Fitness of Isidorella newcombi Following Multi-generational Cu Exposures: Mortality, Cellular Biomarkers and Life History Responses.

The effects of multigenerational Cu exposure on the freshwater gastropod Isidorella newcombi were investigated. Snails were exposed to a range of treatment-specific Cu concentrations in the parental to F2 generations, and a common Cu concentration in the F3 generation. In the parental to F2 generations, some general responses to 3 days Cu exposures included reduced survival and feeding in snails exposed to higher Cu concentrations. This suggested that the snails exposed to the high Cu concentration were experiencing Cu-induced stress that may apply selection pressure. In the F3 generation, when all treatments were exposed to a common Cu concentration, increased survival was correlated with the pre-exposure Cu concentration history. Snails that had been pre-exposed to Cu also displayed reduced stress at a sub-lethal level, indicated by lower lysosomal destabilisation (LD). Mortality and LD responses in the F3 generation were not related to Cu tissue concentrations, indicating increased tolerance and reduced stress were not related to changes in Cu bioaccumulation. Total antioxidant capacity increased in the higher Cu concentration pre-exposure treatments which could be associated with lower Cu-induced stress, however, this is not supported by the oxidative damage marker lipid peroxidation, which also increased. While Cu tissue concentrations and oxidative stress markers were assessed to determine underlying reasons for increased tolerance in snails from a population with a multi-generational exposure history to Cu, the results were not conclusive. Despite this, it was demonstrated through increased survival and reduced LD that Cu tolerance can develop over a short evolutionary time scale.

The Response of the Planorbid Snail Isidorella newcombi to Chronic Copper Exposure Over a 28-Day Period: Linking Mortality, Cellular Biomarkers, and Reproductive Responses.

The native freshwater gastropod Isidorella newcombi attacks the roots of developing rice plants in southern Australia and is controlled using copper sulphate. The apparent tolerance of this species to moderate levels of copper (Cu) exposure led us to investigate its potential usefulness as a biomonitor species. To assess its response to chronic Cu exposure, adult I. newcombi were exposed to 0-120 µg L-1 of Cu for 28 days. Lethal and sublethal responses were investigated. The relationships between subcellular biomarkers and life history traits also were explored. At exposure concentrations of 60 µg L-1 Cu and above, 100% mortality was observed during the 28-day exposure period. In these treatments, there was an exposure concentration dependent decrease in the time that the snails survived. In the surviving snails, there was an exposure concentration-dependent increase in tissue Cu concentration. In the snails exposed to Cu concentrations above 15 µg L-1, no eggs were produced during the final week of copper exposure, indicating that populations would not persist at Cu concentrations above 15 µg L-1. The general stress biomarker lysosomal membrane destabilisation (LD) indicated organisms exposed to 10 µg L-1 Cu and above were experiencing Cu induced stress. This suggests that LD could act as an early warning system for responses at higher levels of biological organisation in I. newcombi exposed to copper.

Metal concentrations in waters, sediments and biota of the far south-east coast of New South Wales, Australia, with an emphasis on Sn, Cu and Zn used as marine antifoulant agents.

Tin, Cu, Zn, Cd, Pb, Ag and Hg concentrations were measured in waters, sediments and three ubiquitous sedentary molluscs: the oyster, Saccostrea glomerata, a rocky intertidal gastropod, Austrocochlea porcata, and a sediment-dwelling gastropod, Batillaria australis, at 12 locations along the far south coast of NSW, Australia, from Batemans Bay to Twofold Bay during 2009. Metal concentrations in water for Sn, Cd, Ag and Hg were below detection limits (< 0.005 µg/L). Measurable water metal concentrations were Cu: 0.01-0.08 µg/L, Zn: 0.005-0.11 µg/L and Pb: 0.005-0.06 µg/L. Mean metal concentration in sediments were Sn < 0.01-2 µg/g, Cu < 0.01-605 µg/g, Zn 23-765 µg/g, Cd < 0.01-0.5 µg/g, Pb < 0.01-0.3 µg/g, Ag < 0.01-0.9 µg/g and Hg < 0.01-2.3 µg/g. Several locations exceeded the Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand (Australian and New Zealand guidelines for fresh and marine water quality 2000) low and high interim sediment quality guidelines' levels for Cu, Zn, Cd and Hg. Some sites had measurable Sn concentrations, but these were all well below the levels of tributyltin known to cause harm to marine animals. Elevated metal concentrations are likely to be from the use of antifoulants on boats, historical mining activities and agriculture in the catchments of estuaries. All molluscs had no measurable concentrations of Sn (< 0.01 µg/g) and low mean Ag (< 0.01-1.5 µg/g) and Hg (< 0.01-0.5 µg/g) concentrations. Mean Cu (24-1516 µg/g), Zn (45-4644 µg/g), Cd (0.05-5µg/g) and Pb (0.05-1.1 µg/g) in oysters were close to background concentrations. Oysters have Cd and Pb concentrations well below the Australian Food Standards Code (2002).] There were no significant correlations between metal concentrations in sediments and in organisms within locations, and no relationship with levels of boating activity and suspected antifouling contamination. Although not pristine, the low levels of metal contamination in sediments and molluscs in comparison with known metal-contaminated areas indicate that this region is not grossly contaminated with metals and suitable for the development of mariculture.].

Factors influencing arsenic concentrations and species in mangrove surface sediments from south-east NSW, Australia.

Arsenic concentrations and speciation of 55 mangrove surface sediment samples from the south-eastern coast of NSW, Australia, have been measured. Arsenic concentrations were in the range 1.6-8.6 µg/g dry mass. All arsenic concentration values were well below 20 µg/g, the ANZEC/ARMCANZ interim sediment quality guideline-low trigger value. The bulk sediment pH was 6.0-7.3 and Eh -80 to -260 mV. The sediments contained variable silt-clay (2-30 % w/w), iron (668-12721 µg/g), manganese (1-115 µg/g), sulphur (70-18400 µg/g) and carbon (5-90 mg/g) concentrations. Arsenic concentrations correlated with silt and clay content, iron and manganese concentrations, indicating silt-clay particles covered and coated with iron and manganese (oxy) hydroxides scavenged arsenic. Arsenic extracted with 0.5 M phosphoric acid (68-95 %) was present only as inorganic arsenic (55-91 %), indicating that other arsenic species such as arsenobetaine derived from marine animal tissues rapidly degrade in sediments. The unextractable arsenic was correlated with increases in organic carbon, iron and manganese content. In conclusion, the cycling of arsenic in mangrove sediments is essentially the cycling of inorganic arsenic and primarily controlled by the redox cycling of carbon, sulphur, iron and manganese.

Arsenic toxicity in a sediment-dwelling polychaete: detoxification and arsenic metabolism.

The accumulation, subcellular distribution and speciation of arsenic in the polychaete Arenicola marina were investigated under different laboratory exposure conditions representing a range of metal bioavailabilities, to gain an insight into the physiological mechanisms of how A. marina handles bioaccumulated arsenic and to improve our understanding of the potential ecotoxicological significance of bioaccumulated arsenic in this deposit-feeder. The exposure conditions included exposure to sublethal concentrations of dissolved arsenate, exposure to sublethal concentrations of sediment-bound metal mining mixtures, and exposure to lethal concentrations of sediment-bound metal mining mixtures and arsenic- and multiple metal-spiked sediments. The sub-lethal exposures indicate that arsenic bioaccumulated by the deposit-feeding polychaete A. marina is stored in the cytosol as heat stable proteins (~50%) including metallothioneins, possibly as As (III)-thiol complexes. The remaining arsenic is mainly accumulated in the fraction containing cellular debris (~20%), with decreasing proportions accumulated in the metal-rich granules, organelles and heat-sensitive proteins fractions. A biological detoxified metal compartment including heat stable proteins and the fraction containing metal-rich granules is capable of binding arsenic coming into the cells at a constant rate under sublethal arsenic bioavailabilities. The remaining arsenic entering the cell is bound loosely into the cellular debris fraction, which can be subsequently released and diverted to an expanding detoxified pool. Our results suggest that a metal sensitive compartment comprising the cellular debris, enzymes and organelles fractions may be more representative of the toxic effects observed.

Determination of total arsenic by use of a zinc-column arsine generator.

A method for the measurement of total arsenic in extracts of environmental materials is described. Arsenic is reduced to arsine with a zinc reductor column, the evolved arsine is decomposed in a heated carbon-tube furnace, and arsenic determined by measurement of its atomic-absorption at 193.7 nm. The detection limit is 0.002 mug/ml and the coefficient of variation is 1.4% at 0.01 mug/ml.

Fluorimetric determination of selenium in some marine materials after digestion with nitric and perchloric acids and co-precipitation of selenium with lanthanum hydroxide.

A modified spectrofluorimetric method for the determination of selenium in some marine tissues is described. Selenium is isolated from potentially interfering elements by co-precipitation, then a piazselenol is formed between selenium and 2.3-diaminonaphthalene at pH 1.0 and extracted into cyclohexane. The selenium is determined fluorometrically (lambda(ex), 377 nm; lambda(em), 519 nm) in the extract. The detection limit is 3.6 rig (6 times the standard deviation of the blank) and the coefficient of variation is 4% at the 10-ng level.

A decomposition procedure for the determination of arsenic in marine samples.

The use of wet and dry ashing procedures to decompose marine biological tissues and to degrade organoarsenic compounds to inorganic arsenic for analysis by zinc-column arsine generation and atomic-absorption spectrophotometry was investigated. Wet ashing with nitric, sulphuric and perchloric acids (10:2:3 v/v) released the largest percentage of arsenic from fish tissue and quantitatively degraded methylated and other organoarsenic compounds to inorganic arsenic. The arsenic concentrations found when standard reference materials were ashed with this acid mixture were in agreement with the certified values.

Polycyclic aromatic hydrocarbons in nearshore marine sediments of Australia.

The occurrence and fate of polycyclic aromatic hydrocarbons (PAH) in nearshore marine sediments of Australia is discussed. Available information indicates that PAH are accumulating in the sediments and organisms of estuaries and harbours with both highly urbanized/industrialized and non-urban catchments. PAH levels in polluted sediments are similar to those of grossly polluted areas of Japan, North America and Europe, however PAH sources cannot be identified from the information available. PAH appear to persist in reducing environments, while in relatively pristine environments that have been previously exposed to PAH, conditions are probably favourable for the aerobic degradation of PAH by microorganisms.

Arsenic in marine organisms : A minireview.

A review of the nature and accumulation of arsenic in marine organisms is presented. A study of the literature has revealed a lack of information about the mechanisms of uptake, molecular transformations, and biochemical associations of arsenic within organisms, and it remains unclear whether a few forms of arsenic are ubiquitous. The arsenic forms present in marine sediments and their role in the biogeochemical cycling of arsenic are also largely unknown.

Response of the hairy mussel Trichomya hirsuta to sediment-metal contamination in the presence of a bioturbator.

The accumulation of metals in tissue compartments of bivalve biomonitors is expected to reflect the phases in which metals are most bioavailable. In concurrent field and laboratory experiments we measured Zn, Cd and Pb concentrations in the gills and digestive glands of mussels exposed to sediments from Lake Macquarie in NSW, Australia. Mussels in the laboratory were also exposed to the bioturbating gastropod Batillaria australis. Zn, Cd and Pb concentrations in gills and digestive glands of mussels from both experiments were accumulated in proportion with levels of metal contamination in the sediments. An interaction in the field between site and tissue type was found for Cd and Pb suggesting variation in the phases in which metals are most bioavailable. No effect of bioturbation on metal accumulation in the bivalve was detected and we conclude that it is unlikely to be a significant factor in metal uptake when these species interact.

Distribution of selenium in marine animals: relationship to diet.

The chemical form of selenium in the muscle tissues of marine animals in relation to diet has been examined. Inorganic selenium concentrations in all muscle tissues were below the detection limits of the analytical method employed (0.001 mg/kg). Selenium was found to be associated in all tissues predominantly with insoluble proteins. Lipid-soluble and ethanol-soluble selenium constituted less than 18% of the selenium present in tissues and was independent of diet.

The presence of arsenobetaine in marine animals.

Methanol soluble arsenic compounds were isolated from the muscle tissues of a crayfish, Jasus novaehollandiae, a prawn, Penaeus latisulcatus, a scallop, Pecten alba, a squid, Sepioteuthis australis and a fish, Sillaginodes punctatus. Arsenobetaine was found to be the major arsenic compound present in all muscle tissues. The prawn and scallop tissues also contained another organo arsenic compound that could be partially degraded to characterized methylated arsenic species.

Distribution of arsenic in marine animals: relationship to diet.

The chemical form of arsenic in the muscle tissues of marine animals in relation to diet has been examined. Inorganic arsenic concentrations in all muscle tissues were found to be low compared to total arsenic concentrations and independent of diet. Arsenic was found to be present in all tissues predominantly as a methanol-water soluble form. The ratio of lipid soluble and unextractable arsenic to total arsenic was higher in plankton feeders than in herbivores and carnivores.

Water quality assessment programs in Australia deciding what to measure, and how and where to use bioindicators.

Effective water quality assessment programs require the formulation of common objectives between managers who are making decisions and scientists who are obtaining the information on which those decisions are to be made. The data collected must be apropriate for use in the decision making process. After the objectives have been formulated a number of testable hypotheses can be proposed and evaluated in terms of what information is required for decision making.From a management perspective it is important to know if an impact occurs and what management strategy to adopt to reduce or eliminate the impact. When bioaccumulators are used to indicate environmental quality the organisms proposed need to be fully evaluated before being used. Communities, which are often used to assess levels of impact, have the capacity to assimilate pollutants and they will function under pollutant stress. Thus managers need to make value judgements about when a community structure or function has shifted from acceptable to adverse. Bioassays in which the effects of pollutants on growth, biochemistry and behaviour are measured, give an indication of the sub-lethal effects of a pollutant, but it is difficult to set meaningful levels that are not to be exceeded for use by managers.Difficulties in using chemical and biological data mainly arise from a lack of appreciation of environmental heterogeneity. The data obtained must meet the needs for statistically testing hypotheses. Before programs can be designed to meet statistical needs the potential sources of variability must be considered. Once the minimum differences that are seen as important have been determined, the number of replicates needed can be calculated. Data verification is also needed, as if the validity of data is questioned, so will any decisions that have been made based on those data. Finally programs should be designed to minimize the sampling effort/cost to meet the objectives.

Framework for designing sampling programs.

A general framework for designing sampling programs is described. As part of the sampling program the problem of concern, or reason for sampling, needs to be clearly stated and objectives specified. The development of a conceptual model will assist the clarification of objectives and the choice of indicators to be sampled.Objectives can then be stated as testable hypotheses and decisions made about the samallest difference/changes that are to be detected/observed by the sampling.To allow the collection of representative samples, and the statistical analysis of data to be collected, the potential sources of variability in the data must be considered. Site, selection, frequency and replication must account for the expected variability.Before field collection of samples occurs, the sample collection device needs to be tested as to its efficiency to collect a representative sample. It also will usually be necessary to consider how samples are to be preserved to inhibit biological and chemical change. All sample programs require a quality assurance program to identify, measure and control errors.As well as the above the cost-effectiveness of the program should be evaluated in terms of maximizing the information obtained/cost.