Article

Spatially variable effects of copper on sessile invertebrates across a marina

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Abstract

Heavy metals often occur at elevated concentrations in bays and estuaries surrounded by urbanised areas and can cause substantial ecological changes to marine communities. The toxic effect of heavy metals can be modified by a several physico-chemical processes in the marine environment. These processes can vary greatly over small scales, so it is likely that the ecological effects of heavy metals on marine biota also vary substantially over similar spatial scales. We used a manipulative field experiment to assess the spatial variation in the effect of copper on sessile invertebrates within a marina and tested whether this variation was influenced by variation in localised water flow. Effects of copper were not consistent over relatively small spatial scales (i.e. metres) for all sessile invertebrate species. Three of the twenty sessile invertebrates from our experimental assemblages showed significant small scale variation in the effect of copper at the scale of metres. For these taxa, the effect of copper varied in magnitude and direction. We had predicted that the effect of copper would diminish with increased water flow, but this did not occur for any taxa. We suggest that variations in the presence of organic or inorganic compounds or in pH within the marina may provide alternative explanations for the spatially variable effects detected in this study. Our study's findings highlight the need for future field assessments of the complex physical, chemical and biological influences on the ecological effects of heavy metals, particularly at small spatial scales. Such studies are the key to improving our prediction about the effects of heavy metals on marine organisms and aid in better characterisation of the risk of heavy metals in the marine environment.

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... Differential tolerance between populations has been found in other species, but these experiments have compared clean and heavily polluted sites (Durou et al., 2005;Johnston, 2011;Piola and Johnston, 2006b) where selection pressures are polarised. Instead it is more likely that small scale temporal and spatial fluctuations in exposure (Addison et al., 2008) would have a greater influence on selection for tolerance. ...
... Within an impacted site, such as a marina where there are multiple sources of copper pollution (Weis et al., 1998;Srinivasan and Swain, 2007), exposure can differ at a spatial and temporal scale. On a fine spatial scale proximity to pollution sources, such as an antifoulant coated surface (Valkirs et al., 2003), will result in heterogeneous exposure between individuals that may only be a few metres apart (Addison et al., 2008). This small scale variation would explain the maintenance of highly tolerant and intolerant individuals, and therefore the variety of offspring sizes in response to individual exposure as a result of maternal provisioning. ...
... Our study supports the growing evidence that variability in trace metal concentration in marine organisms occurs at many scales including: within species (Robinson et al., 2005); between species (Cebrian et al., 2007;Patel et al., 1985); within locations (Addison et al., 2008;Rao et al., 2009); and between locations (Hedge et al., 2009;Philp et al., 2003). Worldwide a number of studies have revealed surprisingly high levels of trace metals within sponges (e.g. ...
Article
To be effective sentinels, organisms must be able to be readily translocated to contamination hotspots. We sought to assess metal accumulation in genetically-identical explants of a relatively common estuarine sponge, Suberites cf. diversicolor. Explants were transplanted to 7 locations across a metal contamination gradient in a large coastal estuary in south-eastern Australia in order to first establish that explants of this species could be successfully translocated. Second, that explants accumulated metals (cadmium, copper, lead, selenium and zinc) sufficiently rapidly to be effective sentinels. Third, rates of metal accumulation in explants were in agreement with metal concentrations within sediments (<63 micron fraction) at each of the transplant locations. Finally, changes in explant biomass correlate with overall metal load. Suberites was readily transplanted with no mortality observed for the 2 months of transplantation. Metal accumulation for lead, cadmium and zinc was in close agreement with sediment metal concentrations and explants showed dramatic increases in these metals in the heavily contaminated northern sections of the estuarine Lake. No striking patterns were apparent for copper and selenium. Finally, growth was negatively correlated with total metal load and standardised total metal load in our explants. Taken together, these outcomes confirm that explants of this sponge are amenable to translocation and show considerable promise as biomonitors. Environ Toxicol Chem © 2014 SETAC
... Our study supports the growing evidence that variability in trace metal concentration in marine organisms occurs at many scales including: within species (Robinson et al., 2005); between species (Cebrian et al., 2007;Patel et al., 1985); within locations (Addison et al., 2008;Rao et al., 2009); and between locations (Hedge et al., 2009;Philp et al., 2003). Worldwide a number of studies have revealed surprisingly high levels of trace metals within sponges (e.g. ...
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If sponges are to be effective biomonitors we require a better understanding of the spatial scales over which metals vary in these organisms. We determined how concentration of Cd, Zn, Cu, Pb, Hg and Se varied over four spatial scales for two common estuarine sponge species in the Sydney region. We examined variability with a fully nested sampling design; between coastal lakes, within coastal lakes, between sponges and within sponges. Calculation of variance components confirmed that 'within-sponge' variation in Cd, Zn, Cu, Pb and Se concentrations were low (1-14%) relative to the two largest spatial scales (49-98%) examined. In contrast, Hg concentrations exhibited marked variability 'between-sponges' and were below detection at one location. There was little evidence that sponge size was a good predictor of metal concentration. Taken together, these outcomes confirm that fragments of these sponges could be successfully transplanted and therefore show promise as biomonitors of metal contamination.
... Previous research found that toxicity in fish also varies inversely with respect to salinity, alkalinity, pH and size; other studies performed with several animal species indicate that copper toxicity also diminishes when total organic carbon and interaction with other metals in the water increase. Therefore, copper ions generally considered to be non-toxic can be toxic, interfering with oxygen transport and metabolism, causing hypoxia with the corresponding alteration of the ATP route synthesis, inducing the death of aquatic vertebrates and invertebrates [19][20][21][22][23][24]. Metals are not biodegradable, remaining in ecosystems for a long time. ...
Article
The photochemical process of Cu (II) reduction by heterogeneous photocatalysis using titanium dioxide (TiO2) Degussa P-25 and a 254 nm UV-C lamp was studied. The aim of this work was to determine the efficiency of the photocatalytic process to remove 100 ppm of copper (II) ion concentration from a water solution.A statistics-based experimental design with response surface methodology (RSM) was employed to investigate the effect of operating conditions on photocatalytic reduction. The experimental results were evaluated using multivariate analysis with the program MODDE 7.0. The parameters studied were catalyst mass, pH, and reaction time. After optimizing the variables, degradation kinetics were performed to corroborate the model. The regression analysis with R2 value of 0.98 shows a close fit between the experimental results and the model predictions. The value obtained for the reaction rate constant was 0.0246 min−1. Three-dimensional response surface plots were used to visualize parameter interactions. The optimum pH (4.3) and titanium dioxide mass (0.5 g) achieved the highest efficiency, reaching 80% of copper (II) ion reduction. Two different bioassays, using Daphnia magna and Pseudomonas aeruginosa, were performed to determine acute toxicity reduction after the treatment. The results obtained show that the bio-toxicity reduction reached 80%.
... [5]). Moreover, a species' long-term performance is modulated by abiotic factors across multiple life-history stages, including adulthood [6][7][8][9], and embryonic and larval development (e.g. [10][11][12]). ...
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All ontogenetic stages of a life cycle are exposed to environmental conditions so that population persistence depends on the performance of both adults and offspring. Most studies analysing the influence of abiotic conditions on species performance have focussed on adults, while studies covering early life-history stages remain rare. We investigated the responses of early stages of two widely introduced ascidians, Styela plicata and Microcosmus squamiger, to different abiotic conditions. Stressors mimicked conditions in the habitats where both species can be found in their distributional ranges and responses were related to the selection potential of their populations by analysing their genetic diversity. Four developmental stages (egg fertilisation, larval development, settlement, metamorphosis) were studied after exposure to high temperature (30°C), low salinities (26 and 22‰) and high copper concentrations (25, 50 and 100 µg/L). Although most stressors effectively led to failure of complete development (fertilisation through metamorphosis), fertilisation and larval development were the most sensitive stages. All the studied stressors affected the development of both species, though responses differed with stage and stressor. S. plicata was overall more resistant to copper, and some stages of M. squamiger to low salinities. No relationship was found between parental genetic composition and responses to stressors. We conclude that successful development can be prevented at several life-history stages, and therefore, it is essential to consider multiple stages when assessing species' abilities to tolerate stress. Moreover, we found that early development of these species cannot be completed under conditions prevailing where adults live. These populations must therefore recruit from elsewhere or reproduce during temporal windows of more benign conditions. Alternatively, novel strategies or behaviours that increase overall reproductive success might be responsible for ensuring population survival.
... Trace metal contents of the molluscan tissues are known to vary with changes in salinity (Larsen, 1979;Manuwadi and Yuangthong, 1984), size-classes (Huggett et al., 1975;Szefer et al., 1999), spatial distribution (Jung et al., 2006;Addison et al., 2008), season (Shiber, 1980;Beldi et al., 2006), food source (Metian et al., 2009) etc. In Turbo coronatus, relatively high concentrations of iron, lead and zinc were found in December. ...
... Marine organisms that are able to accumulate high amounts of copper include different species of crustaceans and lter-feeding invertebrates such as bivalve molluscs (mussels, clams, oysters) and ascidians (NAS, 1977). On the one hand as edible species, this bioaccumulation could represent a risk for human health, and on the other hand as key coastal ecosystem species, their survival and reproductive capability could be negatively affected causing signi cant changes in communities (Addison et al., 2008). In these taxa, copper inhibits fertilisation and causes embryotoxicity, larval mortality, and immunotoxicity (Bellas et al., 2004;Zhang et al., 2010;Cima and Ballarin, 2012;Fabbri et al., 2014). ...
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In recent years, after the ban on tributyltin (TBT)-based antifouling paints, copper-based paints have become the main coatings for boat hulls due to their efficiency and endurance. Copper(I) compounds like Cu 2 O and CuSCN are used alone or in combination with booster biocides, i.e. Irgarol 1051, chlorothalonil and dichlofluanid. The expanded use of these paints has increased copper leaching into coastal environments, requiring attention and legislative restrictions for potential long-term effects on benthic populations. This study monitored the ecological succession of macrofouling communities on wooden and stainless steel panels immersed for 10 months in the southern basin of the Lagoon of Venice. The development of macrofouling communities on the panels coated with copper-containing antifouling paints was compared with those on the reference (uncoated) and TBT-coated panels. Series of biodiversity descriptors highlighted the preventing activity of the antifouling paints. The most active paints were those containing booster biocides and with self-polishing copolymers in the matrix. The macrofouling communities appeared dissimilar to those on the reference uncoated panels as regards the species richness, the coverage areas, and the biocoenosis structure. Generally, green algae, bryozoans and barnacles were the most tolerant taxa and a negative species selection occurred for sponges, serpulids and ascidians.
... Marine organisms that are able to accumulate high amounts of copper include different species of crustaceans and filter-feeding invertebrates such as bivalve molluscs (mussels, clams, oysters) and ascidians (NAS 1977). On the one hand as edible species, this bioaccumulation could represent a risk for human health, and on the other hand as key coastal ecosystem species, their survival and reproductive capability could be negatively affected causing significant changes in communities (Addison et al. 2008). In these taxa, copper inhibits fertilisation and causes embryotoxicity, larval mortality, metabolic impairment, neurotoxicity and immunotoxicity (Bellas et al. 2004;Brown et al. 2004;Zhang et al. 2010;Cima and Ballarin 2012;Fabbri et al. 2014). ...
Article
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The expanded use of copper(I)-based antifouling paints (AF) has increased copper leaching into coastal environments, requiring attention and legislative restrictions for potential long-term effects on benthic populations. The ecological succession of macrofouling communities was analysed on wooden and stainless steel panels coated with four copper(I)-based AF (Paints A–D) immersed for 10 months in the Lagoon of Venice. With the exception of Paint B, which contained only copper(I) compounds and was based on hard-matrix technology, the other paints were based on self-polishing matrices and various booster biocides. The booster content was a mix of TBT compounds for Paint A, dichlofluanid for Paint C, Irgarol 1051, and chlorothalonil for Paint D. The macrofouling communities appeared dissimilar to those on the reference uncoated panels as regard the species richness, the coverage areas, and the biocoenosis structure. Generally, green algae, bryozoans, and barnacles were the most tolerant taxa and a negative species selection occurred for sponges, serpulids, and ascidians. Paints A and D showed the highest performance, and Paint D also prevented molluscs on wood panels. Paints B and C rapidly decreased their efficiency, the first probably due to the insoluble matrix with the highest biocidal leaching rate, and the second due to the presence of a booster with low toxicity. Paint B also inhibited red algae and molluscs, but Paint C did not reveal significant differences in types of species settlements with reference panels.
... On a finer spatial scale, proximity to pollution sources (e.g. antifoulant coated surfaces (Valkirs et al. 2003)) will result in heterogeneous exposure between individuals that may only be a few meters apart (Addison et al. 2008). These fluctuating conditions, compared to a constant exposure regime often experienced in chronically polluted environments (Klerks & Levinton 1989) may also select for the ability to survive then recover from a pulse pollution event. ...
... This threat agent includes rubbish, waste (e.g. sewerage, Chapman et al., 1995), toxicants (Addison et al., 2008a), oil/chemical spills, atmospheric fallout, and carbon pollution. These may enter the subtidal habitat through a range of sources both within and outside the marine protected area such as discarded fishing line/nets, and litter (e.g. via stormwater). ...
... Field assessments yielding understanding of the complex physical, chemical and biological influences on the effects of pollutants are key to conserving biodiversity and coastal ecosystems (Addison et al., 2008). These systems are of vital importance to production, climate regulation and nutrient budgets (Falkowski et al., 1998) and are widely influenced by terrestrially derived pollutants. ...
... Human-made structures create novel reef grounds, potentially favoring a suite of diverse assemblages that are often habitat limited (Bulleri and Chapman, 2010;Mineur et al., 2012), which in turn attract nearshore pelagic consumers which feed on them (Zalmon et al., 2002;Rocha et al., 2015;Neves dos Santos and Zalmon, 2015;Pastro et al., 2017). However, the impact of those artificial habitats on surrounding natural systems may also have an array of negative environmental consequences, such as changes in the water circulation regime, which in turn may lead to increased turbidity, temperature and pH (Rivero et al., 2013); light pollution as a result of artificial night-time lighting that may affect recruitment of sessile organisms (Davies et al., 2015) and fish behavior (Bolton et al., 2016); and intense traffic of boats and ships that may increase water pollution through discharge of untreated wastewater, oil leakage or the liberation of biocides contained in anti-fouling paints used in ship hulls (Addison et al., 2008;Piola et al., 2009). All these stressors may reduce nearshore fish diversity and abundance (Marty et al., 1997;Robinson et al., 2003;el Hassani et al., 2005), as well as cause mass mortality of arriving planktonic propagules, which are markedly sensitive to water quality (e.g. ...
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Historical processes affecting biological organization are rarely considered when predicting the effects of disturbance on community structure. In order to assess the relative importance of historical and post-disturbance conditions as determinants of community structure, we undertook reciprocal transplants, at different successional stages, of sessile communities developing at recreational piers that were previously observed to show contrasting fish predation pressure and settlement rate in the São Sebastião Channel, Brazil. Regardless the direction of state shift, after 15 weeks communities converged to the destination site structure, substantially drifting away from the path observed at origin, therefore revealing high susceptibility to environmental change. Although converging, transplanted communities never matched the destination standard in both transplant directions, suggesting that history still mattered, as providing some legacy that lasted, at least, for 15 weeks. The taxonomic groups resisting community drift were hard-bodied invertebrates, which could eventually provide some resilience to these communities through ecosystem engineering.
... Coastal areas are among the ecosystems deeply affected by human activity, since most of the world's population inhabits coastlines (Dafforn et al. 2015). The introduction of man-made structures, such as harbors, piers, marinas and breakwaters (Bulleri & Chapman 2010, Mineur et al. 2012, and also the increased discharge of pollutants (Addison et al. 2008, Piola et al. 2009) are leading to a severe modification of coastal ecosystem functioning, mainly resulting in a loss of biodiversity (Airoldi et al. 2008, Magurran et al. 2015, Bianchelli et al. 2016. The Araçá Bay in the São Sebastião Chanel, São Paulo -Brazil, is an area under intense anthropogenic influence as a result of São Sebastião Harbor proximity, which leads to frequent sewage discharges and oil spills for decades. ...
Article
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Species diversity is regulated by historical, neutral and niche processes, with species tolerance, dispersal and productivity guiding diversity at larger scales, while habitat heterogeneity and biotic interactions acts in smaller scales. In rocky shores, several organisms provide secondary substrates for mobile fauna, with macroalgae being the most abundant and diverse ones. The patchiness promoted by different macroalgae hosts enhances small-scale heterogeneity and may increase and maintain the diversity of the mobile organisms, since there is a close relationship between the associated fauna and its hosts. In this study we selected three morphologically different macroalgae that coexist in the same rocky shore height in the Araçá Bay, an area under the threat of the nearby harbor expansion, and evaluated the fauna associated to each algal host. Even under similar abiotic pressure (same rocky shore height), the associated fauna of each algal host varied in number and composition, revealing a close relationship. The poorly branched foliose Ulva lactuca sustained a lower density of organisms and was dominated by isopods, while the heavily branched turf and Bostrychietum community showed a high density of organisms, with a dominance of peracarid crustaceans and annelids on the turf and more resistant groups, such as bivalves, acaris and terrestrial insects on the Bostrychietum. Previous studies in the Araçá Bay already revealed a large spatial heterogeneity in the processes and sessile organisms distribution, and here we highlight that this heterogeneity can be observed in an even smaller scale, with different algal hosts mediating the turnover of species in a scale of centimeters and meters, resulting in diversity maintenance of the associated fauna. Since the harbor expansion may prevent the occurrence of macroalgae as a result of light limitation by suspended platforms, we may expect not only a decrease in algal cover but also in the total diversity of the associated fauna in the Araçá Bay.
... Ultimately, these structures restrict which species thrive under these conditions (McKinney 2006;Tyrrell and Byers 2007). Marinas, piers and ports are usually sources of pollution (Addison et al. 2008;Piola et al. 2009). The decreased hydrodynamics resulting from these constructions increases turbidity (Pastro et al. 2017;Bishop et al. 2017) which can also affect the associated unconsolidated substrate (Sim et al. 2015). ...
Article
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Marinas create physical and biotic conditions distinct from those in natural habitats which can facilitate the establishment of non-indigenous species (NIS) in coastal ecosystems. Using a series of images spanning nine years, we detected the introduction and followed the expansion of the NIS Tubastraea coccinea and T. tagusensis populations at a recreational marina in a region of Southeastern Brazil where sun-corals are rarely found on natural substrates. Because sun corals are known to reduce diversity in natural invaded environments, we evaluated how different densities of sun-corals affected the benthic community. Overall, the NIS populations have grown exponentially from 2010 to 2019 inside the marina, occupying up to 60% of the available space. However, the population growth in the breakwater stopped in 2016. Local variation in the population growth across the marina might be associated with the high phytoplankton biomass and larval retention inside the marina, which are results of the lower hydrodynamics. The expansion of sun-coral coverage did not significantly affect the richness of benthic communities but was associated with a reduction of the native bryozoan Amathia brasiliensis, the overall abundance of mobile crustaceans, and an increase in the area covered by the exotic bryozoan S. errata. The fast substitution of a native ecosystem engineer for a NIS suggests signs of invasion meltdown associated with the expansion of Tubastraea spp.
... (2008) have shown that the frequency and method of in-situ net cleaning may actually stimulate higher reproduction and colonisation rates in some organisms. Settlement behaviour is also influenced by the age of the treated surface, the current velocity, salinity, pH, inorganic and organic nutrient levels, as these parameters can influence the bioavailability and concentration of metals (Addison et al, 2008). Studies on the spatially variable effects of copper on sessile (fouling) invertebrates have shown that small scale variation (i.e. ...
Article
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Non-Technical Summary Antibiotics and antifoulants are used in aquaculture operations to ensure the health and well-being of farmed stock. Antibiotics are used as a direct response to infectious diseases, whilst antifoulants are needed to counteract bio-fouling, a condition which is a significant problem to the local aquaculture industry and reduces water flow and oxygen supply in the cages, increasing stress levels and hence diseasesusceptibility in the fish. However, there are several environmental concerns associated with the use of both antibiotics and antifoulants. Cage fish farming is essentially an open culture system. Aquaculture is sometimes seen in simple terms such as inputs such as fish, feed, and chemicals and outputs such as harvested fish. Losses to the environment such as escapees, uneaten feed, faeces and excreted metabolic wastes, and chemicals/metabolites associated with therapeutic agents have the potential to cause detrimental environmental effects. These impacts can be localised, such as the accumulation of organic material and uneaten food under cages, or more widespread, for example distribution of soluble nutrients through currents (Butler, 2005; Dean et al., 2007). The timescale of impacts may also differ with short-term effects occurring within an operational cycle or longer term effects continuing over many years. Antibiotics and antifoulants may affect the environment in a variety of different ways. The need for a targeted review to establish environmental risk factors associated with current antibiotic and antifoulant use in Tasmanian aquaculture operations and to develop an appropriate strategy to research and monitor ongoing impacts was identified. This study also considered data on sediment residue levels for both antibiotics and antifoulants, which had been collected by the salmon industry in compliance with drug/chemical licensing permit conditions authorities and by the State government in response to concerns regarding antibiotic and antifoulant use. This information was reviewed to assess the potential ecological impacts of antibiotics and antifoulants currently used in the Tasmanian aquaculture industry. Consequently the aims of this study were: • Undertake a review of the international literature and current research to identify the existing state of knowledge regarding the environmental effects of antibiotics and antifoulants currently used or likely to be used in the Tasmanian salmonid farming industry (marine production phase). • Analyse local datasets on currently used antibiotics and antifoulants, collected in compliance with current licensing requirements, to determine what additional information is needed (if any) to appropriately evaluate the environmental impact of current management practices. Antifoulants – Impact Evaluation The main environmental concerns regarding antifoulant contamination include: • Bioaccumulation • Ecotoxicological effects and subsequent changes to local ecology and biodiversity • Effects on ecosystem function (i.e. microbial and geochemical processes that regulate the cycling, bioavailability, and fate of micro- and macronutrients) The likelihood of these impacts is largely determined by the bioavailability of copper and zinc. The antifoulants used in the Tasmanian aquaculture industry are copperbased. There are several pathways by which metals in antifoulants can become environmentally available: • Dissolution from the active paint surface • Ablation or physical damage of the painted surface • Release from accumulated paint in the sediments However, release from other sources (i.e. not antifoulant in origin) should also be considered when interpreting sediment quality results. On the basis of the limited data currently available, there do not appear to be major acute effects of antifoulant release in the water-column. The greatest risk appears to be the potential for build up of copper and zinc in the sediments around the farms. Industry surveys have shown a significant increase in copper levels at farm sites; particularly at depositional sites with organically enriched sediments, which have a higher capacity to bind and accumulate copper. For these metals to have any effect on local ecology or sediment processes they must be “bioavailable”, which is in turn reliant on the form (speciation) of the metal. Metal speciation in sediments is complex and strongly related to the geochemical status of the sediments (i.e. redox, pH, oxic status, organic content) and on the extent of processes such as bioturbation and resuspension. In anoxic sediments, metals are generally thought to be less bioavailable, being tightly bound as insoluble sulphides. Oxidative release of metals from sediments (i.e. during benthic recovery) has been identified as a potential problem in aquaculture leases (Valkirs, 2003). Many marine invertebrate species have been shown to be sensitive to increased metal loadings, with juvenile (embryo and larval) stages being particularly sensitive, often being several orders of magnitude more sensitive than adults (Bellas, 2006). Copper contamination of the sediments can result in the elimination of vulnerable species as toxic thresholds are exceeded, whilst more robust species, with the capacity to regulate or accumulate metals, will be unaffected or may even thrive. This in turn can lead to problems with bioaccumulation and biomagnification as benthic invertebrates are a food source for many higher trophic level species. Guidelines recently developed for the management of biofouling in Mediterranean aquaculture (IUCN, 2007) seek to ensure that there are “no perceivable toxic effects on non-target organisms” and recommend the use of eco-friendly antifouling coatings and products, encourage the use of environmentally friendly procedures for preventing or eliminating biofouling and suggest that antifouling products based on heavy metals should be avoided where possible. Whilst the local industry continues to support the investigation of alternatives to metal-based antifoulants, replacement of copper and zinc-based antifouling products is unlikely in the short-term. Consequently, the emphasis of sustainable management should be on minimising the environmental impact of currently used products and the development of appropriate monitoring strategies to defining ecologically relevant threshold values over a range of parameters To effectively interpret the sediment monitoring data, both into the future and that which has already been obtained, it is essential to improve our understanding of the mechanisms and processes that affect metal bioavailability and the ecological consequences that might be associated with particular metal loadings. Once there is a clear understanding of bioavailability then chemical estimates or surrogates for bioavailability can be developed. These can then be used, in conjunction with relevant toxicity testing, as indicators of environmental condition. However, to achieve this a range of locally relevant species should first be evaluated (over a range of life stages and copper sensitivities), and for a range of operational and environmental conditions relevant to the salmonid industry in SE Tasmania. The ultimate aim being the development of a rapid toxicity assay using locally relevant species to assess sediment quality and potential impacts. There is information available in the literature to assist with these decisions. This combination of toxicity and chemical bioavailability assessment would provide important information while the industry refines its environmental management strategies. Finally these data would increase the capacity to employ a PEC/PNEC assessment approach, and to model copper distribution and fate with tools such as MAMPEC. The results of this study suggest that the best strategy to minimise and manage environmental concerns would be a combined approach that experimentally investigates the environmental fate of copper and zinc along with the biological effects associated with antifoulant usage in conjunction with the development of theoretical models which take into account operational considerations. A number of potential areas of research are suggested Antibiotics – Impact Evaluation So long as there are bacterial pathogens in the marine environment, occasions will arise where administration of antibacterials is necessary to ensure the health and welfare of fish stocks. When pathogens are known and understood vaccines may be available but where the disease agents are unknown, antibiotics may be necessary until an alternative therapeutic approach can be established. The main environmental concerns associated with antibiotic usage relate to the effects on non-target organisms, environmental persistence and development of resistance. In Tasmania, antibiotics are generally administered in feed and as such the main concerns relate to the presence of waste feed and fish excretory material in the sediments and water column. Feed wastage can be minimised by monitoring feed input and limiting feed wastage. Ensuring best practice in therapeutic administration and disease management will also help to minimise impacts. Although assessment of the available data does not suggest that major environmental changes have occurred, it is still important to identify and monitor suitable indicator species to ensure ongoing sustainability. In addition, where antibiotics are used it is suggested that a measure of bioavailability be obtained, rather than simply a measure of total residue level, and that the effect of local environmental conditions (i.e. oxic status, temperature, pH and salinity) on ecotoxicity be assessed in order to ensure that local data are consistent with findings from overseas, given the very different prevailing environmental conditions in Tasmania. Development of resistance and accumulation in the sediments are also significant environmental concerns. Although current information suggests that human health effects are highly unlikely, it is important to monitor the incidence of resistance in the environment and in fish bacteria. Accumulation in the sediments may affect natural sedimentary processes, such as biogeochemistry, and it would be prudent to confirm this, and to determine threshold effect levels. This could be done either in mesocosm experiments with field validation through targeted assessments, perhaps in conjunction with measurement of biotic loading and resistance. Current data indicate that water column concentrations of antibiotics are extremely low and that impacts on phytoplankton communities are likely to be limited. The testing of wild fish with respect to human health toxicity showed no risk to human health. However, the most important means to reduce and manage the overall antibiotic usage would be to facilitate diagnosis of pathogens and to support development of targeted disease management strategies and alternative therapies, in particular vaccines. Investigation of vaccines is currently underway in Tasmania for all significant pathogens currently affecting the industry. General Conclusions It is important to understand the environmental impacts associated with farming activities in order to manage and minimise those impacts. This can be achieved through ensuring best practice environmental management strategies (including disease management strategies) and robust impact assessment and mitigation approaches, with reliable early warning indicators. The results from the current industry based monitoring focused on the detection of major effects of both antifoulant and antibiotic impacts are encouraging with findings suggesting limited bioavailability of metals under current conditions. However, there are several areas of environmental concern which were not covered in the current monitoring and some of the results were inconclusive, consequently there is a need for additional research to better understand the local situation, to develop targeted and appropriate monitoring and management strategies and to ensure environmental sustainability. The literature suggests a general trend in regulatory approaches towards environmental risk assessment (ERA) frameworks, and modelling could be very useful in helping to address environmental concerns and in predicting impact. A summary of potential areas for further investigation is provided and it is planned to hold a workshop in the next few months with project participants, industry stakeholders and relevant experts to further discuss the project outcomes and proposed research areas, to prioritise research needs and to develop a strategic research agenda.
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Pulse disturbances and habitat patch size can determine community composition independently or in concert, and may be particularly influential on small spatial scales for organisms with low mobility. In a field experiment, we investigated whether the effects of a pulsed disturbance that simulated a grazing event varied with habitat patch size. We focused on the short-term responses of multiple co-occurring emergent salt marsh arthropods with differing levels of mobility and dispersal potential. As part of a marsh restoration project, two types of emergent marsh structures were created: small circular mounds (0.5 m diameter) separated by several meters of aquatic habitat, and larger, elongated terraces (>50 m long). Study plots (0.25 m(2)) were established on both structures; in a subset of plots, we simulated a pulsed grazing disturbance event by clipping the aboveground tissue of emergent plants, primarily Spartina alterniflora. At the end of the two-month recovery period, Ischnodemus (Hemiptera: Blissidae) density was over 50% lower in disturbed treatments within both large (terrace) and small (mound) patches. Predatory spider treatment responses were similar to Ischnodemus responses, suggesting a trophic relationship between those two arthropod groups. Alternatively, spiders may have been directly affected by the loss of shelter in the disturbed plots. Prokelisia (Homoptera: Delphacidae), which are generally more mobile than Ischnodemus, were not affected by disturbance treatment or by patch size, suggesting the potential for rapid recolonization following disturbance. Larval stem borers decreased by an order of magnitude in disturbed plots, but only in the large patches. In general, the disturbance effects of vegetation removal on arthropod density and community composition were stronger than patch size effects, and there were few interactions between pulsed disturbance and patch size. Rather, emergent marsh arthropod responses to disturbance and habitat area treatments were linked to the dispersal potential and mobility of each individual taxon.
Chapter
Antibiotics are typically used in aquaculture operations as a direct response to infectious diseases to ensure the health and well-being of farmed stock. However, there are several environmental issues associated with antibiotic usage that farmers need to understand and address when developing disease management strategies. Some of these can have direct negative implications for farming operations while others relate to effects on the broader environment. Negative outcomes for farming operations include the potential for the development of resistance in the target pathogens. However, the main concerns associated with antibiotic usage relate to effects on non-target organisms, environmental persistence and development of broader resistance. In salmonid aquaculture, antibiotics are generally administered in feed and as such these concerns are primarily related to the presence of waste feed and fish excreta in the sediments and water column. Ensuring good farm management and husbandry practices to maximise the health of fish stocks is the best way to reduce the need for antibiotics and as a result any associated impacts. Rapid and accurate diagnosis of pathogens and development of targeted disease management strategies and alternative therapies, in particular vaccines, is also an important means to reduce and manage overall antibiotic usage. However, where antibiotics are necessary then careful feed management, monitoring feed input and limiting feed wastage, will minimise any impacts. In addition an understanding of the various environmental issues associated with specific antibiotics allows farm managers and veterinarians to make informed choices with respect to treatment regimes. Finally, establishing an effective monitoring approach for evaluation of potential ecological effects is a key factor in assessing the impact of antibiotics. Development of resistance and accumulation in the sediments are significant environmental concerns, consequently it is important to monitor the incidence of resistance in the environment and in fish bacteria. Accumulation in the sediments may affect natural sedimentary processes, such as biogeochemistry, and it would be prudent to confIrm this, and to determine threshold effect levels. Even where assessment of the available data does not suggest that major environmental changes have occurred, it is still important to identify and monitor suitable indicator species to ensure ongoing sustainability. In this chapter we review various antibiotics used in salmonid aquaculture globally, provide a summary of key environmental issues and compare various monitoring and assessment approaches.
Chapter
Antifoulant chemicals are commonly used in aquaculture to counteract biofouling, which may be a particularly significant problem to finfish culture operations. Biofouling reduces water flow and oxygen supply, and in turn leads to increased stress levels and disease-susceptibility in the cultured fish. Copper-based net coatings, the main antifoulant used in marine salmonid operations, act as a biocide thereby preventing the attachment of fouling organisms to the cage. There are several environmental concerns associated with the use of copper antifoulants and their persistence in the marine environment, the most significant of which are i) toxic effects on local ecology and ecosystem processes, especially in sediments and ii) potential for bioaccumulation. Many marine invertebrates have been shown to be sensitive to metal toxicity, with juvenile (embryo and larval) stages often being particularly susceptible. As a result where copper is released from aquaculture operations, vulnerable species can be eliminated changing the ecological balance. Other species may be more robust, with a greater capacity to regulate or sequester metals, and these species may appear unaffected or even thrive in response to the increased metal loads. However, where an animal is able to survive through tolerance or accumulation of metals this can provide an avenue for bioaccumulation and biomagnification as a result of predation from higher trophic level species. Metals in antifoulants can become available to the broader environment either by dissolution from the active paint surface or as a result of ablation or physical damage of the painted surface. Sediments under fish farms using copper-based antifoulants typically show increased total metal loadings, however, it is important to note that for metals in the sediments to have any effect on local ecology or sediment processes they must be "bioavailable", which in tum is dependant on the form (speciation) of the metal. Metal speciation in sediments is complex and strongly related to the geochemical status of the sediments (i.e. redox, pH, oxic status, organic content), which in turn will be influenced by the extent of other processes such as bioturbation and resuspension. In anoxic sediments, metals are generally thought to be less bioavailable than in oxic sediments, as they are often tightly bound as insoluble sulphides. As metal speciation may be influenced by the level of organic enrichment, metal toxicity may fluctuate with variations in organic inputs associated with the farming cycle, and this should be taken into account in any monitoring or evaluation of impact. Until such time as there is a reliable replacement for copper-based antifouling products, sustainable management practices need to ensure that procedures minimise the environmental impact of currently used products and include the development of appropriate monitoring strategies. In this chapter we review possible environmental impacts associated with copperbased antifoulant use, the mechanisms and processes that affect metal bioavailability, the ecological consequences that might be associated with particular metal loadings and monitoring and management strategies. Data from research conducted by the Tasmanian salmonid industry (Australia) are discussed.
Thesis
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Styela plicata is a solitary ascidian introduced all around the world by ship traffic and seems to have many of the required features to become invasive. The main goal of this PhD thesis was to increase our knowledge on the genetic composition of this species, its reproductive features and its capacity to cope with stress during early life-history stages and adulthood. This thesis is structured in four main chapters: • The whereabouts of an ancient wanderer: Global phylogeography of the solitary ascidian Styela plicata • Continual reproduction in a seasonal sea: Biological cycle of the introduced ascidian Styela plicata in the Western Mediterranean • Stress levels over time in the introduced ascidian Styela plicata: The effects of temperature and salinity variations on hsp70 gene expression • Tough adults, frail babies: Sensitivity to abiotic factors across multiple life-history stages of widely introduced marine invertebrates Results indicate that S. plicata is an ancient introduced species that has been travelling around the globe through maritime transport for centuries. It inhabits harbors, marinas and artificial structures, tolerating high concentrations of pollutants. Adults can respond to moderate levels of stressors by adjusting the production of stress-related proteins, but early stages are comparatively much more vulnerable to the harsh conditions that characterize the habitats where this species thrives. A prolonged reproductive period allows S. plicata to exploit temporal windows of favorable conditions and confers a competitive advantage compared to organisms with limited, seasonal reproduction events. Moreover, high genetic variability and the continual presence of larvae also guarantee further reintroduction events and spreading via ship traffic. At present, the distribution of S. plicata appears to be limited by high temperatures, low salinities and other non-investigated factors such as competition and predation. Further studies should determine the dynamics of the few populations co-habiting with native communities to pinpoint all the factors regulating the spread of this species outside enclosed environments.
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This review covers selected 2008 peer-reviewed journal articles on the biological, chemical and physical effects of natural and anthropogenic disturbances on marine and estuarine plants and animals. The first five sections cover reviews and field and laboratory measurement activities (concentrations of contaminants, field surveys, toxicity testing and biomarkers). The last six sections focus further on pollution issues of current interest including endocrine disrupters, vessel and marine coatings, ballast water treatment, marine 1*Emergency Response Division, National Oceanic and Atmospheric Administration (NOAA), 7600 Sand Point Way NE, Seattle, WA 98115; Tel.206-526-6336; email: alan. mearns@noaa. gov ; 2Department of Biological Sciences, California State University, Long Beach, CA; 3Lives in Virginia, works at the U. S. Environmental Protection Agency, and is a graduate of the University of California at Berkeley and California State University Long Beach; 4 Florida Keys Nationa Marine Sanctuary, NOAA, Key West, FL; 5Exponent, Inc, Sedona, AZ; 6Retired, NOAA National Marine Fisheries Service, Seattle, WA. The authors are indebted to Mr. Brian Voss, head of the NOAA Western Regional Center Library debris, oil spills, wastewater discharges, dredging and disposal, etc. There is considerable overlap across subject areas (e.g.some organotin papers may be cited in the biomarker section). As always, readers should only use this as a guide and must consult the original papers before citing them, including double-checking units.
Article
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Transient pollution events have the potential to cause both direct and indirect effects on exposed assemblages, but the test designs used in the majority of toxicity studies have precluded an examination of potentially important indirect effects. Field experiments conducted in marine epifaunal assemblages have revealed that pulse chemical disturbances from copper decrease the densities of large solitary ascidians while increasing the densities of serpulid polychaetes. Field manipulative experiments were carried out to test whether the positive effects of transient pollution events represent the response of serpulids to the release from competition for space (an indirect effect of the toxicant) or a direct positive response to the putative toxicant. Three species of serpulid polychaetes (Ficopomatus enigmaticus, Hydroides sp., and Pileolaria pseudomilitaris) responded positively to pulse copper exposures in the presence of competition, but did not display any density response to pulse copper exposures in the absence of competition for space from other recruits. Pomatoceros taeniata displayed no response to copper exposure in the presence of competition, but was dramatically reduced in density in the absence of competition for space. This was the only species deemed sensitive to the frequency and intensity of pollution disturbance employed. There was no indication of a direct positive effect of the toxicant on any serpulid, confirming the hypothesis that positive responses of serpulids to copper exposure in the whole assemblage are an indirect effect of the toxicant mediated through competition for space. Our results show that the interaction between a pollution disturbance and competition for a limiting resource can modify the response of organisms to a toxicant. Such results could not be predicted from conventional laboratory-based toxicity tests and they suggest that small-scale ecotoxicological field tests are a useful tool in predicting the impacts of pollution events in complex systems.
Article
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The requirement for appropriate quality assurance and quality control in scientific measurements makes it essential that the results of toxicity testing be acceptable from both a chemical and a biological perspective. Whereas biological aspects have generally been satisfactorily addressed, this has not always been so with respect to chemistry. This paper reviews the areas where toxicity testing protocols for metals in natural waters can be deficient. These begin with the choice of test container, and include both physical and chemical aspects of metal-organism interactions that may alter both the bioavailable concentration and the toxic response. The need to consider speciation is emphasized, including the effects of organic complexation, pH, hardness and alkalinity, especially with high metal concentrations and high pH values. The difficulties in using uncensored toxicity data from the literature for the development of water quality guidelines are discussed.
Article
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Despite significant inputs of heavy metals from rivers, creeks and drains and a major sewage treatment plant to Port Phillip Bay, Victoria, Australia, attenuation processes in the water column are such that metal concentrations in the bay waters are comparable to uncontaminated estuaries elsewhere in the world. Sedimentation appeared to be largely responsible for metal removal, with strong correlations between particulate metals and iron in input waters sampled over a storm event. Storm events contributed between 9 (Zn) and 21 (Cr) times the metal loads that enter the bay during low flow conditions. Although metal accumulations in sediments are below guideline concentrations in the major deposition zones, they are highest close to input sources. A unique feature of bay waters was the high concentration of dissolved arsenic (2.8 µg L–1). The source appears to be natural sediment mineralogy, and sediment cores were found to be depleted in arsenic near the sedimentŒwater interface. Overall, the findings suggested that current heavy metal inputs do not represent a threat to the health of the bay.
Article
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Single-species toxicity studies have been criticised for their inability to test for the effects of pollution on interacting species in field conditions. Pollution may have indirect effects on organisms due to changes in the abundance of competitors, predators or species that act as habitat. In marine hard substrate assemblages, pollution from the heavy metal copper causes predictable changes in the composition of sessile organisms in field conditions. The effects on mobile invertebrates associated with these habitats, however, are unknown. We tested the effects of copper on the entire assemblage of mobile and sessile invertebrates that colonise fouling plates, and demonstrated strong changes in the composition of mobile taxa due to the presence of copper. Manipulative field experiments partitioned the direct effects of water-borne copper from possible indirect effects mediated through changes to their habitat. Sessile assemblages were selectively gardened in the absence of copper to create habitats typical of polluted and unpolluted habitats, and then exposed to copper. The assemblages of mobile invertebrates varied between manipulated habitats, indicating that copper can indirectly affect mobile fauna via habitat change. The mechanisms of these effects were then examined with artificial habitats that mimicked the physical structure of polluted and unpolluted habitats. The composition of the mobile fauna was again dependent on habitat. In both experiments, there were interactions between the effect of habitat and the presence of copper, demonstrating the need for multi-species, field experiments to fully identify the effects of pollutants in natural conditions.
Article
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Testing the effects on organisms of a constant exposure to toxicants in uniform environments is unlikely to reflect accurately the majority of toxicant exposures in the field, and environmental managers need tools to help predict impacts especially of pulse toxicant inputs into highly variable natural environments. We investigated the effect of pulse copper pollution events on the development of sessile marine invertebrate assemblages at two sites in Port Phillip Bay, Victoria, Australia. Using a field dosing technique we created localized 2-d copper pollution events close to settlement plates. Pulses were delivered every 2, 4, 8, or 16 wk for the duration of the 16-wk experiments, and the assemblages allowed to develop under these dosing regimes. Pulse pollution events dramatically altered the assemblages at both sites predominantly through a direct negative effect on the densities of large space-occupying tunicates. Most other taxonomic groups responded positively to multiple copper pulses, which was considered a density-mediated indirect effect of the toxicant. In particular, organisms known to be good colonizers but poor competitors for space such as serpulid polychaetes occurred in densities an order of magnitude higher on plates exposed to copper pulses. The responses of the assemblages were predominantly independent of the frequency of pulse pollution events, although a single pulse exposure at the beginning of the experiment had no observable effect when censused at week 16. The impact of these transient pollution events were manifest as changes in the structure of invertebrate assemblages and could persist for some time after the agent of disturbance was removed. The effects of a single pulse copper pollution event on an established (8-wk-old) assemblage were evident for at least a further 8 wk after it occurred.
Article
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Pollution events can be considered as disturbances to an ecosystem and have the potential to be an important structuring force within assemblages of plants and animals. Our understanding of pollution impacts will benefit from the investigation of important aspects of these disturbances such as their timing and frequency. We investigated the effect of pulse copper pollution events on the development of hard-substrate invertebrate assemblages in Port Shelter, Hong Kong, Using a field dosing technique, we created single or repeated copper pollution events of less than 100 mug l(-1) close to settlement plates. In short-term experiments, pulses were delivered in either the first or the second week of substrate immersion. For longer term experiments, pulses were delivered every 2, 4, 8 or 16 wk for the duration of the 16 wk experiments and the assemblages allowed to develop under these dosing regimes, Pulse pollution events had a dramatic effect on densities of the dominant colonizer and space occupier in short-term experiments, Hydroides elegans, The impact was observed as a change in the size structure of the population with large organisms eliminated close to copper sources while new recruits were increased in densities in the same area. Reductions in densities of bryozoans and barnacles were also observed, while a feather hydroid doubled in densities on plates exposed to copper pulses, Young assemblages recovered rapidly from the impact of a copper pulse and reduced impacts were observed from a copper pulse in Week 1 of the experiments compared to exposure in Week 2. In longer-term experiments, copper pulses also dramatically altered assemblages predominantly through a direct negative effect on the densities of large competitively superior colonial and solitary ascidians. In the absence of a regular pollution event, colonial and solitary ascidians and sponges were able to establish, grow-over and/or push out the smaller, more brittle H. elegans. These good competitors were unable to establish and grow to any great size on plates exposed to copper pulses every 2 or 4 wk and under the influence of repeated pulse copper exposures H. elegans maintained its initial dominance. Assemblages exposed every 8 or 16 wk were not significantly different from undosed controls. The results provide information on the type and magnitude of sessile invertebrate responses to transient pollution events as well as an assessment of the time expected to 'assemblage recovery' from single or repeated pulse disturbances. This is discussed in relation to the results of identical experiments conducted in temperate climates.
Article
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CuSO4-treated plaster blocks were used to create localised concentrations of copper significantly above ambient levels. Between October 1996 and March 1997 we used this system to manipulate the timing and frequency of transient copper-pollution events close to settlement plates. We assessed the impacts on the development of assemblages of sessile marine invertebrates that occur on hard substrates at Breakwater Pier in Williamstown, Victoria, Australia. Barnacle densities were reduced by up to one-third, while serpulid polychaetes were insensitive. Assemblages at different stages of development were differentially sensitive to short-term pulses. Reductions in sponge and scyphozoan polyp densities were greatest (50%) when pulse-pollution events occurred at times of high settlement. If a pulse copper-pollution event occurred in the first week of substrate becoming available for colonisation, then it had few observable impacts on recruitment for all invertebrates examined. When the first pulse occurred in the first week of the experiment there was no difference between the impacts of single or double-pulse exposures to the toxicant.
Article
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The bioavailability of copper to Daphnia magna was studied in a complete three factor experiment with variable total copper (TCU), pH, and naturally-derived dissolved organic carbon (DOC). Both pH and DOC were found to be important in controlling the amount of ionic copper (for a given total copper concentration) and a model was developed which explained 94% of the variability in the data. Mortality of Daphnia magna was highly correlated with ionic copper under pH 7 at 24 and 48 hours (r2 = 0.90 and 0.96) and less so at higher pH suggesting that copper complexes may be contributing to the response. When toxicity was expressed in terms of ionic copper, it was concluded that a given amount of ionic copper produced more toxicity as pH increased. The 48-h SP50 for D. magna exposed to ionic copper was in the order of 0.5 nM (0.03 ng.ml−1).
Article
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Laboratory toxicity tests generally expose organisms to a constant concentration of a toxicant in a uniform environment. The two techniques outlined in this paper assess the impact of a model toxicant, copper, on marine fouling assemblages in the field. These techniques allow natural assemblages to develop under a regime of toxicant dosing. The experiments were conducted using both techniques over time frames ranging from 2 weeks to 6 months. Short term experiments using the techniques assess the effects of toxicant exposure on recruitment. The longer term experiments enabled detection of certain indirect impacts of pollution. These include effects due to competition for space and variations in the susceptibility of organisms with age. Over the course of the experiments, a range of responses to copper was observed for different taxa. Both techniques have the potential to be used for testing the impact of other toxicants. Approaches such as those described are necessary in order to understand how communities react to toxicants in real world situations.
Article
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In natural aquatic systems, there is frequently overlap in the spatial distribution of both natural and anthropogenic stressors, particularly at regional geographic scales. Yet the proportional risk associated with individual stressors, their cumulative effects and the manner in which they interact to affect aquatic ecology is frequently unknown, limiting the robustness of multiple-stressor ecological risk assessments (ERA). The current study used historical environmental monitoring data (1984-1999) to identify a combination of natural and anthropogenic stressors that best accounted for observed patterns of benthic biodiversity in Chesapeake Bay. Geographic information systems (GIS) were used to geographically link spatially heterogeneous databases for benthic biodiversity, water quality and sediment toxicant concentrations. Single and multiple variable regression techniques were subsequently used to develop a statistical model to explain observed patterns of benthic biodiversity. Combinations of natural stressors alone accounted for as much as 34% of the variation in benthic biodiversity, and combinations of anthropogenic toxicants accounted for as much as 48% of the variation. The consideration of both natural and anthropogenic stressors resulted in a statistical model that accounted for approximately 73% of the observed variation in benthic biodiversity of Chesapeake Bay. These results suggest that benthic biodiversity in Chesapeake Bay is a function of complex interactions among water quality characteristics and anthropogenic toxicants. Therefore, new risk assessment methodologies are required to assess the risk of multiple stressors at regional scales.
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The large sessile tunicate Pyura stolonifera (Pleurogona: Stolibranchiata: Pyuridae), has been regarded as a complex taxon with disjointed distributions, including Australia (Pyura stolonifera praeputialis), South Africa (Pyura stolonifera stolonifera) and South America (Chile, Antofagasta: Pyura sp., the 'piure de Antofagasta'), and has been cited under at least five taxonomic combinations. The 'piure de Antofagasta' is a competitively dominant species in rocky intertidal habitats and shows a limited geographical range (60-70 km) exclusively inside the Bay of Antofagasta. Using cytochrome oxidase I (COI) mitochondrial sequence data from Pyura specimens of the three taxa we tested whether the Chilean taxon represents: (i) a Gondwana relict; (ii) a more recently divergent species; or (iii) a recently introduced species. The results suggest that the Chilean taxon is a recent introduction to Chile from Australian populations and that Pyura stolonifera praeputialis, from Australia, and the 'piure de Antofagasta' are geographical populations of a single species: Pyura praeputialis; whereas the South African taxon represents a second species: Pyura stolonifera.
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Studies conducted in Port Philip Bay, Victoria, Australia are described that examined the effect of experimentally elevated copper concentrations on the recruitment of epifauna to settlement plates. Simultaneous measurement of the copper concentration using diffusive gradients in thin films (DGT) allowed direct comparisons to be made between the labile copper concentration measured at the settlement surface, and the biological effects observed. Copper concentrations created by the field dosing technique were between 20-30 micrograms l-1 for the first 2 d, but then dropped considerably for the following 4 d (3 micrograms l-1), and were indistinguishable from background for the final 7 d. The first 2 d of a copper pulse reduced the recruitment of barnacles, ascidians, serpulid worms, an encrusting bryozoan, and didemnid ascidians. The impacts occurred despite the copper pulse being much less than published LC50 values for similar species. The impacts were no longer obvious by day 7 or 14, having been obscured by either high mortality of early settlers, or large settlement events that took place after day 2. Thus the greatest impact of the pollution event occurred during the period of highest toxicant concentration. The value of this study lies in the correlation of toxicity effects with bio-available metal concentrations under realistic (natural, in situ) conditions.
Article
The spatial distribution of settled larvae of a sessile, colonial marine invertebrate, the bryozoan Bugula neritina, varied from random to strongly aggregated. Larvae did not respond to the presence of conspecific adults, whether the adults were closely related or not, but did respond to other larvae. This response was variable; larvae did not respond to unrelated larvae, but tended to settle near to siblings, which suggests the presence of a kin-recognition mechanism. This recognition produced aggregations of closely-related juveniles. Circumstantial evidence from natural situations suggests that these aggregations may allow colonies to escape predation by fish and reach an invulnerable size, but that such benefits only go to colonies that are in the centers of such aggregations. It is likely that such aggregative behavior is best explained by a kin-selection hypothesis.
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Using daphnids, we have evaluated the effects of water hardness and humic acid (HA) on the chronic toxicity and bioaccumulation of Cu, Cd and Zn. Although changes in water hardness and HA concentration changed bioaccumulation or chronic toxicity, or both, of each of the three metals, there was no consistent relationship between changes in toxicity and changes in bioaccumulation. Only for Cu in hard water was there a positive correlation between toxicity and bioaccumulation. The uptake of 65Zn by molted exoskeletons suggests that changes in water chemistry do indeed modify the bioavailability of metals as would be expected. That is, an increase in the concentration of Ca2+ or Mg2+ or the increased chelation of metals by HA should decrease bioavailability. The complex storage, transformation and excretion processes in multicellular animals, however, result in there being a poor correlation among bioavailability, bioaccumulation and toxicity.
Article
A review is presented of the database generated to the present concerning trace metals, organochlorines, and petroleum-derived hydrocarbons in water, sediments and biota of Port Phillip Bay. This Bay has been extensively studied over two decades, and has been shown to be significantly contaminated by all three classes of pollutants. Historical changes in the extent of contamination are discussed, and the possible toxic impacts of sedimentary hydrocarbons in particular are assessed by comparison to data produced elsewhere. Recommendations are provided for further investigations.
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A number of features of epifaunal assemblages suggest that they have the potential to provide an excellent integrated field-based measure of marine environmental quality. In this study we have used epifaunal assemblages to investigate the ecological effects of potential gradients of environmental stress arising from marina operations and boating activities. Replicate slate panels, initially colonized by solitary ascidian-dominated assemblages at a site remote from marina operations, were placed at five sites in or near each of two boat mooring areas, Okahu Bay boat harbour and Pine Harbour marina, in the Waitemata Harbour, New Zealand. In addition, panels were immersed at Station Bay, a site remote from marina operations and boating activities. Sites were positioned along putative gradients of contaminant levels (e.g. copper and zinc), as well as hydrodynamic and sedimentation regimes. The changes in assemblage structure on panels immersed at sites along these gradients were compared. After 3–6 months, significant differences were evident among the epifaunal assemblages along the gradients of environmental stress. The most conspicuous effect was the loss of cover by the abundant and spatially dominant solitary ascidians at sites inside the marinas. Concomitant with this loss, was a marked increase in space availability, and a small increase in the cover of sponges, hydroids, erect and encrusting bryozoans, and colonial ascidians. There were also significant differences in assemblage structure between Pine Harbour and Okahu Bay, as well as between the marinas and Station Bay.
Article
Development of general theories and subsequent empirical testing are fun- damental ingredients in ecological science. The progress of such efforts is determined by the logical coherence among central concepts, theories, and predictions on one hand, and experimental design, statistical analyses, and interpretation of results on the other. Here, we specifically explore an example of how differences in the way ecological concepts are defined lead to differences in the formulation and statistical testing of hypotheses and ultimately to differences in conclusions about the relative importance of ecological pro- cesses. In marine intertidal habitats, the notion that wave exposure has an important structuring role is widely agreed upon. Nevertheless, generalizations about its effects and use for accurate prediction of assemblages are often limited. This may partly be explained by the frequent use of categorical rather than quantitative definitions of wave exposure. We com- pared the conclusions about the importance of wave exposure from (1) analyses of variance based on relative classification of wave exposure and geographic location to those of (2) regression analyses based on continuous measures from 16 locations on the Swedish west coast. Variability in richness was substantially better explained by the regression analyses, while for the cover of individual taxa there was no consistent difference between the two analytical approaches in terms of explained variability. The two approaches detected sig- nificant spatial patterns for the same taxa, but conclusions about the nature of these patterns were often divergent. Categorical analyses of relative measures of wave exposure and geographic location indicated that interactive effects and differences between geographic areas were predominant. Regression analyses of absolute, continuous measures suggested that mean significant wave height was a better predictor than geographic location and interactive terms. Thus, the choice of definition of wave exposure has important conse- quences for how causes of spatial patterns of intertidal assemblages are perceived. Cate- gorical analyses appear to provide clearer indications as to which factors are important while the use of continuous predictors sometimes provides a better fit to the data. The consequences of these findings are discussed in the context of rocky shore ecology as well as in a general perspective of ecological models, hypotheses, experimentation, and analysis.
Article
Because the bioavailability of a trace metal, and consequently its toxicity, is dependent on the physical and chemical form of the metal, we have presented a detailed assessment of how speciation of copper would be expected to affect its toxicity. Principles of chemical speciation are applied to demonstrate that inorganic forms will be in constant proportion to each other and to free copper ion during the course of the titration of a sample of natural water with copper or in the various treatments in a toxicity test conducted at constant pH and alkalinity. Binding of copper to dissolved organic matter or to suspended particulate matter may render the copper nonbioavailable. We have considered a simple complexation model to describe the complexation of copper to soluble ligands. Naturally occurring dissolved organic matter is present at concentrations only slightly greater than that of copper. Consequently, titration of water with copper results in a nonlinear relationship between the concentration of copper present as free copper ion plus inorganic copper species. The effects of stability constant of the complex, concentration of ligand, and the total copper concentration are evaluated. We have related bioavailable copper to the concentration of free copper ion plus inorganic copper complexes, which is valid if the pH and alkalinity of the waters used to develop a criteria are not different. On the basis of limited field data for the complexation of copper in Narragansett Bay water, we do not expect that significant differences in water quality criteria (WQC) would result if the criteria were to be based on free copper ion plus inorganic copper complexes rather than total copper concentrations. We examined the effect of speciation of copper in different waters as related to empirical or theoretically calculated water effect ratios (WER). We show that, on the basis of sound chemical principles, it would be expected that the most sensitive organisms would have the greatest WER. This prediction is confirmed by the empirical observations available. For insensitive organisms, knowledge of the concentration of ligand is sufficient to reasonably predict the WER. However, for the more sensitive organisms that give higher WERs, it is necessary to measure or calculate the speciation of copper to predict the WER. Use of predicted WERs may replace use of empirically derived WERs as is now part of regulatory guidance for derivation of site-specific WQC. if correspondence has been demonstrated.
Article
The increased tightening of controls on industrial and municipal wastewater discharges has resulted in steady improvements in the quality of many important rivers over recent years. However, episodic pollution, particularly from farm wastes and combined sewer overflows continues to pose a major problem, and is one of the main causes of poor quality rivers today. Despite our acknowledgement of this continuing problem, very little is known of the mechanistic basis of responses and recovery of aquatic organisms and communities exposed to intermittent pulses of common pollutants. The majority of ecotoxicological studies to date have been concerned with the effects of continuous exposure. Although such studies may provide a means of predicting the impact of episodic pollution events, a more appropriate test design would be to assess toxicity under pulsed and fluctuating exposure. Studies should also include a post-exposure observation period and should consider recovery of individuals and communities. This paper reviews the results of reported studies relevant to the investigation of episodic pollution and pays particular attention to the effects of magnitude, duration and frequency of exposure. Results of field investigations using an in situ bioassay technique are also presented to emphasize the importance of field validation of proposed water quality criteria for intermittent pollution events.
Article
Spatial variation in the recruitment of sessile marine invertebrates with planktonic larvae may be derived from a number of sources: events within the plankton, choices made by larvae at the time of settlement, and mortality of juvenile organisms after settlement, but before a census by an observer. These sources usually are not distinguished. A study of the recruitment of four species of sessile invertebrates living on rock walls beneath a kelp canopy showed that both selection of microhabitats by settling larvae and predation by fish may be important. Two microhabitats were of interest; open, flat rock surfaces, and small pits and crevices that act as refuges from fish predators. The polychaete Spirorbis eximus and the cyclostome bryozoan Tubulipora spp. showed no preference for refuges, but settled apparently at random on the available substrata. Tubulipora was preyed upon heavily by fish, while Spirorbis was relatively unaffected. The bryozoans Celleporaria brunnea and Scrupocellaria bertholetti both recruited preferentially into refuges. Scrupocellaria were preyed upon, while Celleporaria juveniles seemed unaffected. Predation by fish modified the spatial distribution (Tubulipora), abundance (Tubulipora), or size distribution (Scrupocellaria) of the juvenile population, or had relatively little effect (Celleporaria, Spirorbis). All of the above events occur within three weeks of settlement. Since inferences about the effect of larval events on the population dynamics of adult organisms are often based on observations of the patterns of recruitment after one or two months, they are therefore likely to be misleading.
Article
Although laboratory experimental studies have shown that copper is toxic to marine organisms at concentrations found in contaminated sediments, there is little unequivocal evidence of undesirable ecological effects in the field, other than at extreme concentrations. We describe a study in Botany Bay, New South Wales, Australia, in which the concentrations of copper in marine sediments were experimentally enhanced. Changes in the abundance and taxonomic composition of the fauna of copper-treated sediments relative to those of two control treatments were monitored over a period of six months. Univariate (ANOVA) and multivariate (non-metric multidimensional scaling, MDS) analyses of the changes in the fauna showed that increased concentrations of copper (140 to 1200 g g-1 compared with background concentrations of 29 to 40 g g-1) had an impact on the fauna. The nature of the response varied among taxa. For example, in some taxa, numbers of individuals decreased through time relative to controls, whereas the abundance of another taxon remained fairly constant through time in the copper treatment while numbers of control individuals increased. Differences in the changes of the faunas through time among the control and copper treatments were not always consistent among replicate experimental units 5 m apart, nor were they consistent between replicate experimental sites 100 m apart. The magnitudes of the changes in the faunas caused by the copper treatment are considered in the context of the magnitude of previously measured natural temporal variation.
Article
The marine environment is commonly used for the deliberate disposal of industrial, mining and metabolic wastes. Managers will benefit from experimental work that identifies ways of reducing environmental impacts by varying the frequency and intensity of toxicant release. Using a field dosing technique we investigated the effects of three frequencies of pulse copper pollution event, and two intensities of copper dose, on developing assemblages of sessile marine invertebrates. The resulting impacts could then be compared in assemblages exposed to the same amount of toxicant via different disturbance regimes. The experiment was replicated simultaneously at three sites within Port Philip Bay, Victoria, Australia. Pulse pollution events altered assemblage composition through a direct negative effect on densities of large solitary ascidians. In response to the removal of the spatially dominant solitary ascidians, there were increases in recruitment of many different phyla, and in the abundance of older individuals of some serpulid and bryozoan taxa. Biodiversity, as measured by total species number and Shannon's H', did not reflect the dramatic structural changes apparent within assemblages. If pulse pollution events had either a negative or positive effect on a species' density, then that effect was accentuated by increasing the intensity (strength) or the frequency of the pollution disturbance. Within populations, however, adult mortality might benefit new recruits of the same species through the freeing up of settlement space. In this case, the effects of copper pulses were evident as changes in the population size structure rather than the overall density of an organism. There were variable responses to manipulating the output rate of the toxicant between sites that appear to be driven by the rate of recovery of the dominant space occupiers. At one site there was a negligible effect of disturbance intensity and impacts could be minimized through reducing only the frequency of toxicant release. At two other sites both the intensity and frequency of disturbance determined the pollution effect and minimizing impacts was feasible only through an overall reduction in the amount of toxicant released. The management and reduction of pollution impacts through the control of toxicant release will require site- and season-specific modifications.
Article
Concentrations of heavy metals (zinc, copper and lead) were manipulated experimentally to test the hypotheses about effects on intertidal, soft-sediment assemblages of animals in two sand-flats in Port Hacking, Australia. Hypotheses about changes in the structure and composition of whole assemblages and changes in mean abundance and variability of individual taxa were tested. Specific hypotheses were derived a priori from repeated observations of assemblages in urban and non-urban areas of Port Hacking.
Article
Recruitment of sessile marine invertebrates onto small panels at two subtidal sites in southern Australia varied considerably on all spatial and temporal scales. Recruitment at West Lakes was consistently higher than at Edithburgh, usually by an order of magnitude or more. There were strong seasonal trends in the number of recruits and the number of colonizing species per panel at West Lakes, but these trends were unclear at Edithburgh. Small panels received fewer recruits than did larger panels, although the number of recruits per cm² did not change.
Article
Considering the difficulty of making meaningful extrapolations of laboratory bioassay data to real world situations, short-term tests have been carried out in a factorial pattern to determine the magnitude of effect variation resulting from changes in experimental abiotic conditions.Three selected zooplankton species (the rotifer Brachionus plicatilis, the brine shrimp Artemia salina and the waterflea Daphnia magna) have been exposed to increasing concentrations of two chemicals (one inorganic and one organic) in different combinations of two major environmental variables.For the brackish water rotifer B. plicatilis the acute toxicity of potassium dichromate and sodium laurylsulphate was determined in 16 different combinations of temperature and salinity (10–17–24–31°C and 5–20–35–50‰). For the marine crustacean A. salina, the acute toxicity of the same two chemicals was determined in 20 temperature-salinity combinations (10–15–20–25–30°C and 5–20–35–50‰) and for the freshwater crustacean D. magna, 16 combinations of temperature and water hardness (7–14–21–28°C and 80–320–560–800 mg/1 CaCO3) were assayed.The entire study comprised nearly 300 complete toxicity tests. 24-h LC50 values (for Artemia and Brachionus) and 24-h EC50 values (for Daphnia) revealed that the variation in toxicity resulting from changing environmental conditions, is both species- and chemical-specific and (within the limits of this study) ranged from a minimum of a factor 2.5 to a maximum exceeding a factor of 100.The necessity to take such variations into consideration in predictive hazard assessment studies is underlined.
Article
The intertidal invertebrate macrofauna of five creeks in the Fal estuarine system, Cornwall, UK, is compared with data from 40 locations in six other estuaries in south-west Britain. Multivariate analysis shows that the community composition in the Fal is distinct from all the other estuaries. The differences are principally due to the absence of two crustacean species, Corophium voluntator and Cyathura carinata, and the high abundance of small opportunistic annelid species. The Fal Estuary is heavily contaminated with heavy metals as a result of mining in the catchment, and the faunistic features are commensurate with what is known of the relative sensitivities of marine invertebrate taxa to pollution.
Article
The effects of humic acid (HA) on the toxicity of copper to sea urchin Paracentrotus lividus larvae were studied in chemically defined seawater. Square Wave Anodic Stripping Voltammetry (SWASV) was employed to study the complexation of copper in seawater medium. A simple complexation model assuming one ligand type and a 1:1 reaction stoichiometry successfully explained the inverse titration experiments. A conditional stability constant of 6.53+/-0.05 and a complexating capacity of 230+/-7 micromol Cu/g HA were obtained. Sea urchin bioassay tests with two endpoints, embryogenesis success and larval growth were carried out in order to study the toxicity of dissolved copper in both the presence and absence of HA. The toxicity data obtained fitted well into a logistic model, and the high sensitivity of both endpoints (EC(50) were 41.1 microg Cu/l and 32.9 microg Cu/l, respectively) encourages their use for biomonitoring. The HA had a clearly protective effect, reducing the toxicity of Cu to the sea urchin larvae. The labile copper, rather than the total copper concentrations, explained the toxicity of the Cu-HA solutions, and the Cu-HA complexes appeared as non-toxic forms. These results are in agreement with the Free Ion Activity Model, because the labile Cu concentrations in this buffered and chemically defined medium covary with the free ion activity of the Cu, validating the model to naturally occurring HA in the marine environment.
Article
Invertebrate communities in polluted rivers are often exposed to a wide variety of compounds. Due to complex interactions, 'pollution tolerant' species are not necessarily the most tolerant species to toxicants tested under standard laboratory conditions. It was hypothesized that the distribution of species in polluted rivers is not only dependent on the tolerance of species to toxicants, but also on species-specific capacities to modify or compensate for negative effects of toxicants. To test this hypothesis, species-specific responses to metals in organically enriched river water were studied under controlled conditions. The zebra mussel Dreissena polymorpha and the midge Chironomus riparius were exposed to metal-polluted water from the River Dommel. Additionally, the (interactive) effects of metals and humic acids (HA) on both species were evaluated. In spite of a lower tolerance of Chironomus riparius to metals in laboratory studies, the midge was the most tolerant of the two test species to metal-polluted site water. The results indicated that the sensitivities of the two test species determined in laboratory tests were inversely related to their sensitivities to polluted river water. In accordance with these results, midge larvae were protected from copper (Cu) toxicity by HA, while metal toxicity was not reduced (Cu) or even amplified (cadmium) by HA for the zebra mussel. Thus, the presence of (naturally occurring) HA in site water may partly account for discrepancies between responses of species to bioassays and toxicity tests. It is suggested that these differences in responses to metals in site water are strongly influenced by species-specific preferences for organic compounds (like HA). It is concluded that the response to organic compounds present in site water largely determines whether a species is classified as 'pollution tolerant' or 'pollution sensitive'.
Article
Several coastal rocky shores in northern Chile have been affected by the discharges of copper mine tailings. The present study aims to analyze the chemical speciation of heavy metals in relation to the diversity of sessile species in the rocky intertidal benthic community on the northern Chilean coast, which is influenced by the presence of copper mine tailings. In particular, the chemical forms of Cd, Cu, Fe, Mn, Ni, Pb and Zn in beach sediment samples collected in the area influenced by El Salvador mine tailings were studied using a sequential chemical extraction method. In general, all the elements present a maximum concentration in the area near the actual discharge point (Caleta Palito). With regard to Cu and Mn, the concentrations range between 7.2-985 and 746-22,739 microg/g respectively, being lower than background levels only in the control site of Caleta Zenteno. Moreover, the correlation coefficients highlight that Fe, Mn and Ni correlate significantly and positively in the studied area, showing a possible common, natural origin, whilst Cu shows a negative correlation with Fe, Mn and Ni. It could be possible that Cu has an anthropogenic origin, coming from mining activity in the area. Cd, Fe, Mn, Ni, Pb and Zn are mostly associated with the residual phase, whilst Cu presents a different speciation pattern, as resulted from selective extractions. In fact, Cu is highly associated with organic and exchangeable phases in contaminated localities, whilst it is mainly bound to the residual phase in control sites. Moreover, our results, compared to local biological diversity, showed that those sites characterized by the highest metal concentrations in bioavailable phase had the lowest biodiversity.