Zebra mussels engulfing Anodonta anatina. Photo courtesy of David Aldridge
|The use of microencapsulated biobullets in the control of invasive bivalves||DAVID ALDRIDGE|
|The British terrestrial mollusc fauna – a bunch of successful invaders?||ROBERT CAMERON|
|Recruitment and growth of Teredo bartschi (Teredinidae, Bivalvia) in hypersaline, oligotrophic waters at Aqaba on the Red Sea.||S. M. CRAGG, M-C. JUMEL1, F. AL-HORANI AND I. W. HENDY|
|Cross-habitat differences in crush resistance and growth pattern of zebra mussels (Dreissena polymorpha): effects of calcium availability and predator pressure||MARCIN CZARNOLESKI|
|A review of the distribution and ecological impacts of the zebra mussel (Dreissena polymorpha) (Pallas) in Ireland||JON GRENNAN, TARA HIGGINS AND T.K. MCCARTHY|
|Using geographical information systems to predict the spread of an invasive species, the manila clam Ruditapes philippinarum (Adams and Reeve, 1850)||MATT HARRIS|
of zebra mussel infestation on water quality and algal populations
in western Irish lakes
|Synanthropic terrestrial mollusk faunas of Colorado and Utah||JOHN M. C. HUTCHINSON & HEIKE REISE|
of the Japanese oyster Crassostrea gigas by heat
strength, aggregation and movement of the zebra mussel (Dreissena
polymorpha) in the presence of potential predators
||JAROSLAW KOBAK AND TOMASZ KAKAREKO|
occurrence of Potamopyrgus antipodarum (Gray, 1843) (Prosobranchia:
Hydrobiidae) in the mining subsidence reservoirs affected by coal
mine output (Upper Silesia, southern Polland)
decline and extirpation of unionids in large Irish lake invaded
by zebra mussels: invasion history as a predictor of impact
||CAITRIONA M. MAGUIRE, ROBERT ROSELL AND DAI ROBERTS|
cartusiana (Müller, 1974):
the phylogenetic study of the central Europe populations has started
||MÍKOVCOVÁ ALENA, JURICKOVÁ LUCIE AND PETRUSEK ADAM|
asymmetry in mussels
||R. NAGARAJAN, STEPHEN E. G. LEA, AND JOHN D. GOSS-CUSTARD|
non-marine mollusks in Poland
||BEATA M. POKRYSZKO|
molluscan fauna present in the Minho estuary, Portugal
||RONALDO SOUSA, CARLOS ANTUNES, LÚCIA GUILHERMINO|
variability in the alien razor clam Ensis directus: preliminary
data from CO1 gene
||JOAQUIN VIERNA, ANDRES MARTINEZ-LAGE AND ANA GONZÁLEZ-TIZÓN|
The widespread invasion of bivalve molluscs such as the zebra mussel,
Dreissena polymorpha, golden mussel, Umnopema fortunei,
and false mussels, Mytilopsis spp., has made them some of the
world's most economically and ecologically important pests. Despite
the development of numerous control methods, chlorination remains
the only widespread and licensed technique throughout the world. Mussels
are able to sense chlorine and other toxins in their surrounding environment
and respond by closing their valves, thus enabling them to avoid toxic
effects for up to three weeks. Furthermore, prolonged dosing of chlorine
in raw water produces ecotoxic trihalomethanes (THMs) by reaction
with organic material in the water.
We have developed a novel, environmentally safe and effective method for controlling the biofouling mussels; the BioBullet. Our method uses the encapsulation of an active ingredient (such as KCl) in microscopic particles of edible material. The mussels' natural filtering ability then removes and concentrates the particles from the water, without stimulating the valve-closing response. By using the mussels' filtering behaviour to concentrate BioBullets the absolute quantity of active ingredient added to the water can be reduced substantially. Our approach allows us to engineer the particles to break-up and dissolve completely within a few hours, thus eliminating the risk of polluting the wider ecosystem. We have demonstrated that the effectiveness of a toxin in the control of biofouling filter-feeders can be enhanced greatly by using our technique. Furthermore, successful industrial trials indicate that the BioBullet provides a viable and more appealing control option than those currently in use.
Nearly all of our terrestrial mollusc fauna is "Invasive" in the sense that species colonised the post-glacial landscape and many did so very fast relative to their powers of active dispersal. Furthermore, many native species have shown striking changes in distribution and abundance (not always negative) in response to human-induced environmental change. Others seem slower to respond. I use various species, and comparison with faunas elsewhere, to ask questions about which features of dispersal, life history and habitat-tolerance characterise successful spreaders, and about what limits their progress.
Recruitment and growth
of Teredo bartschi (Teredinidae, Bivalvia) in hypersaline,
oligotrophic waters at Aqaba on the Red Sea.
S. M. CRAGG1, M-C. JUMEL1, F. AL-HORANI2 AND I. W. HENDY1
1Institute of Marine Sciences, School of Biological Sciences, Ferry Road, Portsmouth P04 9LY, UK
2Marine Science Station, P.O. Box 195, Aqaba 77110, Jordan
|his study examined life history characteristics
of marine woodborers at Aqaba, a site with extremely limited freshwater
input and no mangrove forests and hence no natural sources of
wood to support an indigenous population of borers. Aqaba has
a prevailing slow northerly surface inflow of warm hypersaline
oligotrophic waters, which due to the limited food for planktotrophic
larvae constrains dispersal and colonisation by members of the
wood boring Teredinidae (Bivalvia). The teredinid Teredo bartschi
(Teredinidae) and the isopod Limnoria tripunctata were
found burrowing into driftwood from Aqaba. Panels placed at depths
from 6m to 36m were heavily colonised by T. bartschi and
a few specimens of another teredinid, Bankia carinata,
were also found, but no limnoriids. T. bartschi releases
larvae that are ready to settle without feeding and are thus not
limited by planktonic food resources, but are less capable of
long-distance dispersal. No variation in colonisation with depth
was evident. Shell size showed an inverse relationship with the
degree of crowding of the panel, suggesting that crowding suppressed
Numerous specimens of shells were found within the wood panels with groups of larval shells adhering to their inner surface. These shells were D shaped. They had little or no trace of the secondary larval shell (prodissoconch II) and where prodissoconch II was present, the prodissoconch I/II boundary was rather indistinct. Indistinct boundaries occur in brooded larvae, suggesting that the larvae belong to the brooding T. bartschi (as does the number of specimens found). The fact that all larvae were at a very similar early stage of development that is probably reached within about a day after fertilization at the temperatures at Aqaba suggests mass spawning of the borers within the sample panels. Such a spawning would have taken place during the period when the summer thermocline breaks down and higher levels of nutrients reach surface waters.
Internal surface of a valve of the teredinid Teredo bartschi
Image of the mass of D veliger larva shells resting within the valve.
in crush resistance and growth pattern of zebra mussels (Dreissena
polymorpha): effects of calcium availability and predator pressure
Institute of Environmental Sciences, Jagiellonian University cza...@eko.uj.edu.pl
We examined the growth pattern and shell strength of zebra mussels
Dreissena polymorpha in eight European locations characterised
by different survival rates, pH levels and calcium availability in
order to test: (1) whether trait variability can be attributed to
anti-predator responses, and (2) how their expression may depend on
the size of mussels and water chemistry.
Differences in chemical factors were unrelated to the cross-population gradient in survivorship, suggesting mussels’ survival is affected by other factors, such as predators. Increased population mortality was associated with production of stronger shells by mussels 8, 10 and 12 mm long, and with slower growth of 12 and 14 mm long individuals. Shell strengthening was unrelated to growth rate across populations. Mortality correlated positively with Bertalanffy's growth coefficient and negatively with asymptotic size.
Chemical parameters were unrelated to growth patterns; however, during the experimental trials on crush resistance of 8 and 10 mm mussels it appeared that they had interactive effects with mortality conditions. Under low-mortality conditions, higher calcium concentrations and lower pH stimulated production of stronger shells; the positive link between shell strength and population mortality was detectable across lower to medium calcium levels and medium to higher pH values.
The results suggest adaptive responses to predation through increasing crush resistance and diversion of resources from growth to reproduction. They also indicate that water chemistry can mediate induction of anti-predator responses, and that their efficacy changes over the mussel’s lifetime. We argue that a full consideration of the post-invasive polymorphism of zebra mussels must incorporate the interplay between environmental conditions and adaptive responses of mortality risk. [POSTER]
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A review of the distribution
and ecological impacts of the zebra mussel (Dreissena polymorpha)
(Pallas) in Ireland
JON GRENNAN, TARA HIGGINS AND T.K. MCCARTHY
Department of Zoology, National University of Ireland, Galway
The introduction of zebra mussels (Dreissena polymorpha Pallas),
one of the most remarkable biological invasions in modern Ireland,
has involved significant ecological and economic impacts. Though native
to the areas surrounding the Black and Caspian seas, the species has
been dispersed widely in central and western Europe indicated an English
origin for the zebra mussel populations in Ireland. It is assumed
that high levels of polymorphism indicate a large founder population
and/or several introductions. First recorded in 1997, in Lough Derg
on the Shannon River, zebra mussels have subsequently been recorded
in most large physico-chemically suitable lakes in the Shannon system
and they also spread rapidly along linked navigation canal systems.
Zebra mussels are now spreading to smaller isolated lakes. A variety
of factors have been implicated in its range extension in Ireland,
including: high levels of inter-lake boat movement by anglers and
eel fishermen, favourable lake substrates and occasional deliberate
Zebra mussels are extremely effective filter feeders and their presence is associated with increased water transparency, elevated benthic production, declines in native unionid populations and they are also thought to be a threat to rare fish species such as pollan (Corgonus autumnalis) and arctic char (Salvelinus alpinus). Existing literature on the introduction and dispersal of the zebra mussel in Ireland is reviewed and the attempts to limit further range expansion discussed. Research now in progress as part of a large scale biodiversity research programme (Biochange), aims to provide a better understanding of the ecological effects of zebra mussel in a selection of small western Irish alkaline lake ecosystems.
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Ruditapes philippinarum is a filter feeding bivalve mollusc.
Its natural distribution is in the western Pacific. It has been introduced
into western Europe, in particular northern France, Italy and the
United Kingdom. It has become established in Poole Harbour.
This project aims to utilise Geographical Information Systems to predict the potential spread of this species. This will be initiated by mapping areas of favourable environmental conditions such as substrate composition onto a map of Langstone Harbour. Once the predictions have been made, these areas will be seeded with adult clams to investigate the actual suitability of the site. An associated study will also be commissioned to determine the effects of environmental conditions on the more sensitive embryological larval stages of R. philippinarum. [POSTER]
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Since it was first recorded in Lough Derg in 1997, the invasive
zebra mussel Dreissena polymorpha has rapidly spread to lakes
across Ireland. Dreissena are effective filter feeders with
extremely high clearance rates of microalgae, cyanobacteria and other
particles. Their infestation has induced profound ecological changes
in lakes worldwide, affecting nutrient cycling, levels of suspended
solids and phytoplankton populations, with associated food-web mediated
effects on native zooplankton and fish populations. Focusing on a
selection of lakes in Western Ireland, the current research examines
the effects of the selective filter-feeding Dreissena on water
quality and nutrient status, with particular emphasis on algal abundance
and community composition.
Detailed comparison is made between two adjacent mesotrophic-eutrophic lake basins, Loughs Doon Upper and Lower, only the latter of which is infested with zebra mussels. Our results support international research associating zebra mussel infestation with increased water clarity, greater periphyton relative to phytoplankton production, an elevated risk of cyanobacterial blooms but a 30%-40% overall reduction in water column chlorophyll-a. Such trends present difficulties to categorising infested lakes according to traditional (OECD) and developing (EU Water Framework Directive) trophic classification schemes. The study aims to establish an effective framework within which the ecological effects of zebra mussel infestation in Irish lakes can be predicted.
mollusk faunas of Colorado and Utah
JOHN M. C. HUTCHINSON1 & HEIKE REISE2
1Max-Planck-Institut für Bildungsforschung, Berlin; maj...@googlemail.com
2Staatliches Museum for Naturkunde Gorlitz; Heik...@smng.smwk.sachsen.de
Our aim was to establish semi-quantitatively the most important
synanthropic species in big conurbations such as Denver and Salt Lake
City positioned on either side of the Rocky Mountains. The conurbations
on both sides of the mountain have similar continental climates, and
are both only 150 years old.
The synanthropic sites surveyed were mostly garden centres, flower beds and bushes around town centres, public gardens, parks and cemeteries. We sampled 31 sites in Colorado, from Fort Collins to Colorado Springs, and 28 sites in Utah, from Logan to Provo. At most cultivated sites the generous and regular watering, usually by automatic systems, sustained a molluscan fauna, and some gardeners even felt the need to apply molluscicides. Wood-chip mulch was extensively used to conserve moisture, which made it particularly favourable for Vallonia species. However, some intensively tended, but sparsely watered, allotments were devoid of molluscs and most uncultivated rough ground also dried out too much.
Results showed that European and Holarctic molluscan species predominated. The introduced Deroceras reticulatum, Oxychilus draparnaudi and Arion fasciatus were particularly widespread, extending also into some less disturbed sites along rivers and up in the mountains. Several other introduced pest species (e.g. Deroceras panormitanum) were more widespread than published records suggest. Species such as Arion circumscriptus, which are mostly not distinguished in the North American literature, were identified by dissection (where necessary after rearing specimens to adulthood).
The garden centres were especially rich in mollusks; supplies of material(s) from out of state were very regular, and provide a ready means for the spread of exotics despite the difficulty of unassisted dispersal in the dry climate. This could explain the similarities in molluscan faunas within and between states, but there are exceptions: e.g. Oxychilus alliarius and Arion intermedius were not uncommon in Utah, but not found in Colorado, whereas Oxychilus cellarius appeared only at two sites in Colorado; similarly within Colorado A. circumscriptus was restricted to localities around Boulder.
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Crassostrea gigas populations have developed on the Dutch
coast at a rather high speed. They often settle in cooling water conduits
and growth is high leading to massive fouling especially in low water
velocity parts of the system. The common heat treatment for killing
of the mussels and barnacles has been shown to be insufficient against
the oysters. C. gigas is not untowardly affected by the traditional
40oC exposure associated with heat treatment.
In a series of experiments at the Eems power plant we found that an exposure to 45oC for 1 h was needed together with a rather slow build up (over 2h) to 45oC to ensure 100% mortality. Such heat treatment could affect any coatings used and could compromise auxiliary cooling circuits depending on detailed plant design. They also revealed the need to repeat the treatment sufficiently frequently to ensure any C. gigas killed would not detach at sizes that would cause problems on narrow-bore systems downstream within the plant. Should such higher temperature regimes be proposed in practice there would inevitably be issues with the regulator over the thermal discharge involved.
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aggregation and movement of the zebra mussel (Dreissena polymorpha)
in the presence of potential predators
JAROSLAW KOBAK1 AND TOMASZ KAKAREKO2
1Department of Invertebrate Zoology, Institute of General and Molecular Biology, Nicolaus Copemlcus University, Gagarina 9, 87-100 Toruli, Poland, jko...@biol.uni.torun.pl
2Department of Hydrobiology, Institute of Ecology and Environmental Protection, Nicolaus Copemicus University, Gagarina 9, 87-100 Toruli, Poland, kak...@biol.uni.torun.pl
We studied the behaviour of the zebra mussel, Dreissena polymorpha,
in the presence of four predator species with different feeding habits:
(1) roach Rutilus rutilus, a specialized molluscivore, (2)
racer goby Neogobius gymnotrachelus and (3) crayfish Orconectes
Iimosus, both opportunistic molluscivores, and (4) perch Perca
fluviatilis, which does not feed on molluscs. The mussels were
separated into small (<10 mm), medium (10-17 mm) and large (>
17 mm), and their behaviour was monitored in 100L tanks. The mussels
were protected by a 1 mm mesh when in presence of predators, but not
when in a control tank.
Small and medium sized mussels were affected only by the presence of roach, the most efficient molluscivore used. Their behaviour was not influenced by the presence of the other species. Large mussels did not respond to the presence of any of the predator species. Large mussels may exceed a threshold size for particular predatory species, and their anti-predator behaviour may be weaker.
The strength of attachment of mussels onto a PVC substrate was measured with a digital dynamometer. Small and medium sized mussels, exposed for six days, attached more strongly in the presence of roach than in other treatments. Furthermore, the percentage of mussels forming aggregations (i.e. touching each other) was higher in the presence of roach than in the control treatment.
To measure horizontal distance moved by mussels, we put a single individual into a circular dish with a 2-3 mm layer of sand. A moving mussel left a trail in the sand, which was photographed and measured. Mussels did not alter the intensity of their movements following exposure to any of the predator species tested.
Small mussels tend to move upwards on a vertical surface. To check if this behaviour would change in the presence of predators, we put a single individual into a test-tube and measured the vertical distance it moved in 24 h while exposed to predators. Our results showed that small mussels reduced their vertical movement significantly in the presence of Rutilus rutilus.
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The occurrence of
Potamopyrgus antipodarum (Gray, 1843) (Prosobranchia: Hydrobiidae)
in the mining subsidence reservoirs affected by coal mine output (Upper
Silesia, southern Polland)
The University of Silesia, Faculty of Biology & Environmental Protection, Department of Hydrobiology, 9 Bankowa Str., 40-007 Katowice, Poland
Potamopyrgus antipodarum (Gray, 1843), the New Zealand mud
snail, was first recorded in Poland in 1933, and its rapid expansion
has been observed in Upper Silesia, southern Poland, from the 1990s.
The study was carried out in the years 1997-2007 in Upper Silesia, south Poland, and investigated the occurrence of P. antipodarum in the mollusc communities in seven mining subsidence reservoirs affected by coal mine output in relation to environmental factors.
It was shown that since 1997, P. antipodarum has been eudominant in the mollusc communities in the mining subsidence reservoirs, and was found in the submerged parts of Glyceria maxima grass and on the concrete lining of water banks.
PCA was employed to analyse ecological and physicochemical data from the different sampling sites. Any significant differences in the shell height of P. antipodarum collected from the different sampling sites were tested by means of the Kruskal-Wallis method. PCA analysis showed a positive correlation between mollusc density and pH, the concentration of chlorides, the total hardness, alkalinity and total dissolved solids, and a negative correlation between the number of species and phosphates.
The survey confirmed that there has been an invasion by P. antipodarum into the reservoirs and rivers of Upper Silesia.
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The decline and extirpation
of unionids in large Irish lake invaded by zebra mussels: invasion
history as a predictor of impact
CAITRIONA M. MAGUIRE1, ROBERT ROSELL2 AND DAI ROBERTS3
1Aquatic Systems Group, Queens University Belfast, Newforge Lane, Belfast. BT9 5PX.
2Aquatic Systems and Fisheries Group. Agri-food and Biosciences Institute, Newforge Lane, Belfast, BT9 5PX
3School of Biological Sciences, Queens University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast
Invasion history of a species is considered to be one of the best
predictors of impact at present. The impacts of the zebra mussel Dreissena
polymorpha in Europe and North America are similar with the
exception of impact on native unionids. In North America some unionid
populations have been extirpated, whereas in Europe, there are no
documented cases and unionids can maintain high densities in the presence
of Dreissena. We hypothesise that the impact in Ireland would
be similar to North America, as Ireland, unlike continental Europe
has no evolutionary experience of Dreissena and has low unionid
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(Müller, 1974): the phylogenetic study of the central Europe
populations has started
MÍKOVCOVÁ ALENA1, JURICKOVÁ LUCIE2 AND PETRUSEK ADAM1
Charles University in Prague, Faculty of Science, Departments of Ecology1 and Zoology2, Prague, CZ. alen...@centrum.cz
The main aim of the study was to explain factors affecting the distribution
of the presumably non-indigenous land snail Monacha cartusiana
(Muller, 1774). Currently, M. cartusiana is spreading from
its original range in the Mediterranean to western and central Europe.
The number of recorded populations of this species in the Czech Republic
has increased significantly especially in the last 15 years. This
data makes M. cartusiana a good model for evaluating factors
that may facilitate invasions of terrestrial molluscs.
The proposed project has two parts. Firstly, Czech populations with different life histories (e.g. well-established over wintering populations vs. short-term invasions) will be compared with populations from the Mediterranean, and the survival ability of individuals from Southern Europe under Central European climatic conditions is tested. Secondly, intraspecific diversity and hypotheses of origin of newly established populations will be tested by means of phylogenetic and phylogeographic analysis of M. cartusiana populations in comparison with populations of other related species.
We would like to establish a partnership with malacologists throughout Europe to obtain new experiences, contacts and materials for the phylogenetic and phylogeographic studies: for further information please contact Alena. [POSTER]
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Shell asymmetry in mussels
R. NAGARAJAN1,2, STEPHEN E. G. LEA2, AND JOHN D. GOSS-CUSTARD3
1Department of Zoology and Wildlife Biology, A.V.C. College (Autonomous) Mannampandal-609305, India
2School of Psychology, Washington Singer Laboratories. Perry Road, University of Exeter, Exeter EX4 4QG, UK
The common edible blue mussel (Mytilus edulis) appears to
be symmetric in morphology. However, we found that the predators that
prey on mussels consistently attack one side of the valve. Morphometric
measurements on symmetrical variables viz., shell depth, weight, dorsal
and ventral thickness of the right and left valves were made on mussels
collected in the Exe estuary of south west England. Almost all mussel
shells (between 95% and 99%) were asymmetrical. Right valves were
consistently thinner than left: the mean difference (right minus left)
was -0.008 to 0.003mm and -0.014 to 0.09mm for ventral and dorsal
thickness respectively and -0.012 to 0.086g for shell weight. All
differences were significantly different from zero. The mean depth
difference between left and right valves was 0.003 to 0.049mm, but
this was only marginally significant.
Furthermore, the right valve is thinner ventrally and dorsally in a significantly higher proportion of mussel shells, whereas the left one was frequently found to be deeper. The asymmetry in ventral and dorsal shell thickness, shell weight and shell depth does not change significantly (Chi-square tests applied) across the length classes of mussels.
Finally, trends of shell asymmetry in different bivalve species from various localities are discussed.
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mollusks in Poland
BEATA M. POKRYSZKO
Museum of Natural History, Wroclaw University, Sienkiewicza 21, 50-335 Wroclaw, Poland
The terrestrial and freshwater malacofauna of Poland includes 265
species: 177 terrestrial gastropods, 56 freshwater snails and 32 bivalves.
Twenty seven (17 terrestrial, 10 aquatic) are regarded as alien components
of the fauna, found in natural habitats (Lithoglyphus naticoides),
both anthropogenic and natural-seminatural habitats (Dreissena
polymorpha, Potamopyrgus antipodarum, Physella acuta,
Ferrissia clessiniana, Arion distinctus, A. fasciatus, Deroceras turcicum,
Boettgerilla pallens, Helicella itala, H. obvia), anthropogenic
habitats (Arion lusitanicus, Oxychilus draparnaudi, Monacha cartusiana)
and synanthropic habitats (Anodonta woodiana, Corbicula fluminalis,
C. fluminea, Melanoides tuberculatus, Menetus dilatatus, Oxychilus
translucidus, Zonltoides arboreus, Tandonia budapestensis, Limax maximus,
L. flavus, Lehmannia valentiana, Deroceras panormitanum, Opeas pumilum).
Considering the relatively short period available for colonisation since the Ice Ages, the native fauna is still unsaturated and - given time - some of the species regarded as alien would have spread in Poland anyway. From this viewpoint the immigrants can be classified into 'potentially native' - species whose expansion was only accelerated as a result of human activities while the adequate habitats had always been there (Dreissena polymorpha, Potamopygrus antipodarum, Lithoglyphus naticoides, Arion distinctus, A. fasciatus, Deroceras turcicum, Boettgerilla pallens) and ‘truly alien’ - species whose expansion was rendered possible due to man-made habitats (Anodonta woodiana, Corbicula fluminalis, C. fluminea, Melanoides tuberculatus, Menelus dilatatus, Physella acuta, Ferrissia clessiniana, Arion lusitanicus, Oxychilus draparnaudi, O. translucidus, Zonitoides arboreus, Tandonia budapestensis, Limax maximus, L. flavus, Lehmannia valentiana, Deroceras panormitanum, Opeas pumilum, Helicella itala, H. obvia, Monacha cartusiana). In the latter group, some species have recently started to penetrate from anthropogenic into natural habitats (Physella acuta, Ferrissia clessiniana, Arion lusitanicus, Helicella itala, H. obvia) while the remaining ones are limited to habitats under continual human impact.
The geographical origin of the immigrants is: elsewhere in Europe (17 species), Asia (4), Nearctic (3), the Caucasus (2) and New Zealand (1). Eight species are early immigrants (19th c. at the latest), and 19 are recent (20th c.) or very recent arrivals. Six have expanded to the entire country whereas three are expanding. 14 are likely to do so, three show no sign of expansion and one - after initial rapid expansion - is now endangered. Sixteen of our alien species are non-pests; two of these (Arion distinctus, Oxychilus draparnaudi) become pests in certain situations, six (Dreissena polymorpha. Arion lusitanicus, Zonitoides arboreus, Limax flavus, L. maximus, Lehmannia valentiana) are regarded as pests, and two are suspected of a negative effect on the native fauna (Potamopygrus antipodarum) or parasite transmission (Melanoides tuberculatus); in one case (Deroceras panormitanum) it is too early to judge the consequences of expansion.
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fauna present in the Minho estuary, Portugal
RONALDO SOUSA1,2, CARLOS ANTUNES3, LÚCIA GUILHERMINO2
1CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental. Rua dos Bragas 289. 40S0-123 Porto, Portugal (e-mail: rona...@ciimar.up.pt)
2ICBAS - Instituto de Ciancias Biomédicas de Abel Salazar, Departamento de Estudos de Populações, laboratório de Ecotoxicologia, Universidade do Porto, Lg. Prof. Abel Salazar 2,4099-003 Porto, Portugal
3Aquamuseu do Rio Minho - Parque do Castelinho, 4920-290 Vila Nova de Cerveira, Portugal
|Estuarine ecosystems have been subjected to several
introductions of non-native invasive species, particularly in
recent decades. Molluscs are one of the most important faunal
groups that contribute to these invasions.
This study results from data gathered during the last 3 years and documents the presence of three non-native molluscan species in the Minho estuary (NW of Portugal) that have self-sustaining populations: Corbicula fluminea, Physella acuta and Potamopyrgus antipodarum. Special attention is drawn to the introduction vectors, the origin of the species introduced, the ecology of each species (e.g. abundance, biomass and distribution), and the environmental and economical damages that may have been caused by these invasive species.
The presence of the Asian clam C. fluminea, which has a great invasive potential, is noted, and a model combining abiotic data and information on C. fluminea biomass in the Minho River estuary was developed. This model showed that redox potential, nutrients concentrations, hardness, organic matter and sediment characteristics explained almost 60% of the variation in C. fluminea biomass in the freshwater subtidal area of this estuarine ecosystem (R2=59.3%, F[9, 86]=13.9, p<0.001). Possible future introductions of molluscan non-native invasive species in this estuarine ecosystem are also considered and discussed.
Genetic variability in
the alien razor clam Ensis directus: preliminary data from
JOAQUIN VIERNA, ANDRES MARTINEZ-LAGE AND ANA GONZÁLEZ-TIZÓN
Department of Cell and Molecular Biology. University of La Coruña. A Zapateira s/n. E-15071. La Coruña. SPAIN. www.udc.es/dep/bm/genetica/a/indice.htm
The American razor clam Ensis directus was introduced in
Europe in the late 1970s, probably in ballast water. By larval and
post-larval drifting this species rapidly spread along European coasts.
Since 1978, it has been recorded in Scandinavia, Denmark, Belgium,
The Netherlands, France and Great Britain. This bivalve inhabits marine
and brackish waters (1-20 m deep), buried in sandy bottoms in inter-
and subtidal areas.
Different studies of invasive mollusc populations have shown higher than expected levels of genetic diversity. These studies have used, preferentially, mitochondrial DNA and/or microsatellite markers.
In the present work we amplified and sequenced a partial region of the mitochondrial cytochrome oxidase subunit I gene (COI) in individuals of E. directus from three Danish localities. Restriction fragment length polymorphism (RFLPs) were performed using Hae III, Taq I and Msp I endonucleases. Results show higher variability than that previously obtained using 16S rRNA. [POSTER]
| The Invasive Molluscs meeting at Cambridge
Top left: Meeting organiser, David Aldridge at the Poster Session.
Top Right: Meeting in progress.
Middle: Reception in the Zoology Museum—from a giant sloth’s viewpoint.
Bottom left: Richard Preece introduces participants to the Museum.
Bottom right: John Hutchinson in reflective/bullish mood.