World Congress of Malacology Antwerp ... - Unitas Malacologica

In summary, most of the common rocky intertidal molluscan species, in spite of being adapted to
abrupt punctual change of temperature during low tide, presented a relatively low thermal tolerance
during prolonged exposure to artificially elevated water temperatures.
Growth of Donax vittatus in the north-west coast of Portugal.
Biological data for the management of a new fishery
Maia, Francisco 1 ; Pimenta, Joana 1 ; Gonçalves, Catarina 2
1 INIAP/IPIMAR, Centro Regional de Investigação Pesqueira do Centro, Canal das Pirâmides, 3800-
242 Aveiro, Portugal,
Email: maia.francisco@gmail.com; jo.pimenta@gmail.com
2 Universidade de Aveiro, Departamento de Biologia, Campus Universitário de Santiago, 3810-183
Aveiro, Portugal,
Email: catarinag@sapo.pt
The marine mollusc fishery in the north-west coast of Portugal (NWCP) has been directed to the
white surf clam (Spisula solida). However, the high fishing effort in the area caused the collapse of
this resource in the 1990s. Thus, there is an urgent need to find alternative or complementary species
for that fishery. Preliminary studies carried by INIAP/IPIMAR showed that the banded wedge shell
(Donax vittatus) could be an important target species for the fishery in this region. The aim of this
work is to study the growth of this species in order to provide basic information for this fishery
management. The shell growth was investigated from samples collected monthly at NWCP from
November 2003 to October 2004. The analysis of the marginal shell growth showed that the annual
growth ring was formed once a year, in the winter. The age and the shell growth of D. vittatus were
assessed using both surface growth rings and internal shell microgrowth patterns (by the acetate peel
method). The estimated von Bertalanffy growth curves, expressed for length and weight, are the
following:
rings on the shell surface: Lt = 43,1 [1-e -0,38 (t+0,20) ] Wt = 7,4 [1-e -0,38 (t+0,20) ] 3,04
acetate peel method: Lt = 40,5 [1-e -0,38 (t+0,50) ] Wt = 6,1 [1-e -0,38 (t+0,50) ] 3,04
Morphological and shell quality natural population diversity of the edible snail
(Helix aspersa M.), in southern Hellas
Malandrakis, Ε. Ε. 1 ; Gogas, A. 1 ; Hatziioannou, Μ. 1 ; Panagiotaki, P. 1 ; Lazaridou-Dimitriadou,
Μ. 2 ; Neofitou, C. 1 ; Exadactylos, A. 1
1. Department of Ichthyology and Aquatic Environment, School of Agricultural Sciences, University
of Thessaly, Fytokou str., 384 46, Nea Ionia Magnesia’s, Hellas,
Email: emalandrak@uth.gr; agogas@uth.gr; mxatzi@uth.gr; ppanag@uth.gr; chneofit@uth.gr;
exadact@uth.gr
2. Aristotle University of Thessaloniki, School of Biology, Department of Zoology,
Panepistimioupolis, 54 124 Macedonia, Hellas,
Email: mlazarid@bio.auth.gr
No relevant information on stock definition has been produced recently concerning edible snails,
which are both commercially and ecologically important species in the eastern Mediterranean region.
The present study addresses on nine (9) quantitative and qualitative traits [on the axial view - SH:
shell height, SD: shell maximum diameter ; on the apertural view - AL: aperture length from the
point of adhesion of aperture to body whorl, AW: maximum aperture width, WW: wet weight; and
number of bands, band colour, shell’s base colour, overall colour pattern], diversity of six (6) natural
populations of the edible snail, Helix aspersa, collected in Peloponnesus (Megalopoli, Corinth,
Argolida, Zacharo) and the island of Crete (Chania, Ierapetra), southern Hellas.
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