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
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.
Available from: Matteo Oliva
- "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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ABSTRACT: Ficopomatus enigmaticus is an ubiquitous fouling reef-forming species, easy to sample and recognize, diecious with gamete spawning along different seasons in different salinity conditions. Due to its characteristics it could become a good candidate for the monitoring of both marine and brackish waters. The suitability of F. enigmaticus as a promising model organism in ecotoxicological bioassays was evaluated by a sperm toxicity and a larval development assay. The fertilization rate in different salinity conditions (range 5-35‰) was first assessed in order to detect the salinity threshold within which profitably perform the assays. Afterward copper (Cu(2+)), cadmium (Cd(2+)), sodium dodecyl sulfate (SDS) and 4-n-nonylphenol (NP) were used as reference toxicants in exposure experiments with spermatozoids (sperm toxicity assay) and zygotes (larval development assay). A dose-response effect was obtained for all tested toxicants along all salinity conditions except for 5‰ salinity condition where a too low (<30%) fertilization rate was observed. NP showed the highest degree of toxicity both in sperm toxicity and larval development assay. In some cases the results, expressed as EC50 values at 35‰ salinity condition, were similar to those observed in the literature for marine organisms such as the sea urchin (Paracentrotus lividus) and the marine serpulid Hydroides elegans, while the exposure of F. enigmaticus spermatozoids' to Cd(2+) and NP resulted in toxicity effects several orders of magnitude higher than observed in P. lividus. Spermatozoids resulted to be slightly more sensitive then zygotes to all different toxicants.
Available from: Pierre-Emmanuel Baurand
- "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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ABSTRACT: This study aims to determine various parameters that allow the evaluation of the toxicity of chemicals to embryos of the ubiquitous land snail Cantareus aspersus. For this purpose, we investigated morphological and physiological endpoints in control embryos and in embryos exposed to a solution of 6 mg Cd/L (CdCl2) in a liquid phase bioassay: size at days 3, 6 and 10, heart rate at 7 days, delay in hatching, states of development of non-hatched eggs after 17 days and the fresh mass of newly hatched embryos. The kinetics of Cd accumulation in eggs and DNA fragmentation were also measured. The first detectable sign of adverse effects appeared after 7 days of development, when the heart rate decreased in Cd-exposed embryos compared with the control. After 10 days of exposure, Cd-exposed hatchlings exhibited a lower fresh mass than control individuals. The majority (75 percent) of non-hatched embryos at 17 days was dead and presented signs of disaggregation or malformations. The hatching of Cd-exposed eggs was delayed 4 days, and DNA fragmentation was later detected after 20 days of Cd exposure. The measurement of Cd in the eggs showed that concentrations are relatively stable during the exposure period from 3 days (20–27 µg Cd/g DW) to the end of exposure. The present study completes the range of endpoints that can be used to study the effects of contaminants and provides new parameters that are readily measured throughout the embryonic development of a terrestrial mollusk.
- "The 96-h LC 50 values for zinc from the present study are within the range found in other toxicity studies using tropical marine invertebrates (Table 3). The tropical mollusc Haliotis diversicolor texta (Liao and Lin 2001), annelid Hydroides elegans (Gopalakrishnan et al. 2008) and crustacean Litopenaeus vannamai (Wu andChen 2004) have LC 50 values similar to the upper end of values determined for A. pulchella in the present study (Table 3). In general, the survival of A. pulchella was more sensitive to zinc than was the survival of other tropical marine invertebrates. "
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ABSTRACT: Currently few studies present sub-lethal toxicity data for tropical marine species, and there are no routine toxicity tests using marine cnidarians. The symbiotic sea anemone Aiptasia pulchella has been identified as a useful species for ecotoxicological risk assessment, and would provide a tropical marine cnidarian representative. Chronic sub-lethal toxicity tests assessing the effects of 28-day trace metal exposure on asexual reproduction in A. pulchella were investigated, and concentration-dependant reductions in the number of offspring that were produced were evident for all metal exposures. Metal concentration estimates causing 50 % reductions in the numbers of asexually-reproduced juveniles after 28-day exposures (28-day effect concentrations 50 %: EC50s) were 14 µg/L for copper, 63 µg/L for zinc, 107 µg/L for cobalt, 145 µg/L for cadmium, and 369 µg/L for nickel. Slightly higher 28-day EC50s of 16 µg/L for copper, 192 µg/L for zinc, 172 µg/L for cobalt, 185 µg/L for cadmium, and 404 µg/L for nickel exposures and were estimated based on reductions in the total number of live developed and undeveloped offspring. These sensitive and chronic sub-lethal toxicity estimates help fill the knowledge gap related to metal effects on cnidarians over longer exposure periods, and this newly-developed bioassay may provide a much needed tool for ecotoxicological risk assessment relevant to tropical marine environments.
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