Search

Little is known regarding potential uptake of metals in Australian saltmarsh flora, thus the current study endeavored to examine patterns of Zn, Cu, Pb and Cd uptake and partitioning in the dominant saltmarsh halophyte, Samphire (Sarcocornia quinqueflora), across three contaminated estuaries in New South Wales, Australia. Average sediment concentrations ranged from 62 to 764 μg/g for Zn, 20–52 μg/g for Cu, 27–311 μg/g for Pb and 0.45–1.90 μg/g for Cd across estuaries. Lake Macquarie was the most contaminated estuary, with the Hunter River estuary and Sydney Olympic Park exhibiting intermediate levels of sediment metal contamination. Bioconcentration factors for metal uptake from sediment to roots were ≥ 1 (except for Cu). Translocation within the plant was low for most metals, with apparent barriers to transport identified at the root: non-photosynthetic stem interface for Zn, Cu, Pb and Cd, and at the non-photosynthetic stem: photosynthetic stem transition for Pb and Cd. All metals accumulated in roots with increasing sediment exposure, and lower soil organic matter predicted greater Pb and Cu uptake to roots. Further, increases in sediment pH predicted greater Cd root accumulation. However, transport was regulated to the non-photosynthetic stem for Zn, and to the PS stem for Zn and Pb. In terms of employing S. quinqueflora as a bioindicator, all root metals, and Pb and Cd in non-photosynthetic stem tissue exhibited relationships with sediment metal loads, though high variability made their predictive ability limited.

Sewage effluent has been identified as a potential source of metal(loid) contamination in the aquatic environment. The Sydney rock oyster, Saccostrea glomerata, can accumulate most metals and is well established as a biomonitor of metals in the marine environment. To determine if Burwood Beach wastewater treatment works (WWTW) is a source of metal(loid) contamination, S. glomerata was deployed for 6 weeks in effluent receiving waters (Burwood Beach near and Burwood Beach far) and at reference locations (Redhead, Fingal Island 1 and Fingal Island 2) at depths 4, 8 and 12 m. In dried oyster tissue, inductively coupled plasma mass spectrometry (ICPMS) was employed to measure concentrations of a suite of metal(loid)s including aluminium, arsenic, cadmium, copper, lead, iron, manganese, mercury, nickel, selenium, silver and zinc. It was found that for all metal(loid)s, S. glomerata tissue concentrations were not significantly higher at Burwood Beach locations in comparison to all reference locations. Concentrations of metal(loid)s were similar to those which have been detected in previous studies of background locations in New South Wales (NSW). Further, all metals fell below National Food Authority maximum residue levels (MRLs), except for arsenic and this does not appear uncommon for concentrations in biota within NSW. Comparisons to historical data suggested that concentrations of metal(loid)s in sewage effluent from Burwood Beach WWTW, assessed via concentrations in oyster tissue, are similar or lower, suggesting that changes in treatment processes initiated in the intervening time have lowered metallic inputs.

This study aimed to reveal possible alterations to lipidomic profiles in Sydney rock oysters, Saccostrea glomerata, exposed to estrogenic mixtures (i.e., estrone, E1; 17β-estradiol, E2; estriol, E3; 17α-ethinylestradiol, EE2; bisphenol A, BPA; 4-t-octylphenol, 4-t-OP; and 4-nonylphenol, 4-NP) at “low” and “high” concentrations, typical of those detected in Australian and global receiving waters. A seven-day acute exposure window exhibited significantly lower abundances of many non-polar metabolites in digestive gland, gills, and gonads. Overall, there was a strong effect of the carrier solvent ethanol (despite a low exposure of 0.0002%), with all solvent containing treatments exhibiting lower abundances of lipidic metabolites, especially in the gill and digestive gland. No significant changes of the lipidome were exhibited in the male gonad by estrogenic exposure. However, in the female gonad, significant reductions of phospholipids and phosphatidylcholine were associated with exposure to high estrogenic mixtures. We hypothesise that the decreases in these phospholipids in the female gonad may be attributable to 1) lower algal consumption and thus lower uptake of lipidic building blocks; 2) a reduction of available substrates for phospholipid and phosphatidylcholine synthesis; and/or 3) induction of reactive oxygen species via estrogen metabolism, which may cause lipid peroxidation and lower abundance of phospholipids.

An investigation was conducted over three estuaries in SE Australia with a gradient in metal(loid) contamination to assess metal(loid) (Cu, Zn, As, Se, Cd and Pb) accumulation and transport within the halophytic saltmarsh rush, Juncus kraussii. Sydney Olympic Park exhibited the most elevated metal(loid) contamination, followed by Hunter Wetlands and Lake Macquarie. J. kraussii exhibited a strong ability to restrict metal(loid) movement into the root system, with the exception of cadmium (BCFs 1.0) and unrestricted flow from root to culm excepting Se, Cd (TFs 1). Pb and Zn exhibited elevated translocation between roots and culms (TF 4.4 and 7.3, respectively). Despite barriers for uptake into the below-ground tissues, most metal(loid)s were accumulated to the roots with environmental dose (except for Cu and Cd) and linear relationships were present between the root and culm (for As and Se) and the sediment and culm (for As, Se, Cd, and Pb).

The current study represents the first attempt to analyse quantitatively, within a phylogenetic framework, uptake and partitioning patterns of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in extant saltmarsh taxa globally, and to assess associations of these patterns with various plant traits indicative of their halophytic adaptations. Despite saltmarsh being diverse taxonomically, most saltmarsh taxa accumulate metals to roots at, or above, unity (> 1). Further, there is significant translocation from roots to shoot for Cu, Zn and Cd (≤ 1), however, Pb is less mobile (TF = 0.65). Patterns of accumulation were similar among families, except greater Cd accumulation to roots in members of Juncaceae. Patterns of uptake to roots and translocation to leaves were broadly similar among plant type, plant form, habitat and photosynthetic mode. Zinc is lower in the leaves of salt-secreting species for some closely related taxa, suggesting some species co-excrete sodium (Na+) and Zn2+ through glands in leaf tissue. Salinity tolerance has no relationship to metal uptake and translocation. Translocation of Zn is greater at lower Zn sediment exposures, reflecting its active uptake and essentiality, but such bias does not affect outcomes of analyses when included as a covariate.

Estrogenic compounds enter waterways via effluents from wastewater treatment works (WWTW), thereby indicating a potential risk to organisms inhabiting adjacent receiving waters. However, little is known about the loads or concentrations of estrogenic compounds that enter Australian WWTWs, the efficiency of removing estrogenic compounds throughout the various stages of tertiary WWTW processes (which are common in Australia), nor the concentrations released into estuarine or marine receiving waters, and the associated risk for aquatic taxa residing in these environments. Therefore, seven estrogenic compounds, comprising the natural estrogens estrone (E1), 17β-estradiol (E2) and estriol (E3), the synthetic estrogen (EE2), and the industrial chemicals bisphenol A (BPA), 4-t-octyl phenol (4-t-OP) and 4-nonyl phenol (4-NP), in wastewater samples were quantified via liquid chromatographic-mass spectrometry (LC-MS) after solid-phase extraction at different stages of wastewater treatment and associated receiving waters. The concentrations of the target compounds in wastewater ranged fromLOQ (limit of quantification) to 158 ng/L for Tanilba Bay WWTW andLOQ to 162 ng/L for Belmont WWTW. Most target compounds significantly declined after the secondary treatment phase. Appreciable removal efficiency throughout the treatment process was observed with removal from 39.21 to 99.98% of influent values at both WWTWs. The reduction of the natural estrogens (E1, E2 and E3) and 4-t-OP were significantly greater than EE2, BPA, and 4-NP in both WWTWs. Risk quotients (RQs) were calculated to assess potential ecological risks from individual estrogenic compounds. In predicted diluted effluents, no targeted compounds showed any ecological risk (RQ ≤1.65 × 10

The current study investigated the effect of environmentally relevant mixtures of estrogens at levels representative of receiving waters on the metabolome of the Sydney rock oyster, Saccostrea glomerata. Oysters were exposed to a "low" and a "high" mixture of (xeno) estrogens (representative of Australian and global receiving waters respectively) for 7 days and digestive gland, gill, and gonad tissue were sampled for quantification of polar metabolites by 1H NMR spectroscopy. Exposure to both mixtures lowered body mass and altered the metabolite profile in the digestive glands. Comparatively, gills, and ovaries demonstrated lesser sensitivity to the mixtures, with significant metabolomic alterations observed only for the high mixture. The male gonad did not respond to either estrogenic exposure. In the responsive tissues, major metabolites including amino acids, carbohydrates, intermediates of the tricarboxylic acid cycle and ATP were all down-regulated and exhibited tissue-specific patterns of down-regulation with the greatest proportion of metabolites down-regulated due to estrogenic exposure in the digestive gland. Exposure to (xeno) estrogen mixtures representative of concentrations reported in receiving waters in Australia and globally can impact the metabolome and associated energy metabolism, especially in the digestive gland, translating to lower pools of available ATP energy for potential cellular homeostasis, somatic maintenance and growth, reproduction and fitness.

Soil in urban areas contains the residues of past land-uses and practices. Urban farming (keeping chickens, vegetable gardening) requires soil disturbance and can increase exposure of residents to these contaminants. We measured the level of lead, arsenic, cadmium, copper and zinc contaminants in soil and eggs from 26 backyard chicken coops across the Lower Hunter, NSW Australia. We compared the levels of metals in soil to Health Investigation Levels and metals in home-grown eggs to the levels in commercial eggs tested in this study or published by Food Standards Australia New Zealand. The levels of arsenic, cadmium, copper and zinc were low, both in soil and in home-grown eggs and were comparable to commercial eggs tested in this study. The Health Investigation Level for lead in soil (300mglead/kg soil) was exceeded at 7 of the 26 sites. The level of lead in home-grown eggs was generally higher than in commercial eggs. The reference health standard for meat (including chicken), fruit and vegetables of 0.1mglead/kg produce was exceeded in home-grown eggs from 7 of the 26 sites. There was a significant relationship between the lead level in eggs and the lead level in soil accessible to chickens. As soil lead increased, concentrations of lead in eggs tended to increase. No relationship was detected between the lead level in feed and in eggs. We recommend strategies to reduce ingestion of soil by chickens thereby reducing metal contamination in home-grown eggs.

Remnant endangered saltmarsh communities in Australia often occur in urbanised estuaries where industrial processes have contaminated sediments with metal(loid)s. Despite this issue, virtually nothing is known on local plant species exposure to metal contaminants, nor their ability to uptake and translocate metal(loid)s from contaminated estuarine sediment. In the current study, we assessed the accumulation and partitioning of the metal(loid)s Zn, Cu, Pb, Cd and Se in the dominant saltmarsh primary producer, Sporobolus virginicus, across three urbanised estuaries in NSW Australia. Lake Macquarie was the most contaminated estuary, while Sydney Olympic Park, Port Jackson exhibited intermediate metal(loid) loadings and Hunter Wetlands exhibited the lowest loadings among estuaries. Essential metals (Zn and Cu) were more mobile, with sediment:root bioconcentration factors (BCFs) greater than unity and translocation among plant organs greater than, or equal to, unity. Other metal(loid)s were less mobile, with BCFs equal to unity and translocation factors among organs much reduced. Despite these barriers to translocation, all metal(loid)s were accumulated to roots with dose, and further accumulative relationships between metal(loid)s in roots and culms, and culms and leaves, were evidenced (with the exception of Cu). Along with sediment metal(loid)s, increases in sediment pH predicted Cu uptake in roots and increases in soil organic matter predicted Se uptake in roots. Although significant positive linear relationships were observed between sediment metal(loid)s and plant organ metal(loid)s(withholding Cu), the variance explained was low to intermediate for most metal(loid)s suggesting employing S. virginicus as an accumulative bioindicator would be impractical.

The metal-binding protein metallothionein (MT) is widely used as a biomarker of metal contamination. In this study, we cloned a MT gene (sgMT) from the Sydney rock oyster Saccostrea glomerata. The gene encodes a MT-I protein with a classical αβ domain structure and is expressed as two transcripts resulting from alternative polyadenylation. The gene promoter contains two putative metal-responsive elements (MREs) which are known to be required for metal-inducible transcription. A specific and efficient qPCR assay was developed to quantify sgMT mRNA expression. Further, we assessed whether prior metal exposure history influences sgMT mRNA expression upon subsequent metal exposure. Oysters with varying prior metal exposure histories (contaminated and reference) were exposed to Cu, Cd and Zn. Expression of sgMT generally increased with metal dose, and oysters with an elevated past metal exposure history exhibited higher sgMT expression under Cd and Zn stress, representing a potential acclimatory response to prior metal exposure.

The Sydney rock oyster, Saccostrea glomerata, has been demonstrated as a useful biomonitor of estrogenic compounds following laboratory exposures, yet its utility in the assessment of estrogenic exposure and effects under field conditions requires investigation. To achieve this aim, S. glomerata were deployed in Newcastle, Australia in the effluent receiving marine waters of Burwood Beach WWTP (Burwood Beach "near"

The current study represents the first investigation of the suitability of marsupial and eutherian mammalian hair as indicator tissue for metal exposure and accumulation within contaminated Australian terrestrial ecosystems. A soil metal contamination gradient was established across 22 sites at increasing distances from a decommissioned Lead/Zinc smelter in NSW, Australia. Within each site, soil and small mammal populations were sampled. An Australian native marsupial, the insectivorous Brown Antechinus, Antechinus stuartii: Dasyuridae, and introduced rodents, the omnivorous Brown or Norway Rat, Rattus norvegicus: Muridae and the Black Rat, Rattus rattus: Muridae were assessed for hair concentrations of Cadmium (Cd), Copper (Cu), Lead (Pb) and Zinc (Zn). Metals in soil were most elevated at sites within close proximity to the smelter, with soil metal concentrations decreasing with distance from the smelter. The non-essential metals Pb and Cd were accumulated in hair, both metals exhibiting positive linear relationships with environmental exposure (soil metal concentrations). When the variables of weight and snout-vent length were considered, no further contribution in terms of explaining the variability in hair Cd or Pb was observed for all species examined. The essential metals Cu and Zn were regulated in hair, remaining similar across the metal contamination gradient. A significant negative correlation between snout-vent length and hair Cu concentration was found for the Brown Rat; greater hair Cu concentrations were found in smaller individuals of this species. Accumulation of Pb to hair was similar among species while concentrations of Cd in Brown Rat hair were higher than both Black Rat and Brown Antechinus hair. As each of the three aforementioned species exhibit similar bioaccumulation relationships for Pb, we suggest that sampling hair from introduced rodents (pest species) may provide a suitable proxy for the assessment of Pb bioavailability for a range of small mammals within Australian urban remnants.

Alterations in the glutathione antioxidant system and lipid peroxidation in Avicennia marina were studied under laboratory and field conditions. The activity of glutathione peroxidase (GPx) was found to respond to Zn exposure, and a significant positive relationship between leaf Zn concentration and GPx activity was observed after 96 h and 8 weeks. Lipid hydroperoxides increased proportionally with increasing leaf Zn concentration after 2 and 8 weeks, while no changes in total glutathione were observed. Induction of GPx at 96 h predicted effects at the individual level at a later time interval (reduced biomass at 8 weeks). Results from the field revealed that increasing leaf metal concentration (Zn, Cu or Pb) produced a proportional increase in GPx activity whereas lipid hydroperoxides and total glutathione were not affected. The utility of GPx as an early warning biomarker is suggested, since GPx activity increases in a dose-dependant fashion in response to accumulated leaf metals, and is predictive of later effects on growth.

Adult Saccostrea glomerata were exposed to environmentally relevant concentrations of 4-nonylphenol (1microg/L and 100microg/L) and 17alpha-ethynylestradiol (5ng/L and 50ng/L) in seawater over 8 weeks. Exposures were performed to assess effects on vitellogenin induction and gonadal development during reproductive conditioning. Chronic direct estrogenicity within gonadal tissue was assessed via an estrogen receptor-mediated, chemical-activated luciferase reporter gene-expression assay (ER-CALUX). Estradiol equivalents (EEQ) were greatest in the 100microg/L 4-nonylphenol exposure (28.7+/-2.3ng/g tissue EEQ) while 17alpha-ethynylestradiol at concentrations of 50ng/L were 2.2+/-1.5ng/g tissue EEQ. Results suggest 4-nonylphenol may be accumulated in tissue and is partly resistant to biotransformation; maintaining its potential for chronic estrogenic action, while 17alpha-ethynylestradiol, although exhibiting greater estrogenic potency on biological endpoints possibly exerts its estrogenic action before being rapidly metabolised and/or excreted. A novel methodology was developed to assess vitellogenin using high-performance liquid chromatography (HPLC). Exposure to both 17alpha-ethynylestradiol (50ng/L) and 4-nonylphenol (100microg/L) produced increases in vitellogenin for females, whereas males exhibited increases in vitellogenin when exposed to 50ng/L 17alpha-ethynylestradiol only. Females exhibited greater vitellogenin responses than males at 50ng/L 17alpha-ethynylestradiol only. Histological examination of gonads revealed a number of individuals exhibiting intersex (ovotestis) in 50ng/L 17alpha-ethynylestradiol exposures. Male individuals in 1microg/L and 100microg/L 4-nonylphenol exposures and 5ng/L 17alpha-ethynylestradiol were at earlier stages of spermatogenic development than corresponding controls.

This study compared the accumulation of arsenic, copper and chromium by Pteris vittata and Pteris umbrosa grown in a glasshouse in soil from a timber treatment facility. Soil was collected from three locations. Accumulation (as percentage removed) varied between these soils but was not related to soil concentration. P. vittata was more efficient than P. umbrosa, both in accumulating As and metals in the below-ground plant parts and in translocating As to the fronds. Under the experimental conditions, only P. vittata could be effectively used in soil from one location for phytoremediation purposes.

Variation in glutathione antioxidant biochemistry in response to metal contamination and accumulation under field conditions was examined in the brachyurid grapsid, Parasesarma erythodactyla. Significant relationships suggesting accumulation were found between sediment metals and metals in crab tissue for Pb, Cu, Cr, Zn, and Se in males and Cd, Pb, Cr Zn, As, and Se in females. Higher pH and lower organic content were associated with greater uptake of selected metals in males and females. Higher salinity was related to increased metal uptake for Cu and Zn in males and lower salinities to increased Se uptake for males and females. When examining metals, which were elevated in crabs, patterns of site discrimination were similar to sediment metal site discrimination for both males and females. In terms of biochemical responses, glutathione levels remained constant while glutathione peroxidase activity was elevated in individuals where metals were elevated. Only females with the highest levels of accumulated metals exhibited increases in lipid peroxidation products. Glutathione peroxidase activity may be a sensitive biomarker of metal exposure and biological effect and lipid peroxides as a secondary marker when accumulated metals are high.

The Akoya pearl oyster (Pinctada imbricata) was experimentally exposed to (a) constant levels of lead (Pb) at 180 microg L(-1) for nine weeks, or (b) two short term (pulse) exposures of Pb at 180 microg L(-1) (three weeks each) with an intervening depuration period (three weeks), to assess its utility as an (i) accumulative monitor of Pb contamination and an (ii) archival monitor for discriminating constant versus pulsed Pb exposure events. P. imbricata showed similar reductions in growth (based on shell morphology and wet weight) and Pb accumulation patterns for whole tissue and shell in response to both Pb exposure regimes. Thus the whole oyster was deemed an inappropriate accumulative monitor for assessing short-term temporal variation of Pb exposure and effect. However, using secondary ion mass spectrometry, Pb was shown to accumulate in the successively deposited nacreous layers of the shell of P. imbricata, documenting the exposure history of constant versus pulsed Pb events. Patterns of Pb deposition not only reflected the frequency of Pb exposure events but also their relative durations. Thus, the shell of P. imbricata may be employed as a suitable biological archive of Pb exposure.

Pearl oysters (Pinctada imbricata) were held in the laboratory and exposed to various levels of the heavy metals lead and zinc and the aliphatic hydrocarbons hexadecane and octacosane for 2 months. Individual oysters were followed over the course of the experiment, allowing specific calculation of total oyster growth (wet weight) and shell growth. Significant reductions in total oyster growth were observed when oysters were exposed to high concentrations (270μg L−1) of either zinc or lead. Exposure to the aliphatic hydrocarbons had no effect on total oyster growth. High concentrations of lead completely halted shell growth, the first demonstration of pollutant induced cessation of biomineralization in pearl oysters. Conversely, exposure to moderate levels of lead and the long-chain hydrocarbon octacosane resulted in significant increases in shell width growth. The results from this study indicate that P. imbricata is relatively tolerant of the selected pollutants and could be deployed within a re...

Mangroves have been observed to possess a tolerance to high levels of heavy metals, yet accumulated metals may induce subcellular biochemical changes, which can impact on processes at the organism level. Six month-old seedlings of the grey mangrove, Avicennia marina (Forsk.) Vierh, were exposed to a range of Cu (0-800 micrograms/g), Pb (0-800 micrograms/g) and Zn (0-1000 micrograms/g) concentrations in sediments under laboratory conditions, to determine leaf tissue metal accumulation patterns, effects on photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), and the activity of the antioxidant enzyme peroxidase. Limited Cu uptake to leaves was observed at low sediment Cu levels, with saturation and visible toxicity to Cu at sediment levels greater than 400 micrograms/g. Leaf Pb concentrations remained low over a range of Pb sediment concentrations, up to 400 micrograms/g Pb, above which it appeared that unrestricted transport of Pb occurred, although no visible signs of Pb toxicity were observed. Zn was accumulated linearly with sediment zinc concentration, and visible toxicity occurring at the highest concentration, 1000 micrograms/g Zn. Significant increases in peroxidase activity and decreases in photopigments were found with Cu and Zn at concentrations lower than those inducing visible toxicity. Significant increases in peroxidase activity only, were found when plants were exposed to Pb. Positive linear relationships between peroxidase activity and leaf tissue metal concentrations were found for all metals. Significant linear decreases in photosynthetic pigments with increasing leaf tissue metal concentrations were observed with Cu and Zn only. Photosynthetic pigments and peroxidase activity may be applicable as sensitive biological indicators of Cu and Zn stress, and peroxidase activity for Pb stress in A. marina.

The distribution and excretion of Cu, Pb and Zn in the root and leaf tissue of the grey mangrove, Avicennia marina was studied using scanning electron microscope (SEM) X-ray microanalysis and atomic absorption spectroscopy. SEM X-ray microanalysis of nutritive root tissue in seedlings dosed with 4 g/l Cu, Pb and Zn revealed accumulation of all metals predominantly in cell walls. The root epidermis provided a major barrier to the transport of Pb only. The endodermal casparian strip was shown to provide a barrier to movement of all three metals into the stele. Washings from mature leaves contained significantly higher amounts of Zn and Cu than control plants after 1 month, suggesting excretion of both metals from the glandular trichomes. In addition, salt crystals exuded from the glands on the adaxial surface of mature leaves were composed of alkaline metals: Zn in Zn-treated plants, and Cu in Cu-treated plants. Leaf tissue in seedlings dosed with 4 g/l Zn showed a decreasing gradient of the metal from xylem tissue, through photosynthetic mesophyll, to hypodermal (water) tissue, with a subsequent increase in concentration in the glandular tissue. A similar gradient was observed across leaf tissue in seedlings dosed with 4 g/l Cu, however, there was no subsequent increase in Cu concentration in glandular tissue. For both metals leaf cell wall metal concentrations were consistently higher than intracellular concentrations.

Mangroves are important as primary producers in estuarine food chains. Zinc is often a major anthropogenic contaminant in estuarine ecosystems and has potential ecotoxicological consequences for mangrove communities. Accumulation, distribution and excretion of zinc in the leaf tissue of the grey mangrove, Avicennia marina was studied using SEM X-ray microanalysis and Atomic Absorption Spectroscopy. The first leaves of A. marina grown in 500 μg Zn as ZnCl 2 per g of dry soil were found to accumulate 106.3±18.5 μg Zn per g dry tissue, significantly higher than control plants, after a 7-month period. Washings from first leaves contained significantly higher amounts of zinc (0.30±0.14 μg/cm 2 Zn) than control plants after 1 month, suggesting excretion of zinc from glandular trichomes. SEM X-ray microanalysis revealed salt crystals exuded from glandular tissue on the adaxial surface of first leaves to be composed of alkaline metals and zinc in zinc treated plants. SEM X-ray microanalysis of seedlings dosed with 4 g/l Zn as Zn Cl 2 revealed a decreasing Zn gradient from xylem tissue, through photosynthetic mesophyll, to hypodermal (water) tissue. A subsequent increase in Zn concentration was observed in glandular tissue. Cell wall Zn concentrations were consistently higher than intracellular Zn concentrations.

We report the findings of a comparative analysis examining patterns of accumulation and partitioning of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) in mangroves from available field-based studies to date, employing both species level analyses and a phylogenetic approach. Despite mangroves being a taxonomically diverse group, metal accumulation and partitioning for all metals examined were broadly similar across genera and families. Patterns of metal accumulation were also similar regardless of whether species were classified as salt secreting or non-secreting. Metals were accumulated in roots to concentrations similar to those of adjacent sediments with root bio-concentration factors (BCF; ratio of root metal to sediment metal concentration) of ⩽1. Root BCFs were constant across the exposure range for all metals. Metal concentrations in leaves were half that of roots or lower. Essential metals (Cu and Zn; translocation factors (TF; ratio of leaf metal to root metal concentration) of 0.52 and 0.53, and leaf BCFs of 0.47 and 0.51, respectively) showed greater mobility than non-essential metals (Pb; TF of 0.31 and leaf BCF of 0.11). Leaf BCFs for the essential metals Cu and Zn decreased as environmental concentrations increased. The non-essential metal Pb was excluded from leaf tissue regardless of environmental concentrations. Thus mangroves as a group tend to operate as excluder species for non-essential metals and regulators of essential metals. For phytoremediation initiatives, mangrove ecosystems are perhaps best employed as phytostabilisers, potentially aiding in the retention of toxic metals and thereby reducing transport to adjacent estuarine and marine systems.

The capacity of the Australian native fern Pteris umbrosa to function as an arsenic (As) hyperaccumulator (shoot:soil As concentration >1) was examined by growing plants under glasshouse conditions in an inert medium supplemented with As. Arsenic preferentially accumulated in the fronds, a trait of a hyperaccumulator. The As concentration of fronds decreased with age, being particularly high in the croziers and low in the senesced fronds. Below ground, rhizomes accumulated more As than adventitious roots. Uptake from a range of solution concentrations followed Michaelis Menten kinetics up to a soil solution As concentration of 400 mg l−1. The Km for As uptake by roots suggested the operation of a low-affinity carrier. The predicted Nernst membrane potential indicated that uptake was against the electrochemical gradient of As. At 600 mg l−1, the rate of As uptake increased and phytotoxic effects were indicated by a significant decline in biomass. Arsenic uptake and translocation in P. umbrosa and Pteris vittata were similar at low exposure to As. At higher exposure, As uptake and translocation by P. vittata increased more than in P. umbrosa. The growth rate of both ferns was similar, whereas the biomass distribution was not, with P. vittata having a much larger root mass. This suggests that As uptake by P. umbrosa roots was very efficient and may be improved by stimulating root growth to enhance its potential.

Surveys conducted after a crude oil spill indicated that the intertidal gastropod mollusc Austrocochlea porcata may be highly sensitive to the pollutant, and therefore also valuable as a biomonitoring organism. Toxicity tests conducted in the laboratory and field established cause-effect for A. porcata mortalities on exposure to environmentally relevant concentrations of crude oil constituents. Glutathione antioxidant system components (glutathione and glutathione peroxidase, GPx) and oxidative damage (lipid peroxidation) in A. porcata were measured to determine whether any of these biochemical parameters showed potential as biomarkers of sublethal oil exposure. GPx was the most promising candidate for field-based biomarker studies after showing a dose-dependent induction to a crude oil water accommodated fraction (WAF) in laboratory assays. However, subsequent manipulative field experimentation indicated that the GPx response was not sufficiently sensitive and not necessarily predictive of population level effects when measured in situ.

The accumulative partitioning of the heavy metals Cu, Pb and Zn in the grey mangrove, Avicennia marina, were studied under field conditions. Copper and Pb were accumulated in root tissue to levels higher than surrounding sediment levels. Zinc was accumulated to levels reflecting sediment concentrations. Strong linear relationships existed for all metals in sediments with metals in root tissue. Accumulation of Cu in leaf tissue followed a linear relationship at lower sediment concentrations, with an exclusion or saturation mechanism at higher sediment concentrations. Lead showed little mobility to leaf tissue. Zn showed restricted accumulation in leaf tissue, which correlated with sediment concentrations. Decreases in sediment pH were found to increase Zn accumulation to root tissue. Increasing concentrations of Pb and Zn in sediments resulted in a greater accumulation of Pb to both root and leaf tissue. A. marina roots may be employed as a biological indicator of environmental exposure of Cu, Pb and Zn and leaves for Zn, with temporal monitoring. © 2003 Elsevier Science Ltd. All rights reserved.

The effects of three heavy metals Copper (Cu), lead (Pb) and zinc (Zn), and the interaction of an essential (Zn) and non-essential (Pb) metal on germination, growth, and accumulation of metals in the grey mangrove, Avicennia marina (Forsk.) Vierh var. australasica (Walp.) Moldenke, were studied under laboratory conditions. Avicennia marina was found to be highly tolerant to the metals applied. Copper was accumulated in root tissue in a linear relationship at lower sediment concentrations, but at concentrations of 200 microg/g and higher, no further increases in root Cu levels occurred. Translocation of Cu from the root to leaf tissue was low, yet revealed similar accumulation patterns as root tissue. Significant reductions in seedling height leaf number and area were found with significant increases in Cu concentrations in tissues at 100 microg/g sediment Cu. At Cu sediment levels of 400 microg/g, a decrease in total biomass and root growth inhibition was observed. Emergence was retarded with increasing copper concentration, with 800 microg/g sediment Cu resulting in a total inhibition of emergence. The LC50 for emergence and EC50 for biomass was 566 and 380 microg/g Cu respectively. Lead accumulation in root tissue was lower that other metals, yet increased in a dose dependant fashion across the sediment Pb concentration range examined. Lead was excluded from leaf tissue at Pb sediment concentrations up to 400 microg/g, above which limited transport of Pb occurred. Little negative effects on growth were observed due to the low accumulation of Pb. Zinc uptake was high, and was accumulated in a linear fashion in root tissue across the sediment Zn concentration range applied. Zinc translocation to leaf tissue exhibited a dose dependant relationship with both root and sediment Zn levels. Emergence decreased with increasing sediment Zn concentrations, with 1000 microg/g sediment Zn showing 100% mortality. Significant reductions in seedling height, leaf number, area, biomass and root growth inhibition were found at concentrations of 500 microg/g sediment Zn. The LC50 for emergence and EC50 for biomass was 580 and 392 microg/g Zn respectively. Lead and Zn in combination resulted in an increased accumulation of both metals in leaf tissue and increased toxicity than individual metals alone, and is the first noted occurrence of a Pb and Zn additive response in angiosperms. Possible mechanisms of accumulation and toxicity are discussed.

The effects of heavy metals Cu, Pb, and Zn on a number of biological structural components of Avicennia dominated mangrove ecosystems is reviews and their potential as biological indicators of metal stress discussed. Three main taxa groups were chosen for examination, representing key structural components of Avicennia systems at different trophic levels. As the primary producer, Avicennia marina (Forsk.) Vierh, the grey mangrove, was studied most intensely. Heloecious cordiformis (Milne Edwards, 1852), the semaphore crab, was chosen as a higher level consumer. A suite of benthic organisms were also studied, representing a range of trophic associations at the community level. Potential biological indicators of metal stress were investigated in each group, at various organisational levels. A combination of laboratory and field based experiments have shown that most biological indicators investigated have merit in terms of reflecting exposure and effect of heavy metal stress in Avicennia systems. Avciennia marina was found to be highly tolerant to Cu, Pb and Zn. Both field and laboratory studies revealed the three metals were accumulated in root tissue in proportion to sediment metal loadings, and Cu and Zn showed some limited mobility to leaf tissue. Zn was the only metal in leaf tissue. Zn was the correlated with sediment loadings. All metals in root tissue and Zn in leaves were appropriate for accumulative indication. In both field and laboratory studies, increases in peroxidase activity and decreases in photopigments (most notably the chlorophyll a/b ratio) were found with increasing Cu and Zn. Significant relationships with peroxide ase activity only, were found for Pb. Both peroxidise activity and photopigment may be employed as sensitive early warning biomarkers of metal stress in A. Marina. For H. Cordiformis, Cu and Zn were regulated in the hepatopancreas. Lead was accumulated in the hepatopancreas in proportion to sediment Pb levels, and Pb was the main metal loadings tended to support lower numbers of crabs, greater proportions of females with purple chelae (rather than orange) and less females in the population, and thus may be employed as population level indicators of metal stress. Monitoring of macrobenthic community assemblage diversity and abundance along with natural variables and low-level anthropogenic contaminnts including Cu, Pb, Zn, revealed no significant pollutant related patterns. Natural physiochemical sediment differences were found to be the main determinants in species assemblage patterns among sites. An integrated approach of both field and laboratory based testing, with a range of species measured at various organisational hierarchies, is most instructive in the assessment of metal impacts on mangrove ecosystems.