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Murray-Darling Freshwater Research CentreMDFRC item.Rates of exoenzyme activity in the water column of 17 sites in the Murray-Darling Basin were determined over a one-year period. The most active exoenzyme was aminopeptidase, followed by alkaline phosphatase, lipase, N-acetyl beta-D-glucoaminidase, alpha-D-glucosidase and beta-D-glucosidase, beta-D-galactosidase and endopeptidase. Exoenzyme activity in rivers (alkaline phosphatase, 0.9-8.2 micromoles/L/day; aminopeptidase, 3.5-32 micromoles/L/day) was within the range reported for Northern-Hemisphere systems, but activity in billabongs (alkaline phosphatase, 4.4-222 micromoles/L/day; aminopeptidase, 8.7-1134 micromoles/L/day) was generally higher than that in rivers and other previously studied systems. Strong relationships were detected between aminopeptidase activity, chlorophyll-a concentrations, bacterial numbers and concentrations of ammonium and dissolved primary amines in the billabong. These interactions were not evident in the river. There were few clear relationships between alkaline phosphatase activity and environmental conditions in either billabong or river.

Murray-Darling Freshwater Research CentreMDFRC item.We investigated the importance of lacunar gas transport for the release of methane from beds of Eleocharis sphacelata R. Br. in a freshwater wetland in southeastern Australia. Gases were transported in the E. sphacelata lacunar system by pressurized convective flow, which was apparently driven by humidity induced pressurization. Internal culm temperatures were 1.9–4.2° C lower than at the external culm surface, suggesting that thermal transpiration was not responsible for lacunar pressurization. Some of the culms (influx culms) provide a net gas flux from the atmosphere into the plant, whereas others (efflux culms) act as conduits for flux from the rhizosphere to the atmosphere. The mean gas influx was 1.0±0.2 (SE) ml min−1 per culm, and the mean gas efflux was 0.2±0.0 (SE) ml min−1 per culm. The difference in influx and efflux flow rates is due to unequal numbers of the two culm types, and the total gas flux through three adjacent E. sphacelata beds was estimated from this flow ratio and the total culm density. It ranged from 1.1 to 2.5 1 m−2 h−1. The methane concentration in the efflux culms was 2–3%, resulting in a total methane efflux from E. sphacelata of 22–75 ml CH4 m−2 h−1. These rates represented 1–15 times the rate of methane release from the E. sphacelata beds by ebullition of methane in bubbles released from the sediment. Diffusive methane fluxes in the lacunar s system (< 300 μl m−2 h−1) were an insignificant mechanism of methane release compared with lacunar convective flow and ebullition fluxes from sediments. The interstitial methane concentration in sediments from E. sphacelata beds was approximately 0.6 times that of adjacent unvegetated sediment, highlighting the role of convective flow by E. sphacelata in accelerating methane release from sediments.

Murray-Darling Freshwater Research CentreMDFRC item.Continuous centrifugation and tangential flow ultrafiltration were used to size-fractionate and concentrate suspended particles from various turbid rivers of south-eastern Australia. These preparative steps produced highly concentrated samples, but the high load of suspended solids (up to 3.28 gl-1) did not interfere with the determination of phosphatase activity with an enzyme assay using p-nitrophenyl phosphate as the substrate. Phosphomonoesterase activity was an order of magnitude greater than phosphodiesterase activity; acid, neutral and alkaline phosphatases were detected. Most neutral (pH 7.5) and alkaline (pH 9.0) phosphatase activity was in the 0.2 - 1 mum size fraction: the next most active fractions were usually the 1-25 mum and the 100,000 daltons - 0.2 mum classes. Activity associated with free enzymes (i.e., that in the 10,000 - 100,000 daltons fraction) was usually low. Similar profiles were obtained with p-nitrophenyl phosphate and methylumbelliferyl phosphate substrates. Across the various size fractions within each river-water sample, phosphatase activity was usually more highly correlated with organic-matter content than with dry-matter content. Phosphatase activity was poorly related to chlorophyll-a contents. Phosphatase-producing bacteria were detected in all particulate fractions. The high activity in the 0.2 - 1 mum size fraction of turbid rivers might, therefore, be a function of either phosphatases associated with planktonic bacteria, or phosphatases adsorbed to the organic coating of suspended inorganic particles. In the coarser fractions, the additional contribution of attached bacteria cannot be excluded.

Murray-Darling Freshwater Research CentreMDFRC item.Sediment oxygen demands and water-atmosphere methane emissions of a highly productive, freshwater wetland on the floodplain of the River Murray in south-eastern Australia were quantified over a 14 month period in 1993–1994. Total sediment oxygen demands ranged from 1.3 to 3.3 mmol m−2 h−1, of which < 3 to 90% was due to chemical oxygen demand. Methane emissions ranged from < 0.01 mmol m−2 h−1 in winter to 2.75 mmol m−2 h−1 in summer. Methanogenesis accounted for at least 60% of the combined aerobic and methanogenic carbon flux in sediments from Eleocharis sphacelata beds, and at least 30% and 40% of the combined flux in sediments from Myriophyllum sp. beds and Vallisneria gigantea beds, respectively. In vitro incubations, using additions of sulfate and of molybdate, failed to indicate unequivocally competition for substrates between sulfate-reducing and methanogenic bacteria. However, in vitro methanogenesis was strongly inhibited by nitrate, suggesting an interaction between benthic methanogens and denitrifying or other nitrate-reducing bacteria. Fe3+ decreased in vitro methanogenesis by 16–49% during January, February and March 1994; oxidation of organic matter at the expense of the reduction of ferric ions could be a significant route for detritus processing in Eleocharis-bed sediments in the warmer months. Methanogenesis was increased consistently by additions of some low molecular weight substrates, such as acetate, but not by others, such as methanol, propionate and trimethylamine. Complex polymeric substrates, such as cellulose, starch and aquatic plant matter, increased in vitro methanogenesis rapidly and markedly. Despite this, no relationship between methane emissions and benthic cellulase activity was observed in the field. Methanogenesis was strongly temperature dependent, being maximal at 30 to 40°C and minimal at 5°C, thereby explaining the strong seasonality observed in methane emissions in situ.

Murray-Darling Freshwater Research CentreMDFRC item.1. The accrual of organic matter, chlorophyll a and bacteria, and the activities of various extracellular enzymes were studied during biofilm formation on River Red Gum (Eucalyptus camaldulensis) wood submerged in two temperate Australian billabongs for 24 weeks over summer and winter of 1989–90.2. Peak organic matter content of the biofilm ranged from 0.7 to 3.3mg AFDW cm−2, chlorophyll a content from 1.3 to 4. 2μg cm−2 and bacterial abundance from 18 × 106 to 94 × 106 cells cm−2. Most variation in organic matter content, chlorophyll a content and bacterial abundance in the biofilms couid be attributed to the duration of immersion (28–48% of variation) and to the interaction between site and submergence period (11–12%). Differences between sites and between seasons were less important in explaining total variation.3. Alkaline phosphatase, aminopeptidase and [3-D-glucosidase activities, determined per unit substratum surface area, were up to 138 ± 26 nmol cm−2h−1, 113 ± 1 nmol cm−2h−1 and 9.3 ± 2.2 nmol cm−2h−1, respectively. Activities of these three enzymes determined per unit organic biomass were up to 203 ± 25, 157 ± 13, and 16 ± 2.1 nmol mg1 AFDW h−1 respectively. Enzyme activities expressed on an area- or biomass-specific basis responded differently to the effects of season, site and duration of substratum exposure.4. Few consistent relationships could be established between the activity of a given enzyme system and the activity of other enzymes, nor with the various biomass parameters, such as total organic matter content, chlorophyll a content or bacterial abundance.5. We suggest that submerged wood of the River Red Gum is an important site for biofilm development in lentic systems in south-eastern Australia, and thus as a food resource for grazing invertebrates and for transformations of various nutrients and organic matter.

Murray-Darling Freshwater Research CentreMDFRC item.Both phytoplankton and bacterioplankton produce alkaline phosphatases, but the techniques currently available for discriminating between the two sources are poor, especially when samples are from turbid waters. A novel approach, based on the differential inhibition of alkaline phosphatases by various physical and chemical treatments, was assessed as a rapid and inexpensive technique for determining whether phytoplankton or bacterioplankton were the more important producers of alkaline phosphatases in turbid rivers of south-eastern Australia. Eight phytoplankton strains and 14 bacterial strains (eight isolated from the Ovens River and six isolated as bacterial contaminants of the phytoplankton cultures) were grown in laboratory culture. Rates of alkaline phosphatase activity in the bacterial cultures varied from 70% of cases) grouped separately from those of the laboratory cultures of bacteria and phytoplankton, perhaps because the microbes studied in laboratory culture were not representative of native assemblages or because the culture conditions did not mimic those in nature. Nevertheless, differential-inhibition techniques have much potential for determining the origin of the alkaline phosphatases found in natural waters, with the major factor limiting their application being the collection of valid inhibition profiles for native bacterial and algal communities.

Murray-Darling Freshwater Research CentreMDFRC item.1. We examined the temporal (seasonal and diel) and spatial variation in methane flux from sediments of a billabong in south-eastern Australia, and related it to variations in the rate of organic matter decay, concentration of interstitial metabolites, and sediment redox.2. Total gas ebullition ranged from 59mlm−2h−1, and was highest in the summer months when water temperatures were >25°C. These rates are equivalent to carbon fluxes of about 16–30gC—CH4m−2yr−1. Ebullition was greater from unvegetated sediments than from sediments colonized by the emergent macrophyte Eleockaris sphacelata, R, Br. or the submerged macrophyte Vallisneria gigantea Graeb. There were no consistent differences in the rate of ebullition over the day and the night.3. Methane accounted for about 42–45% of total sediment gas in the vegetated sediments, but about 60% in the unvegetated sediments. These ratios did not vary greatly throughout the year. Carbon dioxide was a minor component of sediment gas, usually comprising

Murray-Darling Freshwater Research CentreMDFRC item.1. We examined the effects of an emergent macrophyte (Eleocharis sphacelata R. Br., Cyperaceae) and a submerged macrophyte (Vallisneria gigantea Graeb., Hydrocharitaceae) on the biogeochemistry of the sediments of a billabong in south-eastern Australia.2. Sediments from an E. sphacelata bed had significantly lower concentrations of exchangeable phosphorus than did sediments from a nearby bare area or a V. gigantea bed, but neither macrophyte had a measureable effect on their sediment's exchangeable ammonium content.3. The redox potential in the upper 10cm of E. sphacelata sediments was about 100 mV higher than that of bare sediments, or of sediments colonized by V. gigantea.4. There were few consistent differences between vegetated and bare sediments in terms of the activity of extracellular enzymes, such as α-amylase, protease, β-d glucosidase, lipase or alkaline phosphatase. Rates of alkaline phosphatase activity (235–306μmol (g dry wt)−1 day−1) were markedly higher than those commonly reported for sediments or soils.5. Rates of gas release were higher from bare sediments (21–93 ml m−2 h−1) than from E. sphacelata or V. gigantea sediments (17–23 and 21-24ml m−2 h−1, respectively). Gas bubbles consisted mainly of methane (26–66%) and nitrogen (15–68%). Rates of methane ebullition varied from 5 to 60ml m−2 h−1.6. In-vitro methanogenesis was most rapid in samples of the upper flocculent sediment. Methanogenesis was slower in V. gigantea sediments than in bare area or E. sphacelata sediments, but was markedly accelerated by additions of acetate and/or H2/CO2 in all sites.7. Profiles of total extractable fatty acids and phospholipid fatty acids demonstrated that material derived from higher plants dominated the sediment organic matter in all sites. Bacteria were also a significant component of sediment organic matter, as fatty acids for which bacteria can be assumed the sole source accounted for 18–30% of total fatty acid content. Biomarkers for sulphate-reducing bacteria (Desulfobacter spp.) were detected, and for type II methanotrophic bacteria.

Murray-Darling Freshwater Research CentreMDFRC item.The antibiotic resistance of bacteria from the water column of various rivers and billabongs in north-eastern Victoria was studied during 1988-91. Two indices were used as measures of resistance: conventional disc-sensitivity tests with culturable bacteria, and the effect of antibiotics on the uptake of 14C-glucose and 14C-amino acids by native bacterial assemblages. Culturable bacteria were resistant to ampicillin, methicillin and penicillin but generally sensitive to nalidixic acid, neomycin, streptomycin, sulfafurazole and tetracycline. Responses to chloramphenicol, erythromycin, nitrofurantoin and sulfamethizole were variable. Bacteria isolated from rivers were more resistant to antibiotics than were those isolated from billabongs. Methicillin, even at 200 mg L-1, had little effect on the uptake of 14C-labelled compounds. Nalidic acid (20 mg L-1) also was ineffective unless lengthy pre-incubations (24 h) were used. Chloramphenicol and tetracycline at 20 mg L-1 markedly reduced amino acid uptake but not glucose uptake. The widespread antibiotic resistance of aquatic bacteria casts doubt on the suitability of these compounds to selectively inhibit the prokaryotic component in ecological studies and may be cause for concern regarding the spread of antibiotic resistance through natural aquatic communities.

Murray-Darling Freshwater Research CentreMDFRC item.Methane emissions were quantified from beds of Eleocharis sphacelata R.Br., Myriophyllum sp., and Vallisneria gigantea Graeb. in a small floodplain lake (Ryans 1 Billabong; 36°07′S, 146°58′E) in south-eastern Australia over a 15-mo period, from March 1993 to May 1994. Gas from sediments of Vallisneria beds had the highest methane concentrations (about 60-90% v/v); methane concentrations in gas from sediments of Myriophyllum beds were the lowest (falling to 17 ± 3% v/v in May 1994), and concentrations in sediments of Eleocharis beds varied from about 25% v/v in winter to about 60-82% v/v in summer-autumn. Total water-atmosphere methane fluxes, measured with 0.8 m3 static chambers, varied from -2 h-1 in Eleocharis beds, -2 h-1 in Myriophyllum beds, and -2 h-1 in areas of open water colonised by Vallisneria. Total fluxes were highly seasonal, being greatest in summer-autumn, when sediment temperatures exceeded 20°C. Strong diurnal and diel variations were also observed, especially in Eleocharis beds during the warmer months. Ebullition rates varied from -2 h-1 and, like total water-atmosphere fluxes, fluctuated according to season, being lowest in winter and highest in summer-autumn. Ebullition seemingly accounted for 6-15% of total methane fluxes from Eleocharis beds in the cooler months, and 30-90% in the warmer months. Eleocharis shoots could generate pressures of up to 550 Pa during summer days, and the seasonal pattern to plant pressurization matched closely the seasonality of total methane emissions from Eleocharis beds. Manipulative experiments provided additional evidence that emergent shoots of Eleocharis were a significant pathway for methane transport from the benthos to the atmosphere, because cutting shoots below the water decreased emissions.

Saline coastal wetlands, such as mangrove and coastal salt marsh, provide many ecosystem services. In Australia, large areas have been lost since European colonization, particularly as a result of drainage, infilling and flood-mitigation works, often starting in the mid-19th century and aimed primarily towards converting land to agricultural, urban or industrial uses. These threats remain ongoing, and will be exacerbated by rapid population growth and climate change in the 21st century. Establishing the effect of wetland loss on the delivery of ecosystem services is confounded by the absence of a nationally consistent approach to mapping wetlands and defining the boundaries of different types of coastal wetland. In addition, climate change and its projected effect on mangrove and salt marsh distribution and ecosystem services is poorly, if at all, acknowledged in existing legislation and policy. Intensifying climate change means that there is little time to be complacent; indeed, there is an urgent need for proper valuation of ecosystem services and explicit recognition of ecosystem services within policy and legislation. Seven actions are identified that could improve protection of coastal wetlands and the ecosystem services they provide, including benchmarking and improving coastal wetland extent and health, reducing complexity and inconsistency in governance arrangements, and facilitating wetland adaptation and ecosystem service delivery using a range of relevant mechanisms. Actions that build upon the momentum to mitigate climate change by sequestering carbon – ‘blue carbon’ – could achieve multiple desirable objectives, including climate-change mitigation and adaptation, floodplain rehabilitation and habitat protection.

Historical ecology documents environmental change with scientific precepts, commonly by using statistical analyses of numerical data to test specific hypotheses. It is usually undertaken by ecologists. An alternative approach to understanding the natural world, undertaken instead by historians, geographers, sociologists, resource economists or literary critics, is environmental history. It attempts to explain in cultural terms why and how environmental change takes place. This essay outlines 10 case studies that show how rivers have affected perceptions and attitudes of the Australian community over the past 200+ years. They examine the influence at two contrasting scales, namely, the collective and the personal, by investigating the role that rivers had in the colonisation of Australia by the British in 1788, the establishment of capital cities, perceptions of and attitudes to the environment informed by explorers’ accounts of their journeys through inland Australia, the push for closer settlement by harnessing the country’s rivers for navigation and irrigation, anxiety about defence and national security, and the solastalgia occasioned by chronic environmental degradation. Historical ecology and environmental history are complementary intellectual approaches, and increased collaboration across the two disciplines should yield many benefits to historians, to ecologists, and to the conservation of Australian rivers more widely.

Common reed Phragmites australis is the dominant vascular plant species of the shorelines of the Gippsland Lakes, south-eastern Australia. Although substantial declines have been reported for over 50 years, with increasing salinity posited as the cause, P. australis still occurs around the Gippsland Lakes, including in environments with near-oceanic salinities. The occurrence of P. australis in highly saline environments cannot be explained in terms of either seasonal variations in surface water salinity or a freshwater subsidy provided by intrusions of non-saline groundwater into the root zone. An experimental growth trial with plants of different provenance showed that P. australis grew vigorously even at 8–16PSU (with maximum aboveground biomass at 2–4PSU). There was some evidence that specimens from saltier sites were more salt tolerant than those from fresher sites. The selection of salt-tolerant strains is the most likely explanation for the occurrence of P. australis in saline sites. However, anthropogenic salinisation is unlikely to be the only factor involved in the historical loss of reed beds, and lower and more stable water levels following the permanent opening of the Gippsland Lakes to the ocean in 1889 are probably also contributing factors.

Conservation biologists are obliged to function in a ‘post-truth’ environment in which ‘alternative facts’ are used by those who oppose meaningful action to conserve the natural world. Objections to public advocacy by scientists are usually based on the inter-related assumptions that (1) advocacy calls into question the objectivity of scientific advice and its special place in policy formulation; (2) conservation biologists are no better qualified to advise on conservation topics than anyone else in the community; (3) advocacy leads to conservation science being politicised; and (4) the conflation of advocacy with individual self-promotion. These objections are shown to fall short in the face of two obvious conservation failures: (1) the manifest inability of current approaches to generate globally sustainable fisheries; and (2) the lack of success in convincing the wider public about anthropogenic climate change. Instead of refraining from public advocacy, conservation biologists should acknowledge their primary responsibility in a civil society as informed citizens possessing specialised knowledge and experience that most other citizens lack. They should aim to influence conservation policy and on-ground works through a multitude of channels: (1) traditionally, through peer-reviewed articles in the scientific literature; (2) through formal input into professional advisory panels to inform government; and (3) through public advocacy. The positions adopted with regard to contentious issues by practitioners in other branches of scientific enquiry can provide useful guidance as to how conservation biologists can contribute meaningfully to discourse in the public interest without compromising their professional standing.

Environmental monitoring is an essential feature of environmental assessment and natural resource management. Whilst the focus of monitoring programs is often on the response of chosen variables to a disturbance of particular concern, it is also important to consider the variability of disturbance pressures in relation to the variability of the ecosystem state. In this paper, we discuss the need to relate environmental variability to disturbance variability in small-scale monitoring programs designed to assess the impact of short-term pulses of visitors on the condition of aquatic ecosystems in protected areas. We use data from protected areas from six Koppen climate zones in Australia to highlight the fact that peaks in visitation do not always coincide with existing monitoring protocols or with optimal times for monitoring on the basis of environmental variability, particularly in relation to rainfall and temperature and, hence, likely biological activity. We highlight how recognising the inter...

In this study, the effectiveness of experimentally reinstating a drawdown phase at Dowd Morass, a large, chronically inundated brackish-water wetland in the Gippsland Lakes Ramsar site of south-eastern Australia was examined. Rehabilitation was most successful in sites that had been shallowly flooded prior to drawdown and that remained dry for longest.

Seasonality in tourism is a regular and predictable cycle of visitation across a year. Although seasonality in visitation is extremely common and is known, in principle, often to be driven by temporal changes in a range of natural and institutional factors, the relative importance of different individual pressures has yet to be quantified for any large-scale geographical areas. To assess the relative importance of natural versus institutional factors in driving tourism seasonality, data on visitation patterns were collated from 23 protected areas across six Koppen climate zones in eastern Australia. Analyses sought to determine the degree to which climatic variables (such as mean monthly rainfall and minimum and maximum temperatures) explained visitation patterns, and to understand how these relationships could assist in the prediction of tourism futures. Climate was the principal force driving seasonal patterns of visitation in equatorial, tropical, desert, grassland and temperate zones, whereas...

Periods of low water level ('drawdown') may kill mature submersed aquatic plants and their vegetative propagules. Re-establishment from a sediment-based seed bank may be limited by desiccation, high temperatures and increased salinity, environmental changes that may often accompany drawdown. Vallisneria australis (Hydrocharitaceae) is a common, submersed clonal wetland plant in southeastern Australia, which reportedly reproduces mainly by vegetative spread. Although vegetative growth in this species is inhibited by drying and salinity, it is not known how such conditions influence the germination of sediment-stored seed, and so whether re-colonisation from seeds can occur after drawdown. Hence, this study examined whether drying, high temperature or high salinity reduced the germination of V. australis seeds. Germination was slowed by drying, with significant germination still occurring 20-30 weeks after re-wetting. The final percentage germination of seeds that had been dried for 8, 16 or 32 weeks and then rewetted was approximately twice that of seeds that remained wet. Moreover, sediment-stored seeds germinated only after drying, suggesting that drawdown would promote germination of V. australis in the field. Final germination of wet-stored seeds was 44 % at 25 °C but only 7 % at 35 °C, indicating that germination may be inhibited over summer in southeastern Australian wetlands. Although percentage germination declined with increasing salinity, some seeds still germinated (∼10 %) at the highest salinity tested, 23 dS m-1. Variability in the time V. australis seeds take to germinate may represent a mechanism that increases the opportunities for regeneration in an unpredictable environment. The demonstrated tolerance of seeds to drying and salinity suggests that, even in salinised wetlands, V. australis may be able to recolonise from the sediment-based seed bank following the loss of mature plants after a drawdown, provided viable seeds are present.

1. In most cases, the most important determinant of wetland vegetation is the water regime. Although water regime is usually described and managed at the scale of whole wetlands, the patterning of vegetation is likely to be determined by water regimes that are experienced at much finer spatial scales. In this study, we assess the significance of internal heterogeneity in water regimes and the role that this heterogeneity plays in vegetation patterning. 2. The effects of water regime on wetland plant species richness and vegetation structure were studied at Dowd Morass, a 1500 ha, Ramsar-listed wetland in south-eastern Australia that is topographically heterogeneous. Data on plant variables and water depth were collected along 45 (50 m) transects throughout the wetland and related to water regimes assigned individually for each transect. Wetland plants were assigned to plant functional groups (PFG) that describe the response of plants to the presence or absence of water at different life stages. 3. The classification of water depth data indicated four distinct water regimes in the wetland that were differentiated primarily by the duration of the dry period. Representatives of all PFGs co-existed over small spatial scales where topographical variation was present, and the richness and cover of understorey species declined as transects became more deeply and permanently flooded. Some PFGs (e.g. amphibious fluctuation tolerator-low growing and amphibious fluctuation responder-morphologically plastic) were eliminated by extended periods of flooding, which increased the cover but not richness of submerged plants. Species richness and foliage projective cover declined as water regimes shifted from shallow and frequently exposed conditions to regimes typified by deeper and longer inundation. Cover of the structurally dominant woody species was compromised by deeply flooded conditions but vegetative regeneration occurred despite high water levels. 4. Internal topographical variation generates mosaics of water regimes at fine spatial scales that allow plant species with different water regime requirements to co-exist over small distances. Deep water and an absence of dry periods result in decreased cover of plants and an overall loss of species richness in the understorey. Water regimes are described that promote regeneration and cover of structurally dominant taxa and increased species richness in the understorey. The study demonstrates a strong association between vegetation and the diverse water regimes that exist within a single wetland, a pattern that will be useful for modelling the effects of modified water regimes on wetland vegetation.

The decay rate of leaves of five Australian tree species, Acacia melanoxylon R. Br., Atherosperma moschatum Labill., Eucalyptus regnans F.Muell., Lomatia fraseri and Nothofagus cunninghamii (Hook.) Oerst., was quantified to determine whether differences in decay rates influence leaf fossilization potential. Decay rates were determined under 4 sets of conditions that mimicked the main ecological settings where a leaf could come to rest after abscission: the forest floor; buried in terrestrial forest sediments; the sediment–water interface of a stream or lake; and buried in stream sediments. Leaf physiochemisty was characterized to identify the chemical constraints that may affect decay rates, and leaf decay (measured as loss of mass and change in leaf lamella area) was examined to determine whether leaves lost area (a quantity often measured by palaeobotanists) at the same rate as they lost mass (the quantity often measured by limnologists). A. moschatum decayed rapidly regardless of treatment conditions, whilst N. cunninghamii not only decayed more slowly than the other taxa but decayed significantly more slowly when buried than when on the sediment surface. Differences in decay rates across the 5 species were similar when expressed as mass loss or as loss of leaf area, indicating that species that undergo rapid mass loss also undergo rapid area loss and thus become rapidly unrecognizable in the leaf fossil record. An important predictor of decay rates was lignin-tonitrogen ratio; species with high lignin-to-nitrogen ratios had the lowest decay rates and, by implication, the best chances of entering the fossil record. Published leaf-decay rates in the soil ecology and limnological literature thus can be used to indicate which species could be over or under represented in the leaf fossil record using nearest living relative analysis; such an approach may enhance the accuracy of palaeobotanical reconstructions.

Although water regime modification and salinity are recognised as significant threats to wetland ecosystems worldwide, the effects of long-term saline flooding (decades) on woody tree persistence are poorly quantified. We compared the condition, growth, structure and reproduction (sexual and asexual) of mature individuals of the clonal tree, Melaleucaericifolia (Myrtaceae), that experienced continual (>30 years) flooding with trees that were only intermittently (approximately every 5 years) flooded. An index developed to assess the condition of multi-stemmed trees found that continually flooded trees were in significantly poorer condition than intermittently flooded trees, having lower crown cover, foliar cover and foliar density, and a higher incidence of dead stags and dieback. Annual stem growth correlated strongly with condition scores. Evidence for a trade-off between sexual and asexual reproductions was found; flooded trees were constrained in their vegetative lateral spread (

Managing the spread of cinnamon fungus, an exotic root-rotting pathogen which kills a wide range of native plants, is an over-riding management concern in the Brisbane Ranges National Park of south-eastern Australia. Parks Victoria has implemented a suite of approaches for informing recreational users about the disease and its ecological impacts. To assess longitudinal changes in the effectiveness of the educative programme, recreational users were surveyed in 1993 and in 2003. 81% were not aware of cinnamon fungus dieback in 1993; the proportion in 2003 was almost unchanged at 83%. Despite the lack of awareness of cinnamon fungus dieback, a large majority (76% in 1993; 74% in 2003) of respondents replied that they had viewed information boards in the park or read visitor guides with information on the disease and its ecological impacts. When recreational users were informed of the impact of infection, there was unanimous support for track closures for quarantine purposes. Our findings indicate that current methods of educating recreational users about cinnamon fungus dieback are not effective. Recommendations are made to improve the penetration of the educational and interpretive information, including the incorporation of affective and cognitive approaches.

Aerial seed banks are potentially the main source of sexual recruitment for woody wetland plants. Whilst the importance of soil seed banks for the persistence and recruitment of wetland plants has been examined in many studies, the role of aerial seed banks has been largely neglected. We used seed traps and the seedling emergence technique to quantify the seed rain from aerial seed banks of the Swamp Paperbark Melaleuca ericifolia Sm. (Myrtaceae) in Dowd Morass, a Ramsar-listed, brackish-water wetland in south-eastern Australia. Nine plant species germinated from material collected in seed traps over 2004–2005, but emergents were dominated (80–97%) by M. ericifolia. The mean number of M. ericifolia emergents ranged from

Melaleuca ericifolia Sm. (Swamp paperbark) is a common tree species in freshwater and brackish wetlands in southern and eastern Australia. The survival of this species in many wetlands is now threatened by increased salinity and inappropriate water regimes. We examined the response of 5-month-old M. ericifolia seedlings to three water depths (exposed, waterlogged and submerged) at three salinities (2, 49 and 60 dS m−1). Increasing water depth at the lowest salinity did not affect survival, but strongly inhibited seedling growth. Total biomass, leaf area and maximum root length were highest in exposed plants, intermediate in waterlogged plants and lowest in submerged plants. Although completely submerged plants survived for 10 weeks at the lowest salinity, they demonstrated negative growth rates and were unable to extend their shoots above the water surface. At the higher salinities, M. ericifolia seedlings were intolerant of waterlogging and submergence: all plants died after 9 weeks at 60 dS m−1. Soil salinities increased over time, and by Week 10, exceeded external water column salinities in both the exposed and waterlogged treatments. In exposed sediment, ∼90% of plants survived for 10 weeks at 60 dS m−1 even though soil salinities reached ∼76 dS m−1. No mortality occurred in the exposed plants at 49 dS m−1, and small but positive relative growth rates were recorded at Week 10. We conclude that at low salinities M. ericifolia seedlings are highly tolerant of sediment waterlogging, but are unlikely to tolerate prolonged submergence. However, at the higher salinities, M. ericifolia seedlings are intolerant of waterlogging and submergence and died rapidly after 5 weeks exposure to this combination of environmental stressors. This research demonstrates that salinity may restrict the range of water regimes tolerated by aquatic plants.

Wetlands dominated by Swamp Paperbarks (Melaleuca spp., Myrtaceae) are common in coastal regions across Australia. Many of these wetlands have been filled in for coastal development or otherwise degraded as a consequence of altered water regimes and increased salinity. Substantial resources, often involving community groups, are now being allocated to revegetating the remaining wetland sites, yet only rarely is the effectiveness of the rehabilitation strategies or on-ground procedures robustly assessed. As part of a larger project investigating the condition and rehabilitation of brackish-water wetlands of the Gippsland Lakes, we overlaid a scientifically informed experimental design on a set of community-based planting trials to test the effects of water depth, microtopography, plant age and planting method on the survival and growth of seedlings of Melaleuca ericifolia Sm. in Dowd Morass, a degraded, Ramsar-listed wetland in south-eastern Australia. Although previous laboratory and greenhouse studies have shown M. ericifolia seedlings to be salt tolerant, the strongly interactive effects of waterlogging and salinity resulted in high seedling mortality (>90%) in the field-based revegetation trials. Seedlings survived best if planted on naturally raised hummocks vegetated with Paspalum distichum L. (Gramineae), but their height was reduced compared with seedlings planted in shallowly flooded environments. Age of plants and depth of water were important factors in the survival and growth of M. ericifolia seedlings, whereas planting method seemed to have little effect on survival. Improved testing of revegetation methods and reporting of success or otherwise of revegetation trials will improve the effectiveness and accountability of projects aiming to rehabilitate degraded coastal wetlands.

Salinization, a widespread threat to the structure and ecological functioning of inland and coastal wetlands, is currently occurring at an unprecedented rate and geographic scale. The causes of salinization are diverse and include alterations to freshwater flows, land-clearance, irrigation, disposal of wastewater effluent, sea level rise, storm surges, and applications of de-icing salts. Climate change and anthropogenic modifications to the hydrologic cycle are expected to further increase the extent and severity of wetland salinization. Salinization alters the fundamental physicochemical nature of the soil-water environment, increasing ionic concentrations and altering chemical equilibria and mineral solubility. Increased concentrations of solutes, especially sulfate, alter the biogeochemical cycling of major elements including carbon, nitrogen, phosphorus, sulfur, iron, and silica. The effects of salinization on wetland biogeochemistry typically include decreased inorganic nitrogen removal (with implica...

The utility of shallow water bodies in urban environments is frequently compromised either by dense beds of submerged plants or cyanobacterial blooms associated with nutrient enrichment. Although submerged plants are often harvested to facilitate recreational uses, this activity may alter the phytoplankton community, which in turn, also may restrict the use of the lake. We tested whether (i) plant harvesting reduced the abundance of flagellate algae and increased the abundance of cyanobacteria, and (ii) whether increasing levels of nutrient enrichment caused shifts in the dominance of heterocytous cyanobacteria, non-heterocytous cyanobacteria and Chlorophyta, in a shallow urban lake in Southern Australia as has been observed for shallow Danish lakes in previous studies. These predictions were tested with large (3000 l), replicated mesocosms in a warm, highly productive, shallow lake densely colonised by the submerged angiosperm, Vallisnaria americana Michaux. The heterokont algae, Chlorophyta, Cyanobacteria and Cryptophyta were the most numerous algal divisions in the lake. The Euglenophyta, although uncommon in early summer, became more abundant towards the end of summer. The Dinophyta and Charophyta were rare. The abundance of the heterokont algae and Euglenophyta was significantly reduced by plant harvesting even after plants had partially re-established 18 weeks after initial harvesting. The decline in the Euglenophyta in response to plant harvesting is consistent with earlier findings, that the relative abundance of flagellate algae tends to be greater in the presence of submerged plants. Contrary to our prediction, we found that the Cyanobacteria did not increase in response to plant harvesting, however the response may be altered under higher nutrient levels. Algal responses to nutrient enrichment in the presence of dense V. americana plants generally followed the patterns observed in shallow Danish lakes despite the large differences in climatic conditions. Both studies found that the abundance of heterocytous cyanobacteria declined at higher levels of nutrient enrichment, whereas non-heterocytous cyanobacteria and chlorophytes increased.

We examined the effects of increasing salt concentrations on the decay of the common aquatic angiosperm, Triglochin procerum R. Br. (Juncaginaceae) from a freshwater wetland close to Gippsland Lakes, eastern Vic., Australia. Rate of decay, measured as leaf mass loss, and microbial enzymatic activity, used as a surrogate for microbial activity, were measured on leaves placed in mesocosms ranging in electrical conductivity from 100 to 45,000 EC. The rate of leaf mass loss was up to three times slower in salt concentrations of 45,000 EC (∼69% ash-free dry leaf weight remaining after 21 days), compared to salt concentrations of 100 EC (∼23%). Enzymatic activity on the leaves at 45,000 EC (0.56, A 490 ) was about one-half that on leaves in 100 EC (1.00, A 490 ). A second experiment measured the same variables for leaves placed in solutions of NaCl, marine salt, or an organic osmoticum, polyethylene glycol (200 Da molecular weight). Results indicated that the inhibition of leaf mass loss was ∼1.5 times greater in NaCl (∼39% remaining after 21 days) than an organic osmoticum, polyethylene glycol (∼24% remaining after 21 days), indicating a role for ionic toxicity in the salt effects. Enzymatic activity on leaves was significantly inhibited in NaCl (0.50, A 490 ) compared with marine salt (0.74, A 490 ) or polyethylene glycol (0.72, A 490 ). Our findings suggest several implications for the effects of acute secondary salinisation on organic matter decomposition. Inhibition of decay rates due to acute increase in salt concentration is related to decreased enzymatic activity on decaying leaves. This relationship has ramifications for microzoan food webs based on a microbial loop of bacterial production and consumption and availability of degraded organic matter entering metazoan food webs.

Taphonomic processes that may bias plant-fossil assemblages are important in explaining many aspects of the Cenozoic plant fossil record. Two tree genera, Eucalyptus and Nothofagus, are especially important for understanding the evolution of Australia's forests, because the former currently dominates the continent, whereas the latter is dominant in Cenozoic microfloras. Nothofagus also is prominent in temperate forests of South America and New Zealand, and in the Cenozoic history of these land-masses and Antarctica. This study measures standing biomass and leaf-litter production in contiguous cool temperate rainforest dominated by nanophyllous Nothofagus cunninghamii and wet sclerophyll forest dominated by macrophyllous Eucalyptus regnans in southeastern Australia. It tests an a priori hypothesis that the under-representation of Eucalyptus in the Australian Cenozoic record may reflect differential organ production by Eucalyptus and Nothofagus, respectively. A taphonomic bias was observed between ...

Essential oils of paperbarks, Melaleuca spp., have been shown in laboratory studies to inhibit bacterial activity and slow the rate of cellulose decay. Field (Gippsland Lakes, south-eastern Victoria, Australia) and glasshouse experiments were conducted to test the hypothesis that leaves of Melaleuca ericifolia SM. (the swamp paperbark) suppressed the decay of leaf litter under conditions existing or mimicking those in natural wetlands. Under field conditions, neither brown nor green M. ericifolia leaves, at loadings that would normally occur in a typical paperbark wetland and over a range of leaf-mass ratios, significantly affected the decay rate of two common freshwater macrophytes, Triglochin procerum (water ribbon) and Phragmites australis (common reed). In contrast, glasshouse experiments showed that Melaleuca ericifolia leaves (both intact and ground, and both brown and green) suppressed decay of T. procerum when placed in moist conditions on the sediment surface. However, no inhibitory effect was observed when leaves were flooded. Purified, commercially available Melaleuca essential oil (extracted from Melaleuca alternifolia leaves) decreased the rate at which T. procerum leaves decayed under glasshouse conditions by as much as 43 %. As with entire leaves, the inhibitory effect of purified Melaleuca essential oil was greatest when the leaves were placed in moist, but not submerged, conditions. Experiments designed to test the possibility that the inhibition was due to a simple, physical (coating) effect rather than metabolic inhibition of microbes showed clearly that the effect was not due simply to the hydrophobic nature of essential oils. This study indicates that M. ericifolia leaf litter in freshwater wetlands probably exerts only a small effect on the rate at which leaves from other wetland plant species decay. Any inhibitory effect is likely to be greater after water levels drop (e.g., seasonally in a Mediterranean climate) and remaining leaf material is left moist on the surface of water logged sediments than when material is totally submerged, as during the wetland's high water phase.

Leaf transport - especially differences among species from diverse taxonomic groups - is generally less well understood than are the other phenomena that influence the fate of leaves in streams, such as conditioning by bacteria and fungi and fragmentation and consumption by invertebrates. To address this topic, we compared the transport behaviour of entire leaves from five indigenous species of tree in a naturally forested, upland stream in south-eastern Australia: two cool temperate rainforest taxa (Nothofagus cunninghamii (HOOK) OERST. and Atherosperma moschatum LABIL.), two sclerophyllous taxa (Acacia melanoxylon R. BR. and Eucalyptus regnans F. MUELL.) and one taxon from the ecotone between the two forest types (Lomatia fraseri R. BR.). Laboratory experiments indicated that, irrespective of flow regime, rainforest leaves sank markedly more slowly than did sclerophyllous leaves. Eucalyptus regnans leaves, for example, in moving water typically sank within 2 days of immersion, whereas Nothofagus cunninghamii leaves in moving water had a mean time before sinking of 8 to 67 days. These differences in flotation behaviour were reflected in field experiments that used marked leaves to quantify transport down a first-order stream in the study area. The field experiments showed the stream to be highly retentive, with leaves from no taxon travelling more than 100m in six hours. Leaves from rainforest taxa, however, were transported longer distances in a given time than were sclerophyllous leaves, and in some of the latter cases (e.g., Acacia melanoxylon) retention commenced in distances as short as 5 m. There was some evidence that small leaves were transported greater distances than were large leaves; leaf texture and flexibility (a reflection of leaf morphology) also influenced transport distance, but the characteristics of the leaf margins seemingly did not. The ecological significance of these findings is that differential transport will influence the relative contribution made by various species to the pool of coarse particular leaf matter occurring in a given reach of a stream. It will also influence the amount of material available to downstream ecosystems and the formation of allochthonous fossil leaf assemblages.

The region of south-eastern Australia has significant potential for the development of sustainable nature-based tourism. In particular, the three sites of Refuge Cove at Wilsons Promontory, the Kent group of islands in Bass Strait, and the Port Davey region of south-west Tasmania provide good examples of where tourism product may be developed, as they each possess high conservation value, environmental and aesthetic appeal, as well as potential for niche market tourism activities. In order to clarify the issues surrounding this proposition, the concepts of sustainable tourism and ecotourism are discussed. Additionally, a review is made of the issues which may compromise sustainable tourism generally. A key role in this process is that of the ecologist in providing environmental information for managers and planners who utilise this in the formulation of a management framework within which the tourism operator may develop product. Optimisation of sustainable outcomes is perhaps more likely to occur for sup...

Temperature, dissolved oxygen and dissolved methane profiles were measured during autumn and summer, in a shallow floodplain lake in south-eastern Australia to determine the effects of water-column stability on methane and oxygen dynamics. The water column was well mixed in autumn. Strong thermal stratification developed in the late afternoon in summer, with top-to-bottom temperature differences of up to ∼6 °C. Methane concentrations in surface waters varied over a daily cycle by an 18-fold range in summer, but only by a 2-fold range in autumn. The implication of short-term temporal variation is that static chambers deployed on the water surface for short times (less than a day) in summer will significantly underestimate the diffusive component of methane emissions across the water–atmosphere interface. There was a marked diel variation in dissolved oxygen concentrations in summer, with the highest oxygen values (commonly 5–8 mg l−1) occurring in the surface waters in late afternoon; the bottom waters were then devoid of oxygen (< 0.2 mg l−1). Because of high respiratory demands, even the surface water layers could be nearly anoxic by morning in summer. The concentration of dissolved oxygen in the surface waters was always less than the equilibrium value. When the water column became thermally stratified in summer, the dissolved oxygen and methane maxima were spatially separated, and planktonic methanotrophy would be limited to a moving zone, at variable depth, in the water column. In summer the whole-wetland rates of oxygen production and respiration, calculated from long-term (∼5 h) shifts in dissolved oxygen concentrations over a diel period, were approximately 6–10 and 3–6 mmol m−3 h−1, respectively. These values correspond to net and gross primary production rates of ∼0.7–1.2 and ∼1.0–1.9 g C m−3 day−1, respectively.

In a recent Forum Essay in Pacific Conservation Biology, the well known ecologist Harry Recher argued that over the past three decades Australia had experienced a ‘failure of science’ and a concomitant ‘death of nature’. In this essay we examine some of the propositions put forward by Recher (2015), with particular reference to the role played by neoliberal ideology in nature conservation in Australia. Since the early 1980s the neoliberal value system has effectively shaped a new paradigm for nature conservation in Australia with its own language, tools and institutions, and through such a process has redefined nature in its own terms. We focus on two of the most significant neoliberal, free-market mechanisms – (1) monetary valuation of biodiversity and of ecosystem services, and (2) the provision of complementary areas to offset losses of high-quality habitat – and show how they have come to dominate policy development and on-ground activities in wetland management and conservation in Australia. Despite the wide reach of neoliberal ideology, ecologists and conservation biologists seem largely unaware of its practical implications. In some cases, such as with offset programs and with carbon valuation, they have become complicit with the ruling ideology, without, it seems to us, being fully aware of their involvement, tacit or explicit, or of the likely connotations of that participation. Hedging the future of wetland conservation to ‘market-driven environmentalism’ is simply an expected overreach in the broader context of neoliberal economic and political ideology, and provides rich grounds for a critique in support of a more considered approach to nature conservation.

The distribution and productivity of mangroves is directly affected by a wide range of climatic drivers, including temperature, frost, rainfall, evaporation and storm activity, which, in turn, influence a suite of secondary drivers, including changes in freshwater run-off and sediment supply, groundwater dynamics and inter-species competitiveness. The highest-latitude expression of mangroves globally is at Millers Landing, Victoria (38°45′S), and because the vigour and productivity of mangroves across much of Victoria is thought to be limited by low winter temperatures and the incidence and severity of frosts, it is likely that mangroves will be among the first plant communities to be affected by climate change in coastal south-eastern Australia. An increase in plant vigour is likely, but there are almost no historical data with which to compare current rates of primary production. An extension of mangroves to higher latitudes on the mainland is impossible because of the geomorphology of the land that lies further to the south. Small-scale changes in distribution, including the progressive encroachment of mangroves into coastal saltmarsh, are likely to be among the clearest indications of the response of mangroves to a warming climate. Increased effort into tracking changes in mangrove vigour, productivity and distribution is clearly warranted.

The physicochemical and microbial properties of the burrows of Biffarius arenosus, a ghost shrimp common in temperate south-eastern Australia, were investigated and shown to be more similar to the surface sediments than to the surrounding subsurface sediments. The burrow walls had a similar organic carbon content to that of the surrounding sediment, a result which was consistent with their lack of a discrete mucous lining. Burrow walls, however, were lined with compacted and smoothed sediment and were coloured a distinct light yellow/brown compared with the dark grey of the surrounding subsurface sediments. Moderately reducing redox conditions were found in both the burrow wall and surface sediment (means 213 mV and 243 mV, respectively), indicative of a burrow environment regularly flushed with overlying water by the resident shrimp. Microbial activity (measured as fluorescein diacetate hydrolysis) in the burrow walls was higher than in the surrounding sediments, but there were no significant differences across sediment types in bacterial abundances (epifluorescence microscopy total counts, using DAPI) or in microbial biomasses (total phospholipid contents). Biomarker analysis of the phospholipid fatty acid (PLFA) profiles indicated that bacteria dominated the benthic community (∼80% of total PLFAs), and showed the presence of both aerobic and anaerobic bacteria in all sediment samples.

(2000). Carbon cycling in Australian wetlands: the importance of methane. SIL Proceedings, 1922-2010: Vol. 27, No. 1, pp. 37-50.

Essential oils are a common component of the leaves of many plants, and may be a factor that, to date, has been overlooked as a determinant of leaf decay in natural environments. Cellulose sheets and dried leaves of Platanus sp. (common plane tree) treated with essential oil extracted from Melaleuca alternifolia CHEEL and buried in soil in laboratory mesocosms decayed at a significantly slower rate than did control materials not treated with the oil. Inhibition of bacterial activity may account in part for this effect on organic matter decay, since Melaleuca essential oil at concentrations of greater than 0.001% v/v markedly inhibited the growth of the bacterium, Escherichia coli. Melaleuca essential oil was lethal to starved bacteria (E. coli, Staphylococcus aureus and Pseudomonas aeruginosa), especially at higher concentrations (>0.I % v/v) of the oil. EC 50 values, determined with the Microtox assay, were c. 0.01 % v/v, a value equivalent to an essential oil concentration of about 100mg/l. Essential oil derived from Melaleuca leaves and twigs may have a significant role in organic matter processing and nutrient cycling in coastal wetlands by slowing the decomposition of organic detritus and inhibiting or killing microbes.

Four approaches were used to assess the effect ofinundation on methane emissions from floodplainwetlands in Victoria, Australia: (i) fieldobservations following natural rainfall events; (ii)experimental manipulation of water levels in smallfloodplain depressions; (iii) experimentalmanipulation of water levels in replicated mesocosms;and (iv) in vitro incubation of floodplainsediment under laboratory conditions. Raftery'sSwamp, a large (150 ha) wetland on the floodplain ofthe Goulburn River, became inundated in June 1993following autumn-winter rainfall. Methane emissionspeaked (1.7 ± 0.05 mmol m-2 h-1) somesix months later, and the methane content of sedimentgas bubbles reached 59% v/v, even though the positivesediment redox potentials (176 to 243 mV) indicatedthat sediments were only moderately reducing. Threesmall (< 1 ha) depressions on the floodplains of theRiver Murray and Kiewa River were inundated eithernaturally (by rain and/or overflow from nearby rivers)or artificially by flooding at specific times of year;emissions from these sites were usually negligibleafter flooding in autumn or winter. In contrast, theonset of methane emission was very rapid (within 3 to6 days) after the depressions had been flooded insummer, and the methane content of sediment gasbubbles could then reach 36% v/v. At their peak,emissions from the ephemeral wetlands were similar topeak emissions from permanent wetlands insouth-eastern Australia. Emissions from replicatedwetland mesocosms (4.5 m diameter, 0.9 m deep) werealways very small (

The simultaneous measurement ofspecific phospholipid ester-linked fatty acids (PLFA) and diether lipids was achieved using high temperature capillary gas chromatography (GC). A GC method was developed and used to simultaneously determine diether lipid and PLFA content in the same GC run. The key features of the method were a slow (1°C/min) temperature ramp through the fatty acid region of the chromatogram followed by a high temperature ramp where the diether lipid eluted. Using this method on both pure bacterial cultures and aquatic sediments, resolution was achieved of the diether lipid and the PLFA, including novel C16 and C18 monounsaturated fatty acids derived from methanotrophs.

Large amounts of potentially useful information are collected by management agencies as they attempt to identify high-value wetlands and rank them for investment, protection or rehabilitation. Resource constraints frequently mean these information-rich databases are not fully interrogated, with the result that much of their expensively obtained information is only partially analysed or, worse, is not analysed at all. The present paper shows the benefit of rigorously interrogating such databases to identify wetlands of high social, economic or environmental value. Three data-mining methods, namely, univariate analysis, multivariate analysis and artificial neural networks (ANNs), were applied to a large (7.6 MB) but hitherto unanalysed database of 163 wetlands in the Gippsland region of south-eastern Australia. Simple statistical techniques, such as univariate analysis and binary logistic regression, identified high-value wetlands with a prediction accuracy of >90%, using only a small set of environmental indicators. Artificial neural network models with nine environmental-value inputs (six direct indicators plus three threat indicators) correctly also identified 90% of high-value wetlands. Outcomes generated by ANNs were in close agreement with those obtained with more traditional univariate and multivariate analyses. There seems little justification for undertaking economic assessments, and for environmental assessments the best indicators consistently included the presence of listed fauna or flora, vegetation intactness and the absence of hydrological modification. The overall approach, although developed from the analysis of a single (but large) wetland database of wetlands in south-eastern Australia, is likely to find conservation applications in many other regions of the Pacific.