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1.
The occurrence of imposex, imposition of male sex characteristics on female snails, has been extensively documented throughout the world. Tributyltin (TBT) and other organotins have been causally linked to imposex induction at levels as low as 2 ng/l. There are several proposed mechanisms of action. First, TBT has been shown to be neurotoxic and to accumulate in snail ganglia. Peptide hormones control sexual differentiation in gastropods, and one hypothesis is that TBT acts as a neurotoxin to abnormally release the peptide hormone Penis Morphogenic Factor (PMF). However, PMF has not been characterized to date. The neuropeptide APGWamide significantly induces imposex in the mud snail, Ilyanassa obsoleta, at 10(-16) moles sub-cutaneous (SQ) injection over 2 weeks, and could be the PMF in this species. A second hypothesis is that TBT inhibits aromatase activity leading to increased testosterone levels and decreased estradiol. In vitro studies with snail digestive gland microsomes showed that TBT-dosed snails not exhibiting imposex had a 52% reduction in aromatase activity. Although the role of vertebrate sex steroids is not known in gastropods, it is possible that the combination of changes in peptide and steroid hormones may lead to imposex induction at extremely low doses of TBT.  相似文献   

2.
Gastropods and bivalves were collected at 15 sites at Vancouver and Victoria, Canada between 24 May and 7 June, 1999, to establish tissue concentrations of butyltin and phenyltin compounds, to record imposex symptoms in gastropods, and to assess the present status of organotin contamination around Vancouver. No neogastropods (such as Nucella lima) were found around Vancouver. Neogastropod populations could have been extirpated by severe TBT contamination in Vancouver, as relatively high concentrations of TBT were detected in tissues of Mytilus trossulus from Vancouver, and the neogastropods distributed in Vancouver might be sensitive to TBT. Recovery from imposex, however, was observed in neogastropod populations from three sites at Victoria and Mission Point. TBT contamination has continued around Vancouver, arising from continuous use of TBT in antifouling paints for vessels larger than 25 m in length; however, TBT has decreased around Victoria and Mission Point. Different patterns of TBT accumulation in tissue were observed among the bivalve species from Vancouver. The highest TBT concentration detected in Tresus capax suggested some possible adverse effects. TBT was the most predominant butyltin component in almost all bivalve specimens surveyed, suggesting a low rate of TBT metabolism. Phenyltin compounds were not detected in any molluscan specimens in this study.  相似文献   

3.
疣荔枝螺(Thais clavigera)性畸变现象的解剖学和组织学研究   总被引:3,自引:0,他引:3  
以解剖学和组织学的方法研究了有机锡污染生物指示种——疣荔枝螺的正常雄、雌和性畸变个体的生殖系统。结果表明,性畸变个体除具有正常的雌性器官外,还有输精管或阴茎。当性畸变程度严重时,性畸变不育个体的卵囊腺组织出现破损,并具有不规则块状的不育卵囊和未排出的正常卵囊。虽然性畸变个体的雄性器官具有表现出雄性功能的潜能,但由于缺少精巢或完整的前列腺,不可能发展成为具有雄性功能的个体,这与性逆转有着本质上的区别。有机锡污染引起的性畸变已对疣荔枝螺种群生存构成了潜在的威胁,深化此类负面生态效应的研究是人类面临的重要课题。  相似文献   

4.
The presence and the development of imposex were investigated in the common whelk (Buccinum undatum) and the red whelk (Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (< 63 microm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of > or = 100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (> 10 ships day(-1)), intermediate (5--10 ships day(-1)), and low (< 5 ships day(-1)). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction < 63 microm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea.  相似文献   

5.
Abstract. In the Azores the gastropod Thais haemastoma shows varying degrees of imposex, the induction of male sex characters in the female. It is inferred that imposex in T. haemastoma is caused by tributyltin (TBT) associated with boats using organotin-based antifouling paints. The two indices - relative penis size and vas deferens sequence - employed previously for Nucella lapillus , were used without alteration. T. haemastoma is only the third species reported as exhibiting 'effective sterilisation' of the female. Unlike Nucella lapillus, T. haemastoma has a planktonic larva, allowing populations to be sustained even when local TBT pollution is high. This makes T. haemastoma potentially a better indicator species, as monitored populations can be maintained by the influx of larvae. T. haemastoma may thus provide a cheap method of assessing the extent of TBT contamination in warm waters, particularly in the Mediterranean and Atlantic Islands. Preliminary examination of material from a marina in Spain showed a high incidence of 'sterile' animals.  相似文献   

6.
Stramonita haemastoma was investigated as a suitable bioindicator of TBT and TPhT contamination in the tropical Atlantic Ocean by: 1. Imposex induction in healthy females after inoculation with TBT and TPhT in the laboratory; and 2. Determining incidence of imposex in S. haemastoma collected from areas with various levels of tributyltin (TBT) and triphenyltin (TPhT) and determining the concentrations of these chemical in its tissues and that of its prey, the mussell Perna pernas. Imposex intensities and organotin concentrations in tissues showed good correlation, indicating S. haemastoma as a reliable bioindicator of TBT and TPhT contamination in coastal waters. Body burden threshold of TBT and TPhT for imposex induction was estimated to be 10-20 ng g(-1).  相似文献   

7.
Imposex was measured in the rock shell, Thais clavigera, from the coast of the Korean peninsula. Frequency of imposex was 0% at two reference sites, but at 47 out of 61 sites, frequency of imposex was recorded as 100%. The degree of imposex was relatively high at the sites near a harbor and a shipyard. Tributyltin (TBT) and triphenyltin (TPT) concentrations in T. clavigera ranged from 5 to 508 ng/g and from 3 to 2460 ng/g, respectively. A significant positive relationship was found between degree of imposex and organotin concentration, whereas a significant negative relationship was obtained between female-to-male sex ratio and the degree of imposex. During a field transplantation of T. clavigera from a pristine area to a port, TBT and TPT were accumulated in T. clavigera, and imposex was induced. T. clavigera shows considerable potential as a bioindicator species of the adverse effects of TBT and TPT contamination.  相似文献   

8.
TBT induces imposex and sterilisation in female Nucella lapillus. Interestingly, there are populations where individuals (both males and imposexed females) may suffer from a genetic aberration [Dumpton Syndrome (DS)] which results in the development of no penis (i.e. aphally). This anomaly confers a so far unexplained protection against TBT. Six populations with contrasting DS frequency were sampled; the imposex stage in females and the mean calibre of every vas deferens (VDC) were assessed. While the sex ratio in the 600 specimens examined was close to 1, aphally was more frequent in females than in males (31 and 7%, respectively). VDC was significantly higher in normal than in aphallic (DS) specimens, independently of sex and/or site. It is concluded that the vas deferens imposed by TBT onto DS females is less prone to develop thick enough so as to interfere with normal egg laying.  相似文献   

9.
Caged dogwhelks (Nucella lapillus) and mussels (Mytilus edulis) were placed in situ at sites along the River Tyne (UK) in order to investigate the potential for monitoring any change in tributyltin (TBT) mediated effects. After 6 months the development of imposex was investigated in the dogwhelks and concentrations of TBT were determined in the whole tissues of both species. Sites within the estuary showed a high degree of imposex, whilst those at sites North and South of the estuary mouth exhibited significantly lower induction. Concentrations of TBT measured in the dogwhelk and mussel tissues showed the same pattern. The success of the caging technique, occurrence of imposex at other UK sites and the need for further monitoring at TBT impacted locations in the light of current international controls on the use of TBT-based antifouling paints on sea-going vessels are discussed.  相似文献   

10.
A survey of imposex in Thais orbita (Neogastropoda) along the New South Wales (NSW) coast, Australia, found imposex was still widespread 10 years after a partial ban on tributyltin (TBT) based antifouling paints. Transplant experiments also revealed that imposex was induced in T. orbita over a period of 9 weeks in Sydney Harbour, NSW. A comparison of the imposex data with that collected shortly after the introduction of restrictions on TBT revealed a general decline in imposex frequency occurring at open coast sites, an exception being the site at South West Rocks. Sites located within harbour/bay areas did not display a decline in imposex frequency but a decline in the severity of imposex was apparent. The observed decrease in imposex values in T. orbita may reflect a general decrease of butyltin contamination within the coastal environment. However, the persistence of contamination "hotspots" within harbours and bays remains a concern.  相似文献   

11.
Two-month flow-through exposure experiments of tributyltin (TBT) and triphenyltin (TPhT) were conducted with abalone, Haliotis gigantea. Nominal concentrations of 100 ng TBT/l and 100 ng TPhT/l caused significant spermatogenesis in ovaries of exposed females. There were also significantly more contracted primary oocytes observed in females exposed to either TBT or TPhT than controls. The incidence of two types of unknown cells was also significant in females exposed to TPhT. No significant histological changes were observed in testis of exposed males. This ovarian spermatogenesis caused by TBT and/or TPhT resembles gastropod imposex. Remarkably high concentrations of TBT and TPhT were observed in the head (including central nervous system ganglia), compared to muscles concentrations. Accumulation of TBT and TPhT in the head may disturb reproductive hormonal regulators through neuropeptides released from ganglia. This, as well as possible aromatase inhibition, may be one of the inducers for spermatogenesis in the abalone ovaries.  相似文献   

12.
该文概述三丁基锡在海洋防附着涂料中的应用及其环境效应,综述因TBT污染而导致某些螺类雌性个体中发育出雄性性征的性畸变现象发生情况,探讨性畸变在TBT污染生物监测中的应用。并以香港地区性畸变的发生为例,论证性畸变在生物监测中的应用,同时比较香港及世界其他地区性畸变的程度。  相似文献   

13.
Imposex incidence and biometric parameters were investigated in six muricid species along of 1200 km of Ecuadorian shore and in Galapagos archipelago. The obtained data, were compared to previous studies performed in the same area in 2009. The results showed that moderate imposex levels still occur in coastal areas of Ecuador, even after global TBT ban. However, a reduction in imposex parameters was detected in the sampled sites, indicating probably relationship to the global TBT ban issued by IMO at 2008. On the other hand, the levels currently reported in present study indicates that TBT environmental concentrations are still high enough to produce biological effects in studied areas. In addition, imposex incidence in four muricid species from Galapagos islands were detected suggesting that this marine protected area is under threat of antifouling contamination. These findings, after TBT global ban, denotes that current regulations and conservation plans still need to address such an issue and incorporate more restrictive management rules, particularly in complex coastal areas, vulnerable and unique systems such as the Galapagos Islands.  相似文献   

14.
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 (r) 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 microg TBT l(-1) 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 microg TBT l(-1). Although 50% of eggs hatched at 10 microg TBT l(-1), all these hatchlings failed to survive. Survivorship of hatchlings was significantly reduced by TBT at 1 microgl(-1). 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 microg TBT l(-1). Only a decline in r was observed in snails exposed individually to 0.01 microg TBT l(-1).  相似文献   

15.
Normal and imposex-affected female Buccinum undatum were sampled from the open North Sea at three locations, one with low, and two with high shipping densities. Cytochrome P450 components and P450 aromatase activity were determined in the microsomal fractions isolated from pooled digestive gland/gonads. Cytochrome P450 aromatase activity was significantly higher (P < 0.05) in normal females collected in the low shipping density area (1,325 +/- 295 fmol/h/mg protein) than levels from imposex animals from a high shipping density area (620 +/- 287 fmol/h/mg protein). A negative correlation was found between aromatase activity and organotin body burden (r = -0.99). Levels of CYP450, cytochrome b5 and NADPH cytochrome c reductase activity did not show differences among groups. This is the first field evidence of depressed aromatase activity in imposex affected females, although additional research under laboratory controlled conditions is required to fully understand the mechanisms underlying the development of imposex in this species.  相似文献   

16.
Exposure of female Nucella lapillus to tributyltin (TBT) in seawater at a concentration of 40 ng Sn/litre led to accumulation of TBT in the tissues, and an increase in penis length compared to control animals. Investigation of the steroid concentrations by radioimmunoassay revealed a significant increase in testosterone after 28 days exposure to TBT. No significant effect was noted upon the amounts of progesterone or estradiol-17β. When testosterone was injected into female N. lapillus in the absence of TBT, penis length was found to increase significantly. These observation suggest that there may be an association between the change in testosterone titre in response to exposure to TBT and the development of imposex in the dogwhelk.  相似文献   

17.
In habitats where competition for space is a shaping force of animal distribution such as in the intertidal rocky ecosystem, new habitats are readily taken by colonising species. We examined the importance of empty Chthamalus spp. tests as a habitat for the intertidal common periwinkle Melaraphe neritoides on Portuguese rocky shores. The role played by the space between neighbouring barnacles as a habitat for other species has been largely studied with regard to how an ecosystem functions, whereas the equivalent role of empty barnacle tests remains largely unknown. The small periwinkle is one of the most abundant snails in European rocky shores and is an important prey for key mobile predators. Biological facilitation is common in the rocky intertidal zone, where biological structures often potentiate the abundance of other species. The role played by barnacles as biological facilitators through habitat provision is not fully understood. In this study, the abundance and morphometric features of empty barnacle tests and their occupants were examined across shore levels and shores with differing exposures, as these are important gradients explaining barnacle distribution. The availability of empty barnacle tests was also experimentally manipulated to examine the percentage, time and length of occupation. Empty barnacles were more abundant on the midshore of sheltered shores and barnacle tests were wider on the upper shore but taller on the midshore. The minimum barnacle test occupation rate by the periwinkle was 70%. Barnacle shell height was an important factor determining snail occupation, where taller barnacles harboured significantly more, but not necessarily larger, snails. Snails outside the barnacle tests were significantly larger than those found within, suggesting that this crustacean group has an increased importance as a habitat for juvenile snails, thus potentially influencing the population dynamics of M. neritoides. We found that occupation of experimentally created empty barnacles was extremely high (70%) on the day after, and remained at 100% after 3 months of monitoring. Our study is the first of its kind to focus on the features of barnacle tests that snails occupy and their occupying snail traits. According to our results, it is clear that barnacles have an important role in providing additional habitat for young gastropods. The small periwinkle is an important grazer and prey for intertidal and subtidal foraging predators; hence, the potential refuge role of barnacle tests for juvenile M. neritoides may be important in the dynamics of intertidal communities.  相似文献   

18.
Surveys of imposex in dogwhelk (Nucella lapillus) populations around oil terminals in Sullom Voe (Shetland) and Scapa Flow (Orkney) have confirmed that the effects of tributyltin (TBT) released from large vessels in coastal waters can be recognised. The impact of large vessels can be separated from the effects of other inputs of TBT in the areas studied. The intensity of the effects was greater in Shetland than in Orkney, reflecting the higher exposure to TBT resulting from the greater volume of traffic using the Shetland terminal, and the more restricted water exchange in that area. A large proportion of the female dogwhelks in Sullom Voe were unable to reproduce. Females in Scapa Flow were still able to reproduce, except for a small proportion close to two fish farm sites where TBT net-treatments were used prior to 1987.  相似文献   

19.
为了全面评价和考核湘江长沙段各洲滩近几年来采取的不同灭螺措施对洲滩钉螺(Oncomelania hu-pensis)螺情的影响,采用以系统抽样结合环境抽查的查螺方法,2003~2008年对湘江长沙段20个有螺洲滩进行了跟踪调查.结果表明,2008年与2003年相比,活螺洲滩数、有螺框出现率、钉螺平均密度和活螺率分别下降了40.00%,99.10%,99.74%,51.09%.经统计学处理,各洲滩有螺框出现率(Z=91.560 2,P<0.01)、活螺率(Z=65.133 2,P<0.01)不相同,但年度下降趋势明显.在20个有螺洲滩中,有感染性钉螺分布的洲滩5个,占有螺洲滩总数的25.00%;有感染性钉螺分布的洲滩逐年减少,感染性钉螺的平均密度和感染率逐年降低,2007~2008年所有洲滩无感染性钉螺分布.湘江长沙段有螺洲滩采取的各种防治措施中,药物与环改灭螺相结合的效果远好于单纯的药物灭螺.各种环改灭螺措施,又以抬洲降滩、翻耕垦种的灭螺效果更持久,更彻底.  相似文献   

20.
Potamopyrgus antipodum has been found in thermal waters only at temperatures below 28°c. Experimental work indicates that 28°c represents the temperature at which snail activity is first curtailed when temperatures are progressively raised. Although the reduction in available oxygen found at high temperatures appears to have some effect on snail activity, the increase in temperature itself is the major factor depressing activity and consequently limiting snail distribution. No difference in the temperature at which activity is reduced has been found between snails living at different environmental temperatures. When temperature was raised 1°c/24 hours, heat death occurred at 30–32°c.  相似文献   

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