Composition dynamics of epilithic intertidal bacterial communities exposed to high copper levels

Copper has a dual role for organisms, both as micronutrient and toxic element. Copper mining activities have an enormous ecological impact because of the extraction process and the consequent release of copper-containing waste materials to the environment. In northern Chile, mainly in the Cha?aral coastal area, this phenomenon is clearly evident. The released waste material has caused a strong modification of the area, and copper enrichment of beaches and rocky shores has provoked a decrease in the richness and diversity of many species of macroorganisms. However, the effects that copper enrichment has on microbial (e.g. bacterial epilithic) communities associated with the rocky shore environment are poorly understood. Using a culture-independent molecular approach, field sampling and laboratory microcosm experiments, we determined the effects of copper enrichment on bacterial communities inhabiting the rocky shore environment. Field samples showed a strong effect of copper on the structure of the natural bacterial epilithic communities, and microcosm experiments demonstrated rapid changes in bacterial community when copper is added, and reversibility of this effect within 48?h after copper is removed.     

Aquatic pollution increases the relative success of invasive species

Although individual ecosystems vary greatly in the degree to which they have been invaded by exotic species, it has remained difficult to isolate mechanisms influencing invader success. One largely anecdotal observation is that polluted or degraded areas will accumulate more invaders than less-impacted sites. However, the role of abiotic factors alone in influencing invisibility has been difficult to isolate, often because the supply of potential invaders is confounded with conditions thought to increase vulnerability to invasion. Here, we conducted a field experiment to test how the assemblages of exotic versus native marine invertebrates changed during community assembly under different exposure levels of a common pollutant, copper. The experiment was conducted by deploying fouling panels in a Randomized Block Design in San Francisco Bay. Panels were periodically removed, placed into buckets with differing copper concentrations, and returned to the field after 3 days. This design allowed propagule availability to the plates to be statistically independent of short-term copper exposure. The results demonstrate that copper caused significant differences in community structure. Average native species richness was significantly affected by copper exposure, but average exotic richness was not. The total native species pool within treatments exhibited a greater than 40% decline within increasing copper, while the exotic species pool did not change significantly. These results confirm that anthropogenic alteration of abiotic factors influences invader success, indicating that management strategies to reduce invader impacts should include both efforts to improve environmental conditions as well as reduce invader supply.     

Environmental and ecological changes associated with a marina

Anthropogenic modifications to waterways are common and their ecological consequences must be understood to effectively conserve local biodiversity. The facilitation of recreational boating activities often requires substantial alteration of natural areas, however the environmental and ecological consequences of such alterations are rarely described in the scientific literature. In this study, ecological and physico-chemical conditions were investigated in a recreational boating marina, located inside a marine park on the south-east coast of Australia. Recruitment panels were deployed for 8?weeks both inside and outside the marina, and differences in the composition of the developing fouling communities were observed. The recruitment of taxa, which often have short-lived larvae, was increased inside the marina (bryozoans, spirorbids and sponges) while the recruitment of taxa, which often have longer-lived larvae, was reduced or absent (barnacles, solitary ascidians and non-spirorbid polychaetes). Differences were also observed in environmental conditions inside the marina cf. directly outside. The marina environment had higher turbidity, temperature and pH along with higher concentrations of lead and copper in suspended sediments, while flow rates and trapped sediment loads were reduced inside the marina. The differences observed in the study suggest that there may be marked environmental changes associated with marina developments. The potential ecological consequences of these changes should be a primary consideration during the planning process, particularly for developments in locations of notable ecological value.     

Initial Copper Stress Strengthens the Resistance of Soil Microorganisms to a Subsequent Copper Stress

To improve the prediction of essential ecosystem functioning under future environmental disturbances, it is of significance to identify responses of soil microorganisms to environmental stresses. In this study, we collected polluted soil samples from field plots with eight copper levels ranging from 0 to 3,200 mg Cu kg^?1 soil. Then, the soils with 0 and 3,200 mg Cu kg^?1 were selected to construct a microcosm experiment. Four treatments were set up including Cu0-C and Cu3200-C without further Cu addition, and Cu0-A and Cu3200-A with addition of 57.5 mg Cu kg^?1 soil. We measured substrate-induced respiration (SIR) and potential nitrification rate (PNR). Furthermore, the abundance of bacterial, archaeal 16S rRNA genes, ammonia-oxidizing bacteria and archaea amoA genes were determined through quantitative PCR. The soil microbial communities were investigated by terminal restriction fragment length polymorphism (T-RFLP). For the field samples, the SIR and PNR as well as the abundance of soil microorganisms varied significantly between eight copper levels. Soil microbial communities highly differed between the low and high copper stress. In the microcosm experiment, the PNR and SIR both recovered while the abundance of soil microorganisms varied irregularly during the 90-day incubation. The differences of microbial communities measured by pairwise Bray–Curtis dissimilarities between Cu0-A and Cu0-C on day 0 were significantly higher after subsequent stress than before. However, the differences of microbial communities between Cu3200-A and Cu3200-C on day 0 changed little between after subsequent stress and before. Therefore, initial copper stress could increase the resistance of soil microorganisms to subsequent copper stress.     

Influence of hydrodynamic stress on the frictional drag of biofouling communities

The role of hydrodynamic wall shear stresses on the development of the fouling community structure and resulting frictional drag were examined using a commercially available fouling release coating. Immersed test panels were exposed to three different hydrodynamic treatments, one static and two dynamic (corresponding to an estimated wall shear stress of 7.0 and 25.5 Pa). The drag of the panels was measured in a hydrodynamic test chamber at discrete time intervals over 35 days. The fouling community composition on the static panels was significantly different from the organisms observed on the dynamic panels. Despite different fouling community composition, the drag forces measured on the panels were very similar. This suggests that the frictional drag of low form and soft fouling communities are similar and that there may be a stepwise increase in frictional drag associated with the presence of mature calcareous organisms.     

Effects of sediment type on macrobenthic infaunal colonization of laboratory microcosms

We tested the effects of four different sediment types collected from northern Gulf of Mexico estuarine systems on macroinfaunal colonization and community development in our laboratory flow-through microcosm system. Four sediments, types included , a beach sand, two fine-grained muds, but from different locations, and a 50:50 mixture of one of the mud sediments and beach sand. Our hypothesis was that the pattern of colonization would differ among sediment types based on empirical field data and theory but the differences would be expressed most strongly at sediment type extremes (e.g., mud versus sand). A total of 49 taxa colonized the four sediments. Unidentified Actiniaria (sea anemones) numerically dominated densities among all four sediments with densities ranging between 46.5 to 60.5 per microcosm (20 cm side^–1). Average taxa richness per microcosm (N: 10 replicates per sediment treatment) ranged from 10.4 in one of the mud treatments to 14.9 taxa in the sand. These were the only significant differences among sediment types (P0.05) in taxa richness and we detected no significant effects of sediment type on animal densities. Differences in community metrics, although statistically significant, were generally of a relatively small magnitude. Five of 10 microcosms per treatment were randomly selected to test for effects of sediment depth (e.g., top, mid, and bottom). In vertically sectioned microcosms, average taxa richness in sand treatments was significantly greater than those of the other three sediments. A non-parametric multivariate analysis (Primer) revealed that community structure in the vertically sectioned microcosms differed significantly between sand and one of the mud treatments. Mean taxa richness of top sections differed significantly from mid and bottom sections. We detected significantly higher animal densities and taxa richness (p0.05) in vertically sectioned versus non-sectioned microcosms. However, these differences were unexplained based on experimental protocols.     

The use of aeration as a simple and environmentally sound means to prevent biofouling

Biofouling is a major problem faced by marine industries. Physical and chemical treatments are available to control fouling, but most are costly, time consuming or negatively affect the environment. The use of aeration (ie continuous streams of air bubbles) to prevent fouling was examined. Experiments were conducted at three sites with different benthic communities. Experimental panels (10 cm × 10 cm; PVC and concrete) were deployed with or without aeration. Aeration flowed continuously from spigots 0.5 m below the panels at a rate of ～3.3 to 5.0 l min^?1. After 1 and 4 weeks, aerated PVC panels from all sites had significantly less fouling than non-aerated controls. Aeration reduced fouling on both the PVC and concrete surfaces. Fouling was reduced on panels directly in bubble streams while panels 30 cm and 5 m away had significantly more fouling. Thus, under the conditions used in this study, aeration appears to be an effective and simple way to prevent fouling.     

Eukaryotic picophytoplankton community response to copper enrichment in a metal‐perturbed coastal environment

Copper is an essential micronutrient, especially for photosynthetic organisms, but can be toxic at high concentrations. In the past years, coastal waters have been exposed to an increase in copper concentration due to anthropogenic inputs. One well known case is the Chañaral area (Easter South Pacific coast), where a long term coastal copper enrichment event has occurred. That event strongly affected benthic marine diversity, including microbial communities. In this work, microcosm experiments were carried out to address the changes on picophytoplankton community composition of the disturbed area, when challenged to copper additions. Eukaryotic picophytoplankton communities from two areas were analyzed: one in the most copper‐perturbed area and another at the north edge of the perturbed area. Flow cytometry data showed that 25 μg L^?1 of copper addition exerted a positive effect in the growth kinetics on part of the eukaryotic picophytoplankton communities, independently of the site. 16S‐plastid terminal restriction fragment length polymorphisms analysis suggested that eukaryotic picophytoplankton display a short and directional response to high copper levels. Members of the Prasinophyceae class, a Coscinodiscophyceae diatom, as well as Phaeocystis, respond in a short time to the environmental disturbance, making them excellent candidates for further studies to evaluate phytoplanktonic species as sentinels for copper disturbances in coastal marine ecosystems.     

Effect of biostimulants on 2,4,6-trinitrotoluene (TNT) degradation and bacterial community composition in contaminated aquifer sediment enrichments

2,4,6-Trinitrotoluene (TNT) is a toxic and persistent explosive compound occurring as a contaminant at numerous sites worldwide. Knowledge of the microbial dynamics driving TNT biodegradation is limited, particularly in native aquifer sediments where it poses a threat to water resources. The purpose of this study was to quantify the effect of organic amendments on anaerobic TNT biodegradation rate and pathway in an enrichment culture obtained from historically contaminated aquifer sediment and to compare the bacterial community dynamics. TNT readily biodegraded in all microcosms, with the highest biodegradation rate obtained under the lactate amended condition followed by ethanol amended and naturally occurring organic matter (extracted from site sediment) amended conditions. Although a reductive pathway of TNT degradation was observed across all conditions, denaturing gradient gel electrophoresis (DGGE) analysis revealed distinct bacterial community compositions. In all microcosms, Gram-negative γ- or β-Proteobacteria and Gram-positive Negativicutes or Clostridia were observed. A Pseudomonas sp. in particular was observed to be stimulated under all conditions. According to non-metric multidimensional scaling analysis of DGGE profiles, the microcosm communities were most similar to heavily TNT-contaminated field site sediment, relative to moderately and uncontaminated sediments, suggesting that TNT contamination itself is a major driver of microbial community structure. Overall these results provide a new line of evidence of the key bacteria driving TNT degradation in aquifer sediments and their dynamics in response to organic carbon amendment, supporting this approach as a promising technology for stimulating in situ TNT bioremediation in the subsurface.     

Insights into Deep-Sea Sediment Fungal Communities from the East Indian Ocean Using Targeted Environmental Sequencing Combined with Traditional Cultivation

The fungal diversity in deep-sea environments has recently gained an increasing amount attention. Our knowledge and understanding of the true fungal diversity and the role it plays in deep-sea environments, however, is still limited. We investigated the fungal community structure in five sediments from a depth of ∼4000 m in the East India Ocean using a combination of targeted environmental sequencing and traditional cultivation. This approach resulted in the recovery of a total of 45 fungal operational taxonomic units (OTUs) and 20 culturable fungal phylotypes. This finding indicates that there is a great amount of fungal diversity in the deep-sea sediments collected in the East Indian Ocean. Three fungal OTUs and one culturable phylotype demonstrated high divergence (89%–97%) from the existing sequences in the GenBank. Moreover, 44.4% fungal OTUs and 30% culturable fungal phylotypes are new reports for deep-sea sediments. These results suggest that the deep-sea sediments from the East India Ocean can serve as habitats for new fungal communities compared with other deep-sea environments. In addition, different fungal community could be detected when using targeted environmental sequencing compared with traditional cultivation in this study, which suggests that a combination of targeted environmental sequencing and traditional cultivation will generate a more diverse fungal community in deep-sea environments than using either targeted environmental sequencing or traditional cultivation alone. This study is the first to report new insights into the fungal communities in deep-sea sediments from the East Indian Ocean, which increases our knowledge and understanding of the fungal diversity in deep-sea environments.     

Temperature,space availability,and species assemblages impact competition in global fouling communities

Competition drives community composition in many ecosystems and can influence the spread of invasive species. Marine fouling communities are excellent study systems for competition because of space limitation and the abundance of invasive species. While many studies have examined individual or site-specific responses to changes in temperature or presence of invasive species, it is difficult to predict ecological impacts without assessing interspecific interactions over a wide geographic range. This study compared interactions between several globally distributed invasive fouling species over a broad geographic range. Weekly examination of photographs of settlement panels in marinas at 18 sites around the world allowed for the quantification of competitive outcomes. In the north Atlantic, experimental panels became covered with fouling organisms exponentially faster at warmer temperatures, while northeast and south Pacific sites did not. An invasive ascidian (Diplosoma listerianum) and bryozoan (Bugula neritina) were strong competitors, but most species displayed a negative response in high competition settings where there was little available space. Two species (Botryllus schlosseri and Botrylloides violaceus) had better competitive outcomes at cooler temperatures, possibly due to fewer strong competitors at these sites. Thus, warmer sites with little open space and multiple strong competitors are likely most resistant to future invasions, while colder sites with more open space and weaker competitors would be more susceptible to invasive species. These results suggest that the establishment and spread of invasive fouling species is likely to be influence by seawater temperature, available space, and the competitive abilities of community members.     

Alternative community compositional and dynamical states: the dual consequences of assembly history

1. Much work on ecological consequences of community assembly history has focused on the formation of history-induced alternative stable equilibria. We hypothesize that assembly history may affect not only community composition but also population dynamics, with assembled communities differing in species composition potentially residing in different dynamical states. 2. We provided an empirical test of the aforementioned hypothesis using a laboratory microcosm experiment that manipulated both the colonization order of three bacterivorous protist species in the presence of a protist predator and environmental productivity. 3. Both priority effects and random divergence emerged, resulting in two different community compositional states: one characterized by the dominance of one prey species and the other by the extinction of the same prey. While communities in the former state exhibited noncyclic dynamics, the majority of communities in the latter state exhibited cyclic dynamics driven by the interaction between another prey and the predator. 4. Temporal variability of total prey community biovolume consequently differed among communities with different histories. 5. Changing productivity altered priority effects on the structure and dynamics of communities experiencing only certain histories. 6. Our results support the dual (compositional and dynamical) consequences of assembly history and emphasize the importance of incorporating the dynamical view into the field of community assembly.     

Life cycle contributions of copper from vessel painting and maintenance activities

Copper-based epoxy and ablative antifouling painted panels were exposed in natural seawater to evaluate environmental loading parameters. In situ loading factors including initial exposure, passive leaching, and surface refreshment were measured utilizing two protocols developed by the US Navy: the dome method and the in-water hull cleaning sampling method. Cleaning techniques investigated included a soft-pile carpet and a medium duty 3M^? pad for fouling removal. Results show that the passive leach rates of copper peaked three days after both initial deployment and cleaning events (CEs), followed by a rapid decrease over about 15 days and a slow approach to asymptotic levels on approximately day 30. Additionally, copper was more bioavailable during a CE in comparison to the passive leaching that immediately followed. A paint life cycle model quantifying annual copper loading estimates for each paint and cleaning method based on a three-year cycle of painting, episodic cleaning, and passive leaching is presented.     

Ecological effects of Irgarol 1051 and Diuron on a coastal meiobenthic community: A laboratory microcosm experiment

After the Tributyltin world ban, Irgarol 1051 and Diuron have been the most commonly used biocides in antifouling paints. When adsorbed to suspended particulate matter or introduced as paint particles, these compounds accumulate in marine sediments and potentially cause ecological damage to benthic organisms. Therefore, a microcosm experiment was designed to evaluate the effects of Irgarol 1051 and Diuron, individually, on a meiofaunal community with emphasis on the dominant nematode assemblages. The experiment tested two factors: “Treatment” (two types of controls and three environmentally relevant concentrations of each contaminant) and “Exposure time” (5, 15 and 30 days). Significant declines in meiofauna density, nematode species richness and diversity, and changes in multivariate community structure were observed for both biocides at all exposure levels when compared to controls. Decreases occurred early on, within five days of exposure, which suggests that mortality, and not sub-lethal effects, has befallen upon the organisms. Sediment chlorophyll a and pheopigment concentrations, and redox potential were monitored to verify any indirect effects to the fauna through changes in the environment and results gave no indications of such mediated effects pointing to a direct toxic effect of both Irgarol and Diuron on the meiofauna. Although contaminated treatments showed a significant decline in the relative abundances of a particular functional group represented by the larger, longer-lived species, we did not observe the typical expected switch to smaller, more opportunistic taxa. Indeed, differences between controls and contaminated treatments were mainly due to an overall reduction in densities of the most abundant species in contaminated treatments. The high mortality (ca. 50% decline in total abundances), changes in community structure and species loss observed at biocide levels frequently encountered in the field suggest Irgarol and Diuron as a threat to benthic communities. Such severe effects contrast to other studies that have detected lower impacts, suggesting the free-living nematodes as potential indicators of marine pollution and the microcosm approach using natural communities as an impending tool for ecotoxicological studies.     

Phytoplankton growth and stoichiometric responses to warming,nutrient addition and grazing depend on lake productivity and cell size

Global change involves shifts in multiple environmental factors that act in concert to shape ecological systems in ways that depend on local biotic and abiotic conditions. Little is known about the effects of combined global change stressors on phytoplankton communities, and particularly how these are mediated by distinct community properties such as productivity, grazing pressure and size distribution. Here, we tested for the effects of warming and eutrophication on phytoplankton net growth rate and C:N:P stoichiometry in two phytoplankton cell size fractions (<30 µm and >30 µm) in the presence and absence of grazing in microcosm experiments. Because effects may also depend on lake productivity, we used phytoplankton communities from three Dutch lakes spanning a trophic gradient. We measured the response of each community to multifactorial combinations of temperature, nutrient, and grazing treatments and found that nutrients elevated net growth rates and reduced carbon:nutrient ratios of all three phytoplankton communities. Warming effects on growth and stoichiometry depended on nutrient supply and lake productivity, with enhanced growth in the most productive community dominated by cyanobacteria, and strongest stoichiometric responses in the most oligotrophic community at ambient nutrient levels. Grazing effects were also most evident in the most oligotrophic community, with reduced net growth rates and phytoplankton C:P stoichiometry that suggests consumer‐driven nutrient recycling. Our experiments indicate that stoichiometric responses to warming and interactions with nutrient addition and grazing are not universal but depend on lake productivity and cell size distribution.     

Energy input and species diversity patterns in microcosms

Numerous studies document some form of relationship between the energy input to a community (or some surrogate for energy input), and the species richness of all, or part, of the community. Although not consistently so, the relationship is commonly either unimodal or positive. However covariation of energy with other environmental factors, in both field and experimental studies, and the timescale of expected population responses to variation in energy, means that testing the patterns is difficult. Here we use laboratory microcosm systems, of protists and bacteria, to examine the response of artificially constructed communities to an energy gradient (6 levels), on a long timescale (up to 421 days), while in parallel examining the responses of each species individually to the environmental conditions across the gradient. The species richness of individual communities (α-diversity) showed positive responses initially, but after longer periods either no relationship, or a modestly unimodal one. When all replicate communities were considered together at each energy level (γ-diversity), there was a more consistently positive relationship, an effect generated by the fact that at low energy the species composition of replicate communities was almost identical, while at high energy there was considerable variation among replicates. Although when each species used in the multispecies systems was exposed to the same energy gradient individually, there were distinct differences in the their responses to the gradient, the patterns of community composition and diversity seen in the multispecies systems could not be explained simply by the individual species' responses to the environmental conditions along the gradient.     

The Microbial Ecology of a Hyper-Alkaline Spring,and Impacts of an Alkali-Tolerant Community During Sandstone Batch and Column Experiments Representative of a Geological Disposal Facility for Intermediate-Level Radioactive Waste

Naturally occurring hyper-alkaline springs and associated hyper-alkaline environments may have components that are analogous to a cement-based deep geological disposal facility (GDF) for intermediate level radioactive waste (ILW). Such high pH environments could give insights into the biogeochemical processes that could occur in the region of a GDF environment after the ingress of GDF-derived groundwater leads to the formation of a hyper-alkaline plume in the surrounding rock mass. This study focuses on the microbial community composition found at a highly alkaline spring near Buxton, Derbyshire, England, and the variation in community structure across spatially separated sample points of contrasting pH values (ranging from pH 7.5–13). Communities containing alkaliphilic and alkalitolerant bacteria were observed across the site by PCR amplification and 16S rRNA gene pyrosequencing and included members of the families Comamonadaceae and Xanthomonadaceae. At pH 13, the sequence library was dominated by Gammaproteobacteria of the families Pseudomonadaceae and Enterobacteriaceae. Bacterial communities from the site demonstrated the ability to reduce Fe(III) in microcosm experiments up to pH 11.5, suggesting the potential to reduce other metals and radionuclides of relevance to cement-encapsulated intermediate level radioactive waste (ILW) disposal. In laboratory column flow-through experiments, microbial communities present at the field site were also able to colonize crushed sandstone. Bacterial community composition varied between columns that had been supplied with alkali surface waters from the site amended with carbon (lactate and acetate, as proxies for products of cellulose degradation from ILW), and control columns that were not supplied with added carbon. Members of the family Clostridiaceae dominated the sequence library obtained from the carbon amended column inlet (45.8% of library), but became less dominant at the outlet (20.8%). Members of the family Sphingomonadaceae comprised 11.8% of the sequence library obtained from the control column inlet, but were not present in sediments collected from the column outlet, whereas the relative abundance of members of the family Comamonadaceae increased from the column inlet (35.2%) to the column outlet (57.2%). The spatial variation in community composition within the columns is indicative of discrete biogeochemical zonation in these flow-through systems.     

Metagenomic Profiling: Microarray Analysis of an Environmental Genomic Library

Genomic libraries derived from environmental DNA (metagenomic libraries) are useful for characterizing uncultured microorganisms. However, conventional library-screening techniques permit characterization of relatively few environmental clones. Here we describe a novel approach for characterization of a metagenomic library by hybridizing the library with DNA from a set of groundwater isolates, reference strains, and communities. A cosmid library derived from a microcosm of groundwater microorganisms was used to construct a microarray (COSMO) containing ~1-kb PCR products amplified from the inserts of 672 cosmids plus a set of 16S ribosomal DNA controls. COSMO was hybridized with Cy5-labeled genomic DNA from each bacterial strain, and the results were compared with the results for a common Cy3-labeled reference DNA sample consisting of a composite of genomic DNA from multiple species. The accuracy of the results was confirmed by the preferential hybridization of each strain to its corresponding rDNA probe. Cosmid clones were identified that hybridized specifically to each of 10 microcosm isolates, and other clones produced positive results with multiple related species, which is indicative of conserved genes. Many clones did not hybridize to any microcosm isolate; however, some of these clones hybridized to community genomic DNA, suggesting that they were derived from microbes that we failed to isolate in pure culture. Based on identification of genes by end sequencing of 17 such clones, DNA could be assigned to functions that have potential ecological importance, including hydrogen oxidation, nitrate reduction, and transposition. Metagenomic profiling offers an effective approach for rapidly characterizing many clones and identifying the clones corresponding to unidentified species of microorganisms.     

Temporal and spatial variations in macrofouling of silicone fouling‐release coatings

Nontoxic, low surface free energy silicone coatings having reduced biofouling adhesion strength have been developed as an alternative to antifouling paints. Silicone coatings permit macrofouling to adhere; however, fouling can be removed easily by water pressure or light scrubbing. One of the current methods used to evaluate the performance of non‐toxic silicone fouling‐release coatings relies heavily on fouling coverage. The organismal community structure as well as total coverage can affect the ease of fouling removal from these coatings. This paper explores fouling coverage and organismal adhesion over time. Long‐term fouling coverage data were collected at four sites (in Massachusetts, Hawaii and Florida) using static immersion panels coated with silicone and oil‐amended silicone systems. Inter‐site differences in fouling coverage and community structure were observed for each coating. Intra‐site variation and temporal change in coverage of fouling was minimal, regardless of coating formulation. The extent of coverage was affected by the duration of immersion and the local environmental conditions; these factors may also have an impact on the foul‐release capability of the silicone coatings. Organismal adhesion data was collected in Hawaii and Florida. These adhesion measurements were used as a tool to discriminate and rank fouling release coatings.     

Improved estimates of environmental copper release rates from antifouling products

The US Navy Dome method for measuring copper release rates from antifouling paint in-service on ships' hulls can be considered to be the most reliable indicator of environmental release rates. In this paper, the relationship between the apparent copper release rate and the environmental release rate is established for a number of antifouling coating types using data from a variety of available laboratory, field and calculation methods. Apart from a modified Dome method using panels, all laboratory, field and calculation methods significantly overestimate the environmental release rate of copper from antifouling coatings. The difference is greatest for self-polishing copolymer antifoulings (SPCs) and smallest for certain erodible/ablative antifoulings, where the ASTM/ISO standard and the CEPE calculation method are seen to typically overestimate environmental release rates by factors of about 10 and 4, respectively. Where ASTM/ISO or CEPE copper release rate data are used for environmental risk assessment or regulatory purposes, it is proposed that the release rate values should be divided by a correction factor to enable more reliable generic environmental risk assessments to be made. Using a conservative approach based on a realistic worst case and accounting for experimental uncertainty in the data that are currently available, proposed default correction factors for use with all paint types are 5.4 for the ASTM/ISO method and 2.9 for the CEPE calculation method. Further work is required to expand this data-set and refine the correction factors through correlation of laboratory measured and calculated copper release rates with the direct in situ environmental release rate for different antifouling paints under a range of environmental conditions.