Adsorption of tributyltin by tributyltin resistant marine Pseudoalteromonas sp. cells

The isolate, Pesudoalteromonas sp. TBT1, could grow to overcome the toxicity of tributyltin chloride (TBTCl) up to 30 μM in the absence of Cl⁻ in the medium until the cells reached an exponential phase of growth. The viability, however, was reduced after the cells reached a stationary phase. The degradation products, such as dibutyltin (DBT) and monobutyltin (MBT), were not detected in the growth medium, indicating that the isolate has no ability to degrade TBT into less toxic DBT and MBT. Up to about 10^7.5 TBT molecules were adsorbed by a single cell. The observation of morphological changes with an electron microscope showed that the cell surface became wrinkled after exposure to the lethal concentration of 10 mM TBTCl. These results indicate that the resistance of the isolate toward the toxicity of TBTCl is not related to the unique cell surface, which seems to play an important role in preventing the diffusion of TBTCl into the cytoplasm.     

Adsorption of tributyltin by tributyltin resistant marine Pseudoalteromonas sp. cells

The isolate, Pesudoalteromonas sp. TBT1, could grow to overcome the toxicity of tributyltin chloride (TBTCl) up to 30 microM in the absence of Cl(-) in the medium until the cells reached an exponential phase of growth. The viability, however, was reduced after the cells reached a stationary phase. The degradation products, such as dibutyltin (DBT) and monobutyltin (MBT), were not detected in the growth medium, indicating that the isolate has no ability to degrade TBT into less toxic DBT and MBT. Up to about 10(7.5) TBT molecules were adsorbed by a single cell. The observation of morphological changes with an electron microscope showed that the cell surface became wrinkled after exposure to the lethal concentration of 10 mM TBTCl. These results indicate that the resistance of the isolate toward the toxicity of TBTCl is not related to the unique cell surface, which seems to play an important role in preventing the diffusion of TBTCl into the cytoplasm.     

Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.     

Toxicity of tributyltin in the marine mollusc Mytilus edulis

Our previous studies have demonstrated that tributyltin (TBT) is genotoxic to the early life stages of marine mussels and worms. Here, the toxicity of TBT to adult organisms was determined using a suite of biomarkers designed to detect cytotoxic, immunotoxic and genotoxic effects. Exposure of adult mussels, Mytilus edulis, to environmentally realistic concentrations of TBTO for 7 days resulted in a statistically significant decrease in cell viability at concentrations of 0.5 μg/l and above. TBT had no effect on phagocytic activity or antioxidant capacity (FRAP assay). There was a statistically significant increase in DNA damage detected using the comet and micronucleus assays between the controls and 0.5, 1 and 5 μg/l of TBTO (P > 0.0005). Furthermore there was a strong correlation between DNA strand breaks (comet assay) and formation of micronuclei (P = 0.0005; R² = 61.5%). Possible mechanisms by which TBT could damage DNA either directly or indirectly are discussed including the possibility that TBT is genotoxic due to its ability to disrupt calcium homeostasis.     

Removal of tributyltin (TBT) by live and dead microalgal cells

The removal of tributyltin (TBT) from artificial wastewater by dead and live cells of four microalgal species, Chlorella miniata, C. sorokiniana, Scenedesmus dimorphus and S. platydiscus was investigated. Dead cells were generally more efficient in removing TBT during three days exposure. More than 90% and 85% TBT were removed by dead cells of Scenedesmus and Chlorella, respectively. Although the removal percentages of live microalgae were smaller, TBT was continuously absorbed and degraded, and TBT removal percentages similar to respective dead cells were achieved at the end of 14 days treatment. Degradation products, DBT and MBT, were recorded mainly inside the cells, and intracellular MBT concentrations were significantly higher than DBT. In terms of TBT removal, Scenedesmus cells were more effective than Chlorella, probably due to larger cell sizes and biomass. However, TBT specific uptake and degradation by Chlorella was higher than in Scenedesmus. The highest specific TBT uptake values, as well as the highest degradation, were recorded in C. miniata, a Hong Kong isolate.     

Assessment of organotin (butyltin species) contamination in marine biota from the Eastern Aegean Sea, Turkey

The marine environment continues to be adversely affected by tributyltin (TBT) release from maritime traffic. Therefore the concentrations of TBT, dibutyltin (DBT) and monobutyltin (MBT) were measured in barnacles, mussels and fish along the Eastern Aegean coastline. The average concentrations of TBT ng Sn g⁻¹ were found to be 235 in fish, 116 in mussels and 635 in barnacles. The highest concentrations of TBT, DBT and MBT were observed in the barnacles which had been sampled in marinas and harbors. All mussels sampled showed values of TBT + DBT, which were below the “tolerable average residue level (TARL)” as currently accepted. This indicates a lack of risk to the consumer. However, 7 out of the 15 fish sampled displayed TBT + DBT levels above the TARL, which indicates that a fish consumer group may be at risk. Barnacles have high potential as biomonitors for the presence of organotin in the Aegean Sea.     

TBT toxicity on the marine microalga Nannochloropsis oculata

Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l⁻¹) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC₅₀ (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed.     

Assessment of tributyltin contamination in a shipyard area using a mussel transplantation approach

Mussels (Mytilus galloprovincialis) were transplanted to seven stations around a large shipyard for 126 days to evaluate tributyltin (TBT) contamination. Although the application of TBT-based paints to ships is totally banned in Korea, butyltin compounds were found to accumulate in mussels following transplantation. Concentrations of TBT and total butyltins in transplanted mussels near the shipyard were in the range of 40–350 ng Sn/g and 74–530 ng Sn/g on a dry weight basis, respectively. Obviously, low TBT concentrations (6.0–53 ng Sn/g dw) were determined in mussels at four stations outside the shipyard. A negative gradient of TBT concentrations and TBT portion to total butyltin concentrations were found in both the surface water and transplanted mussels according to distance from the shipyard. In addition, TBT concentrations in surface water and transplanted mussels showed significant correlation (r² = 0.71; p < 0.001). These results indicate that the shipyard still releases fresh TBT into surrounding waters even after TBT regulation in Korea, and mussel transplantation is useful in evaluating TBT contamination in shipyard area.     

Chronic effects of tributyltin on the caprellid amphipod Caprella danilevskii

In order to examine the biological effects by TBT exposure, experiments involving the exposure of five levels of TBT concentrations (0, 10, 100, 1000 and 10,000 ngl(-1)) were conducted on the caprellid amphipod Caprella danilevskii, over a generation after hatching. Marked delays in growth and molting during the early developmental stage and maturation were found in both 100 and 1000 ng TBTCl l(-1) concentrations in spite of the sex. All specimens died in 10,000 ng TBTCl l(-1) within 4 days after hatching. Inhibition of maturation and reproduction such as delaying in the achievement of maturity and a decrease in the number of juveniles hatched was apparent in 10 and 100 ng TBTCl l(-1) concentrations. Furthermore, brood loss, and failure in egg formation and hatching were observed as the TBT concentration became higher. No significant changes in sex ratio were seen at any of the TBT exposure levels during hatching and maturation in the present study. This phenomenon was different from a previous study in which the proportion of females was increased with an increase in TBT concentrations in the embryonic exposure experiment. This suggests that sex disturbance is induced during the embryonic stage of the species. A drastic decrease in survival rate was observed at 10 ng TBTCl l(-1) (25%) which corresponds to the mean level in coastal waters. Therefore, the present encountering ambient TBT concentration may influence populations of C. danilevskii in the coastal environment.     

Baseline of butyltin pollution in coastal sediments within the Basque Country (northern Spain), in 2007-2008

Tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) were measured in surficial sediments at, the ports of Pasaia and Bilbao, together with other mid- and small-size harbours of the Basque Country (northern Spain), in 2007-2008. The highest values of the sum of the three measured butyltin species (3523-3640 ng g⁻¹, as Sn) were found at sampling stations near to shipyards located within the port of Pasaia. The highest value of TBT concentration (3143 ng g⁻¹, as Sn) was found at the marina of Getxo, in the port of Bilbao. The degree of TBT degradation varied greatly between sampling stations, being found to be generally higher in those sediments with higher values of redox potential and lower values of TBT concentration (normalized by organic matter content).     

Distribution of butyltins in the waters and sediments along the coast of India

Water and surface sediment samples were analyzed for butyltins (TBT, DBT, MBT) from various ports along the east and west coast of India. The total butyltin (TB) in water samples varied between ∼1.7 and 342 ng Sn l⁻¹, whereas for sediments it varied between below detection limit to 14861 ng Sn g⁻¹ dry weight of sediment. On an average Chennai port recorded the highest level of butyltins in the sediments while Paradip recorded the highest level of butylins in the waters. A fairly good relationship between the TB in the sediment and overlying water samples, as well as between organic carbon and TB, implicates the importance of adsorption/desorption process in controlling the levels of TBT in these port areas. In India the data on organotin pollution is very sparse; most of the port areas have been surveyed for butyltins for the first time during this study.     

Effects of tributyltin at concentrations below ambient levels in seawater on Caprella danilevskii (Crustacea: Amphipoda: Caprellidae)

Hatched juveniles of Caprella danilevskii (Crustacea: Amphipoda) were exposed to one of two concentrations of tributyltin (TBT) (1.1 and 10.7 ng TBT L⁻¹) for 49 d at 20 °C. These concentrations are near or below ambient levels in seawater. In both treatments and control, the survival rate was 100% at maturation, and >85% at the end of the experiments. Females reached maturation at 20 (median) to 21.5 d at instar VII, and repeated spawning 4–5 times during the experiment. The total number of juveniles per female decreased significantly from 39.5 in the control to 24.5 and 17.5 in 1.1 ng L⁻¹ and 10.7 ng L⁻¹ treatments, respectively. An earlier study reported that as the TBT concentration in seawater increased from a 0–10 ng L⁻¹ regime to a 10–20 ng L⁻¹ regime, the number of stations where Caprella spp. could be collected decreased along the coast of the Seto Inland Sea, of Japan. Thus, the present study indicates the possibility that the extremely low concentration of TBT measured in Japanese waters after 2000 lead to a reduction in reproductive success of Caprella spp.     

Status of butyltin pollution along the coasts of western Japan in 2001, 11 years after partial restrictions on the usage of tributyltin

Restrictions on the use of tributyltin (TBT) in aquaculture and on boats in coastal regions, except for ocean-going vessels, have been in place in Japan since 1990 due to the strong toxic effects of TBT on marine organisms. However, TBT pollution along the Japanese coasts has been reported after this legislation was enacted. In order to elucidate the present status of contamination by butyltin (BT) compounds, we measured the levels of BTs [monobutyltin (MBT), dibutyltin (DBT) and TBT] in seawater and Caprella spp. samples obtained from the western part of Seto Inland Sea, Uwa Sea and Uranouchi Bay in western Japan during March to September, 2001. Butyltins were detected in more than 90% of the seawater samples (n = 59), with average concentrations of 8.2 ± 9.2 (SD) ng MBT L⁻¹, 3.3 ± 3.0 ng DBT L⁻¹ and 9.0 ± 7.0 ng TBT L⁻¹. Among 41 stations situated on coastal lines, a sufficient number of Caprella organisms for chemical analysis could be collected from only 16 stations. The butyltin concentrations in seawater and Caprella samples from Uwa Sea and Uranouchi Bay, in which the dominant industry in both waters is aquaculture, showed significantly higher than or no significant differences from those samples from the western part of Seto Inland Sea, a major heavy-industry area in Japan. As the TBT concentration in seawater increased, the number of Caprella organisms collected decreased. The mean TBT concentration among the seawater samples was above the estimated lowest observable effect concentration (LOEC) that reduces the survival rate of Caprella danilevskii. Thus, the present study indicates that TBT is still a potential ecological hazard to the survival of marine invertebrates inhabiting coasts along western Japan, even 11 years after the partial ban on TBT usage was implemented.     

Testes specific accumulation of tributyltin in turbot Scophthalmus maximus from the southern Baltic Sea

Concentrations of tributyltin (TBT) and its breakdown products, dibutyltin (DBT) and monobutyltin (MTB), were measured in tissues of male turbot Scophthalmus maximus from the Gulf of Gdańsk (GDA) and the Pomeranian Bay (POM) in the southern Baltic Sea. The fish (n = 206) were collected during the spawning seasons of 2008-2009. All specimens were at the same maturity stage and in full breeding condition. The ripe testes of the turbot appeared to be a target tissue for TBT accumulation. We report that TBT is extensively eliminated at the specific whole-body level and that the males from TBT-contaminated location (GDA) reach this specific level at 23-24 cm in total length.     

Evaluation of butyltin compounds in Maryland waters of Chesapeake Bay

A monthly sampling programme for dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TTBT) was initiated for a period of one year (July 1985–June 1986) in the Maryland waters of Chesapeake Bay. Concentrations of the above butyltin species were evaluated in the microlayer and water column of eight sampling stations representing two small and two large marinas, a large harbour, two major river systems and a heavily used shipping channel. DBT concentrations in the microlayer were generally higher in the four marinas when compared with the other stations. The highest DBT concentration reported in the microlayer was 1156 ng l⁻¹. Mean microlayer TBT concentrations ranged from 54–310 ng l⁻¹ in the four marinas. Three TBT concentrations ranging from 1049–1171 ng l⁻¹ were reported in the microlayer of the marinas. TBT concentrations of 41 and 29 mg l⁻¹ were detected in the microlayer of a heavily used shipping channel (C & D Canal) during May and June. TTBT concentrations were not detected in the microlayer at most stations during the 12 month sampling period.Mean DBT concentrations in the water column ranged from 23–145 ng l⁻¹ in the four marinas. DBT concentrations in the water column of the other stations were < 35 ng l⁻¹. Mean water column concentrations of TBT ranged from 51–408 ng l⁻¹ in all four marinas. Peak concentrations of TBT were reported in May and June for the various marinas. The highest TBT concentration reported in the water column was 998 ng l⁻¹. TBT concentrations of 20–24 ng l⁻¹ were reported in one of the river systems (Potomac River). TTBT concentrations were not detected in the water column at most of the stations.     

Decade-long monitoring reveals a transient distortion of baseline butyltin bioaccumulation pattern in gastropods

Worldwide measures to restrict tributyltin (TBT) in antifouling paints have been legislated for decades, and were upgraded to a total ban on September 2008. With a view to test the response of coastal biota to changing pollution, since 1996 we have determined the concentration of TBT and derivatives di- and mono-butyltin (DBT and MBT) in NW Spain populations of two gastropods of contrasting biology, the rock-snail Nucella lapillus (n = 18) and the mud-snail Nassarius reticulatus (n = 24). TBT pollution in the study area has decreased consistently and considerably over time. In addition, the baseline butyltin (BT) bioaccumulation patterns showed a marked but transient distortion. These field observations are consistent with BT desorption from sediments, a natural phenomenon that is now to be expected in developing countries recently subject to the global TBT ban.     

Imposex levels and concentrations of organotin compounds (TBT and its metabolites) in Nassarius nitidus from the Lagoon of Venice

Specimens of Nassarius nitidus were collected in seven stations of the Venice Lagoon to assess the levels of tributyltin (TBT) and its metabolites monobutyltin and dibutyltin in the tissues and monitor their effect on organisms, in particular the phenomenon of imposex (superimposition of male sexual characteristics on females). The following values of population indices were found: vas deferens sequence: 1.2 ± 0.7–4.0 ± 0.5; relative penis length: 6–47%. The least impacted station was situated in the northern part of the Lagoon, where females without imposex were found and Butyltin (BuTs) concentrations in the organisms (average sum of BuTs = 43 ± 14 ng Sn g⁻¹ w.) were significantly lower than in the other stations (range of average sum of BuTs: 101 ± 22–217 ± 27 ng Sn g⁻¹ d.w.). Population indices were found to be related to the TBT content in the tissues. In particular VDSI had a significant logarithmic correlation: r = 0.95, n = 8, p < 0.05.     

Continuing observation of disturbed reproductive cycle and ovarian spermatogenesis in the giant abalone, Haliotis madaka from an organotin-contaminated site of Japan

Histological examination of gonads as well as chemical analysis of organotin compounds in tissues of the giant abalone, Haliotis madaka, was conducted to evaluate continuing endocrine disruption in abalone populations in Japan. Abalone specimens were collected from two different areas, Tsushima as a reference site and Jogashima as a site representative of declining abalone populations where serious organotin contamination had been observed, each month from January 1998 to March 1999. Scores were given to the development stages of reproductive cells in the ovary and testis. The degree of sexual maturation was evaluated by calculating the mean value of a histogram of these scores for the reproductive cells of each abalone. The temporal variations in degree of sexual maturation showed that female and male abalone from Tsushima matured synchronously, while those from Jogashima did not, which were similar to results of the previous study during September 1995–November 1996. Approximately 19% of the female abalone from Jogashima were masculinized with an ovo-testis, which was also similar to the result of the previous study. The masculinization of female abalone is reported to be induced by tributyltin (TBT) and triphenyltin (TPhT) from antifouling paints. Concentrations of the sum of butyltins (TBT, dibutyltin (DBT) and monobutyltin (MBT): ΣBTs) and the sum of phenyltins (TPhT, diphenyltin (DPhT) and monophenyltin (MPhT): ΣPhTs) in the muscle of abalone from Jogashima (n = 73) of 7.8 ± 9.0 ng/g wet wt. and 4.5 ± 6.8 ng/g wet wt., respectively, were significantly higher than those from Tsushima (n = 87) of 4.7 ± 4.9 ng/g wet wt. and 0.8 ± 1.7 ng/g wet wt., respectively (p < 0.05 for ΣBTs; p < 0.001 for ΣPhTs), although concentrations of TBT and TPhT in the muscle of abalone from Jogashima (n = 73) of 2.2 ± 2.5 ng/g wet wt. and 5.8 ± 5.1 ng/g wet wt., respectively, were insignificantly and significantly higher than those from Tsushima (n = 87) of 0.4 ± 0.6 ng/g wet wt. and 0.5 ± 0.9 ng/g wet wt., respectively, (p > 0.05 for TBT; p < 0.001 for TPhT). Thus, endocrine disruption as well as contamination by organotins in the giant abalone from Jogashima is still persisting.     

Effect of prolonged hypoxia on food consumption, respiration, growth and reproduction in marine scavenging gastropod Nassarius festivus

The effects of prolonged exposure to reduced oxygen levels (3.0 and 1.5 mg O₂ l⁻¹) on marine scavenging gastropods Nassarius festivus were studied for 8 weeks. The percentages of individuals engaged in feeding and amount of food consumed were reduced as oxygen level decreased; absorption efficiency, however, did not vary significantly with oxygen level. Oxygen consumption rates and specific oxygen consumption rates were lower at reduced oxygen levels. Reproduction occurred at all oxygen levels with less egg capsules being produced at lower oxygen levels. Egg size and number of eggs per capsule, however, were not significantly affected by oxygen level. The increase in shell length was 12%, 6% and 5% at 6.0 mg O₂ l⁻¹ (normoxia), 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹, respectively. At the end of the experiment, the amount of energy allocated to growth and reproduction decreased at reduced oxygen levels with values obtained at 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹ being 48% and 70% lower than those at 6.0 mg O₂ l⁻¹. At all oxygen levels, most of the accumulated energy was allocated to shell growth and reproduction, and the amount allocated to somatic growth was relatively insignificant. The reduction in energy allocated to reproduction was greater than that to shell growth as the oxygen level was reduced, indicating a strategic energy allocation of marine scavengers under stressful conditions to enhance survival.