Trace metals in seaducks of the Fraser River Delta intertidal area,British Columbia

Surf Scoters and Greater Scaup and samples of species which comprise the major part of their diets, from Iona Island and Roberts Bank tidal flats, near Vancouver, British Columbia, were analysed for metal residues. Significantly higher silver, copper, lead and zinc levels were found in Greater Scaup than Surf Scoters. The latter species had higher mercury levels. Differences in residue levels between the species reflect interspecific variation in prey as well as feeding habitat. Significantly higher silver, mercury, lead and zinc in Surf Scoters and silver and lead in Greater Scaup observed at Iona Island than at Roberts Bank can be explained by higher levels of those metals occurring in a more metal-contaminated prey and sediment near the Iona Island sewer outfall. Ducks feeding on organisms in different intertidal zones show different accumulation of metal residues and constitute valuable indicators of pathways of toxic chemicals in specific estuarine regions.     

Crustacean assemblages in a polluted estuary from South-Western Spain

The spatial-temporal variation in crustacean assemblages of the Odiel-Tinto estuary, one of the most polluted areas in the world, was studied in 2000, 2002 and 2004. The crustacean assemblages were mainly established according to the natural gradient from estuarine to marine environment (based on water and sediment characteristics such as dissolved oxygen, salinity, granulometry or organic content). Pollutants such as copper, zinc or phosphates could also explain partially this pattern based on BIOENV and canonical correspondence analyses. However, there were clear symptoms of perturbation, mainly in the inner areas, such as a low number of species and a low abundance, especially in relation to the typical estuarine species (e.g. Cyathura carinata, Corophium spp.). This study provides baseline information which can be used as a reference point in a long-term perspective.     

Seasonal variation in the trace metal content of Mytilus edulis

The possible seasonal variation in the trace metal content of the mollusc Mytilus edulis has been studied by analysing cadmium, cobalt, copper, lead, manganese, mercury, nickel and zinc in 560 individuals collected from the same mussel bed over a period of two years. A clearly discernible effect of size on metal concentration was detected. However, no seasonal trends could be seen in the data.     

Trace metals in algae from the Great Barrier Reef

Zinc, copper, cadmium, nickel, lead and mercury concentrations were examined in 48 species of algae from the Great Barrier Reef. In general the data showed considerable inter- and intra-specific variation with mean levels for each metal ranging from 0.27 to 38.6; 0.74 to 11.2; 0.08 to 2.2; 0.41 to 46.1; <0.45 to 6.7, and 0.005 to 0.320 μg g⁻¹ dry weight, respectively. Not-withstanding this, levels of all metals were substantially lower than reported values for algae from metal contaminated environments. The green alga, Chlorodesmis fastigiata, was the only species examined which was abundant at all study sites and, as a consequence, was considered to be the most suitable candidate for continued surveillance studies in the area.     

Detection of multiple potentially pathogenic bacteria in Matang mangrove estuaries,Malaysia

The deltaic estuarine system of the Matang Mangrove Forest Reserve of Malaysia is a site where several human settlements and brackish water aquaculture have been established. Here, we evaluated the level of fecal indicator bacteria (FIB) and the presence of potentially pathogenic bacteria in the surface water and sediments. Higher levels of FIB were detected at downstream sampling sites from the fishing village, indicating it as a possible source of anthropogenic pollution to the estuary. Enterococci levels in the estuarine sediments were higher than in the surface water, while total coliforms and E. coli in the estuarine sediments were not detected in all samples. Also, various types of potentially pathogenic bacteria, including Klebsiella pneumoniae, Serratia marcescens and Enterobacter cloacae were isolated. The results indicate that the Matang estuarine system is contaminated with various types of potential human bacterial pathogens which might pose a health risk to the public.     

Toxicities of ten metals to Crassostrea gigas and Mytilus edulis embryos and Cancer magister larvae

Pacific oyster (Crassostrea gigas Thunberg) embryos, bay mussel (Mytilus edulis Linnaeus) embryos, and Dungeness crab (Cancer magister Dana) zoea I stage larvae were exposed to arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc salts. The two bivalve species were exposed through the completion of embryogenesis (48 h), and the effects of the metals upon abnormal development were monitored. The crab larval stages were exposed to the metal solutions for 96 h. Concentrations (μg l_.^?1 as metal) which caused 50% abnormal development in the two species of bivalve larvae and which were fatal to 50% of the crab larvae ranged from 5.3 (oyster) to 49 (crab) for copper; 5.8 (mussel) to 8.2 (crab) for mercury; 14 (mussel) to 55 (crab) for silver; 119 (oyster) to 456 (crab) for zinc; 232 (crab) to 3000 (mussel) for arsenic; 247 (crab) to 1200 (mussel) for cadmium; 349 (oyster) to 4360 (crab) for nickel; 476 (mussel) to 758 (oyster) for lead; 3440 (crab) to 4538 (oyster) for hexavalent chromium; and selenium greater than 10 000 for the three species. The acute toxicity testing of C. gigas embryo together with two California native species confirmed its usefulness for predicting toxicity to the latter species.     

Metal accumulation in four molluscs

Specimens of mussels (Mytilus edulis), winkles (Littorina littorea), dogwhelks (Nucella lapillus) and limpets (Patella vulgata) were collected from the north-east coast of England in 1980–1981 in order to analyse the dried whole soft tissue for zinc, copper and iron. In each case, only a narrow size range of organisms was collected from a small environmentally homogeneous site and sex was taken into account. Most of the frequency distributions of metal concentrations obtained were found to show significant positive skewness. This skewness could not be explained either by the degree of mobility or type of feeding mechanism of the organisms or by any other known parameter, e.g. size, sex, habitat variation. Some individual mussels were found to be extremely good regulators of their zinc concentrations. On the other hand, other individual mussels had the ability to accumulate unusually high levels of zinc.     

Detecting shifts in ecosystem functioning: The decoupling of fundamental relationships with increased pollutant stress on sandflats

In this study, we investigated the influence of low level contamination by copper, lead and zinc on the functioning of estuarine sandflat ecosystems by comparing the strength and variability of relationships between benthic macrofauna and fluxes (oxygen and nutrients) at three clean and three mildly contaminated sites. Specifically, as indicators of ecosystem functioning, we examined relationships between bivalve biomass, total benthic respiration and ammonium release, and ammonium uptake and benthic primary production. Furthermore, a small amount of organic matter was added to experimental plots at all sites (35 g/0.2 m²) to evaluate stress-on-stress responses relative to controls. Relationships were strongest at the clean sites (steepest slopes, highest r² values, lowest p-values) and weakest at the mildly contaminated sites and in organically enriched plots. Our results suggest that changes in ecosystem functioning may be occurring at mild (<ERL) levels of pollution that are unlikely to cause widespread mortality of macrofauna.     

Mercury in tissues of mussel off southern California

Total mercury content has been determined in three tissues of the intertidal mussel Mytilus californianus collected at locations along the southern California coast and at island control stations. The apparent influence of certain harbours and municipal wastewater outfalls was reflected by the relatively higher levels of mercury in all tissues of mussels from these areas. In general, the concentrations reported here are lower than those in mussels on west European coasts.     

Sublethal effects of heavy metal contaminated sediments on the bivalve Macoma balthica (L.)

Sublethal effects of estuarine sediments containing high levels of heavy metals were studied using the marine bivalve, Macoma balthica. Burrowing behaviour was inhibited in all contaminated sediments compared to the control. The time required for 50% of the population to burrow (ET50) ranged from 0.17 h in the control to 4.8 h in the most contaminated substrate. A comparison of linear regressions of the concentrations of individual metals in the sediments vs the burrowing response times showed the regressions for mercury and cadmium to be significant (P < 0.05 and < 0.001 respectively). An active threshold avoidance response by burrowed M. balthica was also demonstrated as clams showed a significant (P < 0.05) avoidance of the sediment containing the highest metal levels. Both behavioural responses were considered useful sublethal tests to assess the impact of polluted sediments.     

Experimental studies on the accumulation of copper and zinc in the green mussel

Toxicity of copper and zinc to the green mussel, Mytilus viridis was evaluated by short-term bioassays. Probit analysis was used for calculating 48 h median tolerance limits, 95% fiducial limits and slope functions (S). The rates of copper and zinc accumulation were determined by analysing the metal content in the soft parts of the mussels at fixed intervals of time by atomic absorption spectrometry. Bioaccumulation was determined as a function of metal concentration in the experimental medium. The correlations for the regression lines (P < 0.1%) indicate that the uptake of metal is linear at least for the first five weeks. During a more extended experimental period, adjustment to a steady state probably occurs.     

Schoenoplectus californicus as Potential Remover of Metal Elements from Mine Effluents: A Laboratory Assessment

Acid mine drainage (AMD) is one of the most significant environmental challenges facing the mining industry worldwide. For this reason, many methods for AMD treatment are developed, being wetlands a good option for metal elements removal from these mining effluents. The efficiency of Peruvian native plants such as Schoenoplectus californicus (S. californicus) to remove metal elements in effluents through artificial wetlands is studied. Batch removal tests are carried out with different effluents containing copper, zinc, lead, and iron. For iron-metal binary effluents, copper, zinc, and lead are removed by 82%, 75%, and 88%; while in the effluent containing all metals, the removal rate is 90% and 92% for copper and lead, respectively. According to the preliminary results, it is concluded that iron interferes more in the removal of zinc and lead than in copper from binary effluents. The use of S. californicus turns out to be an efficient, attractive, and economical alternative for the treatment of effluents contaminated with copper, zinc, lead, and iron.     

A baseline study of metal contamination along the Namibian coastline for Perna perna and Choromytilus meridionalis

The use of bivalves such as the brown mussel (Perna perna) and the black mussel (Choromytilus meridionalis) is common in the study of marine pollution and the effect of these pollutants on ecosystems and are important in both economic and ecological roles. Namibian marine ecosystems are threatened by pollution from mining, commercial fishing and population growth. The aims of this study were to determine baseline metal concentrations, spatial variation and variation between species. Metal levels in C. meridionalis from Guano Platform (GP) are the lowest of all the sites. The most polluted sites are Rocky Point (RP), Halifax Island (HIL) and between Walvis Bay and Swakopmund (WS). The bioaccumulation of metals between P. perna and C. meridionalis were not uniform for all metals. Overall the study indicates the condition of the coastline to be mostly normal, with Cd and Pb levels being of concern.     

Trace metals in corals from the Great Barrier Reef

Various octocorallian and scleractinian corals from within the Great Barrier Reef Province were analysed for zinc, copper, cadmium, nickel and lead by atomic absorption spectroscopy. Of the two coral groups, the octocorals accumulated significantly greater amounts of all detectable metals. The soft coral, Sarcophyton sp., revealed distinct inter-locational differences for zinc, copper and cadmium. The potential of this genus for monitoring trace metal pollution in tropical reef waters is briefly discussed.     

Effects of heavy metal contamination on the macrobenthic fauna in estuaries: the case of the Seine estuary

Heavy metal contamination levels are generally higher in estuaries than in the open sea. Some estuaries, the Seine estuary for example, have particularly high pollution levels of metals, yet continue to support a very high benthic biomass and remain quite productive. Measurements of sediment contamination are highly variable due to diverse chemical analysis methods, sediments origin and sources of contaminants found in the estuaries. Salinity appears to be the principal factor controlling contaminant distribution in the sediment and the overlying and/or interstitial waters; it also affects the bioavailability of contaminants in estuarine sediments. Of course, the response to contaminants varies greatly among species and assemblages. Trace metals explain only a small part of the variation in benthic community structure. Some species, such as the shrimp Crangon crangon, appears vulnerable to metal pollution, while other species, such as Scrobicularia plana, are able to tolerate quite high levels of cadmium in their tissue. This paper demonstrates the wide variability of benthic responses to contamination, which is probably due to the high spatio-temporal heterogeneity of the estuary. To reduce the problems due the heterogeneity and variability observed to date in the available results, it will be necessary to encourage integrated estuarine studies, in which sedimentologists, chemists, and biologists work together on the same campaigns at the same sites.     

Old cannery wastes,a potential source of trace metals in the marine environment

High levels of lead and zinc have been measured in the California Mussel Mytilus californianus taken from southern Monterey Bay as part of the California State Mussel Watch programme. The levels of lead and zinc increase steadily from Cypress Point towards Cannery Row. The California State Water Resources Control Board (which funded but did not conduct the State Mussel Watch) has attributed the high levels to heavy metals contributed by sewage. The state mussel watch data reports have not considered the historic canning wastes from more than 30 canneries along Cannery Row as a possible source of trace metals. Leachates from old cannery wastes may be a major source of lead and zinc in mussels in southern Monterey Bay and must be considered in assessing any data from the State Mussel Watch programme.     

Heavy metals in surface sediment and epibenthic macroinvertebrates from the coastal zone and continental slope of Kenya

In surface sediments, a statistically significant increase was measured in the concentration of copper and cadmium along all transects, and of zinc along only the most southern (Gazi) transect, radiating into the Indian Ocean perpendicular to the Kenyan coast. Mean copper and cadmium increased from 5 to 30 μg g⁻¹ dry wt and from 0.01 to 0.34 μg g⁻¹ dry wt in shallow coastal (±20 m depth) to deep-sea stations (±2000 m depth), respectively. These gradients were found both during the south-east monsoon and north-east monsoon period. The shallow estuarine zone of the Sabaki river mouth showed significantly enhanced levels of total organic carbon and nitrogen and all metals analysed, except cadmium.In crustaceans, the concentration of copper and particularly cadmium was significantly above baseline levels, varying from 45 to 90 μg g⁻¹ dry wt and 1.0 to 8.5 μg g⁻¹ dry wt, respectively. Zinc levels (49–102 μg g⁻¹ dry wt) were at about baseline levels or a little elevated. On the contrary, lead showed very low concentrations, varying from 0.1 to 0.6 μg g⁻¹ dry wt. Other species generally showed the same pattern.     

Metal levels in seston and marine fish flesh near industrial and metropolitan centres in South Australia.

Port Pirie is the site of the largest lead smelter in the world, depositing 250 t of zinc, and 100 t of lead annually into Spencer Gulf. Barker Inlet is adjacent to metropolitan Adelaide, and receives unknown quantities of urban and industrial discharges. Both areas are sites of major commercial and recreational fisheries, contained within delicately balanced marine wetland ecosystems, comprising large areas of mangrove and seagrass habitats. Aldrichetta forsteri and Sillago schomburgkii are major species within these fisheries and as estuarine-dependent species were chosen for this study as indicator species for the detection and monitoring of pollutant impacts in the nearshore marine ecosystems of South Australia. Seston sediment collectors were deployed at each site and analysed seasonally for the presence of cadmium, lead and copper. Flesh samples from A. forsteri and S. schomburgkii were examined seasonally for the presence of cadmium, lead and copper and the results correlated with levels found in the seston sediment at each site. Metal concentrations were also correlated with a biomarker of genotoxicity measured in the same animals (micronuclei in erythrocytes) that were reported previously. Seston levels of cadmium, lead and copper were highest at Port Pirie, followed by Barker Inlet and were lowest at Wills Creek, with cadmium undetectable at the latter site. Metals in seston varied considerably with season, with generally higher levels in winter samples. In fish flesh, metal levels followed broadly similar trends as for seston. Spearman rank correlations between metals in seston and in flesh were strongly positive. There was also a significant correlation between flesh concentrations of each metal and the frequency of micronuclei in erythrocytes. This study has shown that seston concentration of pollutant metals are high in areas of industrial activity, and that these levels are also reflected in metal content of fish flesh. Mean flesh levels of cadmium and copper did not exceed Australian health based maximum permitted levels of fish for human consumption, whereas flesh levels of lead in fish from Port Pirie and Barker Inlet exceeded these standards in each of the seasons monitored. This may represent a significant dietary source of lead in humans, especially at Port Pirie where human lead exposure from terrestrial sources is important. There may also be the potential for accumulation of metals in residents of metropolitan Adelaide whose diets are high in fish (and/or crustaceans), particularly estuarine-dependent species, such as A. forsteri and S. schomburgkii. The study also showed that a non-specific biomarker of genotoxicity (micronuclei in erythrocytes) is potentially useful as a monitoring technique in fish species to evaluate their exposure and genotoxic responses to pollutants in South Australian waters. These data represent a snapshot of the current situation in this area and may act as background levels against which future improvements or decrements in water quality may be compared.     

The potential use of fairy prions (Pachyptila turtur) as monitors of heavy metal levels in Tasmanian waters

The purpose of the present study was to examine the potential use of the fairy prion to monitor contamination in the marine food chain following ocean dumping of industrial waste in S.E. Tasmania. Factors considered that can complicate interpretation of heavy metal levels detected include age, sex, seasonal, and other ecological aspects of the indicator species chosen. Unlike some other species of seabirds, the influence of sex and season on metal levels was unimportant. Copper, zinc, cadmium, and lead were tested in the liver and muscle tissue of fairy prions. In this preliminary study, cadmium levels were found to be significantly higher statistically in fairy prions closest to a potential source of pollution compared to levels from distant locations. This trend was not found in other metals investigated. However, it is suggested that this species would provide a useful future means of monitoring heavy metal levels.