Click Here To Visit Malacological Society Website Click Here To Visit Malacological Society Website Click Here To Visit Malacological Society Website Click Here To Visit Malacological Society Website Click Here To Visit Malacological Society Website..Click An Image To Visit Society Website  

Appropriately, our main photograph (above) features the young researchers from Europe who took part in the 6th annual Forum. Representing the future of malacology, they stand in front of the Natural History Museum, which has always provided steady support for The Society and its aims. The event was again organised by Alex Ball, with assistance of young researchers from the Museum, and The Society contributed towards the travel costs of several participants. Hugh Jones generously donated a large collection of the Journal of Molluscan Studies and other reprints for distribution. An application form for this year’s Forum in early November is available from The Society’s website. Abstracts of the presentations follow.

ABSTRACTS in alphabetical order of first author:

Background matching in Littorinids: testing selection

Katie Lawson Cruickshanks

Biodiversity and Ecology Division, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX. Email:

Numerous studies have investigated the adaptive significance of colour polymorphisms in molluscs in relation to crypsis. For marine molluscs, visual selection by fish has been shown to act on Littorina fabalis (Reimchen, 1974). Generally, all previous classifications of colour polymorphisms in intertidal snails have been based on the human perception of colour. However, the assumption that predators of these molluscs receive the same visual signals as humans is fundamentally flawed (Hart, 2001).

A series of predation experiments were conducted under laboratory conditions to test the role of predators in possibly maintaining the colour polymorphism. Combinations of different colour morphs of L. fabalis were presented to blennies, Lipophrys pholis, under two different light regimes which made the two morphs appear conspicuous in turn. The brown reticulata morph, which was conspicuous when light was transmitted through the algal background, was taken preferentially to the yellow citrina morph under transmitted light conditions. However, when light was reflected from the algae, citrina was not significantly preferred to reticulata.

Spectroradiometry was used to test for any correlation between the coloration of the snails and backgrounds. Results of spectra-analysis models have not yet been analysed but may eventually explain the choices made by the fish.

Fig: Blenny approaching prey under reflected light conditions.

Influence of slug defense mechanisms on food preferences of their predators from the carabidae family

Pavel Foltan

Faculty of Biological Sciences, University of South Bohemia, Branisovska 31, CZ 37005, Czech Republic

Two-choice experiments on food preferences of a generalised predator Pterostichus melanarius and five species of slug prey were conducted in the laboratory. Different preferences of P. melanarius amongst five slug species are described and interpreted as outcomes of differing species-specific defence mechanisms of slugs, while influences of hunger level, temperature, day/light period, condition of slugs and beetles, weights of slugs and beetles and the sex of beetles were controlled experimentally or statistically. Slugs were preferred in the following order (from the most preferred): Deroceras reticulatum, Malacolimax tenellus, Lehmania marginata, Arion distinctus and A. subfuscus. Efficiency of slugs’ species-specific defence mechanisms reflected their phylogeny. Defence mechanisms of slugs from Arionoidea superfamily were significantly more efficient in deterring an attack of non-specialised ground beetles than the defence mechanisms of slugs from Limacoidea superfamily. P. melanarius significantly preferred Agriolimacidae to Limacidae and Limacidae to Arionidae. Slug species was the strongest factor influencing food preference of P. melanarius amongst slug prey, but weight of slugs also had a significant effect. Weight and sex of P. melanarius had no impact on its food preference.

The "Killer Slug" taking over Sweden: Species invasion from the front row

Jan Hagnell

Göteborg university, Department of Zoology, Box 463, SE-405 30 Göteborg, Sweden.

The invasion and spread of the Iberian Forest Slug Arion lusitanicus (Mabille) in Sweden over the last decade has generated great public and media interest. The big question is, of course, how to get rid of this unwanted garden pest.
At the institution of Zoology at Göteborg university we work with the morphological, ecological and physiological impact of this recent immigrant. We have here a great opportunity to study over time an alien species in its new environment and how it interacts with our domestic species, primarily Arion ater.
Parallel to this, we work on the pest control aspect of the issue. In laboratory and field tests we evaluate a wide array of substances and control methods with the aim of finding cheap and easy-to-use solutions which are not harmful to the environment.

Acicula parcelineata (Clessin, 1911) – New fossil molluscan species of the Czech Republic

Jaroslav Hlavac

Institute of Geology Academy of Sciences of the Czech Republic, Laboratory of Environmental Geology, Rozvojová 135, CZ-165 02 Praha 6, Czech Republic.

In the western part of flysch West Carpathians in Vsetín Upland (Vsetínská hornatina), Czech Republic, a Holocene calcareous tufa cascade was studied from the viewpoint of lithology and malacozoology in order to explain the conditions of palaeoenvironmental development. A rich molluscan assemblage was discovered in a relatively thin (0.8 m) tufa cascade. It consists of some important species related to malacostratigraphy, ecology and zoogeography. The most important discovery is the find of the prosobranch Acicula parcelineata, the first fossil record in the Czech Republic. The fossil malacocoenosis with the occurrence of A. parcelineata and other index species enables the tufa horizon to be stratified to the Holocene climatic optimum – Atlantic and Epiatlantic, indicating the fully developed woodland habitats surrounding the tufa deposit. The site is located in a region with no previous finds of fossil molluscan assemblages.

Classification of the western carpathian spring fens based on mollusc communities

Michal Horsak

Department of Zoology and Ecology, Faculty of Science, Masaryk University, Kotlárská 2, CZ-61137 Brno, Czech Republic.

Mollusc communities were investigated at 48 spring fens situated in the borderland between the Czech Republic and Slovakia in 1997-2000. In each site,a sample of 12 litres was collected. The purpose of this study was to test whether the gradient from mineral-poor to mineral-rich fens is reflected in the composition and species richness of mollusc communities. Altogether, 57 mollusc species were found; of these, 51 were terrestrial and 6 aquatic (4 snails and 2 bivalves). A cluster analysis of mollusc communities separated the fens studied into five basic clusters which accord well with the results of detrended correspondence analysis (DCA). These clusters are arranged along the 1st DCA axis following the poor-rich trophic gradient.

The Impact of Human Presence on Malacocenoses, studied in the Novohradské hory Mountains
(South Bohemia, Czech Republic)

Magda Hrabakova

Department of Zoology, Faculty of Science, Charles University, Vinicná 7, CZ-128 44 Praha 2, Czech Republic.

Preparation of a catalogue of molluscs in the Czech republic is just running. Therefore, data from the Novohradské hory Mountains needed to be completed. The faunistic studies have been finished. Since 1999, eighty-one mollusc species have been found. This represents about 34% of the whole Czech republic mollusc fauna.
The occurrence of several Carpathian and Alpine species supports the hypothesis about the influence of both of these regions on the fauna of the South Bohemia.

The impact of the human presence was studied by comparing the malacocenoses of primeval forests with those of old abandoned villages. Examination of many environmental variables proved human presence and quantity of nutrients to be the most important factors.

While almost all natural environment was damaged by the planting of unoriginal spruce forests, the enriched localities of the abandoned villages serve as mollusc refuges. The majority of the original species can survive there in places enriched by nutrients (from organic litter) and calcium (mortar from walls).

Ruins of medieval castles as refuges of interesting land snails in the landscape

Lucie Jurickova

Department of Zoology, Faculty of Science, Charles University, Vinicná 7, CZ-128 44 Praha 2, Czech Republic.

The ruins of castles have become very specific habitats. They have locally enriched the substratum with lime, and their disintegrated walls have changed into artificial scree. The space of the ruins thus constitutes a very diverse habitat. Data from 114 Czech castles were processed in the programs STATISTICA and CANOCO. The model shows especially the influence of phytogeographic areas (mid-European zonal vegetation, mountain vegetation, temophilous vegetation), the stage of the ruin, the century of desolation and castle isolation on species variability. The snail communities inhabiting the ruins of castles reached the highest species richness. The ruins offer favourable habitat conditions for rare species of snails. Ruins of castles are not only important dominant features of a landscape, but often islands of species diversity and refuges of rare species, especially in landscapes with acidic soils.

Impact of gravity on distribution of Dreissena polymorpha (Bivalvia) on artificial substrates

Jaroslaw Kobak

Nicolaus Copernicus University, Institute of General and Molecular Biology, Department of Invertebrate Zoology, Gagarina 9, 87-100 Torun, Poland.

Mussel recruitment on 10 x 10 cm plastic plates was studied in the Wloclawek Dam Reservoir (the Vistula River, Poland). Juveniles aggregated at the upper edge of vertical surfaces and along all edges of horizontal ones. The cause of this phenomenon was neither larval selection (newly settled plantigrades did not show this pattern) nor lower mortality at the edge (density on 7.5 x 7.5 cm plates, with higher circumference/area ratio, was similar). Thus, mussel distribution must have resulted from locomotion of settled individuals. The hypothesis that mussels on vertical plates were influenced by gravity was then tested in the laboratory. As expected, juveniles (< 10 mm) exhibited negative geotaxis on surfaces inclined at > 3°. This behaviour was inhibited by light. Adults (> 10 mm) moved downward, which probably demanded the minimum effort. Locomotion of settled individuals may be an important, and so far underestimated, factor influencing mussel distribution.

The systematics, phylogeny and biogeography of the family Bullidae
(Mollusca: Gastropoda: Opisthobranchia): preliminary results

Manuel Antonio E. Malaquias

Department of Zoology, The Natural History Museum, Cromwell Road, SW 7 5 BD London, UK.

The Bullidae is a small, world-wide family of cephalaspidean gastropods believed to comprise about 30 to 40 valid living species, of predominantly tropical distribution, but with a few species also present in temperate waters. These attributes make this group an excellent case study to evaluate patterns of biogeography and evolution on a global scale. Nevertheless, the use of Bullidae as a model requires first a comprehensive systematic revision of the group. At present the nomenclature is confused and incongruent, because taxonomic descriptions have been based mainly on shells, which are extremely similar in shape and colour among species.

This project is the first attempt to incorporate all available data and new data from shell structure, anatomy and molecular sequences in a phylogenetic and biogeographic analysis of the family Bullidae. The three main objectives are:

(1) to review and clarify the taxonomy of the worldwide Bullidae, based on morphological, anatomical and molecular data of all available living species;

(2) to construct a phylogenetic hypothesis for the Bullidae through the use of parsimony-based cladistic analysis of morphological characters and phylogenetic analyses of DNA sequence data, and as a result to review the generic classification of Bullidae; and

(3) to use the phylogeny as a basis for hypotheses of evolutionary radiation, adaptation and biogeography of the Bullidae.
The morphological characters investigated so far will be demonstrated together with a preliminary evaluation of their systematic value.

Physiological and behavioural mechanisms of winter torpor in Helix pomatia

Anna Nowakowska, Michal Caputa, Justyna Rogal Ska & Katarzyna Wentowska

N. Copernicus University, Institute of General and Molecular Biology, Department of Animal Physiology, Ul.Gagarina 9, 87-100 Torun, POLAND.

Overwintering in terrestrial snails is often called hibernation. We tried to check whether the nature of winter dormancy in Helix pomatia snails is similar to that observed in hibernating mammals, or whether the winter torpor is a passive phenomenon evoked by low temperature. Particular attention was paid to the influence of seasons on thermal preference of the snails (recorded automatically in a thermal gradient system) and on blood and organ concentrations of cryoprotectants (glycerol, glucose).

Behavioural data show that both the entry of snails into winter torpor and the maintenance of the torpor are passive phenomena. In contrast, spring arousal seems to be an active process. Seasonal changes in concentration of the cryoprotectants also provide evidence of endogenous timing of the response.

In conclusion, overwintering in Helix pomatia is a complex physiological phenomenon involving both exogenous and endogenous factors.

Sub-fossil Gastropods of the ‘Bandas del Sur Formation’, Tenerife and their palaeoecological inferences

Claire Pannell

The Gatehouse, Bonkyl Lodge, Preston, Berwickshire, TD11 3TG.

Tenerife, a stratovolcano, was probably formed by hotspot volcanism over a slow moving plate 12.5 mya. It has suffered extensive volcanism in the last million years, involving at least 13 eruptions that resulted in the collapse and subsidence of the original volcano to form the massive caldera that is Las Cañadas. The ‘Bandas del Sur’ has been extensively studied over the last thirty years and records some of these eruptions. Pumice fall deposits and interbedded palaeosols retain a record of a snapshot of the biota prior to eruptions, and inferences of the past environment and climate may be made by reference to modern land snail ecology and supported by analysis of stable isotopes from both fossil and modern snail shell carbonate. Results of an investigation into the spatial distribution of modern land snails are presented also and sub-fossil snail assemblages discussed in the light of these findings.

Measuring the rugosity of surfaces on which snails might live

Simon Pollard

Canterbury Christ Church University College, North Holmes Road, Canterbury, Kent CT1 1QU.

If rugosity is a component of the complex scenario that is a habitat then it would be advantageous if it could be quantified.

Scale is always of importance when considering rugosity, especially when attempting to give differing rugosities a quantitative value. At the continental scale a satellite would record values that may be kilometres apart. At regional scales, a cartographer may well use metres. At local scales an observer is likely to use metres or mm, but at the stand scale measurements will be made using centimetres, millimetres or probably micrometres. The equipment used will also vary with each scale.

Although each scale presents difficulties to the relevant observer, possibly the most difficult to accurately measure is the stand scale, where measurements will be very small and thus any error could be significantly large. Many molluscs spend their entire life interacting with substratum of varying rugosities, feeding or laying eggs. Thus the relationship between substratum rugosity and a resident organism might be of ecological importance.

This presentation will consider the advantages and disadvantages of three different methods of measuring rugosity. These comprise (i) a basic manual method of measurement, (ii) the method used on the Laser scanning microscope (LSM) and it's related computer, (iii) a method I have designed and am testing using the LSM. I will also introduce Mex software applicable to Scanning Electron Microscopy.

Fig. Forum participants view 3D display during Simon Pollard’s talk.

Littorina saxatilis an example of polymorphism

Susana Isabel Rocha Ribeiro

Instituto Português de Malacologia.

Littorina Férussac (1822) is one of the most thoroughly studied genera of all marine gastropods. Littorina saxatilis Olivi (1792) is a marine taxon showing a high degree of intraspecific variation in shell characters. The specific status of taxa within the Littorina saxatilis complex has been extensively debated. Initially L. saxatilis was considered a sub-species of the “saxatilis-complex”. Recently authors consider only three species: L. saxatilis, L. arcana and L. compressa (=L. nigrolineata).

Most studies describe populations with big apertures and low spire in exposed habitats and big, thick shells with big spires in sheltered shores. All this variation was explained as a genetic response to natural selection imposed by wave action, desiccation and predation. Fast growth, time spent feeding, salinity and temperature also influence shell shape as well as damaged shells. Correlations between colour frequency and substrata suggest that colour is under visual selection by predators. Some authors say that shells from exposed shores are tessellated and in sheltered places tend to be fawn/orange. Shell shape polymorphism may occur over long distances or between populations only a few meters apart. Shell colour can also present local variation.

In the present study, the marine gastropod Littorina saxatilis was collected from the North Wales coast and SW England in order to make an analysis of shell characters – shape and colour - along a horizontal (along shores) gradient. I attempted to establish a relationship between shell characters and exposure to wave action. Results confirmed the relationship between exposure and shape or light/dark colour of shells. Colour pattern was related with the substrate.

Are there endemic snails on Zanzibar?

Ben Rowson

Dept. Biodiversity & Systematic Biology, National Museums & Galleries of Wales, Cathays Park, Cardiff CF10 3NP.

The islands of Zanzibar, Pemba and Mafia were separated from coastal Tanzania (c.30 km away) around 15,000 years ago and share most of that region’s climate, geology, history and ecology. The islands’ biota, particularly in forest remnants, identify them as part of the mainland’s “Coastal Forests” centre of endemism, but c.40 endemic species and subspecies are now recognised from the islands themselves. These are all butterflies, birds, mammals, reptiles, or vascular plants (recent reviews record no island endemic amphibians or diplopods). Gibbons (unpublished MS) and Taylor (1877; 1880) described 19 land snails from Zanzibar Island, most now recorded on the mainland or synonymised with mainland species. Of another 65 land snails now recorded from Zanzibar, all but 9 are found elsewhere (5 are known only from the types). The taxonomy of the putative endemics is under review, but these figures are close to the level of endemism in each of the fragmented Coastal Forests. This is interpreted as suggesting that the islands permit no more endemism than their forests would were they on the mainland. In turn this may indicate that the island and Coastal Forests were fragmented before rising sea level cut off the islands, suggesting a minimum period of isolation required for forest snail speciation.

Fig. Museum specimens from Zanzibar. (Image To Follow Soon)

The Microstructural Deformation Mechanisms of Natural Composite Materials


Manchester Materials Science Centre, UMIST/University of Manchester, Grosvenor St, Manchester, M1 7HS, UK

This study characterises the razor shell, Ensis siliqua, with respect to density, thermogravimetry, differential thermal analysis, scanning electron microscopy (SEM), x-ray diffraction and Raman spectroscopy. These techniques have shown that the shell is composed almost entirely of calcium carbonate (CaCO3), in the aragonite polymorph, with a crossed lamellar layered microstructure. Raman spectroscopy of the shell and standard aragonite samples have shown a direct relationship. Standard aragonite materials show significant variations in peak intensity related to orientation which the shell samples do not. Raman band shifts have been observed in deformed areas of the Ensis siliqua shell, and also during pressurisation. This characterisation study provides insight into the relationship between microstructure and mechanical properties of the shell, and could ultimately aid biomimicry.

Fig. SEM of crossed lamellar layer in Ensis shell.

Impact of unregulated harvesting on native oyster restoration programmes in Strangford Lough Northern Ireland

David Smyth

School of Biology and Biochemistry, Queen’s University, Belfast BT9 7BL.

Strangford Lough historically had a productive Ostrea edulis fishery supporting up to 20 boats in oyster dredging although by 1903 oyster fishing in the Lough had effectively ceased. Growth trials of oyster spat in the Lough in the 1970’s produced favourable results for both O. edulis and C. gigas. Between 1997 and 99 an EU-funded project led by fishermen was started to re-establish a sustainable native oyster fishery in the Lough. As a result, fishermen have started to take the first harvest of native oysters from Strangford Lough for nearly 100 years.

Surveys of oysters have been completed for 30 intertidal and 16 subtidal sites between October 2002 and August 2003. During these surveys hand gathering of oysters was recorded at a number of sites. The study involved an assessment of unregulated harvesting and its likely impact on the restoration project. Catch per unit effort studies estimate the current unregulated harvesting to be in the region of 108 tonnes per annum.

The nature, functioning and ontogeny of the ciliature on mantle folds and velum rim of ostreid larvae

Sam Stanton

Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, Ferry Road, Portsmouth, PO4 9LY, UK.

The nature, functioning and ontogeny of the ciliature on mantle folds and velum rim of larvae of Crassostrea gigas and Ostrea edulis was examined by still and video light microscopy, and by SEM. Complex and ordered cilia groupings on the mantle folds of veligers and pediveligers were revealed by SEM of specimens that had been fractured using fine glass needles. Single cilia surrounded at the base by a ring of microvilli occur on the mantle just anterior to the hinge in C. gigas veligers. Information from fractured specimens is being integrated into maps of the distribution of mantle ciliation. Some of the cilia on the mantle rim have been observed beating in moribund larvae: in more healthy larvae, the beating of preoral cilia obscures other cilia. These maps already reveal both similarities with, and differences from the mantle ciliation of pectinid larvae. SEM has revealed a previously undescribed row of compound cilia on the velum of O. edulis beneath the two rows of pre-oral compound cilia typical of bivalve veligers. Differences between the velar ciliation of O. edulis and C. gigas could relate to differences in early life history: O. edulis is a short-term brooder, while C. gigas is a broadcast spawner.

Fig. Larva of Crassostrea gigas

Fig. Minor pre-oral cilia on feeding groove

Fig. Dorsal mantle cilia bases showing microvilli

Small-scale spatial distribution of molluscan fauna: movement into set-aside land

Colleen Wolski

School of Science and the Environment, Bath Spa University College.

The study investigates molluscan distribution patterns in an eleven year old set-aside deciduous plantation surrounded by old hedgerows. Turf samples were taken over the plantation at 5 m intervals and live and total molluscan numbers and species assessed. A thorough survey of the hedges was also undertaken. It was evident that each molluscan species demonstrated a different dispersal capability and/or tolerance to changing conditions. The reservoir of species in the hedgerows and the aspect of the plantation are factors that best explain the distribution of molluscan species in the plantation at this time. Some species demonstrated a high degree of movement from the hedgerows to the plantation suggesting good colonisation abilities and/or suitable conditions, for example, Cochlicopa lubrica, Vitrea contracta, Aegopinella nitidula and Trichia hispida. Some species were restricted to the hedgerows or near to the hedgerows suggesting either poor colonisation ability and/or conditions in the field were not yet suitable or only recently becoming suitable, for example, Acanthinula aculeata, Ena obscura, Clausilia bidentata and Arianta arbustorum.

Initial study of non-specific defence reactions of Lymnaea stagnalis (L.) individuals, naturally parasitised with trematode larvae

Elzbieta Zbikowska

Department of Invertebrate Zoology, Institute of General and Molecular Biology, Nicholas Copernicus University in Torun, Poland.

The objective of study was to determine whether snails parasitised with trematode larvae had different thermal preferences than non–parasitised ones, and whether parasitic infection of the snail host influenced the morphotic composition of their hemolymph.

Snails under observations were kept in an oblong thermal gradient. Temperatures selected by snails were automatically registered during 24 hours. Hematological study was made using the Fuchs-Rosenthal counting camera (3.2 ?l vol.).
Lymnaea stagnalis individuals parasitised with two among four different trematode species chose a lower temperature than non-parasitised ones. However, only individuals which released cercariae of parasites had different thermal preferences from the non-larvae-releasing ones.

More spectacular proved the results of the hematological study. Snails naturally parasitised with three of the four trematode species under study, possessed more hemocytes in 1 of hemolymph than non-parasitised ones. All noted differences were statistically significant. It was noticed that a low hemocyte number in the hemolymph of parasitised snails was correlated with lower vitality of those snails.



Contact Information Mini-Reviews Join The Malacological Society of London Bulletin Board Home