents as Africa, Asia, Europe, North America, or New Zealand. Transport vectors that contribute to the introduction and the rapid spread of alien species are river shipping, deliberate crayfish and fish stocking, pet trade, release from aquaria, and food consumption. The invasions of the studied species have a potential to alter the structure and the function of Danubian ecosystems and create new biodiversity and economic problems. Due to the international importance of the River Danube, efforts should be made to prevent new invasions and manage the existing invaders along the whole river.
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Range extensions of aquatic Ponto-Caspian macroinvertebrate species in Europe have mainly been facilitated by the interconnection of river basins through man-made canals and intentional introductions. Three inland migration corridors can be distinguished: (i) a northern corridor: Volga → Lake Beloye → Lake Onega → Lake Ladoga → Neva → Baltic Sea, (ii) a central corridor connecting the rivers Dnieper → Vistula → Oder → Elbe → Rhine, and (iii) a southern corridor connecting the Danube and Rhine rivers. Important trade harbours in Europe were connected via these corridors allowing further range extensions of macroinvertebrate species attached to a vessel's hull or in ballast water. The central corridor was the main migration route before 1992, after which the southern corridor became the most important migration route for the range expansions to the west because of the reopening of the Main-Danube Canal, connecting the Rhine and Danube basins. Especially the water level maintenance in the upper part of the canal, with water supply from the Danube basin, facilitated migration of mobile animals (e.g., crustaceans) from the Danube basin towards the Rhine basin; however, contribution of other transport mechanisms (e.g., shipping) is expected in the near future.
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We contrast ecological and life history traits of the well studied freshwater invader, the zebra mussel (Dreissena polymorpha), with the lesser known invasive golden mussel (Limnoperna fortunei) to compare salient biological traits and environmental limits, and to predict the potential spread and ecosystem impacts of L. fortunei in areas where it is introduced. Both species are sessile, byssate bivalves with a planktonic larval stage and extremely high reproductive capacity. For both species adults attain much higher biomass in waterbodies they invade than all of the native invertebrates combined, and they create substrate complexity otherwise not found in freshwater systems. Both are very active suspension feeders, greatly enhance benthic-pelagic coupling, and act as effective ecosystem engineers. Although taxonomically unrelated, their ecosystem impacts are surprisingly similar and follow from the novel ecological niche they share, rather than being species specific. The golden mussel has broader environmental tolerances and therefore may be a much more successful invader than D. polymorpha in regions dominated by acidic, soft and contaminated waters. In the near future L. fortunei may colonize the southern and central parts of North America, much farther north than has been previously predicted. Although to date the zebra mussel is considered the most aggressive freshwater invader, soon many waterbodies may receive another, even more aggressive invader.
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Zebra mussels colonise new regions at different rates. Their rate of spread from isolated water bodies is slow but if introduced to upstream navigable regions their colonisation can be rapid and encompass a wide a rea. Zebra mussels continue to colonise European regions. Its recent appearance in Ireland since 1993/4 has incurred rapid colonisation through the inland navigation routes and it is poised to expand to other isolated regions. The management of controlling further spread has been successful to-date but its subsequent expansion is expected in time with human activities. It is likely that the species may also spread to other regions in Europe and North America with the potential to colonise large rivers and lakes in other temperate regions of the world.
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Questions: 1. Which habitats have the highest degree of invasion? 2. Do native species-rich communities have also a high degree of invasion? 3. Do the patterns of association between native and alien species richness vary between habitats. Location: Catalonia region (NE Spain). Methods: We conducted a large regional analysis of 15655 phytosociological relevés to detect differences in the degree of invasion between European Nature Information System (EUNIS) habitats representative of temperate and Mediterranean European areas. Results: Alien species were present in less than 17 % of the relevés and represented less than 2% of the total number of species per habitat. The EUNIS habitats with the highest alien species richness were arable land and gardens followed by anthropogenic forb-rich habitats, riverine and lakeshore scrubs, southern riparian galleries and thickets and trampled areas. In contrast, the following habitats had never any alien species: surface running waters, raised and blanket bogs, valley mires, poor fens and transition mires, base-rich fens, alpine and sub-alpine grasslands, sub-alpine moist or wet tall-herb and fern habitats, alpine and sub-alpine scrub habitats and spiny Mediterranean heaths. There was a unimodal relationship between the mean native and mean alien species richness per EUNIS habitat with a high number of aliens in habitats with intermediate number of native species and a low number of aliens at both extremes of the native species gradient. Within EUNIS habitats, the relationship was positive, negative or non-significant depending on the habitat type without any clear pattern related to the number of native species. Alien species richness was not related to plot size, neither between habitats nor within habitats. Conclusions: The analysis emphasised that the habitats with a higher degree of invasion were the most disturbed ones and that in general habitats rich in native species did not harbour less invaders than habitats poor in native species.
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A vital population of Physa acuta, a globally invasive species of freshwater gastropods was dicovered in ancient Lake Titicaca in April 2007. The population was found near Chucuito (Bahia de Puno) on the Peruvian side in close proximity to a boat landing of the aquaculture facility of the University of Puno. Physids occured in great abundances at this site on macrophytes in depths from 0 to 2m. Physa acuta was associated with members of the Heleobia andicola species complex as well as with Heleobia otorni, Biomphalaria andecola, and Uncancylus crequi. Species identity was confirmed by morphological and molecular methods. We discuss the mode of introduction and raise a cautionary note on the potential impact of this global invader on the endemic gastropod fauna of ancient Lake Titicaca.
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We identified different distributions of marine nonindigenous species (NIS) and native species on some artificial structures versus natural reefs and using experimental manipulations, revealed some possible causal mechanisms. In well-established subtidal assemblages, numbers of NIS were 1.5–2.5 times greater on pontoons or pilings than on rocky reefs, despite the local species pool of natives being up to 2.5 times greater than that of NIS. Conversely, on reefs and seawalls, numbers of native species were up to three times greater than numbers of NIS. Differential recruitment to different positions and types of surfaces appeared to influence distribution patterns. NIS recruited well to most surfaces, particularly concrete surfaces near the surface of the water, whilst natives occurred infrequently on wooden surfaces. The position of rocky reefs and seawalls close to the shore and to the seabed appeared to make them favourable for the recruitment of natives, but this positioning alone does not hinder the recruitment of NIS. We argue that pontoons and pilings represent beachheads (i.e. entry points for invasion) for many nonindigenous epibiota and so enhance the spread and establishment of NIS in estuaries. Habitat creation in estuaries may, therefore, be a serious threat to native biodiversity.
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The impact of multiple invading species can be magnified owing to mutual facilitation--termed 'invasional meltdown'--but invasive species can also be adversely affected by their interactions with other invaders. Using a unique reciprocal host-parasite relationship between a bitterling fish (Rhodeus amarus) and unionid mussels, we show that an invasive mussel reverses the roles in the relationship. Bitterling lay their eggs into mussel gills, and mussel larvae parasitize fish. Bitterling recently colonized Europe and parasitize all sympatric European mussels, but are unable to use a recently invasive mussel, Anodonta woodiana. The parasitic larvae of A. woodiana successfully develop on R. amarus, whereas larvae of European mussels are rejected by bitterling. This demonstrates that invading species may temporarily benefit from a coevolutionary lag by exploiting evolutionarily naive hosts, but the resulting relaxed selection may facilitate its exploitation by subsequent invading species, leading to unexpected consequences for established interspecific relationships.
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Many plant seeds and invertebrates can survive passage through the digestive system of birds, which may lead to long distance dispersal (endozoochory) in case of prolonged retention by moving vectors. Endozoochorous dispersal by waterbirds has nowadays been documented for many aquatic plant seeds, algae and dormant life stages of aquatic invertebrates. Anecdotal information indicates that endozoochory is also possible for fully functional, active aquatic organisms, a phenomenon that we here address experimentally using aquatic snails. We fed four species of aquatic snails to mallards (Anas platyrhynchos), and monitored snail retrieval and survival over time. One of the snail species tested was found to survive passage through the digestive tract of mallards as fully functional adults. Hydrobia (Peringia) ulvae survived up to five hours in the digestive tract. This suggests a maximum potential transport distance of up to 300 km may be possible if these snails are taken by flying birds, although the actual dispersal distance greatly depends on additional factors such as the behavior of the vectors. We put forward that more organisms that acquired traits for survival in stochastic environments such as wetlands, but not specifically adapted for endozoochory, may be sufficiently equipped to successfully pass a bird's digestive system. This may be explained by a digestive trade-off in birds, which maximize their net energy intake rate rather than digestive efficiency, since higher efficiency comes with the cost of prolonged retention times and hence reduces food intake. The resulting lower digestive efficiency allows species like aquatic snails, and potentially other fully functional organisms without obvious dispersal adaptations, to be transported internally. Adopting this view, endozoochorous dispersal may be more common than up to now thought.
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Several freshwater mussel species represent some of the most problematic invasive species and have considerably altered ecosystems worldwide. Their invasion potential has been partially attributed to their free-living larvae, which have a high dispersal capability. We investigated the invasion potential of Anodonta (Sinanodonta) woodiana, a species of East Asian unionid mussel established worldwide despite having an obligatory parasitic stage (glochidium), which must encyst on host fish. The invasion success of A. woodiana has been attributed to the success of worldwide introductions of its sympatric fish hosts. We experimentally found, however, that A. woodiana is a broad host generalist, which can complete its development on all eight fish species tested, both coinvasive and native. Subsequently, we used a data on the occurrence and relative abundance of potential hosts in river habitats in the Czech Republic to project scenarios of the effect of host availability on A. woodiana invasion. We found th
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This is the first comprehensive review to examine the role of the central European invasion corridor on fish introductions into Belarusian and Polish inland waters (Dnieper-Bug-Vistula-Oder-Elbe-Spree-Havel). Historical and recent data were assessed,including the results of a 2003 - 2008 survey along the Belarusian and Polish sections of the corridor. Since the eighteenth century, at least six fish species of Ponto-Caspian origin have spread via the corridor and migrated westwards to the Baltic basin, with five species found in recent surveys, namely the monkey goby Neogobius fluviatilis, round goby N. melanostomus, racer goby N. gymnotrachelus, tubenose goby Proterorhinus marmoratus and the white eye-bream Abramis sapa.
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This thesis summarised and analysed especially data about distribution of aquatic molluscs in the Czech Republic and its changes. Altogether 27.857 data about occurrence of 76 species of aquatic molluscs in the temtory of the Czech Republic in the period 1851-2000 were collected, transformed to the database and analysed. One of the longest parts of this thesis is presented to the survey of particular species of aquatic molluscs with histograms of altitude and distribution maps in mapping periods (1851-1900, 1901-1950, 1951-1990, 1991-2000, 1851-2000). Data were also ušed for classification of habitats, theirmolluscan communities and the study ofdynamics ofthese molluscan commumties. First author’s results of dispersal of aquatic molluscs and development of molluscan communities in some new or restored localities and also results of intentional transfers (introductions) of choice endangered species were presented. The Red List of aquatic molluscs of the Czech Republic was actualised on the base of analysis of data at database and compared with previous versions.
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The spread of non-native species is one of the most harmful and least reversible disturbances in ecosystems. Species have to overcome several filters to become a pest (transport, establishment, spread and impact). Few studies have checked the traits that confer ability to overcome these steps in the same species. The aim of the present study is to review the available information on the life-history and ecological traits of the mud snail, Potamopyrgus antipodarum Gray (Hydrobiidae, Mollusca), native from New Zealand, in order to explain its invasive success at different aquatic ecosystems around the world. A wide tolerance range to physico-chemical factors has been found to be a key trait for successful transport. A high competitive ability at early stages of succession can explains its establishment success in human-altered ecosystems. A high reproduction rate, high capacity for active and passive dispersal, and the escape from native predators and parasites explains its spread success. The high reproduction and the ability to monopolize invertebrate secondary production explain its high impact in the invaded ecosystems. However, further research is needed to understand how other factors, such as population density or the degree of human perturbation can modify the invasive success of this aquatic snail
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Biological invasions are a major global environmental and economic problem. Analysis of the San Francisco Bay and Delta ecosystem revealed a large number of exotic species that dominate many habitats in terms of number of species, number of individuals and biomass, and a high and accelerating rate of invasion. These factors suggest that this may be the most invaded estuary in the world. Possible causes include a large number and variety of transport vectors, a depauperate native biota, and extensive natural and anthropogenic disturbance.
Article
Widely different sex ratios in certain New Zealand populations of the hydrobiid gastropod Potamopyrgus antipodarum (Gray) were generally found to vary little though in one stream a high-male/low-male boundary moved steadily upstream over 20 years. Laboratory breeding and chromosome studies indicated that New Zealand high-male populations are diploid with 2n = 34 and reproduce sexually, while New Zealand low-male populations and all those from Europe and Australia have 2n = 52 or 46 and reproduction is largely parthenogenetic.
Article
Biologists are nearly unanimous in their belief that humanity is in the process of extirpating a significant portion of the earth's spe­ cies. The ways in which we are doing so reflect the magnitude and scale of human enterprise. Everything from highway construction to cattle ranch­ ing to leaky bait buckets has been implicated in the demise or endan­ germent of particular species. Ac­ cording to Wilson (1992), most of these activities fall into four major categories, which he terms "the mind­ less horsemen of the environmental apocalypse": overexploitation, habi­ tat destruction, the introduction of non-native (alien) species, and the spread of diseases carried by alien species. To these categories may be added a fifth, pollution, although it can also be considered a form of habitat destruction. Surprisingly, there have been reIa­ tively few analyses of the extent to which each of these factors-much less the more specific deeds encomDavid S. Wilcove is a senior ecologist at the Environmental Defense Fund, Wash­ ington, DC 20009. David Rothstein re­ ceived his J.D. in 1997 from Northeastern
Article
In 1991, the hydrobiid snail Potamopyrgus antipodarum (Gray 1843), native to New Zealand, was found 1 km offshore Wilson, New York, in Lake Ontario. This is the first known occurrence of the snail in eastern North America. Densities of P. antipodarum have increased since its discovery, and the snail is expected to spread quickly throughout the Great Lakes area. The biofouling potential of P. antipodarum is probably low; however, its most serious threat may be resource competition with native molluscs. This species was probably introduced in ballast water from transoceanic vessels, thus increasing the list of nonindigenous aquatic organisms introduced into the Great Lakes since the 1800s to 140 different organisms. The risk of other species invasions into the Great Lakes is still possible, despite the now mandatory ballast water regulations.
Article
Summary • Artificial structures have become ubiquitous features of coastal landscapes. Although they provide novel habitats for the colonization of marine organisms, their role in facilitating biological invasions has been largely unexplored. • We investigated the distribution and dynamics of the introduced green alga, Codium fragile ssp. tomentosoides, at a variety of spatial scales on breakwaters in the north Adriatic Sea, and analysed experimentally the mechanisms underlying its establishment. We assessed the provision of sheltered habitats by breakwaters, the role of disturbance (e.g. from recreational harvesting and storms) acting at different times of the year, and the interactions between Codium and the dominant native space-occupier, the mussel Mytilus galloprovincialis. • Codium fragile ssp. tomentosoides has established viable populations on artificial structures along the shores investigated. The density, cover and size (length, branching and weight) of annual erect thalli of Codium was enhanced in sheltered conditions, resulting in the monopolization of landward low-shore habitats of breakwaters. • On the landward sides of breakwaters, disturbance enhanced recruitment of Codium. The time when bare space was provided within mussels beds was crucial. Removal of mussels in April or January did not affect the recruitment of Codium, whereas harvest in August, shortly before Codium gamete release, doubled its success. On the seaward sides of breakwaters, the effects of disturbance were more complex because mussels both inhibited recruitment of Codium and provided shelter from wave action to adult thalli. • Synthesis and applications. Artificial structures can provide suitable habitats for non-indigenous marine species and function as corridors for their expansion. Physical (wave exposure) and biotic (resident assemblages) features of artificial habitats can be important determinants of their susceptibility to biological invasions. Alternative options in the design of artificial structures and effective management of native assemblages could minimize their role in biological invasions. In particular, increased water motion and retention of space by mussels in spring–summer would be effective in reducing the ability of C. fragile ssp. tomentosoides to persist on the breakwaters investigated in this study. Journal of Applied Ecology (2005) doi: 10.1111/j.1365-2664.2005.01096.x
Article
The trematode fauna of Potamopyrgus antipodarum, an introduced and invasive gastropod mollusc species native to New Zealand, was studied in Mont Saint Michel Bay (France). The study revealed, for the first time in Europe, the occurrence of larval digenean species, Sanguinicola sp., a blood fluke of fish never previously recorded in this prosobranch. Phase contrast and scanning electron microscopy was used to investigate the morphology of the parasite. Hypotheses on the origin of the P. antipodarum–Sanguinicola sp. association are discussed in relation to the history of invasion of the gastropod into brackish and fresh waters and the structure of local gastropod communities.
Article
In one of the largest European rivers, the Elbe, from its source in the Czech Republic to the German North Sea, 31 alien macrozoobenthic species have been recorded in total. Most of these species have been introduced by shipping activities. With a total number of 21 species, many of the established aliens occur—partly exclusively—in the brackish area of the Elbe estuary. In order to explain this observed settlement characteristic, four main arguments come into consideration: (1) estuaries with intensive international shipping have a higher potential infection rate than other aquatic zones; (2) brackish water species have, due to specific physiological characteristics, a better chance of being transported alive than euhaline or freshwater species and they also probably have a higher perennation and establishment potential after release; (3) brackish waters have the greatest natural ‘indigenous species minimum’, so that more alien species can potentially establish; and (4) salt-tolerant limnetic alien species introduced into inland water reached the coast at first in the estuaries. It seems that the combination of brackish water with its unsaturated ecological niches and intensive international ship traffic has the highest potential infection rate for aquatic systems with alien macrozoobenthic species. And, estuaries are subjected to a two-sided invasion pressure by alien species, via the ocean (mainly shipping) and via inland waters (mainly shipping canal construction). The identification of such patterns is an important prerequisite for the development of a forward-looking alien monitoring and management strategy.
Article
The exotic freshwater clam speciesCorbicula fluminea (Asiatic clam) was first reported in the tidal freshwater Potomac estuary near Washington, D.C., in 1977, and was found in benthic surveys, conducted in 1978, 1982, 1984, 1986, and 1992. In 1981 a tripling of water clarity was reported in the region of the clam beds, followed in 1983 by reapperance of submerged aquatic vegetation (SAV) absent for 50 yr. Submerged aquatic vegetation (SAV) has been surveyed and mapped over the entire Potomac estuary region in almost every year from 1976 to 1993 by aerial photography, as part of the United States Environmental Protection Agency's Chesapeake Bay program. Fish surveys in 1986 found populations increased up to 7× in beds of SAV. Starting in 1984, the Washington, D.C. Christmas Bird Census reported significant increases in several aquatic bird populations both nonmigratory and migratory. An extensive benthic survey in September 1986 estimated a spring-summer population of 8.7×106 kg Asiatic clams (wet weight including shell) in the 5-km region of the Potomac below Washington, D.C. This population was calculated as having the capacity to filter one-third to all of the water in this region of the estuary daily, depending on river flow. The 1986 clam population was smaller than that of 1984 and the 1992 population was 25% of that in 1986. Since 1986, SAV acreage has been decreasing in this area of the Potomac. Aquatic bird populations have declined. Yearly nuisance algae (Microcystis) blooms, which had been absent since 1983, reappeared in 1993. This paper presents evidence to support the theory the invasive Asiatic clam population in the 10 km below Washington, D.C., was responsible for SAV resurgence through filtration affecting turbidity. It suggests the clam populations triggered system-level changes in biota, including increase and decrease in local Potomac estuary populations (SAV, bird, fish, algae) over 10 yr, from 1983 to 1993. Major changes in the Asiatic clam population took place approximately 2 yr before parallel changes in SAV acreage were observed.
Article
The once immense diversity of native Pacific island land snail species, with high single island or archipelago endemism, is declining dramatically. The native/endemic species are being replaced by a much smaller number of widespread tropical tramps, that is, those species that are most readily transported by humans. The 82 introduced (including 14 cryptogenic) land snail species recorded include some that were distributed accidentally by Pacific islanders before European exploration of the Pacific and that are now widespread. However, the majority are modern introductions, with many recent accidental introductions often associated with the horticultural trade. Native freshwater faunas were less diverse than the terrestrial faunas and exhibited much lower endemism. Among the 59 alien freshwater species recorded (including 38 cryptogenic species), the most diverse and widespread are the thiarids. Predation by and competition with these aliens (as well as habitat loss) are probably important mechanisms underlying the loss of native taxa, but almost no quantitative or experimental work has been done to demonstrate such ecological interactions. Prevention of further spread and of new introductions should be the main approach. Increased public education and development of public trust is essential to the success of these efforts.
Article
1. Coastal landscapes are being transformed as a consequence of the increasing demand for urban infrastructure to sustain commercial, residential and tourist activities. A variety of man-made structures, such as breakwaters, jetties and seawalls have thus become ubiquitous features of intertidal and shallow subtidal habitats. This transformation will accelerate in response to the exponential growth of human populations and to global changes, such as sea-level rise and increased frequency of extreme meteorological events (e.g. storms). Here, we provide a critical overview of the major ecological effects of increasing infrastructure to marine habitats, we identify future research directions for advancing our understanding of marine urban ecosystems and we highlight how alternative management options might mitigate their impacts.
Article
Asks 1) what attributes of communities make them more likely to be invaded? and 2) what attributes of individual species make them more likely to be successful invaders? Data are drawn from 1) the large-scale, but unintentional introduction of alien plant species into British plant communities, and 2) the recorded attempts to establish introduced insects for the biological control of weeds. -from Author
Article
Freshwater mussels (Order Unionoida) are the most imperiled faunal group in North America; 60% of described species are considered endangered or threatened, and 12% are presumed extinct. Widespread habitat degradation (including pollution, siltation, river channelization and impoundment) has been the primary cause of extinction during this century, but a new stress was added in the last decade by the introduction of the Eurasian zebra mussel, Dreissena polymorpha, a biofouling organism that smothers the shells of other molluses and competes with other suspension feeders for food. Since the early 1990s, it has been spreading throughout the Mississippi River basin, which contains the largest number of endemic freshwater mussels in the world. In this report, we use an exponential decay model based on data from other invaded habitats to predict the long-term impact of D. polymorpha on mussel species richness in the basin. 2. In North American lakes and rivers that support high densities (> 3000 m$^{-2}$) of D. polymorpha, native mussel populations are extirpated within 4-8 years following invasion. Significant local declines in native mussel populations in the Illinois and Ohio rivers, concomitant with the establishment of dense populations of D. polymorpha, suggest that induced mortality is occurring in the Mississippi River basin. 3. A comparison of species loss at various sites before and after invasion indicates that D. polymorpha has accelerated regional extinction rates of North American freshwater mussels by 10-fold. If this trend persists, the regional extinction rate for Mississippi basin species will be 12% per decade. Over 60 endemic mussels in the Mississippi River basin are threatened with global extinction by the combined impacts of the D. polymorpha invasion and environmental degradation.
Article
The Asian clam Corbicula fluminea is one of the most invasive species in freshwater aquatic ecosystems. The rapid growth, earlier sexual maturity, short life span, high fecundity and its association with human activities makes C. fluminea a non-indigenous invasive species likely to colonize new environments. This species, originally distributed in Asiatic ecosystems, is now a common inhabitant of American and European freshwater habitats. The present paper reviews the information related to the life cycle, ecology and potential ecological and economic impacts caused by C. fluminea in the invaded habitats. Furthermore, this paper also proposed future works that may be implemented in order to increase our general knowledge about the ecology of this bivalve.
Article
The effects of multiple infections on the host-parasite relationship between bluegill sunfish (Lepomis macrochirus) and parasitic glochidial larvae of the freshwater mussel Utterbackia imbecillis were examined. Naïve, young-of-the-year bluegills were infected with glochidia and placed in individual observation chambers. Each day, water was drained from each chamber and the numbers of dead glochidia, live glochidia, partially metamorphosed glochidia, and fully metamorphosed juvenile mussels were counted. The same fishes were infected a total of 4 times. After 2 infections, the fish began to exhibit evidence of acquired resistance to glochidia. During the third and fourth infections, this resistance was clearly evidenced by the marked increase in the percentage of dead and live glochidia shed during the first 5 days of the infection and by the significant decrease in the success of metamorphosis. The total number of glochidia that successfully attached to the fish decreased significantly during the fourth infection relative to the first. The number of larvae attached to the host fish was positively correlated with the size of the fish during the first infection but was negatively correlated during all subsequent infections. Variance to mean ratios indicated that larvae were aggregated among host fishes during the infections. This study has important implications in propagation and conservation efforts of this endangered group of organisms.
Simulation modelling of competition between freshwater mussels for fish hosts
  • B Rashleight
RASHLEIGHT, B., 1995, Simulation modelling of competition between freshwater mussels for fish hosts. Association of Southeastern Biologists Bulletin, 42: 114.
DAISIE -100 of the Worst -Dreissena polymorpha. Swindon: delivering alien invasive species inventories for Europe -DAISIE. Online at www.europe-aliens. org/speciestheworst.do
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Současný stav invaze a neobvyklá lokalita korbikuly asijské [Unusual site of the Asian Clam]
BERAN, L., 2013b, Současný stav invaze a neobvyklá lokalita korbikuly asijské [Unusual site of the Asian Clam]. Živa, 61: 25 [in Czech].
Potamopyrgus jenkinsi poprvé v Československu [First record of Potamopyrgus jenkinsi in the Czechoslovakia
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KUCHAř, P., 1983, Potamopyrgus jenkinsi poprvé v Československu [First record of Potamopyrgus jenkinsi in the Czechoslovakia]. Živa, 31: 23 [in Czech].
Mollusca (Partim) -Vodní měkkýši
  • L Beran
BERAN, L., 2006a, Mollusca (Partim) -Vodní měkkýši. Pp. 216-217, in: J. Mlíkovský, & P. Stýblo, eds., Nepůvodní druhy fauny a flóry České Republiky [Non-native species of fauna and flora of the Czech Republic].
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