[14] study was conducted in the field (long-term exposure), while the present study was conducted in the laboratory with short-term exposure, and differences in accumulation trend and strategies (higher accumulation in soft tissues or shell) may exist.Aquatic molluscs possess very diverse strategies in the handling and storage of accumulated selleck inhibitor metals, which include being in the forms of metal-rich granules metallothioneins (MT) or metallothionein-like proteins [60�C62]. Accumulation strategies of invertebrates vary intraspecifically between metals and interspecifically for the same metal in closely related organisms [62, 63]. Moolman et al. [18] showed that M. tuberculata had a much higher uptake of Zn in the Zn and in the mixed Cd/Zn exposures compared to Helisoma duryi, and Zn was readily accumulated with increasing metal concentrations.
Lau et al. [14] also demonstrated that Zn concentrations in M. tuberculata were significantly higher than those in the molluscs Brotia costula and Clithon sp. The present study shows that the CF of Zn was higher than the Cd in the soft tissues of M. tuberculata. With the juvenile apple snail, Hoang et al. [56] showed that the snails accumulated Cu during the exposure phase and eliminated Cu during the depuration phase. Metals accumulated in animals can be stored without excretion leading to high body concentrations (accumulators), or the metal levels in the body can be maintained at a low constant body concentration (regulators) by balancing the uptake with controlled rates of excretion [64].4. ConclusionsThis study showed that M.
tuberculata was equally sensitive to metals compared to other freshwater gastropods. Cu was the most toxic metal to M. tuberculata followed by Cd, Zn, Pb, Ni, Fe, Mn, and Al. A comparison of the bioconcentration of metals in soft tissues of M. tuberculata showed that among the eight metals studied; Cu, Pb, and Zn were the most accumulated and Al was least accumulated. M. tuberculata is widely distributed in urban and suburban areas which makes it easy to sample and very useful in ecotoxicology studies. This study indicates that M. tuberculata could be a potential bioindicator organism of metals pollution and in toxicity testing.AcknowledgmentsThis study was funded by the Ministry of Science and Technology, Malaysia (MOSTI) under e-Science Fund code nos. 06-01-02-SF0217 and 06-01-02-SF472.
The authors do not have any direct financial relation with the commercial identity mentioned in this paper.
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