Text Box:     Number 52 (February 2009)
Text Box: The Malacologist

Land snail shell degradation - big unknown

Dagmar Rihova1, Zdenek Janovsky2 & Lucie Jurickova

1Dept. of Zoology, Charles University Prague.

2Dept. of Botany, CharlesUniversityPrague, Czech Republic


Analyses of land snail shell degradation in the Czech forest ecosystems during the last three years allow us to propose preliminary results. We found that shell persistence is mainly affected by size (tiny species e.g. Carychium minimum can completely disappear after six months, massive species e.g. Arianta arbustorum can persist for three years almost intact). There is also a strong influence of forest type for forests in which the shell is corroding. Types of calcareous microstructures, morphometric characteristics and shell shape are probably important for shell degradation. In the initial phase of the degradation, particular biotopes relate to unique characteristics (dark colouring in spruce forest, mycelium infestation in beech wood etc.). Those characteristics gradually disappear over time. In the early stages of corrosion, shells of particular species degrade in a specific way. During the later stages, the specificity of corrosion is reduced. [Poster Presentation]


Freshwater bivalves as biomonitors for heavy metal pollution

Nicole Spann

Department of Zoology, University of Cambridge, CB2 3EJ, Cambridge, UK  ns4...@cam.ac.uk


Molluscan Forum 2008 cont

Text Box: Molluscan Forum
Text Box: Molluscan Forum

Bivalves are frequently used for monitoring contaminants, for

example the concentration of heavy metals, in aquatic

environments. Compared to the measurement of substances of

interest in the water and in the sediment directly, analysis of

bivalve soft tissue has distinct advantages: the tissue

concentration represents only the bioavailable fraction of the

compound integrated over the organism’s life span, accumulation

 of substances to measurable levels, indication of effects to the


I am presenting some preliminary results on metal

concentrations measured in the invasive clam Corbicula

fluminea from the Norfolk Broads. In addition to the common

metal analysis of soft tissues I would like to show new ways in

which bivalves can be used for biomonitoring.


The snorkel snail genus Rhiostoma (Caenogastropoda: Cyclophoridae) from Thailand

Piyoros S Tongkerd1, Chirasak Sutcharit1, Fred Naggs2 & Somsak Panha1

1Animal Systematic Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok10330, Thailand.  piyo...@hotmail.com

2Department of Zoology, The Natural History Museum, London SW7 5BD, United Kingdom.


More than 30 genera of the enigmatic  land-operculate snail family Cyclophoridae have been reported. The snorkel snail genus Rhiostoma is one of the most poorly investigated group, and is endemic to Indochina and Malay peninsular region. With this paper we initiate a taxonomic review of the genus Rhiostoma from Thailand and nearby countries, indicating the comparative shell characteristics, radula, male and female anatomy and geographic distribution of the species. A total of 19 species are recognized, of which 7 species will be described as new. A key to species is included, and the geographic distribution of all species are mapped. The taxonomic placements in relation to closely related genera, and the synonymy of R. hainesi and R. housei, are discussed. [Poster Presentation]


Tissue accumulation of aluminium cannot be used to predict its toxicity in Lymnaea stagnalis

Rachel Walton

University of Manchester, Faculty of Life Sciences, 3.614 Stopford Building, Manchester M13 9PT.



The level of tissue accumulation of a toxic metal is often taken as an indicator of its potential toxicity. Lymnaea were exposed to Al (500 μl-1) alone or in the presence of ligands (either a fulvic acid surrogate (FAS; 10 mg.l-1) or phosphate (500 μl-1P) that were predicted to have different effects on the lability, and hence bioavailability, of Al. Behavioural toxicity over 30 days exposure was assessed, and tissue accumulation of Al quantified. FAS increased both lability and observed toxic behaviour, whereas phosphate decreased lability and abolished Al-induced behavioural toxicity. More Al accumulated in the tissues of snails exposed to Al+P compared with those exposed to Al alone (p<0.05), whereas there was less Al accumulation in the snails exposed to Al+FAS. These findings demonstrate that the degree of tissue accumulation of a metal cannot be used to predict its potential toxic effects. [Poster Presentation]


Restoration trials for Margaritifera margaritifera using captive bred mussels

Conor Wilson1, Dai Roberts1, Jane Preston1, Jim Provan1 & Alan Keys2

1Quercus, School of Biological Sciences, Queens University Belfast, Medical Biology Centre, Belfast, Northern Ireland, BT9 7BL. cwil...@qub.ac.uk

2Ballinderry Fish Hatchery, Orritor, Cookstown, Northern Ireland.

Since 1998 we have been successfully culturing M. margaritifera at the Ballinderry fish Hatchery, Northern Ireland1. Approximately 700 juvenile mussels are now available for restoration trials on the natal river of the parent mussel stocks. This presentation describes proposed experimental trials in the context of developing strategies for M. margaritifera in the broader context. Captive bred mussels will be introduced in areas with and without adult mussels at each of two sites.

The aim is to test the hypothesis that juvenile mussels introduced alongside existing wild mussels will have a greater survival rate than mussels introduced on their own, due to increased stability of the river bed. Information derived from the proposed trials will include growth and survival of the juveniles after their introduction. However, gathering such information is dependant on relocating the experimental mussels. Passive Integrated Transponders (PIT) tags, which provide each mussel with an individual identity, have been used elsewhere with 72-80% recovery success2 and will be used in the proposed trials.

1Preston S.J., Keys A. & Roberts D.(2007) Culturing freshwater pearl mussel Margaritifera margaritifera: a breakthrough in the conservation of an endangered species. Aquatic Conservation: Marine and Freshwater Ecosystems 17:539-549.

2Kurth J., Loftin C., Zydlewski J. & Rhymer J.(2007) PIT tags increase effectiveness of freshwater mussel recaptures. Journal of the North American Benthological Society 26:253-260.


Phylogeny and phylogeography of Drouetia

Kai Winkelmann

Grtner Str. 1, 18055 Rostock, Germany


The Azores Archipelago has a wealth of endemic terrestrial molluscan species, of which those of the subgenus Drouetia Gude, 1911 (Pulmonata: Zonitidae: Oxychilus) constitute a clear case of evolutionary radiation. Spread throughout the whole archipelago, it appears to be a suitable model for studying aspects of the evolutionary processes. Studies on their morphology and anatomy have revealed patterns of speciation associated with the geological history of the islands.

However, a phylogenetic and phylogeographic approach is needed, in order to obtain clarification of the relationships of the observed anatomical variability and also interpretation of their spatial and temporal distribution.

The phylogeny will be generated using both nuclear and mtDNA sequences and some individuals for each nuclear genes will be cloned to test for possible multiple copies. Phylogeny estimates and population genetics methods will be used to infer about population history and demography. All data will be analysed in a biogeographic context.


A preliminary classification and analysis of species traits and attributes for the British molluscan fauna

Tim Worsfold

Unicomarine, 7 Diamond Centre, Works Road, Letchworth. SG6 1LW.  timw...@unicomarine.com


Species biological traits are becoming increasingly popular as tools for the characterisation of ecological communities and the assessment of human impacts upon them. Trait classifications for selected species have been drafted by others and used to demonstrate biological traits analysis but there has previously been little done to clarify the definitions or means of assignment of traits or other species information and classification appears never to have been attempted for an entire fauna. This paper reviews some definitions of species traits and presents summary data on the distribution of selected basic attributes across the British molluscan fauna. Methods and information sources for the assignment of attributes are also discussed, along with the limitations and potential uses of such information.


First observations of shell microstructure in juvenile freshwater mussels (Unionoida) using SEM

Alexandra Zieritz

Department of Zoology, University of Cambridge, CB2 3EJ, Cambridge, UK           az2...@cam.ac.uk


In contrast to the well studied larvae (glochidia) and adults of freshwater mussels (Unionoida), literature on shell microstructure of the intermediate juvenile stage is virtually non-existent. However, given the disparate life habits of juvenile and adult unionoids (eg. juveniles are interstitial deposit feeders while adults are filter feeders), juvenile shell features such as microstructure are likely to differ considerably from those of adults. Identifying such differences could give vital insights into functional morphology of juvenile shells and subsequently, into the ecology of this crucial life stage.

This study is a first attempt to analyse juvenile shell ultrastructure of five British and one Chinese unionoid species using SEM. Preliminary results indicate that juvenile shells differ from adults in composition of their microstructure and some species have additional periostracal protrusions (spikes) during their early life stage, possibly increasing friction force for life within the sediment. [Poster Presentation]

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