Comparison of mussels and semi-permeable membrane devices as intertidal monitors of polycyclic aromatic hydrocarbons at oil spill sites

Side-by-side comparisons of polycyclic aromatic hydrocarbon (PAH) concentrations in resident blue mussels (Mytilus trossulus) and in semi-permeable membrane devices (SPMDs) were made at four sites in Prince William Sound, Alaska. SPMDs were deployed for approximately 30 days on the surface of the beach sediment at three tidal elevations on each shore and in 0.5 m deep open pits in the middle intertidal zone. Total PAH (TPAH) concentrations in mussels and in SPMDs were correlated, but the PAH compositions were different. The lower molecular weight PAH were relatively more abundant in the SPMDs than in the mussels at oiled and HA sites. TPAH concentrations in SPMDs deployed in pits and mussels collected adjacent to those pits at oiled sites were higher than in SPMDs and mussels from non-pitted SPMD locations approximately 3-15 m from the pits. Pitting released buried oil making its PAH bioavailable. SPMDs deployed in the supratidal zone (+4.0 m tidal elevation) were exposed to atmospheric contaminants for a large fraction of the deployment time and accumulated primarily pyrogenic (combustion-sourced) PAH from the atmosphere. The SPMD strips supplied by the manufacturer contained significant amounts (approximately 125 ng/strip) of primarily alkylated 2-3 ring PAH. These blank levels make SPMDs unsuitable for shoreline assessments when environmental PAH concentrations are low. Consequently, where available, mussels are recommended for use in assessments of the bioavailability of buried oil residues sequestered in intertidal sediments following an oil spill. Mussels are the preferred monitoring tool when the assessments involve food-chain effects. At locations where the absence of mussels necessitates the use of SPMDs or other passive sampling devices, their limitations need to be carefully considered in the interpretation of results.     

The 1974 spill of the Bouchard 65 oil barge: petroleum hydrocarbons persist in Winsor Cove salt marsh sediments

Petroleum hydrocarbons persist in salt marsh sediments in Winsor Cove (Buzzards Bay, Massachusetts) impacted from the 1974 spill of No. 2 fuel oil by the barge Bouchard 65. Intertidal sediment cores were collected from 2001 to 2005 and analyzed for total petroleum hydrocarbons (TPHs). TPHs content was greatest (as high as 8.7 mg g(-1) dry weight) in the surface sediments and decreased with distance landward. Select samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) with values as high as 16.7 microg g(-1) for total naphthalenes and phenanthrenes/anthracenes. These remaining PAHs are mainly C(4)-naphthalenes and C(1)-, C(2)-, and C(3)-phenanthrenes/anthracenes revealing preferential loss of almost all of the naphthalenes and the parent compound phenanthrene. Inspection of the data indicates that biodegradation, water-washing and evaporation were major removal processes for many of the petroleum hydrocarbons in the marsh sediments. In addition, historical data and photographs combined with their recent counterparts indicate that erosion has physically removed these contaminants from this site.     

Interannual (1999-2005) morphodynamic evolution of macro-tidal salt marshes in Mont-Saint-Michel Bay (France)

This paper provides a detailed study on the sedimentation patterns and the recent morphodynamic evolution affecting the macro-tidal salt marshes located west of the Mont-Saint-Michel (France). Twenty-two stations along three transects on the marshes were seasonally monitored for marsh surface level variations from 1999 to 2005, using a sediment erosion bar. The corresponding erosion/accretion rates were obtained together with data on topography, vegetation cover, and grain size of surface sediment. To examine the mechanisms contributing to the salt marsh sedimentation, the data and their evolution were treated with respect to tides, relative mean regional sea level, and wind speed/frequency variations.From 1999 to 2005, the marsh was globally accreting (from 3.45 to 38.11 mm yr⁻¹ in the low marsh, up to 4.91 mm yr⁻¹ in the middle marsh, and up to 1.35 mm yr⁻¹ in the high marsh), while the study was conducted during a window of decreasing trend in mean regional sea level (−2.45 mm yr⁻¹ according to regional-averaged time series). These sedimentation rates are one of the highest recorded worldwide; however, the sedimentation was not found to be continuous over the period in question. This pattern is illustrated by the strong extension of the marshes from 1999 to 2002, and the relative stability observed from 2003 to 2005. The imported and reworked sediments are trapped and fixed by the dense vegetation (Puccinellia maritima, Halimione portulacoides), inducing the general seaward extension of the marshes. The processes governing sediment budget (accretion/erosion) show annual, seasonal, and spatial variability on the marsh. Spatial variations display contrasted patterns of erosion/sedimentation between the low, middle, and high marsh, and between the different transects. These patterns are a result of distance from sediment sources, strong heterogeneity in vegetation cover (human induced or not), and contrasting topographic and micro-topographic characteristics. The higher accretion rates are observed in distal settings in the low marsh, and strongly decrease toward the middle and high marsh. This evolution results from a decrease in accommodation space/water column thickness, and frequency of inundation coupled with an increase in station elevation, but also from the cumulated effects of vegetation cover and micro-topography. The vegetation cover of the low and middle marsh enhance the settling and fixing of fine sediments imported through tides or dispersed by flood and ebb currents.The seasonal evolution of the marshes is marked by contrasting effects of water storage in the sediment. The overall seasonal sediment budget is controlled by the variation of the frequency of inundation relative to tidal range and marshes topography. Autumns are influenced by the tide (equinoxes), relative mean regional sea level, and variations in wind speed/frequency. Winter wind speed and frequency in relation with tidal variations appear to be the main parameters regulating winter marsh evolution. Summers are predominantly under the influence of local variations in water storage (desiccation) while external parameters generally display a low influence. Although it is not governed by any one parameter, springtime sediment budget seems to result from strong interaction between the above-cited parameters, despite the significant frequency of inundation (equinoxes).     

Selection of bioindicators for monitoring marine environmental quality in the Bay of Fundy,Atlantic Canada

Distribution of metals, PAH's and PCB's in lobsters, mussels, and sediments were used to assess marine environmental quality of the Bay of Fundy. This study demonstrates that the lobster (Homarus americanus) is a better bioindicator for monitoring contaminants in the marine environment and has a greater capacity for the uptake and accumulation of contaminants than the mussel (Mytilus edulis) and sediments. A definite pattern in the spatial distribution of lobster Cu, Cd, and Ag was evident. The distribution of organic contaminants for both mussels and lobsters in the Bay of Fundy lacked a spatial trend, and organic contaminants were undetectable in sediments from all sites. The Gulf Watch Programme, which monitors chemicals in mussels in the Bay of Fundy, did not indicate a problem with high levels of Cu, Cd, and Zn in the ecosystem. Analytes below the detection limit, such as in mussels and sediments, increase the difficulties of chemical analysis and detection for environmental monitoring. Deficiencies of mussels in monitoring the Bay of Fundy were discussed.     

Agricultural inputs of mecoprop to a salt marsh system: Its fate and distribution within the sediment profile

The mass of mecoprop discharged in agricultural drainage waters directly onto a salt marsh has been determined and the subsequent fate and distribution of mecoprop within the vegetated and mud flat sediments investigated. The results show the leaching of high mecoprop concentrations from the agricultural soils following heavy rain, with peak concentrations in drainage waters preceding peak water discharges. A direct increase in mecoprop concentration within salt marsh sediments was also identified and, consequently, a preliminary evaluation of the potential threat of the mecoprop loadings to the indigenous biota of the dynamic salt marsh system was made.     

Comparison of the role of two Spartina species in terms of phytostabilization and bioaccumulation of metals in the estuarine sediment

In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals.     

Long-term chemical effects of petroleum in south Louisiana wetlands—I. Organic carbon in sediments and waters

The chemical effects of chronic petroleum input into a shallow water marsh were examined by measuring hydrocarbon levels and dissolved organic carbon content of sediments associated with two active oil fields in south Louisiana. Annual levels of total organic carbon in the surface waters of the oil fields were higher by 1 mg C/l. in the salt marsh and 5 mg C/l. in the fresh marsh than the respective controlsites. Average dissolved organic carbon concentrations in the interstitial waters of cores taken within the oil field environments were 105% higher than the control in the salt marsh and 43% higher than the control in the fresh marsh. Significantly lower ratios of C₁₇ to pristane occurred in both oil field sediments; however, average odd-even predominance values were not indicative of petroleum contaminated sediments. The results indicate that microbial processes are responsible for dissolution of petroleum into dissolved organic carbon and that dissolved organic carbon concentrations may be a more significant measure of chronic petroleum input than hydrocarbon distribution.     

Influence of multiple stressors on the auto-remediation processes occurring in salt marshes

Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni - micronutrients, and Cd - class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health.     

Quality assessment of the blue mussel (Mytilus edulis): Comparison between commercial and wild types

This study compared species identity, microplastics, chemical and microbial contamination between consumption mussels and wild type mussels, collected at Belgian department stores and Belgian groynes and quaysides, respectively. Species identification based on genetic analysis showed a high number of Mytilus (M.) edulis compared to M. galloprovincialis and M. edulis/galloprovincialis hybrid mussels. The number of total microplastics varied from 2.6 to 5.1 fibres/10 g of mussel. A higher prevalence of orange fibres at quaysides is related to fisheries activities. Chemical contamination of polycyclic aromatic hydrocarbons and polychlorobiphenyls could be related to industrial activities and water turbidity, with maximum concentrations at the quayside of port Zeebrugge. The inverse was noted for Escherichia coli contamination, which was relatively low at Zeebrugge quayside with a total count of 3.9 × 10² CFU/100 g tissue, due to limited agricultural effluents. Results of this complementary analysis stress the importance of integrated monitoring and quality assessment.     

An Assessment of Potential Oil Spill Damage to Salt Marsh Habitats and Fishery Resources in Galveston Bay, Texas

We sampled nekton, benthic infauna, and sediments in salt marshes of upper Galveston Bay, Texas to examine relationships between habitat use and sediment hydrocarbon concentration. Most marsh sediment samples were contaminated with relatively low concentrations of weathered petroleum hydrocarbons. We found few statistically significant negative relationships between animal density and hydrocarbon concentration (6 of 63 taxa examined using simple linear regression). Hydrocarbon concentration did not contribute significantly to Stepwise Multiple Regression models we used to explore potential relationships between animal densities and environmental parameters; in most cases where hydrocarbon concentration was an important variable in the models, the relationship was positive (i.e., animal densities increased with hydrocarbon concentration). Low hydrocarbon concentrations in sediments of upper Galveston Bay marshes could have contributed to our results either because levels were too low to be toxic or levels were toxic but too low to be detected by most organisms.     

Size effects of suspended particles on gill damage in green-lipped mussel Perna viridis

The green-lipped mussels Perna viridis were exposed to <500 μm suspended solids (SS) with concentrations of 0 (control), 250, 500, 750 and 1000 mg/L for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significantly higher damages to the cilia on the frontal surface of the gill filaments than that on the abfrontal surface in both demibranchs. Percent ciliary depletion varied with SS concentrations and time. No sign of recovery of the gill filaments was observed after the mussels were transferred to clean seawater. In a second experiment, mussels were exposed to SS with size range from <63, >125–<250 and >250–<500 μm at 600 mg/L, together with a control (0 mg/L) for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significant ciliary damages in both the ascending and descending lamellae under the three particle size groups as compared with the control. Percent depletion of frontal cilia was most serious for the >250–<500 μm size group and least for the <63 μm size group. However, percent depletion of abfrontal cilia was most serious for the >125–<250 μm size group and least for the <63 μm size group. No recovery of ciliary damages was observed. The effects of particle size of suspended sediments on the morphological damages of gill filaments in the green-lipped mussels were discussed.     

Vertical structures of PM10 and PM 2.5 and their dynamical character in low atmosphere in Beijing urban areas

The vertical structures and their dynamical character of PM2.5 and PM10 over Beijing urban areas are revealed using the 1 min mean continuous mass concentration data of PM2.5 and PM10 at 8, 100, and 320 m heights of the meteorological observation tower of 325 m at Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP CAS tower hereafter) on 10―26 August, 2003, as well as the daily mean mass concentration data of PM2.5 and PM10 and the continuous data of CO and NO2 at 8, 100 (low layer), 200 (middle layer), and 320 m (high layer) heights, in combination with the same period meteorological field observation data of the meteorological tower. The vertical distributions of aerosols observed on IAP CAS tower in Beijing can be roughly divided into two patterns: gradually and rapidly decreasing patterns, I.e. The vertical distribution of aerosols in calm weather or on pollution day belongs to the gradually decreasing pattern, while one on clean day or weak cold air day belongs to the rapidly decreasing pattern. The vertical distributive characters of aerosols were closely related with the dynamical/thermal structure and turbulence character of the atmosphere boundary layer. On the clean day, the low layer PM2.5 and PM10 concentrations were close to those at 8 m height, while the concentrations rapidly decreased at the high layer, and their values were only one half of those at 8 m, especially, the concentration of PM2.5 dropped even more. On the clean day, there existed stronger turbulence below 150 m, aerosols were well mixed, but blocked by the more stronger inversion layer aloft, and meanwhile, at various heights, especially in the high layer, the horizontal wind speed was larger, resulting in the rapid decrease of aerosol concentration, I.e. Resulting in the obvious vertical difference of aerosol concentrations between the low and high layers. On the pollution day, the concentrations of PM2.5 and PM10 at the low, middle, and high layers dropped successively by, on average, about 10% for each layer in comparison with those at 8 m height. On pollution days, in company with the low wind speed, there existed two shallow inversion layers in the boundary layer, but aerosols might be, to some extent, mixed below the inversion layer, therefore, on the pollution day the concentrations of PM2.5 and PM10 dropped with height slowly; and the observational results also show that the concentrations at 320 m height were obviously high under SW and SE winds, but at other heights, the concentrations were not correlated with wind directions. The computational results of footprint analysis suggest that this was due to the fact that the 320 m height was impacted by the pollutants transfer of southerly flow from the southern peripheral heavier polluted areas, such as Baoding, and Shijiazhuang of Hebei Province, Tianjin, and Shandong Province, etc., while the low layer was only affected by Beijing's local pollution source. The computational results of power spectra and periods preliminarily reveal that under the condition of calm weather, the periods of PM10 concentration at various heights of the tower were on the order of minutes, while in cases of larger wind speed, the concentrations of PM2.5 and PM10 at 320 m height not only had the short periods of minute-order, but also the longer periods of hour order. Consistent with the conclusion previously drawn by Ding et al., that air pollutants at different heights and at different sites in Beijing had the character of "in-phase" variation, was also observed for the diurnal variation and mean diurnal variation of PM2.5 and PM10 at various heights of the tower in this experiment, again confirming the "in-phase" temporal/spatial distributive character of air pollutants in the urban canopy of Beijing. The gentle double-peak character of the mean diurnal variation of PM2.5 and PM10 was closely related with the evident/similar diurnal variation of turbulent momentum fluxes, sensible heat fluxes, and turbulent kinetic energy at various heights in the urban canopy. Besides, under the condition of calm weather, the concentration of PM2.5 and PM10 declined with height slowly, it was 90% of 8 m concentration at the low layer, a little lesser than 90% at the middle layer, and 80% at the high layer, respectively. Under the condition of weak cold air weather, the concentration remarkably dropped with height, it was 70% of 8 m concentration at the low layer, and 20%―30% at the middle and high layers, especially the concentration of PM2.5 was even lower.     

Ammonium occurrence in a salinized lowland coastal aquifer (Ferrara,Italy)

To understand the spatial distribution and the possible sources of high ammonium concentration in the unconfined coastal aquifer of the Po River Delta lowland (Italy), a detailed characterization of inorganic nitrogen species was completed. A total of 59 boreholes were drilled to collect core samples and groundwater samples of the aquifer. Among them, four piezometers, located along a representative flow line, were chosen to monitor the inorganic nitrogen concentrations with depth. Ammonium is the prevalent nitrogen inorganic species in groundwater, and its concentration increases with depth and salinity. Very high ammonium concentrations are found in coincidence with peaty sediments in the salinized anoxic aquifer and in the low‐lying aquitard. In particular, the elevated ammonium concentration derives from mineralization of organic matter present in fine sediments deposited in paleo‐marsh environments. Copyright © 2012 John Wiley & Sons, Ltd.     

Shellfish from Todos os Santos Bay, Bahia, Brazil: treat or threat?

This study determined the concentrations of major and trace elements in shellfish (oysters, clams and mussels) and conducted an assessment of the health risks due to the consumption of contaminated seafood. Samples were collected at 34 sites along Todos os Santos Bay, Brazil. The elements were determined by ICP OES and Hg by Direct Mercury Analysis. Relatively high concentrations of trace elements (As, Zn, Se and Cu) were found in seafood tissues. Potential daily intake of As, Co, Se, Zn and Cu associated to shellfish consumption suggested relevant non-carcinogenic risk for all studied locations. Copper was the element that posed the greatest non-carcinogenic risk, while Pb posed the highest carcinogenic risk. Health risks for humans were greatest from the consumption of mussels. Contaminated shellfish offer the greatest risk for children, subsistence fishers and subsistence shellfish consumers.     

Polycyclic aromatic hydrocarbons in sediments,mussels and crustacea around a former gasworks site in Shoreham-by-Sea,UK

Concentrations of polycyclic aromatic hydrocarbons have been determined in sediments, mussels and crustacea in the vicinity of a former gasworks site by Shoreham Harbour, UK. Very high concentrations of PAH were found in the substrate, an ash-like material deposited on the former gasworks site, which exhibited a profile consistent with the major source of contamination being coal or coke tar produced during the period of gas production at the site. Elevated PAH concentrations were also found in mussels both from the beach below the former gasworks site, and from sites further to the east in Portslade and Hove. The significance of these concentrations were assessed using an approach which involved the calculation of benzo[a]pyrene equivalent conoentrations (BaPEs), summing concentrations of individual PAH on the basis of their comparative potency as carcinogens. BaPE ranged from values of, or close to, zero for crustacea, to 336 microg kg(-1) wet weight in mussels from Southwick Beach. The contaminated mussels are not exploited commercially but may be taken by casual gatherers, and notices have been posted to warn potential consumers.     

Erosion of a cyclic saltmarsh in Morecambe Bay,North-West England

This paper presents results of investigations (1983–1992) into rates of change, morphology and processes occurring during the current erosional phase in a Morecambe Bay cyclic saltmarsh, in which it has narrowed from c. 1000 m (1975) to c. 150 m (1992). Monthly monitoring of marsh edge erosion and creek knickpoint retreat has revealed temporal and spatial variations. Highest frequency changes of low magnitude coincided with non-storm conditions and overmarsh tides above 5·80 m OD, which submerged the whole marsh. Less frequent changes of greater magnitude were associated with both overmarsh tides and strong onshore winds over 15 ms^?1, which generated high energy waves. The lowest frequency change of greatest magnitude occurred during an extreme onshore storm event and surge. Morphologically, during the erosional phase, a low angled landward slope was generated as erosion of the c. 0·5 m high active seaward cliff coincided with vertical accretion of 0·07 ma^?1 of relatively coarse sediment on the marsh surface immediately landward. Tidal hydrodynamics strongly influence the saltmarsh, which is confined to the upper 2·5 m of the macrotidal range (maximum c. 10·5 m). During overmarsh spring tides (maximum creek flood flow rate 0·13 ms^?1, up to bankfull level), flooding begins over lower landward creek banks before submerging the higher marsh edge. During ebb tides, water trapped by this higher edge can escape seaward only via the creeks (maximum ebb velocities 2·07 ms^?1 below bankfull level). Wave erosion also is limited to spring tides. Monthly mapping of the Kent Estuary channel pattern seaward of the saltmarsh showed that medium term higher erosion rates were related to the presence of a large channel, which lowered the adjacent creek base level and allowed larger waves to attack the marsh edge than when a sandbank flanked the marsh. Major River Kent channel shifts appear to initiate accretional or erosional phases of cyclic saltmarsh development.     

Contaminant exposures at the 4H shell mounds in the Santa Barbara Channel

Remobilization, bioavailability, and potential toxicity of chemical contaminants were evaluated at the 4H shell mounds – the site of abandoned offshore oil and gas production platforms in the Santa Barbara Channel region of the Southern California Bight. Evaluations used a weight-of-evidence approach based on results from bulk phase chemical analyses and laboratory toxicity testing of shell mound cores, in situ field bioassays using caged mussels, and surficial sediment chemistry. Shell mound cores contained elevated concentrations of metals associated with drilling wastes (e.g., Ba, Cr, Pb, and Zn), as well as monocyclic and polycyclic aromatic hydrocarbons (PAHs). The highest concentrations along with pockets of free oil were associated with the middle “cuttings” stratum. Sediments composited from all core strata caused significant acute toxicity and bioaccumulation of Ba and PAHs in test organisms during laboratory exposures. In contrast, caged mussels placed at each of the shell mounds for a period of 57–58 days had greater than 90% survival, and there were no significant differences in survival of mussels placed at the shell mounds and corresponding reference sites. While all mussel samples exhibited increases in shell length, whole animal weight, and tissue lipid content, in some cases growth metrics for the shell mound mussels were significantly higher than those for the reference sites. Concentrations of metals, PAHs, and polychlorinated biphenyls (PCBs) in tissues of the shell mound mussels were not significantly different from those at reference sites. The presence of labile aromatic hydrocarbons in shell mound cores and absence of significant contaminant accumulation of tissues of caged mussels indicated that chemical contaminants are not being remobilized from the 4H shell mounds. Surficial bottom sediments near the shell mounds contained elevated Ba concentrations that probably were associated with drilling wastes. However, concentrations did not exhibit clear spatial gradients with distance from the shell mounds. Despite a number of storm events during the mussel exposures, maximum currents were 34 cm s⁻¹ and unlikely to erode materials from the shell mounds. Thus, Ba distributions in bottom sediments probably were due to episodic disturbance such as platform removal or trawling rather than ongoing erosion and dispersion of shell mound solids by near-bottom currents. These results suggest that, in the absence of physical disturbances, contaminants are expected to remain sequestered in the shell mounds.     

The influence of diet on comparative trace metal cadmium,copper and zinc accumulation in Thais clavigera (Gastropoda: Muricidae) preying on intertidal barnacles or mussels

The influence of diet on comparative metal accumulation was investigated using a predatory muricid gastropod Thais clavigera. Individuals were fed for up to 56 days on either barnacles, i.e., Tetraclita squamosa, or mussels, i.e., Perna viridis, collected from metal-contaminated and clean sites. Barnacles and mussels have contrasting metal handling strategies and, therefore, different body concentrations, intracellular distributions and detoxification systems. Field collection of prey items that accumulated body metal concentrations over a lifetime of exposure allowed bioavailability to the predator, T. clavigera, to be assessed naturally, which may not be the case for prey exposed to metals for a short time in the laboratory. T. clavigera that was fed cadmium- and copper-contaminated barnacles or mussels ingested significantly greater amounts compared to those fed conspecifics collected from clean locations. T. clavigera body cadmium and copper concentrations were not, however, significantly different between individuals fed either contaminated or clean prey. Amount of zinc ingested was similar in mussels collected from clean and contaminated environments but much less when compared to the barnacle prey. The body concentrations of zinc in T. clavigera fed mussels collected from both sites fell. In contrast, the amount of zinc ingested from barnacle prey was significantly greater from those collected from the metal-contaminated site as compared to the clean one. This was reflected as significantly greater body zinc concentrations in T. clavigera fed contaminated barnacles compared to those fed clean individuals. Copper and zinc accumulation from prey was, therefore, complex. It varied between metal and between prey type, but appeared to be related to the amount ingested and the metal handling strategy of the prey.     

Size effects of suspended particles on gill damage in green-lipped mussel Perna viridis

The green-lipped mussels Perna viridis were exposed to <500 μm suspended solids (SS) with concentrations of 0 (control), 250, 500, 750 and 1000 mg/L for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significantly higher damages to the cilia on the frontal surface of the gill filaments than that on the abfrontal surface in both demibranchs. Percent ciliary depletion varied with SS concentrations and time. No sign of recovery of the gill filaments was observed after the mussels were transferred to clean seawater. In a second experiment, mussels were exposed to SS with size range from <63, >125–<250 and >250–<500 μm at 600 mg/L, together with a control (0 mg/L) for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significant ciliary damages in both the ascending and descending lamellae under the three particle size groups as compared with the control. Percent depletion of frontal cilia was most serious for the >250–<500 μm size group and least for the <63 μm size group. However, percent depletion of abfrontal cilia was most serious for the >125–<250 μm size group and least for the <63 μm size group. No recovery of ciliary damages was observed. The effects of particle size of suspended sediments on the morphological damages of gill filaments in the green-lipped mussels were discussed.     

Integrated use of biomarkers (superoxide dismutase, catalase and lipid peroxidation) in mussels Mytilus galloprovincialis for assessing heavy metals' pollution in coastal areas from the Saronikos Gulf of Greece

Mussels are used as sentinel organisms and bioindicators to evaluate the toxic effects of chemical pollutants in marine organisms, especially heavy metals, representing an important tool for biomonitoring environmental pollution in coastal areas. Antioxidant defence enzymes play an important role in cellular antioxidant defence systems and protect from oxidative damage by reactive oxygen species (ROS). Indigenous mussels Mytilus galloprovincialis of the Saronikos Gulf of Greece were used for monitoring heavy metal pollution in three polluted sites in the area and in one unpolluted site. Seasonal variations of the activity of antioxidant defence enzymes, superoxide dismutase (SOD) and catalase (CAT), as well as lipid peroxidation (LP) were measured as biomarkers in a period of three years in relation to concentrations of trace metals in their gills and mantle and compared to mussels from an unpolluted sampling site. SOD activity increased at least 2 fold at the polluted sites when compared to the control site (the high activity was recorded in the spring time). CAT activity was increased 2-3 times at the polluted sites, with high activity in the winter and spring time, compared to the control site. LP concentration was twice higher at the polluted sites, following the same seasonal pattern. Trace metals contents in mussels collected at polluted sites were 3-4 fold higher compared to the control site and showed moderate variations along the months, with a winter maximum followed by a summer pre-spawning minimum matching the seasonal trends of temperature and salinity. Our results showed that metal pollution in the Elefsis Bay (the most polluted coastal area) causes relatively medium levels of oxidative stress in tissues of mussels due to cellular oxy-radical generation. This study, which is the first in the area, showed that seasonal variations of the activity of antioxidant defence enzymes and LP concentrations in mussels can be used as potential biomarkers of toxicity for long-term monitoring in marine coastal ecosystems.