Imposex in Japanese gastropods (neogastropoda and mesogastropoda): Effects of tributyltin and triphenyltin from antifouling paints

In Japan, marine pollution by organotin compounds is serious and imposex is known to occur in marine gastropods. However, a detailed survey on imposex had not previously been conducted. The first country-wide survey and laboratory experiments on imposex in Japanese gastropods has now been carried out, and the results are reported herein.     

Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers

Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 microug L(-1) Irgarol vs. > 200 microg L(-1) M1; S. costatum, 0.29 microg L(-1) Irgarol vs. 11.32 microg L(-1)M1; and T. pseudonana, 0.41 microg L(-1) Irgarol vs. 16.50 microg L(-1)M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.     

Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers

Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 μg L⁻¹ Irgarol vs. >200 μg L⁻¹ M1; S. costatum, 0.29 μg L⁻¹ Irgarol vs. 11.32 μg L⁻¹ M1; and T. pseudonana, 0.41 μg L⁻¹ Irgarol vs. 16.50 μg L⁻¹ M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.     

Natural antifouling compounds produced by a novel fungus Aureobasidium pullulans HN isolated from marine biofilm

A fungus, Aureobasidium pullulans, was isolated from marine biofilm and identified. A bioassay-guided fractionation procedure was developed to isolate and purify antifouling compounds from A. pullulans HN. The procedure was: fermentation broth—aeration and addition of sodium thiosulfate–graduated pH and liquid–liquid extraction—SPE purification—GC–MS analysis. Firstly, the fermentation broth was tested for its toxicity. Then it was treated with aeration and addition of sodium thiosulfate, and its toxicity was almost not changed. Lastly, antifouling compounds were extracted at different pH, the extract had high toxicity at pH 2 but almost no toxicity at pH 10, which suggested the toxicants should be fatty acids. The EC₅₀ of the extract against Skeletonema costatum was 90.9 μg ml⁻¹, and its LC₅₀ against Balanus amphitrete larvae was 22.2 μg ml⁻¹. After purified by HLB SPE column, the EC₅₀ of the extract against S. costatum was 49.4 μg ml⁻¹. The myristic and palmitic acids were found as the main toxicants by GC–MS.     

Acute toxicities of five commonly used antifouling booster biocides to selected subtropical and cosmopolitan marine species

Since 1990s, various booster biocides have been increasingly used as substitutes of organotins. However, knowledge about their toxicities on tropical/sub-tropical marine species is significantly lacking. This study comprehensively investigated the acute toxicities of copper, tributyltin (TBT), and five commonly used booster biocides including Irgarol, diuron, zinc pyrithione (ZnPT), copper pyrithione (CuPT) and chlorothalonil on the growth or survival of 12 marine species in which eight of them are native species of subtropical Hong Kong. We found that Irgarol was more toxic than TBT on the growth of autotrophic species. The toxicity of CuPT was comparable to that of TBT on almost all test species, while it showed higher toxicity than TBT on medaka fish larvae. As the usage of these biocides is expected to further increase worldwide, accurate assessments of their ecological risks are required for better informed decision on their management. This study provided useful datasets for such purposes.     

The effects of a copper-based antifouling paint on mortality and enzymatic activity of a non-target marine organism

Antifouling paints are used on a wide range of underwater structures in order to protect them from the development of fouling organisms. The leaching of the toxic substances from the matrix of the paint causes toxic effects not only to the fouling organisms but also on other "non-target" biota. The present study addresses the impact of the antifouling paint Flexgard VI-II on brine shrimp nauplii selected as convenient test organisms. The surface to volume (S/V) concept developed by Persoone and Castritsi-Catharios (1989) was used to determine S/V-LC50s for the test biota exposed to PVC test panels of 400-1000 mm2 surface coated with the antifouling paint in test vessels containing 20 ml seawater. Total ATPase and Mg2+-ATPase were also analyzed for coated surface areas inducing less than 50% mortality in the brine shrimp nauplii. The calculated S/V-LC50 (24 h) was 24.6 mm2/ml, which shows the high toxic character of the antifouling paint. Decreased enzymatic activities were noted in the brine shrimp nauplii exposed to test panels of 50 and 100 mm2 in 20 ml seawater. The present study indicates that the "surface to volume" concept is an interesting methodology that can be applied with both lethal and sublethal effect criteria for the determination of toxic stress from leaches of painted surfaces.     

Effects of antifouling biocides to the germination and growth of the marine macroalga, Hormosira banksii (Turner) Desicaine

The International Maritime Organisation's (IMO) ban on the use of tributyltin in antifouling paints has inevitability increased the use of old fashioned antifoulants and/or the development of new paints containing 'booster biocides'. These newer paints are intended to be environmentally less harmful, however the broader environmental effects of these 'booster biocides' are poorly known. Germination and growth inhibition tests using the marine macroalga, Hormosira banksii (Turner) Desicaine were conducted to evaluate the toxicity of four new antifouling biocides in relation to tributyltin-oxide (TBTO). Each of the biocides significantly inhibited germination and growth of Hormosira banksii spores. Toxicity was in increasing order: diuron < zineb < seanine 211< zinc pyrithione < TBTO. However, the lack of knowledge on partitioning in the environment makes it difficult to make a full assessment on whether the four biocides tested offer an advantage over organotin paints in terms of environmental impact.     

Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies

The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed. Copper release rates were measured on several self-polishing, tin-free coatings and an ablative Cu reference coating applied to steel panels using three measurement methods. The panels were exposed in natural seawater in San Diego Bay, and release rates were measured both in the laboratory and field over 2 years. Results with the static (20 cm x 30 cm) panels indicated that Cu release rates were initially high (25-65 microg Cu cm(-2)day(-1)), with a large range of values between paint types. Release rates declined to substantially lower rates (8-22 microg cm(-2)day(-1)) with reduced variability within 2 months. Release rates continued to decrease over time for approximately 6 months when relatively constant release rates were observed for most coatings. Over time, relative differences in Cu release rates measured by three exposure methods decreased, with all coatings exhibiting similar behavior toward the end of the study. Lowest overall Cu release rates were observed with the self-polishing experimental paint no. 7 in static-dynamic and in situ treatments. The highest periodic release rates were measured from panels that experienced periods of both static and dynamic exposure (8.7 ms(-1) rotation). The lowest release rates were measured from panels that experienced static, constant depth exposure, and where release rates were evaluated in situ, using a novel diver-deployed measurement system. Results from this in situ technique suggests that it more closely reflects actual Cu release rates on vessel hulls measured with intact natural biofilms under ambient conditions than measurements using standardized laboratory release rate methods. In situ measurements made directly on the AF surface of vessels demonstrated typically lower release rates than from the panel studies, averaging 8.2 microg cm(-2)day(-1) on pleasure craft, and 3.8 microg cm(-2)day(-1) on Navy vessels. The data suggest that the presence of an established biofilm likely serves to moderate the release of Cu from field-exposed antifouling coatings both on panels and hull surfaces.     

Evaluation of nonwoven polypropylene oil sorbents in marine oil-spill recovery

Mechanical recovery of oil by oil sorbents is one of the most important countermeasures in marine oil-spill response. Polypropylene is the ideal material for marine oil-spill recovery due to its low density, low water uptake and excellent physical and chemical resistance. Different forms of polypropylene nonwoven sorbents were evaluated in this study in terms of initial oil-sorption capacities and oil-retention properties. The investigation revealed that the fibre diameter, sorbent porosity and oil property are the most important factors in the oil-sorption performance of polypropylene nonwoven sorbents.     

Butyltin compounds,sterility and imposex assessment in Nassarius reticulatus (Linnaeus, 1758), prior to the 2008 European ban on TBT antifouling paints,within Basque ports and along coastal areas

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^?1 – 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.     

Evaluation of the presence of major anionic surfactants in marine sediments

The contamination of aquatic environments has become the focus of increasing regulation and public concern due to their potential and unknown negative effects on the ecosystems. The present work develops a monitoring and statistical study, based on the analysis of variance test (ANOVA) and the multivariable analysis, both for insoluble soap and LAS in order to compare the behavior of different anionic surfactants in this environmental compartment. First, a novel and successfully validated methodology to analyze insoluble soap in these samples is developed. The matrix effect and the comparison of different extraction techniques were also performed. The optimized analytical methodologies were applied to 48 representative samples collected from the Almeria Coast (Spain) and then a statistical analysis to correlate anionic surfactant concentration and several variables associated with marine sediment samples was also developed. The results obtained showed relevant conclusions related to the environmental behavior of anionic surfactants in marine sediments.     

Possible use of non-toxic industrial spillage as a hydrographic tracer

There is a lack of information on deep water or bottom drift in the Firth of Clyde. Dust spillage from the iron ore unloading terminal at Hunterston in the inner Firth offers an opportunity for tracing bottom water movements by determination of ferric oxide levels in the sediments.     

Forecasting models to quantify three anthropogenic stresses on coral reefs from marine recreation: anchor damage, diver contact and copper emission from antifouling paint

This research focuses on damage to coral reefs from three anthropogenic stresses: the dropping of anchors and their chains, human contact, and emission of copper from antifouling paints. Forecasting models are described that quantify degradation in terms of percentage of coral cover damaged/year or increasing levels of water toxicity/year. The models utilize a Monte Carlo simulation that applies a range of values or a probability distribution to each of the numerous uncertain variables. This model has the flexibility to adapt, and become more accurate, when users input assumptions specific to their diving sites. Given our specific assumptions for a frequently visited site, anchors and their chains forecast a distribution of coral reef cover damage with a mean of 7.11%+/-4.77%, diver contact forecast a distribution of coral reef cover damage with a mean of 0.67%+/-0.38%, and antifouling paint forecast a distribution of copper level increase in the water with a mean of 0.037+/-0.014ppb. The results support recommendations for the implementation and sustained use of several specific marine recreation practices.     

A practical ranking system to compare toxicity of anti-fouling paints

The toxicity of a number of new anti-fouling paints, claimed to function by physical means and not by leakage of toxic substances, have been tested on two common organisms in the Baltic Sea, i.e., the red macro alga Ceramium tenuicorne and the copepod Nitocra spinipes. In order to compare the toxicity between the paints a ranking system was developed based on the EC₅₀- and LC₅₀-values. The results showed a wide span in toxicity with the most toxic paints ranked 160 times more toxic than the ones ranked least toxic.

Also, TBT, irgarol and diuron, which have been used as active ingredients in traditional anti-fouling paints, were used to evaluate the sensitivity of the two test organisms. The results showed that the test organisms were equally sensitive to the substances as similar organisms in earlier studies.

In conclusion, the ranking system presented in this study permits ranking and comparison of total toxicity of complex mixtures.     

Inhibition of coral photosynthesis by the antifouling herbicide Irgarol 1051

International regulation of organotin compounds for use in antifouling paints has led to the development and increased use of replacement compounds, notably the s-triazine herbicide Irgarol 1051. Little is known about the distribution of Irgarol 1051 in tropical waters. Nor has the potential impact of this triazine upon photosynthesis of endosymbiotic microalgae (zooxanthellae) in corals been assessed. In this study Irgarol 1051 was detected in marinas, harbours and coastal waters of the Florida Keys, Bermuda and St. Croix, with concentrations ranging between 3 and 294 ng 1(-1). 14C incubation experiments with isolated zooxanthellae from the common inshore coral Madracis mirabilis showed no incorporation of H14CO3- from the sea water medium after 4-8 h exposure to Irgarol 1051 concentrations as low as 63 ng 1(-1). Reduction in net photosynthesis of intact corals was found at concentrations of l00 ng 1(-1) with little or no photosynthesis at concentrations exceeding 1000 ng 1(-1) after 2-8 h exposure at all irradiances. The data suggest Irgarol 1051 to be both prevalent in tropical marine ecosystems and a potent inhibitor of coral photosynthesis at environmentally relevant concentrations.     

Effects of new antifouling compounds on the development of sea urchin

Tributyltin oxide (TBTO) has been used worldwide in marine antifouling paints as a biocide for some time. However, it produced toxic effects, especially in marine water/sediment ecosystems. Consequently, its use in antifouling paints has been prohibited in many countries. In this study, the toxicity of alternative and/or new antifouling biocides compared with TBTO is assessed by a biological method. The effects of these chemicals on marine species have not been well studied. This paper assesses, comparatively, the effects of eight biocides on sea urchin eggs and embryos. The chemicals assessed were TBTO, Irgarol 1051, M1 (the persistent degradation product of Irgarol), Diuron, zinc pyrithione, 'KH101', 'Sea-Nine 211', and copper pyrithione. For these chemicals, toxicity appears to be in the order zinc pyrithione > Sea-Nine 211 > KH101 > copper pyrithione > TBTO > Diuron approximately = Irgarol 1051 > M1. Here, we show that zinc pyrithione, Sea-Nine 211, KH101, and copper pyrithione are much more toxic to sea urchins than TBTO or the other chemicals.     

A study on the treatment of antifouling paint waste from shipyard

A study on the treatment of antifouling paint waste from shipyards, including sandblast waste and ship hull washing wastewater, was performed. The sandblast waste could be effectively detoxified by heat treatment, and the efficiency was affected by the temperature of the heating vessel and treatment time. The removal efficiency of total organotin compounds from the sandblast waste was over 99% at 1000 °C and treatment for 1 h. For the treatment of ship hull washing wastewater by the solvent extraction, ship diesel was a good solvent for the tributyltin (TBT) extraction, and the proper amount of solvent was about 10 mL for TBT extraction from 1 L of wastewater. The extraction efficiency of TBT was significantly affected by the agitation intensity. The TBT in the wash wastewater was rapidly extracted within 1 h. The level of the TBT residual in the wastewater extracted for 1 h was 2.8 μg L⁻¹, and this was further decreased to 0.8 after 5 h extraction.     

Contamination of Caribbean coastal waters by the antifouling herbicide Irgarol 1051

Irgarol 1051 is a s-triazine herbicide used in popular slime-resistant antifouling paints. It has been shown to be acutely toxic to corals, mangroves and sea grasses, inhibiting photosynthesis at low concentrations (>50 ng l(-1)). We present the first data describing the occurrence of Irgarol 1051 in coastal waters of the Northeastern Caribbean (Puerto Rico (PR) and the US Virgin Islands (USVI)). Low level contamination of coastal waters by Irgarol 1051 is reported, the herbicide being present in 85% of the 31 sites sampled. It was not detected in water from two oceanic reference sites. In general, Irgarol 1051was present at concentrations below 100 ng l(-1), although far higher concentrations were reported at three locations within Benner Bay, USVI (223-1,300 ng l(-1)). The known toxicity of Irgarol 1051 to corals and sea grasses and our findings of significant contamination of the Northeastern Caribbean marine environment by this herbicide underscore the importance of understanding, more fully, local and regional exposure of reef and sea grass habitats to Irgarol 1051 and, where necessary, implementing actions to ensure adequate protection of these important ecosystems.