Unpolluted Locations Research Articles

Limited genetic variability and spatial population structure in grasshoppers between natural and metal-contaminated areas in Egypt.

Pollutants in an environment can have long-term implications for the species living there, resulting in local adaptations with implications for their genetic structure. Heavy metal pollutants infiltrate soils and groundwater, bioaccumulate in food webs, and negatively impact biota. In this study, we investigated the degree to which the genetic structure and variability of the slender green-winged grasshopper (Aiolopus thalassinus (Fabricius) (Orthoptera: Acrididae)) were impacted by heavy metal pollution and distance. We used the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) method to examine the genetic variability of populations in 3 heavy metal-polluted and 3 unpolluted locations across varying geographical distances in Egypt. The heavy metal concentrations of cadmium, copper, lead, and zinc were measured from the grasshopper tissue and soils. Sixty-nine unique and polymorphic bands were produced by 4 primers. Cluster and principal component analyses separated the populations inside and outside Cairo into 2 main branches, which were further divided into smaller branches corresponding to their geographical regions. We found no differences in the Shannon genetic diversity index between populations or with increasing heavy metal concentrations in either the soil or the grasshopper tissue. Our results showed a greater genetic variation among populations than between populations within the same location, indicating populations within locations were less differentiated than those between locations. The moderate correlation between genetic similarity and spatial distance suggests geographical isolation influenced grasshopper population differentiation. Based on the RAPD analysis, environmental pollutants and geographical distances impact the A. thalassinus population structure, potentially restricting gene flow between sites even at small spatial scales.

Concentración de nitrogeno y fósforo en el agua de lluvia de Corrientes (Argentina)

Inorganic nitrogen, phosphorus, pH and conductivity in rainwater were measured at Corrientes (27°27’S, 58°47’W) during 1984-1985. Mean water pH was 5.97 (4.60 - 7.15) and mean conductivity was 11.5 uS/cm (2.7 - 21 uS/cm) showing good waterquality. Concentration showed positive correlation with the length of time betweensuccessive rains and were inversely correlated with precipitation volume. Both inorganic nitrogen concentrations and fallout, were low (mean conc.: 315 µg Ninorg/1 mean fallout: 190 µg Ninorg/m2 yr) when compared with the reported figures in unpolluted locations. Total phosphorus concentration (36 µg TP/1) and fallout (16.5 µg TP/m2 yr) were relatively high probably because of dust contribution. Fallout rates resulted an order of magnitude lower than those of very polluted areas.lt was shown that nutrient fallout is important in determining trophic status of shallow lakes and ponds profuselly distributed in Corrientes province.

The use of muscle biomarkers for assessing physiological effects of heavy metal pollution in the greater white-toothed shrew (Crocidura russula)

The greater white-toothed shrew Crocidura russula has been used as a sentinel species for estimating environmental risks to human populations. Previous studies in mining areas have focused on the liver of shrews as the primary target of physiological and metabolic changes due to heavy metal pollution. However, populations persist even when detoxification by the liver seems to be compromised and damage is observed. These pollutant-adapted individuals inhabiting contaminated sites may exhibit altered biochemical parameters that confer increased tolerance in various tissues other than the liver. The skeletal muscle tissue of C. russula might be an alternative tissue that allows the survival of organisms inhabiting historically polluted sites due to the detoxification of redistributed metals. Organisms from two heavy metal mine populations and one population derived from an unpolluted site were used to determine the detoxification activities, antioxidant capacity, and oxidative damage, as well as cellular energy allocation parameters and acetylcholinesterase activity (a biomarker of neurotoxicity). Muscle biomarkers differ between shrews from polluted sites and shrews from the unpolluted location, with the mine animals showing: (1) a decreased energy consumption concomitant with increased energy reserves and total available energy; (2) reduced cholinergic activity, suggesting an impairment of neurotransmission at the neuromuscular junction; (3) an overall decrease in detoxification capacity and enzymatic antioxidant response and a higher level of lipid damage. Also, some of these markers differed between females and males. These changes may have resulted from a decreased detoxifying capacity of the liver and could potentially bring about significant ecological effects for this highly active species. Heavy metal pollution induced physiological changes in Crocidura russula showing that skeletal muscle may serve as a backup sink organ allowing rapid species adaptation and evolution.

Pollution and Risk Evaluation of Toxic Metals and Metalloid in Water Resources of San Jose, Occidental Mindoro, Philippines

Clean and safe drinking water is an integral part of daily living and is considered as a basic human need. Hence, this study investigated the suitability of the domestic water (DW) and groundwater (GW) samples with respect to the presence of metals and metalloid (MMs) in San Jose, Occidental Mindoro, Philippines. The MMs analyzed in the area of study for DW and GW were Arsenic (As), Barium (Ba), Copper (Cu), Chromium (Cr), Iron (Fe), Lead (Pb), Manganese (Mn), Nickel (Ni), and Zinc (Zn). The results revealed that Pb has the mean highest concentration for DW, while Fe is in GW resources in the area. Quality evaluation of DW and GW was performed using Metal Pollution Index (MPI), Nemerow’s Pollution Index (NPI), and Ecological Risk Index (ERI). The mean NPI value calculated for DW was 135 times greater than the upper limit of the unpolluted location category. The highest NPI observed was 1080 times higher than the upper limit of the unpolluted site category. That of the ERI observed in the area was 23.8 times higher than the upper limit for a “low” ERI category. Furthermore, the health risk assessment (HRA) of the GW and DW of the study area revealed non-carcinogenic health risks of the MMs analyzed in GW samples, and potential carcinogenic health risks from As, Cr, Pb, and Ni in DW. The use of machine learning geostatistical interpolation (MLGI) mapping to illustrate the PI and health risk (HR) in the area was an efficient and dependable evaluation tool for assessing and identifying probable MMs pollution hotspots. The data, tools, and the process could be utilized in carrying out water assessment, the evaluation leading to a comprehensive water management program in the area and neighboring regions of similar conditions.

Nutrient Remediation Efficiency of the Sedge Plant (Cyperus alopecuroides Rottb.) to Restore Eutrophic Freshwater Ecosystems

The current study investigated the nutrients removal efficiency of the sedge macrophyte Cyperus alopecuroides to treat water eutrophication, besides evaluating the recycling possibility of the harvested material. Samples of sediment, water, and plant tissues were taken seasonally from six polluted and three unpolluted locations for this investigation. The growth properties of C. alopecuroides showed remarkable seasonal differences in plant density and biomass, with the maximum values (7.1 individual/m2 and 889.6 g/m2, respectively) obtained during summer and the minimum (4.1 individual/m2 and 547.2 g/m2, respectively) in winter. In polluted locations, the above-ground tissues had an efficiency to remove more contents of N and P (11.9 and 3.8 g/m2, respectively) than in unpolluted ones (7.1 and 3.4 g/m2, respectively). The high-nutrient standing stock of C. alopecuroides supports its potential use for nutrient removal from eutrophic wetlands. The tissues of C. alopecuroides had the maximum nutrients removal efficiency to remediate great amounts of Na, K, and N in summer, and Ca, P, and Mg in spring. Above- and below-ground parts of C. alopecuroides from unpolluted locations can be considered as a rough forage for beef cattle, dairy cattle, goats, and sheep. The present study indicated the potential of C. alopecuroides in restoring eutrophic freshwater ecosystems, and, thus, it can be used in similar habitats worldwide.

Metallothionein level, non-specific esterases, fitness-related traits and integrated biomarker response (IBR) in larvae of Lymantria dispar L. (Lepidoptera) originating from unpolluted and polluted locations after chronic cadmium treatment

Long-term exposure of invertebrate populations to pollution might result in adaptations that must be taken into account when evaluating physiological parameters as biomarkers of contamination. In the present study we investigated whether previous exposure of gypsy moth, Lymantria dispar L. (Lepidoptera), population to pollution affects the sensitivity of larvae to cadmium treatment under laboratory conditions. Our goals in the current study were to compare metallothionein (MT) level and non-specific esterase activity including isoform expression in the midgut and fitness-related traits between caterpillars originating from polluted and unpolluted localities after chronic oral intake (50 and 100 µg Cd/g dry food). Besides being individually assessed as biomarkers of cadmium contamination, the responses of above parameters related to the midgut (MT concentration, specific activity of esterases and midgut mass) were summarized into the integrated biomarker response (IBR). Upon cadmium exposure, MT concentration increased significantly only in larvae originating from the polluted site, whereas non-specific esterase activity decreased in caterpillars from the unpolluted forest. We noticed similar patterns of esterase isoforms in both populations, including isoform number three that appeared only after exposure to the lower cadmium concentration. Midgut mass was reduced only in the group from the unpolluted locality exposed to the higher cadmium concentration. IBR index increased in a concentration-dependent manner in both populations, reflecting higher sensitivity of larvae from the unpolluted locality to the metal. Neither cadmium exposure nor population origin influenced larval survival. While MT concentration could be applied as a biomarker of cadmium exposure in populations that have been previously exposed to pollution for a longer time, non-specific esterase activity could indicate metal presence at unpolluted locations. IBR index and expression of esterase isoform number three could be used universally, regardless of the exposure history, except the latter might be limited to lower cadmium concentrations.

Normalized Difference Vegetation Vigour Index: A New Remote Sensing Approach to Biodiversity Monitoring in Oil Polluted Regions

Biodiversity loss remains a global challenge despite international commitment to the United Nations Convention on Biodiversity. Biodiversity monitoring methods are often limited in their geographical coverage or thematic content. Furthermore, remote sensing-based integrated monitoring methods mostly attempt to determine species diversity from habitat heterogeneity somewhat reflected in the spectral diversity of the image used. Up to date, there has been no standardized method for monitoring biodiversity against the backdrop of ecosystem or environmental pressures. This study presents a new method for monitoring the impact of oil pollution an environmental pressure on biodiversity at regional scale and presents a case study in the Niger delta region of Nigeria. It integrates satellite remote sensing and field data to develop a set of spectral metrics for biodiversity monitoring. Using vascular plants of various lifeforms observed on polluted and unpolluted (control) locations, as surrogates for biodiversity, the normalized difference vegetation vigour index (NDVVI) variants were estimated from Hyperion wavelengths sensitive to petroleum hydrocarbons and evaluated for potential use in biodiversity monitoring schemes. The NDVVI ranges from 0 to 1 and stems from the presupposition that increasing chlorophyll absorption in the green vegetation can be used as a predictor to model vascular plant species diversity. The performances of NDVVI variants were compared to traditional narrowband vegetation indices (NBVIs). The results show strong links between vascular plant species diversity and primary productivity of vegetation quantified by the chlorophyll content, vegetation vigour and abundance. An NDVVI-based model gave much more accurate predictions of species diversity than traditional NBVIs (R-squared and prediction square error (PSE) respectively for Shannon’s diversity = 0.54 and 0.69 for NDVVIs and 0.14 and 0.9 for NBVIs). We conclude that NDVVI is a superior remote sensing index for monitoring biodiversity indicators in oil-polluted areas than traditional NBVIs.

Matrix effects on organic pollutants analysis in marine sediment

Interference from the matrix sample can influence of the accurate analytical method. Accelerated Solvent Extraction and their purification methods were tried to separate the organic micropollutants respectively in marine sediment. Those matrix were as organic pollutants evaluation in marine environment. Polychlorinated Biphenyls (PCBs) and Organochlorine pesticides (OCPs) are two examples organic pollutant in environment which are carcinogenic and mutagenic. Marine sediments are important matrices of information regarding the human activities in coastal areas as well as the fate and behavior of organic pollutants, which are persistent in long-term. This research purpose to evaluate the matrice effect and the recovery from marine sediment spiking with several standar solution and deuterium of molecular target from organic pollutants in not polluted sample of sediment. Matrice samples was tested from indicate in unpolluted location. The methods were evaluated with standard calibration curve (linearity < 0.999, LOQ various ranged 0.5-1000 pg.μL-1 and LOD > LOQ). Recovery (YE) relative, Matrice Effect (ME) relative correction with deuteriated standar were evaluated the interference the matrix. Interference effect for OCPs compounds were higher than PCBs in marine sediment.

Metales traza en sedimentos costeros de Costa Rica Jairo

Marine sediment samples from four coastal ecosystems in Costa Rica were taken between the years 2000-2002 and their iron, lead, copper and zinc concentrations were determined by the atomic absorption technique with flame or graphite furnace. In the Pacific coast, Culebra Bay (Papagayo Gulf), Gulf of Nicoya, and Golfito Bay (Dulce Gulf), were selected as representative sites, and Moin Bay, at the Caribbean coast. Mean metal concentrations for all ecosystems followed the same pattern: Fe > Zn > Cu > Pb. No temporal pattern was found for any metal. Iron and copper mean concentrations were higher in Golfito Bay (5.8% and 87 μg / g, respectively) and lower in Moin Bay (3.4% and 52 μg / g, respectively). Zinc mean concentration was also higher in Golfito Bay (96 μg / g), but lower in Culebra Bay (66 μg / g). Lead mean concentration was higher in Moin Bay (6.4 μg / g) and lower in Culebra Bay (3.0 μg / g). Lead highest concentrations occurred in the Caribbean and in Golfito Bay, and for the rest of the elements the maximum values were found in Golfito Bay. On the basis of data obtained in this work, Culebra Bay was considered a relatively unpolluted location; Golfito Bay was more contaminated, and Moin Bay and the Gulf of Nicoya showed an intermediate condition.

Spatial Patterns of bphA Gene Diversity Reveal Local Adaptation of Microbial Communities to PCB and PAH Contaminants.

Biphenyl dioxygenases, encoded by the bphA gene, initiate the oxidation of polychlorinated biphenyls (PCBs) and specify the substrate range of PCB congeners metabolized by bacteria. Increased bphA gene diversity within microbial communities may allow a broader range of PCB congeners to be catabolized, thus resulting in greater PCB degradation. To assess the role of PCBs in modulating bphA gene diversity, 16S ribosomal RNA (rRNA) gene and bphA environmental DNA libraries were generated from bacterial communities in sediments with a steep gradient of PCB contamination. Multiple measures of sequence diversity revealed greater heterogeneity of bphA sequences in polluted compared to unpolluted locations. Codon-based signatures of selection in bphA sequences provided evidence of purifying selection. Unifrac analysis of 16S rRNA sequences revealed independent taxonomic lineages from polluted and unpolluted locations, consistent with the presence of locally adapted bacterial communities. Phylogenetic analysis of bphA sequences indicated that dioxygenases from sediments were closely related to previously characterized dioxygenases that metabolize PCBs and polynuclear aromatic hydrocarbons (PAHs), consistent with high levels of these contaminants within the studied sediments. Structural analyses indicated that the BphA protein of Rhodococcus jostii, capable of metabolizing both PCBs and PAHs, provided a more optimal modeling template for bphA sequences reported in this study than a BphA homologue with more restricted substrate specificity. Results from this study suggest that PCBs and PAHs may drive local adaptation of microbial communities by acting as strong selective agents for biphenyl dioxygenases capable of metabolizing a wide range of congeners.

Characterization, sources and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in long-term contaminated riverbank sediments

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant pollutants common in aquatic ecosystems. Although there is a vast literature on PAH contamination, there is a scarcity of information in long-term contaminated ecosystems. This study is the first detailed characterization of PAHs and their sources from riverbank sediments with a historic legacy of pollution. A total of 27 cores were collected at two highly contaminated locations and at one upstream location where apparently there was no PAH contamination. At each location, three cores were taken at three different depths using stainless steel liners. PAHs were extracted by using a modified sonication method followed by identification and quantification by gas chromatography mass spectrometry. Twelve PAHs were quantified and sources were identified using PAH ratios. High PAH concentrations (94,000–560,000 µg/kg) were detected making this aquatic ecosystem one of the most polluted in the world. Pyrolytic sources of PAHs was indicated by the large relative contribution of four ring compounds, while high levels of low molecular weight PAHs also suggested input from petrogenic sources. Risk quotients assessment overwhelmingly demonstrated that the riverbank sediments of the Mahoning posed a very high ecological risk to aquatic organisms, even at what was previously considered an unpolluted location. These results suggest that there is a great need for implementation of remediation strategy of the riverbanks.

The Application of PCR Reaction for Identification of MHB Bacteria Species

Abstract This study characterizes mycorrhiza helper bacteria (MHB) from selected unpolluted locations as well as subjected to industrial emissions. To determine the species of bacteria isolated from the roots of ectomycorrhizal pine and birch, a method based on the sequence analysis of a 16S rRNA gene was used. The isolated bacteria were initially characterized by available biochemical methods and phenotypic observation. On the selected bacteria representatives isolation of DNA was performed, on which the PCR reaction was carried out. In this way amplified samples were automatically sequenced and the obtained results were compared to public databases. Among the isolated bacteria Pseudomonas fluorescens SBW25 and Burkholderia xenovorans LB400 species were dominant.

Sea Urchin Embryotoxicity Test for Environmental Contaminants—Potential Role of the MRP Proteins

The main goals of this study were (1) to standardize a simple and reliable embryotoxicity test for environmental contaminants and (2) to evaluate the presence and possible protective role of the multidrug resistance-associated (MRP) protein-mediated multixenobiotic defense in two Mediterranean sea urchin species, Paracentrotus lividus and Arbacia lixula. Toxic end-point used was the success of the first cell division in sea urchin embryos. Embryotoxicities of three environmentally relevant contaminants: mercuric chloride (HgCl2, 0.05–6 μM), trybutiltin (TBT, 2.5–500 nM), and oxybenzone (OXI, 0.1–100 μM); as well as seawater samples collected from the polluted and unpolluted locations, were determined and compared. A. lixula embryos were more sensitive to all three toxic compounds, and both P. lividus and A. lixula embryos were highly sensitive to TBT at nanomolar concentrations (EC50 49 ± 5 and 36.8 ± 3 nM, respectively). Inhibition of MRP protein by specific inhibitor MK571 caused significant increase in embryotoxic potency of HgCl2 (EC50 0.697 ± 0.03 and 0.245 ± 0.04 μM, respectively), TBT (EC50 24 ± 3 and 7.4 ± 1 nM, respectively) and polluted seawater sample, but not of OXI or unpolluted, natural seawater. Therefore, our results demonstrated for the first time the protective relevance of MRP proteins in early development of these two Mediterranean sea urchin species. Finally, the embryotoxicity protocol described in this study represents a simple and rapid bioassay for determination of environmentally relevant seawater contamination.

Local adaptation of microbial communities to heavy metal stress in polluted sediments of Lake Erie

Microbial communities must balance the assimilation of biologically necessary metals with resistance to toxic metal concentrations. To investigate the impact of heavy metal contaminants on microbial communities, we performed two experiments measuring extracellular enzyme activities (EEA) in polluted and unpolluted sediments of Lake Erie. In the first experiment, inoculations with moderate concentrations of copper and zinc appreciably diminished EEA from uncontaminated sites, whereas EEA from contaminated sediments increased or were only negligibly affected. In the second experiment, we compared the effects of three separate metals (i.e. copper, arsenic, and cadmium) on microbial community metabolism in polluted and unpolluted locations. Although copper and arsenic elicited differential effects by inhibiting EEA only in unpolluted sediments, cadmium inhibited EEA in both polluted and unpolluted sediments. Multivariate analyses of EEA from polluted sediments revealed direct associations among hydrolytic enzymes and inverse or absent associations between hydrolases and oxidases; these associations demonstrated resilience to heavy metal stress. In contrast, addition of heavy metals to unpolluted sediments appeared to have a higher impact on the multivariate pattern of EEA associations as revealed by an increase in the number of associations, more inverse relationships, and potential enzymatic trade-offs. The results of this study suggest community-level adaptations through the development of resistance mechanisms to the types and local levels of heavy metals in the environment.

Autecology and morphology of selected Vaucheria species (Xanthophyceae)

In this study, the yellow-green alga Vaucheria was collected from 86 sites with different environmental characteristics. A principal component analysis of the sites revealed a model with four principal components explaining 64.7% of the total variance in the data set. The principal components were interpreted as nutrient enrichment, ions, current, and buffer capacity. In total, seven Vaucheria species were found: V. taylorii, V. debaryana, V. sessilis, V. geminata, V. terrestris, V. walzii, and V. woroniniana. V. taylorii was noted only three times, V. terrestris occured exclusively at terrestrial sites, the remaining taxa were frequent. Vaucheria seems to have its optimal growth at lower temperatures; in the cold season thick covers were observed, which exceeded the abundance in summer. A discriminant analysis revealed that growth types are highly explained by current; high flow velocity favors the development of pads. Species occurrence along artificial gradients consisting of the obtained principal components were analyzed simultaneously by means of a canonical correspondence analysis. V. sessilis occurred widely with no preferences, but three species showed a distinct pattern within the gradient analysis: V. woroniniana mainly occurred at elevated pH and total alkalinity, V. walzii was favored by increased ion contents and slow current, and V. geminata clearly preferred unpolluted sites with decreased pH and alkalinity values. This species may be used as an indicator species for unpolluted locations, however some taxonomic uncertainties remain to be first resolved.

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 μg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed.

Translational Fluctuating Asymmetry and Leaf Dimension in Seagrass,Zostera capricorniAschers in a Gradient of Heavy Metals

Methodology for measuring translational fluctuating asymmetry (TFA) on leaves of seagrass, Zostera capricorni Aschers has been developed and tested to detect a subtle effect of environmental stress associated with heavy metal pollution on developmental instability. Our analyses showed that concentration of heavy metals (Cd, Pb, Cu, Zn, Se) in leaves and roots of the seagrass were significantly higher in the polluted location than in relatively unpolluted locations. We found significant differences in TFA between different locations, showing that the method is sensitive enough to detect spatial differences even within a rather small water body, but these differences were not associated with a higher concentration of heavy metals, i.e. plants from the polluted location did not show higher TFA. Possibly, seagrass can store heavy metals in their tissues and protect their development from the toxic effect, or the effect of heavy metals in the natural environment is confounded by other environmental factors. At the same time, we found that plants from the polluted location had narrower leaves than in relatively unpolluted ones, which may be caused by heavy metals or associated factors.

Satellite monitoring of the first indirect aerosol effect: Retrieval of the droplet concentration of water clouds

A model for the vertical variation of microphysical and optical properties of single‐layer water clouds is used to design a procedure to obtain cloud droplet concentration from satellite cloud optical thickness/effective radius retrievals. The model allows for smooth vertical variations in microphysical variables including droplet concentration and liquid water content. The procedure is applied to data from the MODIS instrument aboard the EOS‐TERRA satellite platform over a region near Cape Grim, Tasmania, over the Southern Ocean. At this unpolluted location, there are seasonally repeated well‐described variations in cloud condensation nucleus concentration. The satellite observations show that there is a factor 2.5 difference in retrieved droplet concentration between the summer and winter seasons as measured over the 4 year period (July 2000 to July 2004). Comparison of these results with cloud condensation nuclei concentrations observed at Cape Grim showed good agreement. Furthermore, for a fixed solar zenith angle cos (45°) cloud albedo varied between 0.45 and 0.55 and exhibited a clear correlation with the retrieved droplet concentration (correlation coefficient R = 0.80). Such correlation was absent between albedo and the second retrieval product, namely the cloud depth.

Differential tolerance to metals among populations of the introduced bryozoan Bugula neritina

Resistance to heavy metals is a potentially important trait for introduced marine organisms, facilitating their successful invasion into disturbed natural communities. We conducted laboratory and field experiments to examine differential resistance to copper (Cu) between two source populations of the introduced bryozoan Bugula neritina, originating from a polluted (Port Kembla Harbour, NSW, Australia) and an unpolluted (Botany Bay, NSW, Australia) environment. A laboratory toxicity test was conducted to test the relative resistance of B. neritina recruits from the two sources, by measuring the attachment success, survival and growth of individuals exposed to a range of Cu concentrations (0, 25, 50 and 100 μg l−1 Cu). Upon completion, reciprocal transplantation of the colonies to the original polluted and unpolluted locations was carried out to assess ongoing survival and growth of colonies in the field. B. neritina colonies originating from the polluted Port Kembla Harbour had increased resistance to Cu relative to populations from an unpolluted part of Botany Bay. There appeared to be a cost associated with increased metal tolerance. In the laboratory, Botany Bay recruits displayed significantly higher growth in control treatments and significantly poorer growth at 100 μg l−1 Cu with respect to Port Kembla Harbour individuals, which showed unusually uniform and low growth irrespective of Cu concentration. No difference in attachment success or post-metamorphic survival was observed between populations. Field transplantation showed copper resistance in Port Kembla Harbour colonies constituted an advantage in polluted but not benign environments. The findings of this study provide evidence of the benefits to invasive species of pollution tolerance and suggest that human disturbance can facilitate the establishment and spread of invasive species in marine systems.

Changes in benthos following the clean-up of a severely metalpolluted cove in the Hudson River estuary: Environmental restoration or ecological disturbance?

We studied changes in macrobenthic communities following the environmental clean-up of metal-polluted (cadmium, nickel, and cobalt) sediments in Foundry Cove, a small inlet within the Hudson River estuary of New York. We used a BACI-style experiment to test the hypotheses that high levels of cadmium in sediments change macrobenthic assemblages relative to unpolluted areas, and removal of metals (especially cadmium) by dredging will restore the benthos, such that benthic fauna in Foundry Cove are not different from unpolluted areas. In 1984, prior to the restoration work, there were no significant differneces between macrobenthic assemblages in polluted and unpolluted locations, indicating that cadmium had little effect on community structure. The lack of an observed toxicity effect may have been caused by the compensatory evolution of resistance to cadmium in dominant organisms. Six years after the restoration work and despite a substantial reduction in metal pollution, there were lower abundances of oligochaetes, nematodes, and chironomids and a higher abundance of polychaetes at Foundry Cove relative to reference locations. Correlative analyses identified greater sediment compaction caused by dredging at Foundry, Cove as a possible cause of faunal differences. The results demonstrate that it is difficult to accurately predict, the effects of anthropogenic disturbances and restorations in complex natural systems and that unforeseen side effects are inevitable. Documenting these unpredicted effects and experimentally understanding their causes in past restorations will greatly improve the success and cost-effectiveness of future projects of a similar type.