Imposex and butyltin concentrations in snails from the lagoon of Bizerta (Northern Tunisia (original) (raw)
Related papers
Environmental Monitoring and Assessment, 2011
The imposex incidence and butyltin concentration i.e. tributyltin with its di- and mono-substituted metabolites were investigated in the muricid Bolinus brandaris sampled from two sites on the northern Tunisian coast (the Lagoon of Bizerta and the small Gulf of Tunis). Both populations had imposex, with stages of imposex development varying between VDS 1 and VDS 4.3. All imposex indices (imposex frequency (I %), female penis length, female vas deferens length, vas deferens sequence index, relative penis length index, and vas deferens length index) were significantly higher in snails from the Bizerta lagoon. Butyltins were detected in the whole tissues of both sexes from the two sites. TBT levels were higher in gastropods collected from the lagoon of Bizerta (12.65 ±1.48 ng Sn g − 1 dw in female and 15.21 ±1.13 ng Sn g − 1 dw in male) than in individuals from the Gulf of Tunis (10.71 ±1.26 ng Sn g − 1 dw in female and 11.65 ±1.63 ng Sn g − 1 dw in male), corroborating the data of imposex analysis. These results confirmed that B. brandaris could be used as a bioindicator species of butyltin pollution in the studied areas. In addition, this study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet.
Journal of Environmental Monitoring, 2009
We have assessed for the first time the current status of tributyltin (TBT) contamination in Hexaplex trunculus along Tunisian coastal waters. Two sampling campaigns have been performed in July 2004 and July 2007 at seven different sites. The snails were analyzed for imposex status, i.e. Imposex incidence, Relative Penis Length Index (RPLI) and Vas Deferens Sequence Index (VDSI), followed by the quantification of butyltins in their tissues. Imposex was detected in six populations from the 2004 samples and in five populations from the 2007 samples. The imposex incidence ranged from 0 (no imposex) to 100%, the RPLI from 0 to 56.7 and the VDSI from 0 to 4.4. TBT was also detected in six populations in 2004 and five populations in 2007. The concentrations ranged from 1.5 to 73.7 ng Sn g -1 dw in 2004 samples and from 1.2 to 23.9 ng Sn g -1 dw in 2007 samples. Temporal comparison of the data indicates some evidence of imposex recovery in most affected populations. Improvements in reduced body concentrations of TBT in both sexes were also seen in most stations. These TBT concentrations were only significantly correlated to imposex indices in samples from 2007 (r > 0.8, n = 7, p < 0.05). The present results will serve as a reference for long-term monitoring of butyltin contamination in the Tunisian coast, where TBT restrictions were not yet implemented.
Bis (tri-n-butyltin) oxide (TBTO) is an organotin biocide used in marine antifouling paints to prevent encrustation of marine organisms on the hull of ships. The release of tributyltin (TBT) from hull of ships represents one of the main problems of direct, diffuse and continue contamination of the marine environment. To assess the effect of TBT pollution in Warri Harbour, Periwinkle snails, Tympanotonus fuscatus var radula an important shellfish in the Niger Delta ecological zone was exposed to sublethal concentrations (0.1, 1.0, 10 and 20μg/L) of TBTO using direct sediment toxicity bioassay to determine TBT bioaccumulation and its effects on testosterone levels. Tissue analysis for TBT was done using Solid Phase Extraction (SPE) and gas chromatography with flame ionization detection (GC-FID) after derivatization with Grignard reagent pentyl magnesium chloride. The study employed the Organization for Economic Development and Cooperation (OECD) Guideline 218 protocol. Tissue analysis of T. fuscatus var radula for TBT was found to be significantly low for TBT. Serum analysis of the Periwinkles snail after 10, 20 and 30days exposure period to varying TBTO concentrations showed increased significantly (p<0.05) free testosterone levels with increased concentration and exposure durations. TBT induced elevated testosterone in snails may be indicative of imposex expression an irreversible sexual abnormality in female molluscs. The observations in this study showed that T. fuscatus var radula is susceptible to imposex development and may affect their reproductive ability which may lead to population decline.
Butyltins concentration levels and imposex occurrence in snails from the Sicilian coasts (Italy)
Chemosphere, 2003
Two sampling campaigns have been carried out along the Sicilian coasts within the frame of a European project (Hic-TBT) financed by the LIFE programme. Snails and sediments have been sampled at 5 stations, characterised by very low (Ustica natural sea reserve), low (Ustica harbour), intermediate (Castellamare and Termini Imerese) and high shipping densities (Palermo). Biological and chemical analyses were carried out in order to evaluate the incidence of imposex occurring in snails, and the concentration levels of organotins in sediment and snail samples. Despite the low organotin concentration levels in sediment and snail samples, the results show that imposex is widespread around Sicily. In four locations almost all female snails were affected by imposex at advanced development stages, even in areas with a fairly low shipping density. Only in the natural sea reserve of Ustica Island imposex was relatively less severe. Finally a logarithmic correlation between TBT and imposex stages was observed.
Environmental Monitoring and Assessment, 2011
Strombus canarium Linnaeus, 1758 is an important gastropod species within the study area and was traditionally collected for food by the locals. The objective of the present study is to assess the incidence of imposex and its severity in this species. Adult conchs were sampled during their main reproductive period, from October 2005 to January 2006, at Sungai Pulai estuary, Johor Straits, Malaysia. A total of 32.81% of adult females showed imposex characteristics, with varying degrees of severity though. The relative penis size (RPS) index ranged from 1.74 to 33.29 (mean = 13.40 ± 2.27, n = 21), while the relative penis length (RPL) index ranged from 6.28 to 55.19 (mean = 25.83 ± 3.33, n = 21). The use of vas deferens sequence (VDS) index was however cannot be applied as the presence of egg groove obscured any vas deferens development in affected females. Sequence of imposex (male penis) development in female conch, from merely a small stump to an advance male penis homologous was therefore carefully analyzed and described, and an alternative imposex classification scheme was proposed. S. canarium can be a good indicator for monitoring of organotin pollution within the study area. However, more studies are needed in order to further develop and test its validity and application, such as its correlation with levels of pollutant within the tissues and the environment, as well as its application on other Strombus species.
Ecological Indicators, 2012
Tributyltin (TBT)-induced imposex in gastropods is often cited as a prime example of environmental endocrine disruption. Several endocrine-related hypotheses have been proposed to define possible mechanisms by which TBT causes imposex. Recently, it has been demonstrated that mollusks have the ability to control endogenous steroid levels (i.e., testosterone and estradiol) by esterification with fatty acid and TBT may impact this metabolic pathway. Hence, this study was designed to investigate the presence and levels of sexual steroids (testosterone and estradiol) in the two TBT sensitive Muricids species Hexaplex trunculus and Bolinus brandaris, and to clarify the sex related impact of TBT in free and esterified steroid levels. Two months exposure to TBT (5 and 50 ng TBT L −1 ) induced imposex and led to a significant increase in the severity of the phenomenon in the high TBT exposure group but statistical tests failed to detect an effect in 5 ng TBT L −1 treatment. The steroid levels found in both sexes revealed that testosterone and estradiol were present in the free and esterified forms in the digestive gland-gonad complex. Both hormones were predominantly found in the esterified form, although clear sex differences were not observed. In females of B. brandaris, 2 months exposure to TBT at 50 ng TBT L −1 induced a significant elevation of free testosterone and a decrease in the esterified fraction. In females of H. trunculus, TBT led to a significant elevation of both free and esterified testosterone. In contrast, TBT had no effect in male's testosterone levels, although it led to an increased trend in penis lengths. Free and esterified estradiol levels were not affected by TBT in both sexes of B. brandaris but free estradiol was increased in females of H. trunculus. Overall, the present study demonstrates that TBT exposure leads to steroid imbalance in both species, with a boost of free testosterone levels in females. Although TBT increases male penis length, no effects in male steroid levels were recorded in both species. Hence, TBT impacts in testosterone and estradiol metabolism is sex dependent, and does not seem to be associated with the increase of male penis length observed in TBT exposed animals.
Continental Shelf Research, 2009
Levels of imposex (superimposition of male characters, upon females) and the presence of sterile females are assessed in the gastropod Nassarius reticulatus (L.), at 35 locations in the Basque Country. At 18 of these localities, organotin bioaccumulation (tributyltin (TBT); dibutyltin; monobutyltin) was evaluated, using isotope dilution GC-ICP-MS. Higher imposex levels and TBT body burden were found in confined harbours, with large vessel traffic or the presence of an offshore fleet. The highest values were found for the port of Pasaia, near to a shipyard (a relative penis size index of up to 92%, and TBT body burden up to 405 ng g À1 -given on a dry weight basis as Sn). Imposex effects were evaluated also in parasitized females, at some of the sampling sites. The percentage of presence of c-type Vas Deferens sequence stages (i.e., with vas deferens beginning at the oviduct opening) was higher in parasitized females. In turn, there was an absence of highly convoluted oviduct in parasitized females.
Journal of Environmental Sciences-china, 2011
Imposex and butyltin burden were assessed in Nassarius nitidus, Bolinus brandaris and Hexaplex trunculus collected at five stations in the Bizerta lagoon. Biological analysis showed that imposex followed type (a) in N. nitidus (distal evolution), against type (d) in the two muricids (proximal evolution). Imposex indices were higher in sites located nearby sources of tributyltin and N. nitidus was the least affected species of the five sites, followed by B. brandaris and H. trunculus. Butyltin analysis showed lower accumulation in N. nitidus followed by H. trunculus and B. brandaris. This study has allowed the gathering of data on imposex in a snail studied for the first time in Tunisia (N. nitidus). It suggests the possibility of using such snail as a complementary species for organotin monitoring programs in the Mediterranean and further confirmed that H. trunculus is the most suitable species for such investigations.
Marine Environmental Research, 2004
Tributyltin (TBT) is toxic to aquatic organisms and occurs widely in sediments and surface waters of American and European rivers and lakes. This study investigated TBT effects on development and population growth rate ðrÞ of the common, hermaphroditic European freshwater snail Physa fontinalis. Egg ropes of similar age (1-3 days old) were exposed to a control (solvent only) and nominal concentrations of 0.01, 1.0 and 10 lg TBT l À1 in triplicate. Hatching and mortality were recorded during 0-40 days of exposure. At day 40, 18 juveniles were randomly selected from each concentration (i.e., six from each test vessel) and individually exposed to the same concentration of TBT in 50 ml beakers. A cohort of 20 juveniles was allowed to continue developing in the original test vessels, so that individual and grouped results could be compared. Mortality and reproduction were recorded at 48-h intervals throughout the study period (110 days). Abnormal embryonic development was observed at 1 and 10 lg TBT l À1. Although 50% of eggs hatched at 10 lg TBT l À1 , all these hatchlings failed to survive. Survivorship of hatchlings was significantly reduced by TBT at 1 lg l À1. In general, there was a delay in egg production in isolated snails when compared with the grouped snails. Survival, fecundity and population growth rate (r) were reduced in both individual and grouped P. fontinalis at 1.0 lg TBT l À1. Only a decline in r was observed in snails exposed individually to 0.01 lg TBT l À1 .