World Congress of Malacology Antwerp ... - Unitas Malacologica

Assessing effects of heavy-metal pollution on short term growth and periodical growth patterns
of Protothaca thaca (Mollusca: Veneridae) using calcein as a growth marker
Riascos, José M. 1 ; Saavedra, Rodrigo J. 1 ; Heilmayer, Olaf 2 ; Laudien, Jürgen 2 ; Guzman, Nury 3
1. Universidad de Antofagasta, Facultad de Recursos del Mar, Avenida Angamos 601, Antofagasta,
Chile,
Email: josemar.rv@gmail.com; saavedragon@gmail.com
2. Alfred Wegener Institute for Polar and Marine Research, D- 27568 Bremerhaven, Germany,
Email: Olaf.Heilmayer@awi.de; Jurgen.Laudien@awi.de
3. Institut de Recherche pour le Développement (IRD), 32 avenue Henri-Varagnat, F-93143 Bondy
Cedex, France,
Email: Nury.Guzman@ird.fr
Mollusc shells have been successfully used as environmental and paleo-environmental recorders. The
cockle Protothaca thaca inhabits the shallow sublittoral of Chilean sandy bottoms and may be used
for palaeoceanographic reconstructions because of its high temperature tolerance in changing
environments and its presence in archaeological deposits. Prior to the analyses of this species as a
potential recorder, shell growth and growth rate variations under different environmental conditions
need to be investigated. The objective of this study was to assess the effect of heavy-metal pollution
on growth rates and periodicity of shell growth of this species. Tagging-recapture growth
experiments at several locations (polluted and unpolluted) of San Jorge Bay (Antofagasta, Chile)
were carried out. Animals were marked with the florochrome Calcein (100 mg l -1 , 3h). Parameters of
the von Bertalanffy growth model (K and L∞) and the index of overall growth performance (P) were
estimated to compare polluted and unpolluted sub-populations. Preliminary results indicate that
growth parameters and growth performance of P. thaca are lower under polluted environmental
conditions (K=0.127; L∞=70.3; P=4.6) than under unpolluted conditions (K=0.3408; L∞=71.9;
P=5.1). Calcein markings were used to validate increment periodicities under the two growing
conditions and thus, describe the growth modalities of P. thaca to provide the base for a
sclerochronological analysis of this cockle.
This study was financed and conducted in the frame of the EU-project CENSOR (Climate variability
and El Niño Southern Oscillation: Implications for Natural Coastal Resources and Management,
contract 511071) and is CENSOR contribution 0107.
Biogeography and systematic concepts of Helicinidae in the Lesser Antilles
(Gastropoda: Neritopsina)
Richling, Ira
Zoologisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel,
Germany,
Email: ira@helicina.de
Although fairly known, the geological history of the Caribbean region still remains subject of
controversial discussions. The same applies to an even higher degree to our understanding of
distribution patterns of flora and fauna in this area where vicariance and dispersal hypotheses were
repeatedly contrasted. Therefore, exact systematics and data on the distribution of different groups of
organisms are urgently needed. With their low mobility land snails provide an excellent example for
such studies. A preliminary revision of the helicinid fauna of the Lesser Antilles will exemplary
highlight possible misinterpretations of biogeographic issues based on wrong systematic concepts.
Applying previous classifications by WAGNER and BAKER, the helicinid snail fauna of the Lesser
Antilles shows up to be more closely related to the fauna of the Greater Antilles with a comparably
similar assemblage of the present genera, although greatly depleted in the diversity. Besides others
most of the Lesser Antillean species were assigned to Alcadia and subgenera and only few to
Helicina.
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