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Comparison of heavy metal toxicity in life stages (spermiotoxicity, egg toxicity, embryotoxicity and larval toxicity) of Hydroides elegans

Institute for Ocean Management, Anna University, Guindy Campus, Chennai 600 025, India.
Chemosphere (Impact Factor: 3.34). 04/2008; 71(3):515-28. DOI: 10.1016/j.chemosphere.2007.09.062
Source: PubMed

ABSTRACT

A toxicity test was developed to examine the effects of heavy metal contaminants on the early life stages of the marine polychaete. We have studied the effects of metals on fertilization and early development of marine polychaete Hydroides elegans. These heavy metals have often been found in polluted ground and water near industrial discharges, and have therefore been detected from time to time in the food chain. They have been reported to alter various reproduction functions in various animals including marine populations. The toxic effect of mercury, cadmium, lead, nickel and zinc on sperm viability, fertilization, embryogenesis and larvae of H. elegans was examined. We observed that the rate of fertilization decreased when the sperm was incubated with heavy metals. Treatment of eggs with each metal did not prevent fertilization, but delayed or blocked the first mitotic divisions, and altered early embryonic development. All these effects were observed at relatively high concentrations. However, bio-accumulation in sediments and aquatic organisms have been reported. Polychaete eggs may then be in contact with very high concentrations of these heavy metals in areas where these metals are not handled or stocked properly, and then develop into abnormal embryos. In addition to bivalves and sea-urchins, polychaete embryos can provide biological criteria for seawater quality standards taking into account the sensitivity of the invertebrates and their contribution in detection of harmful chemicals with no marked effect on the species. Our results indicate that the early development of H. elegans is highly sensitive to heavy metals and this polychaete can be routinely employed as a test organism for ecotoxicity bioassays in tropical and subtropical regions.

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    • "Comparing results of sperm toxicity assay (S ¼35‰) with data obtained in similar assays at the same salinity condition with different marine organisms such us serpulids and echinoids (literature source, Table 4) it was possible to observe that: (i) the sensitivity of F. enigmaticus to Cd 2 þ was slightly lower (about 3-fold) than observed in H. elegans and higher than P. lividus (about 30-fold); (ii) the sensitivity of F. enigmaticus to Cu 2 þ and SDS was quite similar to P. lividus, while a sensitivity over 100-fold higher than H. elegans was observe; (iii) the sensitivity of F. enigmaticus to NP was about 180-fold higher than P. lividus. Metal ions showed similar toxicity between each others (EC50 values 0.28 mg/L and 0.096 mg/L for Cd 2 þ and Cu 2 þ , respectively); in particular copper showed EC 50 values slightly lower than cadmium at all salinities, differently on what observed inGopalakrishnan et al. (2007Gopalakrishnan et al. ( , 2008) on H. elegans, where cadmium exhibited EC 50 values about 10-fold lower than copper. It could be hypothesized that increased amounts of metals inhibit natural cell functions exerting in toxicity through displacement of other metals at binding sites (George, 1990). "
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    • "For the past 15 years, early life stages (ELSs) have been the subject of numerous studies aimed at assessing the toxicity of chemicals, especially in aquatic environments (Gomot, 1998; Gopalakrishnan et al., 2008; Ismail and Yusof, 2011). Because the embryonic phase is an essential step in the life cycle and thus a key element of population dynamics (Laskowski, 1997; Caswell, 2000), it is relevant to focus on this life stage. "
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