Effect of copper on the scope for growth of clams (Tapes philippinarum) from a farming area in the Northern Adriatic Sea

Impaired reproduction, energy reserves and dysbiosis: The overlooked consequences of heatwaves in a bivalve mollusc

Extreme events like Marine Heatwaves (MHWs) are becoming more intense, severe, and frequent, threatening benthic communities, specifically bivalves. However, the consequences of non-lethal MHWs on animals are still poorly understood. Here, we exposed the Manila clam Ruditapes philippinarum to non-lethal MHW for 30 days and provided an integrative view of its effects. Our result indicated that albeit non-lethal, MHW reduced clam's energy reserves (by reducing their hepato-somatic index), triggered antioxidant defenses (particularly in males), impaired reproduction (via the production of smaller oocytes in females), triggered dysbiosis in the digestive gland microbiota and altered animals' behaviour (by impacting their burying capacity) and filtration rate. Such effects were seen also at RNA-seq (i.e. many down-regulated genes belonged to reproduction) and metabolome level. Interestingly, negative effects were more pronounced in males than in females. Our results show that MHWs influence animal physiology at multiple levels, likely impacting its fitness and its ecosystem services.

Modelling spatial dispersion of contaminants from shipping lanes in the Baltic Sea

Major sources of pollution from shipping to marine environments are antifouling paint residues and discharges of bilge, black, grey and ballast water and scrubber discharge water. The dispersion of copper, zinc, naphthalene, pyrene, and dibromochloromethane have been studied using the Ship Traffic Emission Assessment Model, the General Estuarine Transport Model, and the Eulerian tracer transport model in the Baltic Sea in 2012. Annual loads of the contaminants ranged from 10^-2 tons for pyrene to 100 s of tons for copper. The dispersion of the contaminants is determined by the surface kinetic energy and vertical stratification at the location of the discharge. The elevated concentration of the contaminants at the surface persists for about two-days and the contaminants are dispersed over the spatial scale of 10-60 km. The Danish Sounds, the southwestern Baltic Sea and the Gulf of Finland are under the heaviest pressure of shipborne contaminants in the Baltic Sea.

Evaluating bivalve cytoprotective responses and their regulatory pathways in a climate change scenario

Temperature is a relevant abiotic factor affecting physiological performance and distribution of marine animals in natural environments. The changes in global seawater temperatures make it necessary to understand how molecular mechanisms operate under the cumulative effects of global climate change and chemical pollution to promote/hamper environmental acclimatization. Marine mussels are excellent model organisms to infer the impacts of those anthropogenic threats on coastal ecosystems. In this study, Mediterranean mussels (Mytilus galloprovincialis) were exposed to different concentrations of the metal copper (Cu as CuCl₂: 2.5, 5, 10, 20, 40 μg/L) or the antibiotic oxytetracycline (OTC: 0.1, 1, 10, 100, 1000 μg/L) at increasing seawater temperatures (16 °C, 20 °C, 24 °C). Transcriptional modulation of a 70-kDa heat shock protein (HSP70) and of the ABC transporter P-glycoprotein (P-gp, encoded by the ABCB gene) was assessed along with the cAMP/PKA signaling pathway regulating both gene expressions. At the physiological temperature of mussels (16 °C), Cu and OTC induced bimodal changes of cAMP levels and PKA activities in gills of exposed animals. A correlation between OTC- or Cu- induced changes of PKA activity and expression of hsp70 and ABCB was observed. Temperature increases (up to 24 °C) altered ABCB and hsp70 responses to the pollutants and disrupted their relationship with cAMP/PKA modulation, leading to loss of correlation between the biological endpoints. On the whole, the results indicate that temperature may impair the effects of inorganic and organic chemicals on the cAMP/PKA signaling pathway of mussels, in turn altering key molecular mediators of physiological plasticity and cytoprotection.

Copper effect on the biomarker state of the Mizuhopecten yessoensis tissues in the prespawning period

The aim of this study was to investigate the sensitivity of the marine scallop Mizuhopecten yessoensis to different copper concentrations (10 and 30 μgl-1) in the prespawning period. Reaction of the scallop to this effect was evaluated by a set of biomarkers, including general metabolism enzymes (acid and alkaline phosphatase activities - AcPase, ALP), and oxidative stress parameters (catalase antioxidant enzyme activity - CAT and levels of damage for DNA, lipids and proteins). Experiment results show that when copper is accumulated in tissues, enzyme activity changes are similar and have phasic character. The dynamics of these changes depends on the copper accumulation levels in tissues. Unlike enzyme reaction to copper accumulation, oxidative damage of biologic molecules changes in tissues in different ways. Copper enters into a scallop's organism, mainly through the gills, where there is a more expressed reaction of biomarkers compared to the digestive gland.

Use of the Atlantic nut clam (Nucula proxima) and catworm (Nephtys incisa) in a sentinel species approach for monitoring the health of Bay of Fundy estuaries

Designing an effective environmental monitoring system for population responses requires knowledge of the biology of appropriate sentinel species and baseline information on the area's physical and chemical characteristics. This study collected information in Saint John Harbor, NB, Canada, for two abundant marine benthic invertebrates, the Atlantic nut clam (Nucula proxima) and the catworm (Nephtys incisa) to characterize their seasonal and spatial variability, determine the ideal sampling time and methods, and develop baseline data for future studies. We also evaluated whether contamination is impacting invertebrates by comparing sediment metal concentrations to responses of benthic infauna. Metals were generally below sediment quality guidelines except for nickel and arsenic. Clam densities were variable between sites but not seasons, whereas catworm densities were not significantly different between sites or seasons. Overall, these species show potential for environmental monitoring, although investigation at more contaminated sites is warranted to assess their sensitivity.

Metal and metallothionein distribution in different tissues of the Mediterranean clam Venerupis philippinarum during copper treatment and detoxification

Filter feeding animals can accumulate large amount of contaminants in their body through particles filtered from seawater. In particular, copper is interesting since it plays important roles as co-factor of numerous proteins but its toxicity is well established, also because it can readily generate free radicals or oxidize cellular components through their redox activity. Its availability is tightly regulated within cells: it is immediately transferred to metallothionein (MT) that in turn provides efficient and specific mechanisms for its intracellular storage and transport. The aim of this study was to evaluate the acute effect of sublethal copper concentrations in Venerupis philippinarum, by studying the kinetics of copper, zinc (for its interactions at the sites of intake or elimination with the accumulation of other essential and not essential trace metals) and metallothionein accumulation under laboratory conditions. The time-course of metal accumulation/elimination is similar in digestive gland and gills and importantly it is dose-dependent. Both copper and zinc increase slowly within cells, reaching a maximum concentration at the end of the exposure period. During the detoxification period, the metal levels in digestive gland and gills rapidly decrease, with different kinetics in the two tissues. Positive correlations between metallothionein accumulation and copper or zinc concentrations have been verified in both treated groups. The obtained data demonstrated the involvement of MTs in detoxification strategies after a recovery period in clean seawater.

Cellular Energy Allocation to Assess the Impact of Nanomaterials on Soil Invertebrates (Enchytraeids): The Effect of Cu and Ag

The effects of several copper (Cu) and silver (Ag) nanomaterials were assessed using the cellular energy allocation (CEA), a methodology used to evaluate the energetic status and which relates with organisms' overall condition and response to toxic stress. Enchytraeus crypticus (Oligochatea), was exposed to the reproduction effect concentrations EC20/50 of several Cu and Ag materials (CuNO3, Cu-Field, Cu-Nwires and Cu-NPs; AgNO3, Ag NM300K, Ag-NPs Non-coated and Ag-NPs PVP-coated) for 7 days (0-3-7d). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (Ec) integrated to obtain the CEA. Results showed that these parameters allowed a clear discrimination between Cu and Ag, but less clearly within each of the various materials. For Cu there was an increase in Ec and protein budget, while for Ag a decrease was observed. The results corroborate known mechanisms, e.g., with Cu causing an increase in metabolic rate whereas Ag induces mitochondrial damage. The various Cu forms seem to activate different mechanisms with size and shape (e.g., Cu-NPs versus Cu-Nwires), causing clearly different effects. For Ag, results are in line with a slower oxidation rate of Ag-NMs in comparison with Ag-salt and hence delayed effects.

Contrasted responses of Ruditapes decussatus (filter and deposit feeding) and Loripes lacteus (symbiotic) exposed to polymetallic contamination (Port-Camargue, France)

The use of symbiotic bivalve species to assess the effect of anthropogenic metal pollution was rarely investigated whereas data on filter feeding bivalves are common. The aim of this study was the exposure of two bivalve species, Ruditapes decussatus and Loripes lacteus to polymetallic pollution gradient, originating from harbor activities (Port-Camargue, south of France). Both bivalves differ by their trophic status, filter and deposit feeder for Ruditapes and symbiotic for Loripes that underlies potential differences in metal sensibility. The bivalves were immerged in July (for Ruditapes during 2 and 8 days) and in August 2012 (for Loripes during 2, 6 and 8 days) in the water column of the harbor, at 3 stations according to pollution gradient. Metal concentrations (Cu, Mn, Zn) in the water column were quantified as dissolved metals (measured by ICP-MS) and as labile metals (measured by ICP-MS using DGT technique). For each exposure time, accumulation of metals in the soft tissue of bivalves ("bioaccumulation") was measured for both species. In addition, specific parameters, according to the trophic status of each bivalve, were investigated: filtering activity (specific clearance rate, SCR) for Ruditapes, and relative cell size (SSC) and genomic content (FL1) of bacterial symbionts hosted in the gills of Loripes. The SCR of Ruditapes drops from 100% (control) to 34.7% after 2 days of exposure in the less contaminated site (station 8). On the other hand, the relative cell size (SSC) and genomic content (FL1), measured by flow cytometry were not impacted by the pollution gradient. Bioaccumulation was compared for both species, showing a greater capability of Cu accumulation for Loripes without lethal effect. Mn, Fe and Zn were generally not accumulated by any of the species according to the pollution gradient. The trophic status of each species may greatly influence their respective responses to polymetallic pollution.

Spatio-temporal pattern of community development in dredged material used for habitat enhancement: A study case in a brackish lagoon

Dredged material is a potential resource for beneficial use for create/improve subtidal habitats. In a northwestern Adriatic lagoon, dredged sand was placed in inner areas with the management objective of improving the characteristics of the muddy areas being recharged. With this study we investigated the recolonization dynamics of benthic communities following the placement of dredged sand in a microtidal lagoon. The disposal of dredged sand had an immediate and negative effect on resident fauna. After an initial reduction, benthic communities followed different recovery pathways. One year after disposal, we recorded an almost complete recovery of the benthic invertebrates in terms of univariate parameters. Despite multivariate analyses still showed significantly different community structures, the trajectories of recovery for disposal areas converged towards the same basin of attraction of control areas. The ecological quality of sites, assessed with benthic indices, did not improve, thus no new beneficial habitat was created for macrobenthos.

The "one-out, all-out" principle entails the risk of imposing unnecessary restoration costs: a study case in two Mediterranean coastal lakes

The Water Framework Directive uses the "one-out, all-out" principle in assessing water bodies (i.e., the worst status of the elements used in the assessment determines the final status of the water body). In this study, we assessed the ecological status of two coastal lakes in Italy. Indices for all biological quality elements used in transitional waters from the Italian legislation and other European countries were employed and compared. Based on our analyses, the two lakes require restoration, despite the lush harbor seagrass beds, articulated macrobenthic communities and rich fish fauna. The "one-out, all-out" principle tends to inflate Type I errors, i.e., concludes that a water body is below the "good" status even if the water body actually has a "good" status. This may cause additional restoration costs where they are not necessarily needed. The results from this study strongly support the need for alternative approaches to the "one-out, all-out" principle.

The impact and control of biofouling in marine aquaculture: a review

Biofouling in marine aquaculture is a specific problem where both the target culture species and/or infrastructure are exposed to a diverse array of fouling organisms, with significant production impacts. In shellfish aquaculture the key impact is the direct fouling of stock causing physical damage, mechanical interference, biological competition and environmental modification, while infrastructure is also impacted. In contrast, the key impact in finfish aquaculture is the fouling of infrastructure which restricts water exchange, increases disease risk and causes deformation of cages and structures. Consequently, the economic costs associated with biofouling control are substantial. Conservative estimates are consistently between 5-10% of production costs (equivalent to US$ 1.5 to 3 billion yr(-1)), illustrating the need for effective mitigation methods and technologies. The control of biofouling in aquaculture is achieved through the avoidance of natural recruitment, physical removal and the use of antifoulants. However, the continued rise and expansion of the aquaculture industry and the increasingly stringent legislation for biocides in food production necessitates the development of innovative antifouling strategies. These must meet environmental, societal, and economic benchmarks while effectively preventing the settlement and growth of resilient multi-species consortia of biofouling organisms.

Effect of copper on ion content in isolated mantle cells of the marine clam Mesodesma mactroides

The effect of copper on ion content (Na(+), K(+), Ca(2+), and Cl(-)) was evaluated in isolated mantle gills of the marine clam Mesodesma mactroides. Clams were collected at the Mar Grosso Beach (São José do Norte, Rio Grande do Sul [RS], southern Brazil), cryoanesthetized, and had their mantles dissected. Mantle cells were isolated and incubated in a calcium-free phosphate solution without (control) or with Cu (CuCl(2)). Cells were exposed to Cu for 1 h (5 µM) or 3 h (2.5 and 5 µM). In cells incubated with 2.5 µM Cu, a significant decrease in intracellular Cl(-) content was observed. However, in cells incubated with 5.0 µM Cu, significant reductions in Na(+), K(+), and Cl(-) intracellular content were observed. Given the mechanisms involved in ion transport in mantle cells of the marine clam M. mactroides, the findings described here suggest that Cu exposure inhibits carbonic anhydrase and Na(+)/K(+) -ATPase activity. Also, it can be suggested that Cu is competing with Na(+) for the same mechanisms of ion transport in the cell membrane, such as the Na(+) channels and the Na(+)/K(+)/2Cl(-) cotransporter. Results from the present study also clearly indicate that processes involved in cellular anion regulation are more sensitive to Cu exposure than those associated with the cellular cation regulation. Characterization of sites for Cu accumulation and toxicity in aquatic animals is important for derivation of metal binding constants at the biotic ligand. Also, identification of the mechanism of metal toxicity is needed for modeling metal accumulation in the biotic ligand and its consequent toxicity. Therefore, the findings reported here are extremely valuable for the development of a biotic ligand model version for marine and estuarine waters.

Comparison of toxicity and release rates of Cu and Zn from anti-fouling paints leached in natural and artificial brackish seawater

Biocide-containing anti-fouling paints are regulated and approved according to the added active ingredients, such as Cu. Biocide-free paints are considered to be less environmentally damaging and do not need an approval. Zn, a common ingredient in paints with the potential of causing adverse effects has received only minor attention. Laboratory experiments were conducted in artificial brackish seawater (ASW) and natural brackish seawater (NSW) to quantify release rates of Cu and Zn from biocide-containing and biocide-free labeled eroding anti-fouling paints used on commercial vessels as well as leisure boats. In addition, organisms from three trophic levels, the crustacean Nitocra spinipes, the macroalga Ceramium tenuicorne and the bacteria Vibrio fischeri, were exposed to Cu and Zn to determine the toxicity of these metals. The release rate of Cu in NSW was higher from the paints for professional use (3.2-3.6 microg cm(-)(2)d(-1)) than from the biocide leaching leisure boat paint (1.1 microg cm(-)(2)d(-1)). Biocide-free paints did leach considerably more Zn (4.4-8.2 microg cm(-)(2)d(-1)) than biocide-containing leisure boat paint (3.0 microg cm(-)(2)d(-1)) and ship paints (0.7-2.0 microg cm(-)(2)d(-1)). In ASW the release rates of both metals were notably higher than in NSW for most tested paints. The macroalga was the most sensitive species to both Cu (EC(50)=6.4 microg l(-1)) and Zn (EC(50)=25 microg l(-1)) compared to the crustacean (Cu, LC(50)=2000 microg l(-1) Zn, LC(50)=890 microg l(-1)), and the bacteria (Cu, EC(50)=800 microg l(-1) and Zn, EC(50)=2000 microg l(-1)). The results suggest that the amounts of Zn and Cu leached from anti-fouling paints may attain toxic concentrations in areas with high boat density. To fully account for potential ecological risk associated with anti-fouling paints, Zn as well as active ingredients should be considered in the regulatory process.

Reproductive and life stage-specific effects of aqueous copper on the grass shrimp, Palaemonetes pugio

Palaemonetes pugio exposed to copper (9 or 26 microg Cu(2+)/L) for a full life cycle were unable to produce viable embryos, precluding completion of the life cycle, despite no lethal effects on larval, juvenile, or adult life stages. Exposure to copper also resulted in a significant delay in larval development. When adults raised in copper were transferred to control seawater, they produced viable embryos, but larval output per clutch was reduced by 43% compared to clutches from females that had never been exposed to copper, suggesting reduced energetic allocation to reproduction. In acute exposures, adults exposed to copper for as little as three days were unable to produce viable embryos. Furthermore, exposure of control embryos to copper reduced hatching success by 74%. The reduction in hatching success and energetic allocation to reproduction are unlikely to be completely responsible for the lack of larval production observed in pre-spawning exposures to copper, suggesting that copper may also inhibit processes before or during spawning and fertilization.

Bioenergetic effects of aqueous copper and cadmium on the grass shrimp, Palaemonetes pugio

Adult grass shrimp (Palaemonetes pugio) were exposed to either aqueous copper (ranging from 7.54 to 41.29 microg Cu(2+)/L) or cadmium (2.48- 6.55 microg Cd(2+)/L) for 14 days in laboratory experiments to quantify effects on survival and bioenergetic processes, including respiration, somatic growth, energy (lipid) storage, and food consumption. The lowest observed effect concentrations for mortality were 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L, expressed as free metal ion concentrations. Both copper and cadmium caused a decrease in respiration rate at concentrations of 7.54 to 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L. Exposure to copper (>or=27.03 microg Cu(2+)/L) resulted in negative somatic growth (i.e., weight loss). Cadmium exposure (6.17 microg Cd(2+)/L) caused a decrease in growth rate, relative to the control, but growth remained positive. Nonpolar lipid content and food consumption were not significantly affected by exposure to either copper or cadmium. Our results suggest that both copper and cadmium result in overall metabolic depression, decreasing energy allocation to both maintenance and production.

The performance of benthic indicators of ecological change in Adriatic coastal lagoons: throwing the baby with the water?

The ecological quality of 127 stations from six Adriatic coastal lagoons was assessed using a suite of biotic indices: H', d, 1-lambda', Delta(*), Delta(+), W, AMBI, BOPA and FINE. The analysis indicated the difficulties in deriving and using the existing indices from benthic communities in highly variable environmental conditions in coastal lagoons. Different metrics rendered different results: the use of H' resulted in the classification of all stations as "Moderate/Poor/Bad", whereas BOPA classified the majority of the stations as "Good/High". Using Delta(+), most of the stations resulted as "Not anthropogenically impacted", while the W-statistics gave 82 stations as "Undisturbed" and 45 as "Moderately/Grossly disturbed". AMBI classified 55 stations as "High/Good" and 72 as "Moderate/Poor/Bad", whereas those were 32 and 95 with FINE, respectively. The latter, which was developed just for Italian coastal lagoons, was the most conservative among the indices studied. Yet, it showed the highest correlation with the species/abundance matrix. Using indices developed for coastal waters in lagoons can give the distorted indication that the water body is degraded, when it might be just a natural, low diversity, high abundance community, i.e. a lagoonal community. Moreover, the outcome of the use of a certain index has a financial dimension such that lagoons misclassified as being "poor status" will then require expensive remediation measures. For the lagoons studied, there is probably an adequate quality and quantity of benthic data available for making management decisions, but this study highlights the limits of the existing indices for lagoonal ecosystems. The challenge for the next future is to couple long term conservation of the natural environment with the highly productive activities carried out in lagoonal ecosystems.