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This paper summarises key issues from papers included in a special issue about the impacts of climate change on Australian wetlands. The papers covered: the assessment of wetlands under climate change, adaptation and engineering responses to climate change, and restoring wetlands under a changing climate. The key issues from these papers were used to indicate areas where the Ramsar Convention could develop guidance as part of its' Handbooks for the Wise Use of Wetlands. These included: (i) assessing changes in the distribution of species and whether these constitute a change in the ecological character of the wetland; (ii) assessing the usefulness of models of wetland response to climate change; (iii) assessing the value in allocating water to protected sites where restoration would be contingent on reallocation of larger volumes of water; (iv) assessing the efficacy of engineering responses with the potential to deliver more water-efficient environmental outcomes for wetlands and (v) determining if the description of the ecological character of a Ramsar site at the time of listing is a suitable reference for management purposes. With these issues in mind it is recommended that further attention is directed towards determining and responding to the ecological consequences of climate change. [ABSTRACT FROM AUTHOR]

This paper is the first in a pair investigating potential mechanisms for ecological regime change in salinising wetlands. In this first paper, we investigated some of the factors responsible for the formation and maintenance of a macrophyte-dominated ecological regime by studying the germination and flowering of four submerged macrophyte species common in saline Western Australian wetlands; Ruppia polycarpa R. Mason, Ruppia megacarpa R. Mason, Lamprothamnium macropogon (A. Braun) Ophel and L. cf. succinctum (A. Braun in Ascherson) Wood, and by following the survival of adult R. polycarpa as salinities were increased to a range of endpoints (6, 15, 45, 70 and 100 ppt). Increased salinity led to a decrease in the number of germinating plants, an increase in the time to emergence of germinating plants and a decrease in the number of inflorescences (or fertile plants) produced by R. polycarpa, L. macropogon and L. cf. succinctum. Germination of R. megacarpa was low, providing limited information with regard to salinity response. The survival of adult plants also decreased as salinity increased and was negatively affected by faster rates of salinity increase. The upper salinity limits for germination, within the 70 day experiment, were 40–50 ppt for R. polycarpa and L. cf. succinctum, and 30–40 ppt for L. macropogon. Survival of adult R. polycarpa also declined markedly at above 45 ppt. [ABSTRACT FROM AUTHOR]

The establishment of a system of protected areas that samples all ecosystems, including freshwater environments, in a comprehensive, adequate and representative (CAR) manner is regarded as a cornerstone for the conservation of biodiversity. There have been few quantitative assessments of the comprehensiveness, adequacy and representativeness of freshwater reserves in Australia. This paper reviews and quantifies the effect of classification of freshwater ecosystems for conservation planning, the importance of reservation status and protection measures for developing a CAR reserve system, and aspects of reserve design for freshwater ecosystems. We propose a strategic and iterative process that incorporates these measures to assist in the efficient and effective development of freshwater reserve systems worldwide. However, the provision of suitable water regimes for freshwater reserves presents further ecological and political challenges, and even adequate reservation of freshwater ecosystems may not conserve constituent biodiversity without effective management. [ABSTRACT FROM AUTHOR]

Wetlands are characterised by soils rich in organic matter that accumulate carbon, providing an important pathway for carbon dioxide sequestration. Nevertheless, not all the carbon fixed can be accumulated, and a proportion will decompose through microbial consumption and be partly released into the atmosphere. Rates of organic matter decomposition in tropical wetlands and the factors associated with this process are scarce. We conducted a 2-year field study in three Melaleuca wetlands in tropical and subtropical Australia using standardised tea litter substrates (green-labile and rooibos-recalcitrant) to measure organic matter decomposition and the microbial communities associated with this process. Decomposition rates were 4-fold higher in labile litter, which was low in carbon: nitrogen, compared to recalcitrant litter. The prokaryotic communities associated with the decomposing litter were unique at each site and different from the soil. They contained taxonomic groups adapted to anaerobic, high temperatures, acidic conditions and suggestive of slow anaerobic turnover. Microbial communities changed as decomposition progressed, with the latter characterised by taxa with cellulose-degrading functions. The decomposition of recalcitrant organic matter within Melaleuca soils was relatively slow, with half of the organic matter inputs remaining after two years, supporting long-term carbon sequestration. [ABSTRACT FROM AUTHOR]

The environment of Lake Carey, a large salt lake in the goldfields of Western Australia, has been subjected to mining for the past 100 years. The effect of discharge of hypersaline water to the playa as a result of pit dewatering has been a grave concern. The aim of this paper was to investigate the influences of seasonal parameters and mining activity on the physico-chemical and biological attributes of Lake Carey. Assessment of water and sediment chemistry and benthic microbial communities (BMCs) has been carried out opportunistically since 1999, with particular emphasis on the differences between sites receiving dewatering discharge currently or in the past (Impacted Sites), and those which have never received dewatering discharge (Control Sites). Results of water and sediment analyses indicated that the impacts of dewatering discharge on Lake Carey were localised and evident in the vicinity of the discharge sites. However, large rainfall events, such as the cyclonic rainfall in 2004, could result in flushing and amelioration of sediments. This was also reflected in the sites which were historically impacted by dewatering discharge. The sites directly impacted by dewatering discharge displayed poor abundance and species richness of diatoms compared to the sites unaffected by dewatering discharge. However, recovery of these sites in terms of species richness and abundance is also initiated by large rainfall events, as shown by data collected from the historical dewatering discharge sites. [ABSTRACT FROM AUTHOR]

The effect of human disturbance on mangrove forest may be substantially different from the effects of natural disturbances. This paper describes differences in vegetation composition and structure of five vegetation types in two mangrove areas near Darwin, Australia, 25 years after disturbance. The vegetation in clear-felled forest showed more adult Avicennia marina than in the hurricane-affected forest, and a virtual absence of A. marina juveniles and saplings. This indicates that A. marina will be replaced by other species in the canopy, showing a multi-phase vegetation development in mangrove forest after human disturbance. The mechanism of disturbance and the conditions after clearing therefore affects the vegetation composition for at least 25 years after this disturbance took place. [ABSTRACT FROM AUTHOR]

Diatom analyses of sediment cores extracted from three lakes in coastal southeastern South Australia reveal that, for most of the mid-late Holocene, they were shallow, brackish to saline systems with limited flow of water from continental sources. The construction of a substantial network of drains in the early years of settlement, to maximise transportation and agricultural production through wet winters, lead to abrupt freshening of the lakes. Interestingly, despite substantial nutrient loads to Lake Bonney SE (there are two Lakes Bonney and Frome in South Australia, which is why the lakes in the southeast of the state are differentiated with ‘SE’) associated with the commissioning and expansion of pulp and paper mills, a wastewater treatment plant discharge and agricultural runoff, there is only moderate evidence of nutrient enrichment in the lake, possibly because the post-impact assemblages are dominated by taxa with broad ecological preferences. Despite being preserved within a conservation park, eutrophication associated with agriculture is evident in the diatom assemblages of Lake Frome SE, which has a catchment more than twice that of Lake Bonney SE. Mullins Swamp, on the other hand, supports few indicators of eutrophic conditions. The freshening of these lakes is against the tide of salinisation from rising saline groundwaters in most wetlands across southeastern Australia. [ABSTRACT FROM AUTHOR]

This paper presents the approach and methods used, and the outputs generated, in the derivation of numeric biological objectives for the protection of rivers and streams across Victoria, Australia. Biological objectives have been designed for inclusion in State government legislation for the protection of the State’s waterways. The objectives were developed using data from extensive macroinvertebrate sampling of multiple reference sites across the State. Regional variations are incorporated into the objective-setting process by using an a priori, macroinvertebrate-based regionalisation of the State. The objectives consist of four separate components, including a measure of diversity, two biotic indices and a measure of community composition. The objectives are designed for use across broad regions and any attempt to extend the system to subregional levels would require a careful consideration of the influence of scale upon the grouping of reference sites. [ABSTRACT FROM AUTHOR]

Dryland rivers occur over much of Australia’s inland and have some of the most variable patterns of flow in the world. Despite their dominance in terms of Australia’s river types, dryland rivers have not been the focus of the recent increase in research on indicators of river health, mostly owing to their spatial remoteness and relatively low levels of water resource development and human disturbance. Most rivers in arid and semi-arid regions are ephemeral, and only carry significant flows during the wetter months or following infrequent but intense rainfall events. It is not known which, if any, of the existing approaches to river health assessment can be used to accurately assess the health of these large ephemeral rivers. This paper considers why the standard methods for interpreting the currently-used indicators for river health may need to be adapted for variable systems and suggests the use of trends that recognise natural variation in indicator values for undertaking this. [ABSTRACT FROM AUTHOR]

This article focuses on the life and achievements of Bill Williams, a pioneer of limnology in Australia. It also pays tribute to a man whose personal generosity and academic guidance influenced an entire generation of limnologists. The productive career of Williams was cut short by leukemia, but his publications in the field has contributed much to the advancement of limnology. His relationship with other scientists was respected in the scientific community. The educational background and various publications of the limnologists was considered in the article.

This article explores the various studies made on aquatic ecology, management and conservation in Australia. Australian limnologists and aquatic managers are recognized for their valuable contributions to global limnology and water resource management. The problems of eutrophication and acidification are becoming serious issues to tackle for limnologists. Discussion was made on the trends in salt lake ecology and management. A citation of major limnological research in the country was also presented in this article.

The wheatbelt region of Western Australia has been extensively cleared of indigenous vegetation for agriculture and is now severely affected by dryland salinity. Wetlands that were once freshwater are now saline and others are under threat, as are the animals and plants that inhabit them. Rising groundwater is also affecting the many naturally saline playas. To provide a framework for setting conservation priorities in this region a biological survey was undertaken, including sampling of aquatic invertebrates at 230 wetlands. In this paper, we have used data from the survey to summarise occurrence of species in relation to salinity. Total species richness at a wetland showed no response to salinity below 4.1 g l−1 and then declined dramatically as salinity increased. When halophilic species were excluded from consideration, species richness was found to decline from 2.6 g l−1. These patterns are compared to previous studies of richness-salinity relationships. There is some evidence that the freshwater invertebrate fauna of the wheatbelt may be comparatively salt tolerant, with 46% of freshwater species collected at salinities above 3 g l−1 and 17% above 10 g l−1, though these proportions differed between various invertebrate groups. While this tolerance will provide a buffer against the effects of mild salinisation, many species are at risk of regional extinction as salinisation becomes more widespread. [ABSTRACT FROM AUTHOR]

Two new genera of giant ostracods Lacrimicypris n. gen. and Repandocypris n. gen. from Australia are described and eight new species: L. kumbar n. sp., R. austinensis n. sp., R. gleneagles n. sp., Mytilocypris coolcalalaya n. sp., Australocypris bennetti n. sp., A. beaumonti n. sp., A. mongerensis n. sp. and Caboncypris kondininensis n. sp. The number of known Australian genera and species of giant ostracods are now 6 and 21, respectively. Keys to genera and species are provided: all species can be distinguished using the hemipenis and male first leg. The usefulness of the bursa copulatrix as a species-level taxonomic character is highlighted. Most of the species described in this paper occur in salt lakes and existing ecological information on Western Australian species, as well as the distributions of all species, are summarized. Western Australia has a particularly rich halobiont fauna but current explanations relating richness of the halobiont fauna to the widespread occurrence of salt lakes appear incomplete. Australocypris bennetti is unusual in that it is frequently found at pH < 4. Its morphology differs slightly in acidic and alkaline waters. [ABSTRACT FROM AUTHOR]

This paper presents new data on free-living heterotrophic euglenids (Euglenozoa, Protista) that were found at several freshwater sites in New South Wales, Northern Territory, and Queensland, Australia. Thirty-six species are described with uninterpreted records based on light-microscopy. The records include accounts of two new taxa: Heteronema pterbica nov. spec., Sphenomonas alburiae nov. spec., and of six new combinations: Dinema dimorphum (Skuja, 1932) nov. comb., Notosolenus mediocanellatus (Stein, 1878) nov. comb., Notosolenus steini (Klebs, 1893) nov. comb., Ploeotia obliqua (Klebs, 1893) nov. comb., Ploeotia plana (Christen, 1959) nov. comb., and Rhabdomonas mirabilis (Playfair, 1921) nov. comb. We also introduce the following: Astasia skvortzovi nom. nov., Heteronema hexagonum var. elegans (Playfair, 1921) nov. comb., Petalomonas compressa (Schewiakoff, 1893) nov. comb., and Jenningsia deflexum var dextrum (Shi, 1975) nov. comb. All records of heterotrophic euglenids in Australia are reviewed. The majority of species reported here have also been found at other locations worldwide, and we find little or no evidence that there is endemism in this group. [ABSTRACT FROM AUTHOR]

The Darling River, in New South Wales, Australia, is a large semi-arid system with a highly variable flow regime, characterised by unpredictable flooding and drought. The floodplain and riparian zone of the Darling River is dominated by River Red Gum (RRG), Eucalyptus camaldulensis. The large amount of organic matter they produce accumulates on the floodplain and on benches within the channel, and is subject to alternate periods of flooding and drying. This paper examines the effect of alternate periods of flooding and drying on the processing of E. camaldulensis organic matter. Results suggest that RRG leaves provide the most bio-available source of carbon to the system, while bark may be more important as a habitat for invertebrates and other fauna. Results of the field and lab experiments suggest that RRG leaves represent an important source of carbon to the Darling River, with inputs being influenced by the highly variable flow regime.

Managing and conserving wild animal populations relies on accurately describing changes in populations through time. Density estimates, sex ratios and size structures are used to monitor population trends, including sustainability assessments of populations subject to harvest exploitation. We used a spatially explicit capture–recapture model (SECR) to generate capture probabilities for a threatened freshwater crayfish [Euastacus armatus (von Martens 1866)], within a 6.2 km reach of the Murray River, southeast Australia, previously exposed to harvest. Capture probabilities were critical to our understanding of density, sex ratios, size structure and movement patterns which are all key parameters driving population dynamics. Model outputs, comparing catch rates over a 4-year period, showed declining estimates of density, uneven sex ratios, an unbalanced population size structure and restricted movement, all with potentially severe evolutionary consequences. Through the analysis of multiple indices (density estimates, sex ratios and size structures, and changes therein), we inferred that the illegal harvest of crayfish was likely driving changes in population dynamics within the study population. SECR models are a valuable tool for generating density estimates for a range of taxa and, when combined with information on sex ratios and size structures, provide a powerful means for stock assessments. [ABSTRACT FROM AUTHOR]

Nutrients such as nitrogen and phosphorus are typically considered detrimental to wetland values, but waterfowl can be numerous on nutrient-rich wetlands. Waterfowl were counted three to six times per year on nine treatment lagoons and associated wetlands (2,025 ha) at the Western Treatment Plant (south-east Australia) from 2000, to help maintain ecological values of this Ramsar-listed wetland as well as treating sewage for a large city (Melbourne). Up to 185,000 waterfowl were counted, varying with season, continental rainfall and lagoon operation. Nutrient levels were reduced on Lake Borrie lagoon in 2005 (as part of an Environmental Improvement Program) and restored in 2015. Waterfowl declined on Lake Borrie lagoon from 2005 when it received treated effluent not raw sewage, and increased in 2015 when it received partially treated sewage. This pattern was highly significant for total waterfowl and most species and guilds at Lake Borrie but was not replicated on other lagoons. Modelling revealed positive relationships between waterfowl numbers and nutrient concentrations, including ammonia and nitrite, to moderate levels. This shows that with careful management nutrient enrichment can have positive benefits, allowing artificial wetlands such as wastewater treatment plants to support high densities of waterbirds and the food webs that sustain them. [ABSTRACT FROM AUTHOR]

Freshwater mussels are important functional components of aquatic ecosystems. Westralunio carteri is a threatened freshwater mussel species, endemic to south-western Australia, which has suffered a recent, dramatic decline in range. The density, size structure and distribution of adult mussels of this species within river reaches were investigated using quadrat searches and modelled against a range of microhabitat factors. Mussels were found from 26 sites in 14 different rivers at a mean density of 28.4 ± 2.3 individuals m−2. The distribution of W. carteri was highly aggregated within river reaches. The most important factors explaining mussel distribution were substrate grain size, substrate debris and distance from the riverbank, with finer substrate, the presence of woody debris and proximity to the riverbank associated with greater abundance of mussels. In all rivers where mussels were found, most populations appeared to be actively recruiting. However, no mussels were found in six sites, despite them having been recorded as present within the last 20 years, which suggests that the range of the species is still in decline. The identification of microhabitat requirements for W. carteri will assist in identifying suitable release sites for translocation and/or captive propagation, which may be required to prevent extinction of the species. [ABSTRACT FROM AUTHOR]

Human activities have increasingly impacted rivers globally and influence environmental factors at multiple scales: proximal factors (e.g., light and nutrients) and distal controls (e.g., riparian cover and forest area in the basin) that affect benthic metabolism or algal assemblage structure. Function and structure have been studied separately and thus the linkage between them is not well understood. Furthermore, how much of the variability of benthic metabolism can be explained by changes in the environmental variables is inconclusive. We measured the structural and metabolism of epilithic algae in streams across gradients of catchment forest cover (3.5 to 88.6%) and riparian zone canopy cover (0 to 91.0%) in South East Queensland, Australia. Overall net daily metabolism (NDM) on cobbles was positive (gross primary production, GPP exceeded respiration, R) for all but three of the 34 sites. Chl a biomass of benthic algae on cobbles ranged from 1.37 to 178.05 mg m−2. Shaded streams had the highest percentage of diatoms (95.4%), while the least shaded streams were dominated by cyanobacteria (82.2%). Partial least squares (PLS) regression modeling showed that most of the variation in GPP, R, and NDM was explained by light intensity (photosynthetic photon flux density, PPFD), phosphorus concentration in water, water temperature, and the percentage of mid-dense forest upstream of the site. Path analysis (structural equation modeling, SEM) indicated that, as a surrogate for metabolism, diatom (Bacillariophyta) density was the best predictor of GPP and NDM when we assessed the environmental process in the streams. In comparison, Chl a, which has been traditionally used as a surrogate for measurements of GPP or NDM, performed well only when the percentage of diatoms in the epilithic algal community exceeded 75%. Our results also indicated that both the structure and function of benthic algal communities were sensitive to anthropogenic modifications, including riparian vegetation and forest cover in the catchment in river ecosystems. [ABSTRACT FROM AUTHOR]

Freshwater is a critical input to estuaries but is under increasing demand to support upstream human activities. In this study, otolith biochronology was used to quantify the relationship between river discharge and juvenile growth rates of barramundi (Lates calcarifer) in three regions of the Gulf of Carpentaria in northern Australia. In all regions, river discharge had a strong positive effect on juvenile growth rates. Models were also developed which incorporated the Southern Oscillation Index (SOI) and the Madden–Julian Oscillation (MJO). SOI values corresponding to La Niña events had strong positive consequences for juvenile barramundi growth rates in all regions, and the intensity of positive wet season MJO pulses had a strong positive effect on growth rates in the perennially flowing river, but not the intermittently flowing rivers. The consequences of three hypothetical water development scenarios were estimated for the perennial river. The model predicted a 12%, 8% and 1% reduction in annual barramundi growth rates under proposed scenarios for 18%, 8%, and 3% reduction in river discharge, respectively. Fish growth is a robust, quantitative metric that can be monitored pre and post water resource development to identify the least impactful development scenario and monitor its compliance and success through time. [ABSTRACT FROM AUTHOR]

Reduced streamflow because of climate change presents a major threat to aquatic biodiversity in arid, semi-arid and Mediterranean climatic regions. Freshwater mussels are particularly sensitive to this threat, because of their sedentary nature and limited mobility as juveniles or adults. The freshwater mussel Westralunio carteri, which is endemic to south-western Australia, has undergone a 49% reduction in range in the last 50 years, and a drying climate presents substantial extinction risk, as highlighted by two recent cases of mass mortality. Experimental studies found that mussels respond to water emersion by first tracking receding water levels, then burrowing. The amount of horizontal movement by mussels was not affected by size, but smaller mussels initiated burrowing sooner and were also more likely to be predated if they remained on the surface. Burrowing and shading both significantly reduced mortality rate and increased survival time when mussels were exposed to drying; when shaded or allowed to burrow, mussels could survive at least 62 days out of water. Predicted future reductions in streamflow are likely to increase the mortality rate in W. carteri, but it may be possible to partially avert the adverse effects of drying rivers by increasing riparian shading. [ABSTRACT FROM AUTHOR]

South-western Australia is isolated from other forested regions of Australia by desert and bounded on southern and western sides by the Southern and Indian Oceans, respectively, with Westralunio carteri (Iredale, 1934) as the sole endemic freshwater mussel. Its conservation status is vulnerable. This species has a history of nomenclatural change and its systematic placement and population genetic history are largely unknown. We sampled 46 individuals from 13 sites across W. carteri's distribution and sequenced two mitochondrial genes (16S rDNA and cytochrome c oxidase subunit I) and one nuclear gene (28S rDNA). The mitochondrial haplotype networks and COI phylogenies revealed three evolutionarily significant units (ESUs): "W. carteri" I including the west coast populations, "W. carteri" II from the south and south-eastern range, and "W. carteri" III only occurring in the south-western tip of Australia. Four species delimitation methods identified two molecular operational taxonomic units supporting two distinct species ("W. carteri" I and "W. carteri" II + III). Phylogeographic patterns revealed herein confirm the historical separation of Western and Southern paleo-basins, also highlighting the isolation of the south-western extremity of the region. This underlines the need for taxonomic revision and will require a re-evaluation of W. carteri's conservation status. [ABSTRACT FROM AUTHOR]

Biogeographic investigations of Gondwanan mesic Australian fauna are scarce. The burrowing clade of Australian freshwater crayfish represent an ideal group to provide biogeographic inferences, due to their extensive distribution across the continent and their presumed ancient origin. This study tested the competing hypotheses of a 'early' versus 'late' origin of this clade, coinciding with the early or late fragmentation of Gondwana, respectively. The biogeographic history of this group was investigated through: (a) examination of the phylogenetic relationships between the seven extant taxon groups; (b) reconstruction of four species trees, each using a different calibration method; and (c) reconstruction of ancestral ranges and correlation of estimated dispersal and vicariance events with historical geological data to propose plausible mechanisms responsible for driving diversification. The phylogenetic relationships between the taxon groups were generally well supported (although some uncertainty exists for the oldest genera), and all calibration methods produced concordant results. The hypothesis that the clade arose during the early fragmentation of Gondwana in southern Australia is supported. Divergence between the extant taxa likely resulted from a combination of both short- and long-distance dispersal events (often followed by later vicariance), coincident with phases of sea level oscillation and changing climate continuing into the Eocene. [ABSTRACT FROM AUTHOR]

We investigated the effect of CO2 and nutrient enrichment on competition between two free-floating fern species that co-occur in south-eastern Australia—native Azolla filiculoides and invasive exotic Salvinia molesta. The species were grown in monoculture and competition in a glasshouse experiment where the nutrient medium was replaced weekly to simulate a dynamic system. We found that the relative growth rate (RGR) of both species was greater under high resource conditions, with neither showing a suppressive response due to competition. On the contrary, A. filiculoides had a facilitative effect on S. molesta. In addition, A. filiculoides gained more biomass under high resource conditions relative to S. molesta and the opposite was true under low resource conditions. We conclude that [CO2] and nutrient concentration did not mediate competition between the species but instead influenced RGR independent of competition. These findings suggest that species composition in dynamic water bodies under future conditions may be determined by the species' responses to environmental changes rather than by changes in competitive interactions. [ABSTRACT FROM AUTHOR]

Dormant aquatic invertebrates can remain viable in riverbed sediment during dry phases, forming a source for recolonisation during wet periods. Regional differences in capacity for invertebrates to survive drying in this way are poorly understood, but may indicate regional differences in vulnerability to altered flow regimes. We compared diversity of invertebrates in dry sediment from intermittent rivers in temperate and semi-arid Australia after 4-8 weeks of drying. We predicted adaptations of semi-arid biota to severe and unpredictable drying would make dry sediment a more significant recolonisation source, with higher relative diversity when compared with temperate rivers. Emerging aquatic invertebrate assemblages were compared to those sampled in nearby pools, as a common drying refuge. Relative taxa richness in rehydrated sediments was higher in the semi-arid region (83 ± 16% of pool taxa) than the temperate (47 ± 6% of pool taxa), despite lower overall richness (24 taxa in semi-arid, 32 taxa in temperate). Semi-arid rivers had greater potential for dry riverbeds to act as a source for recolonisation, given high relative diversity and abundance in dry sediment, combined with the frequent absence of alternative refuges. However, dry riverbeds in both regions provided a significant short-term refuge for aquatic invertebrates. [ABSTRACT FROM AUTHOR]

Coastal areas, and thus coastal species, are at increasing risk from human activities. Sections of the coastline of Western Australia are undergoing intense coastal development to fulfil commercial, industrial, and recreational requirements. Multiple populations of bottlenose dolphins ( Tursiops aduncus) occur around this coastline; however, small community sizes and limited genetic exchange rates make them susceptible to anthropogenic pressure. This study investigated the occupancy of dolphins within the Swan-Canning Rivers, an urbanised estuary, with regard to (1) presence/absence, (2) abundance, and (3) duration in terms of time spent in the area. These response variables were related back to environmental conditions (tidal state, tidal height, salinity, temperature), vessel traffic, and dredging activities using generalised additive modelling. Theodolite tracking data revealed high levels of boat traffic at the two sites considered; however, dolphin occurrence was only negatively affected by vessel density at one of these sites. Dolphin occupancy was also significantly influenced by temperature, with possible seasonal effects. No dolphins were sighted on days when backhoe dredging was present; however, low sample sizes limited statistical interpretation. These results highlight the need to consider context in behavioural response studies, in terms of habitat type studied, explanatory variables considered, and response variables selected. [ABSTRACT FROM AUTHOR]

The article discusses various reports published in this issue including studies of Myall Lakes in Australia.

We present new chironomid and stable isotope (δC and δN) data from Little Llangothlin Lagoon, Australia that provides more detail on changes in this wetland since European settlement ca. 1840 AD. We also examine how the updated Holocene paleoecological record provides insights for management of this Ramsar-listed wetland. The current management strategy for Little Llangothlin is to restore the wetland and catchment to its natural state. This strategy is intended to protect the values that allowed it to be listed as a Ramsar wetland; i.e. its role as a drought refuge for waterbirds and to preserve or enhance threatened ecological communities. There are clear conflicts between the Ramsar listing criteria, management objectives and the management strategy in light of information provided by the palaeoecological record. In particular, restoration of terrestrial ecosystems through reforestation may jeopardise the wetlands role as a drought refuge. Some activities, such as artificial raising of the water level in 1989 are intended to restore, but actually introduced a state that did not exist prior to human settlement. We recommend a more integrated management approach that heeds the information provided by the palaeoecological record and focuses more on maintenance or enhancement of ecosystem services and biodiversity. [ABSTRACT FROM AUTHOR]

Dams constitute a major threat to aquatic ecosystems world-wide by modifying habitat and impairing opportunities for many freshwater fish. Subsequently, there can be a loss in fish diversity and change in the species distributions and population structure that ultimately contribute to changes in trophic structure and ecosystem function. In this study, stable isotope analysis (SIA) was used to compare trophic interaction and niche space of five fish species residing upstream and downstream of a significant barrier (Tallowa Dam) on the Shoalhaven River in south-eastern Australia. Significant reduction in niche space was found among predator/prey species residing in upstream habitat, implying limited dietary opportunity. Mixing calculations for Macquaria novemaculeata confirmed ontogenetic differences upstream and downstream of the dam. Causal mechanisms for this variability in trophic structure include habitat modification and/or discontinuity in river connectivity. SIA provides a useful tool for demonstrating the effect of barriers and/or impoundments on aquatic ecosystems, and for developing future monitoring programmes to evaluate restoration strategies. [ABSTRACT FROM AUTHOR]

Willows ( Salix spp.) are listed as a weed of national significance in Australia. Despite this recognition, functional effects of willows on streams compared to native species are largely unknown. Leaves supply carbon to instream food webs, but may also act as surfaces for biofilm, and thus can contribute in different ways to stream metabolism. Salix fragilis L. and Eucalyptus camaldulensis Dehnh. leaves that had been colonised by biofilms were placed into chambers in laboratory conditions, and metabolic rates were measured. Gross Primary Production (GPP) of biofilms on E. camaldulensis leaves after 10 days of incubation were significantly greater than biofilms on S. fragilis leaves. S. fragilis leaves displayed greater rates of microbial decomposition per leaf mass. Autotrophic biomass was one hundred fold greater on E. camaldulensis leaves. The biofilm on E. camaldulensis leaves is likely to support a greater population of grazers, compared to S. fragilis. The alien S. fragilis leaves, therefore, are fuelling a different component of the food web to endemic E. camaldulensis leaves. Endemic Eucalyptus spp. leaves play an important role in temperate Australian streams as a substrate for autotrophic growth and provide a year round pathway for carbon to reach secondary invertebrate consumers. [ABSTRACT FROM AUTHOR]

Strong seasonal trends in reproduction and early development of many invasive species are commonplace and may differ between introduced and native ranges, reflecting differences in abiotic conditions that trigger reproduction, or in selective pressures. The invasive crab Carcinus maenas has been present in south-east Australia for over 100 years, but little is known about its recruitment to benthic substrates in this introduced range. This study assessed the timing of C. maenas and native crab recruitment to Merimbula Lake (36.89S, 149.92E) south-eastern Australia between August 2011 and October 2013. It also assessed the effectiveness of four different types of recruitment bags for detecting the invasive crab. Carcinus maenas recruited in greater numbers to bags that contained live oysters than those with oyster shell, artificial turf or without structure. Recruitment of C. maenas peaked in the late winter and spring, while recruitment of most native species peaked in autumn. The timing of C. maenas recruitment contrasted its native European range where recruitment typically occurs in summer and autumn. Although likely triggered by the warmer water temperatures of south-eastern Australia, this differing reproductive phenology of C. maenas between its native and Australian range may also modify its interactions with native crab recruits. [ABSTRACT FROM AUTHOR]

In the Australian wet-dry tropics, seasonal changes in hydrology can influence abiotic conditions and consequently influence standing stocks of benthic biomass and production. While there is some understanding of these processes at riverscape scales, effects of seasonal hydrology on benthic biomass and production in low-order streams remain largely unquantified. We observed changes in water quality, algal and macroinvertebrate biomass, and stream benthic primary productivity over a 15-month period in three low-order streams with contrasting flow regimes in the wet-dry tropics of northern Australia. Water quantity and quality showed a distinct seasonal signature reflected in seasonal peaks in algal (maximum 1.29 µg cm) and macroinvertebrate biomass (maximum 0.24 g m), and productivity (maximum 0.41 g C m days). In particular, transitional periods between dry and wet seasons were key times of elevated production and algal biomass. Overall, variation in biomass and benthic primary production was greater between seasons than among streams indicating that extrapolation between seasons may not be appropriate. [ABSTRACT FROM AUTHOR]

Floodplain wetlands in semi-arid regions have intricate channel-floodplain networks with highly variable and unpredictable wet and dry phases related to changes in hydrology and geomorphology. We tested the hypothesis that the presence of different hydro-geomorphic habitats in those systems drives structural and functional differences in aquatic communities. To test this hypothesis, we examined the densities and species composition (structural variables), and primary productivity and respiration (functional variables) of plankton communities, and water chemistry in three spatially explicit channel, floodout and lagoon habitat types inundated by environmental water releases in the Macquarie Marshes, semi-arid Australia. Significant differences were recorded among the community-level structural and functional variables among the three habitats. Greater densities of phytoplankton, zooplankton and planktonic bacteria were observed in a hydrologically isolated floodplain lagoon. The lagoon habitat also had greater primary productivity of phytoplankton and planktonic respiration compared with the channel and floodout. Our results suggest that water release to meet environmental flow requirements can be an important driver of planktonic diversity and functional responses in semi-arid wetland systems by inundating diverse, hydro-geomorphically distinct habitats. [ABSTRACT FROM AUTHOR]

Freshwater fishes are vulnerable to changes in water quality, physical habitat and connectivity resulting from drought, particularly in regulated rivers. When adequate river flows return, the recovery of populations might depend on the duration and consequences of drought. Rivers of the highly regulated Murray-Darling Basin in south-eastern Australia terminate at two large, shallow lakes that are separated from the estuary by tidal barrages. Over-abstraction of water and widespread prolonged drought (1997-2010) placed the lakes under severe environmental stress, culminating in critical water level recession from 2007 to 2010. Concurrently, most freshwater fish populations collapsed. We investigate shifts in fish assemblages resulting from habitat inundation in the lakes following the drought. The inundation and re-connection of the lakes and fringing habitats led to a substantial reduction of salinity throughout the region, and aquatic vegetation shifted from salt-tolerant to freshwater species. Fish assemblages became increasingly characterized by common freshwater taxa (ecological generalists), including high proportions of alien species. There were no indications of population recovery for three threatened species. The findings emphasize that short-lived fishes with specialized habitat requirements are vulnerable to severe population declines during prolonged drought in regulated rivers, which might restrict their recovery when adequate flows return. [ABSTRACT FROM AUTHOR]

Abundances of organisms generally increase with structural heterogeneity and complexity of habitat. Patterns of distribution of hydroids on the kelp Ecklonia radiata were studied in Australia to examine the generality of this pattern. It was predicted that the cover of hydroids on E. radiata would be greater in the most heterogeneous (e.g., peripheral, crinkled blades) and complex (e.g., middle and bushy) parts of the alga. When different zones were independently compared along laminae of E. radiata, two clear patterns were found. Covers of hydroids in basal, middle and distal zones were greater in the periphery than in the centre of kelp. Second, covers in the periphery and in the centre of kelp were greater in middle than in distal zones and greater in distal than in basal zones. Both patterns conform to those predicted. At a finer spatial resolution, hydroids were significantly more abundant in troughs than on ridges of the peripheral blades of E. radiata. The primary substrata on which kelp was growing (pier-pilings or shark-nets) did not affect the distribution of hydroids. Biological and abiotic factors associated with the kelp itself most probably influence the distribution of hydroids along fronds, but manipulative experiments are needed to establish what models explain these patterns. [ABSTRACT FROM AUTHOR]

Highly seasonal rivers can experience extended low flow, and often dry, periods. Macroinvertebrate and flow data were used to explore hypotheses on the effects of antecedent hydrology and the low-flow, dry-season period on macroinvertebrate assemblages in northern Australia. Composition differed between early and late dry seasons. Taxa were more sensitive to water quality and more rheophilous in the early dry season when their habitats were lotic than when habitats later became lentic. As flow magnitudes in the antecedent dry season and on the sampling day increased, the habitats became more oxygenated and, in turn, macroinvertebrate richness increased. Higher wet-season flow magnitudes, flow variability and rates of fall were correlated with lower richness in the following dry season. Alteration of the flow-disturbance regime that increases the likelihood of flow cessation in macroinvertebrate habitats, or extends the duration of the dry season beyond that previously experienced in these highly seasonal systems, may alter the resistance and resilience of assemblages such that the seasonal decline and recovery of biodiversity may no longer be so reliable. Given the projected increase in low-flow incidence in many regions of the world, future research needs to examine the effects of reduced flow, flow cessation and stream drying as multiple, interacting stressors on stream biota. [ABSTRACT FROM AUTHOR]

Australia, and especially South-Western Australia, is a diversity hotspot for large branchiopod crustaceans. A significant proportion of this diversity is found in the anostracans (Crustacea, Anostraca) and particularly in the diverse genus Branchinella with at least 34 species. Members of this genus are found exclusively in temporary aquatic habitats which are increasingly threatened by secondary salinization and other anthropogenic pressures. The development of adequate conservation strategies is therefore considered a priority. To define conservation units, however, thorough knowledge of the taxonomy and phylogenetic position of extant lineages is essential. We reconstructed a large scale phylogeny of the Australian Branchinella by analyzing the 16S mitochondrial gene of 31 presumed species, complemented with analysis of morphological structures holding taxonomic information. Results revealed the presence of at least three new cryptic species. On the other hand, some Branchinella lineages, surviving in environments subjected to contrasting selection regimes, appeared to be conspecific. This suggests substantial physiological plasticity or important adaptive variation present in some species, potentially enabling them to better cope with environmental change, such as secondary salinization. Overall, these results further illustrate the benefits of combining molecular markers and classic morphological taxonomy and phylogeny to assess biodiversity and define conservation units in cryptic groups. [ABSTRACT FROM AUTHOR]

Recent studies show a remarkable scarcity of faunal exchange events between Australia and New Guinea in the Pleistocene despite the presence of a broad land connection for long periods. This is attributed to unfavourable conditions in the connecting area associated with the long established northern Australian Monsoon Climate. This would be expected to have impacted strongly on freshwater faunas with the following results: (1) limited overlap in species, (2) most higher taxonomic groups present in both areas sharing no species or even genera and (3) shared species dominated by lentic species with high dispersal capacity. Testing these predictions for dragonflies showed the turnover in the family, genus and species composition between Australia and New Guinea to be higher than anywhere in the world with only 50% of families and subfamilies, 33% of the genera and 8% of the species being shared. Only one of the 53 shared species favors lotic waters compared with 64% of the 652 combined Australian-New Guinean species. These results agree with our predictions and indicate that the dragonfly fauna of Australia and New Guinea have effectively been separated during the Pleistocene probably due to the prolonged unfavourable climatic conditions in the intervening areas. [ABSTRACT FROM AUTHOR]

Early to late Pliocene sedimentary strata present across the northern Bass Strait hinterland, southeastern Australia yield extensive fossil proxy data relevant to the interpretation of high sea level coastal palaeomorphology. Within the Pliocene Whalers Bluff Formation exposed in coastal cliffs near the township of Portland, Victoria, marine microfossil faunas delineate two broad cycles of deposition. Both these sedimentary cycles are bound below by unconformity surfaces. Within the lower sedimentary cycle, a basal stress-tolerant (low diversity) marginal marine microfossil fauna devoid of ostracods and suggestive of bottom-water hypoxia, is succeeded by a diverse shallow marine ostracod fauna dominated by stenohaline species indicative of a sheltered (but open) oceanic embayment. This lower sedimentary cycle has an early Pliocene (Zanclean) age. Equivalent shallow marine (e.g. coastal embayment) deposits occur broadly across the coastal hinterland of southeastern Australia-reflecting the generally higher global sea levels of this time. The upper cycle in the cliff exposures at Portland is late Pliocene (Piacenzian) in age. Equivalent deposits across the Bass Strait hinterland are restricted to former incised river valley settings. Euryhaline estuarine/coastal lagoon Ostracoda are present throughout the upper cycle in the Portland cliffs. These are associated with a low diversity microfauna at the base of the upper cycle and a high diversity microfauna towards the top of the cycle. Early Pliocene coastal marine deposits can be distinguished from late Pliocene coastal marine deposits across the northern Bass Strait hinterland on the basis of the presence or absence of certain open marine ('stenohaline') ostracod species. [ABSTRACT FROM AUTHOR]

This first assessment of sponges on Australia's deep western continental margin (100-1,100 m) found that highly species-rich sponge assemblages dominate the megabenthic invertebrate biomass in both southwestern (86%) and northwestern (35%) areas. The demosponge orders Poecilosclerida, Dictyoceratida, Haplosclerida, and Astrophorida are dominant, while the presence of the order Agelasida, lithistid sponges, and the Verongida are noteworthy in providing contrasts to other studies from the deep temperate Australian margin. Most sponge species appeared to be rare as two-thirds were present in only one or two samples-a finding consistent with studies of the shallow Australian sponge fauna. The Demospongiae and Calcarea had similar distribution and abundance patterns being found in the greatest numbers in the south on the outer shelf and shelf edge in hard substrates. In contrast, the Hexactinellida were more abundant at deeper depths and in soft substrates, and were more common in the north. Although the environmental factors that influence sponge distributions on the western margin cannot be completely understood from the physical covariates analyzed in this study, the data suggest depth-related factors, substrate type, and current regimes are the most influential. Incompletely documented historic demersal trawling may partly account for the lower sponge biomass found in the north. The potentially high importance of sponges to benthic ecosystems, as well as the potential for high impacts on sponges by bottom trawling, indicates that maintaining healthy sponge assemblages should be an important consideration for marine conservation planners. Successful management will need to be under-pinned by additional research that better identifies the ecological roles of sponges, and their distributions over local and broad environmental scales. [ABSTRACT FROM AUTHOR]

The Yalgorup lakes, a groundwater-fed system in south-western Australia recognized as a Ramsar wetland, hold significant scientific and conservation value due to the presence of a unique range of lake systems, resident waterfowl and, on the eastern shore of Lake Clifton, the presence of the only thrombolite reef in the southern hemisphere. Recent concern over changing physico-chemical conditions in the lakes, particularly an increase in salinity, prompted this study: the current status of the inherent thrombolite community is unknown. Salinity, total phosphorous (TP), phosphate, total nitrogen (TN), nitrate, chlorophyll- a and relative abundance of the thrombolite microflora were measured in Lake Clifton to analyse changing conditions in this lake and to determine the effect of these water parameters on the thrombolite community. Comparisons with historical data revealed a significant increase in salinity since 1985 and a possible increase in phosphorus concentrations in the lake in the recent decade, although historical nutrient data are rather sparse. The increased salinity may be due to concentration of lake water through a combination of high evaporation, long-term reduction in rainfall and increased groundwater abstraction. Comparison of the composition of the thrombolite community with historical data indicates a large reduction in relative abundance of Scytonema sp. and other filamentous cyanobacterial species, which are believed to be fundamental for the thrombolite structure. It is concluded the changing physico-chemical environment of the Yalgorup Lakes may have led to the decline in important genera in the thrombolite community; however, the mechanisms underlying this change remain unknown. [ABSTRACT FROM AUTHOR]

Several studies, particularly in the Northern Hemisphere, have demonstrated that chironomids are responsive to pollution (e.g., heavy metals, organic). In Australia, there is limited evidence that chironomid species have differential sensitivities to water pollution, with several studies reporting high tolerance of heavy metal pollution. We investigated the impact of both zinc-rich mine waste and organic effluent on chironomids within an effectively pristine background using the Chironomid Pupal Exuviae Technique (CPET). Chironomid species assemblages were strongly influenced by both mine drainage and organic pollution. Community composition differed between unpolluted streams and locations downstream of the pollution sources, and between the two different sources of pollution. Thirty seven of the most abundant species exhibited strong responses to water pollution varying from greatly increased abundance to complete absence. Ten species had higher abundance at one of the polluted sites compared to unpolluted sites; six in the presence of zinc pollution and five in the presence of organic pollution. One species responded positively to both pollution types. Our results indicate that contrary to the mixed reports of Australian chironomids for being insensitive to pollution, we found that they displayed a strong pollution response to both organic and heavy metal contamination. [ABSTRACT FROM AUTHOR]

The influence of natural populations of the sub-surface deposit-feeding amphipod Victoriopisa australiensis on sediment biogeochemistry was assessed by randomly collecting 21 sediment cores in a zone of Coombabah Lake, southern Moreton Bay, Australia, where the benthic infauna was dominated by this species. Cores were incubated sequentially to determine sediment–water column fluxes of oxygen, dissolved inorganic carbon and inorganic N species, followed by incubations to determine rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) using the isotope pairing technique. Finally, each core was sieved in order to determine the population and biomass of amphipods present. Whilst all measures of overall benthic metabolism (sediment oxygen demand, and effluxes of inorganic carbon and nitrogen) showed increased with amphipod density, with rates being stimulated 70–220% at the highest categorised density range of 2,500–3,500 ind m−2, only the correlation with dissolved inorganic carbon was statistically significant. In contrast, there were no discernable trends between amphipod densities and any of the N-cycle processes with the slopes of all correlations being very close to zero. These results highlight the differences in mesocosm simulations of fauna effects, which primarily relate to shifts in rates of organic matter turnover, compared to natural sediments where fauna effects relate more to induced changes in rates of organic matter deposition. Therefore, while mesocosms represent a powerful tool to investigate the mechanisms by which fauna influences microbial metabolism in the sediment, only studies of natural sediments can determine to what extent these mechanisms function in situ. [ABSTRACT FROM AUTHOR]

The association of diatom assemblages to salinity was studied in 95 lakes and streams ranging from freshwater to hypersaline in the south-west of Western Australia. The relationship between environmental variables and species composition was explored using canonical correspondence analysis (CCA) and partial CCA. Salinity was shown to account for a significant and independent amount of variation in the diatom data, enabling a transfer function to be developed based on the final dataset, which consisted of 89 sites and 150 diatom taxa. The most successful model was derived using tolerance-downweighted weighted averaging. Summary statistics showed that the transfer function performed very well with a high coefficient of determination and low prediction errors that remained high after the cross-validation method of jackknifing ( r = 0.97 and r = 0.89). This suggests that salinity can be accurately predicted using relative abundances of diatoms, and the model can now be applied to paleolimnological reconstructions. However, the transfer function also provides the basis for use in future biomonitoring studies to detect increases in salinity for lakes and streams most at risk, as well as to evaluate the success of remediation measures implemented to secondary salinised systems. [ABSTRACT FROM AUTHOR]

An 18-month-study of 40 saline wetlands, ranging from 6 to 336 g l−1, on the west and southern coasts of Eyre Peninsula yielded 88 species of invertebrates, some aquatic plants and a fish. The invertebrates are taxonomically diverse and include 38 crustaceans, 28 insects, 12 molluscs and significantly an aquatic spider, a nemertean, two polychaetes, two sea anemones, a sponge and a bryzoan. Most were tolerant of wide fluctuations in salinity, there being 51 halobionts, 21 halophils and only 16 salt-tolerant freshwater species. Many invertebrates are restricted to the thalassic springs where marine molluscs dominated. Athalassic wetlands were dominated by crustaceans and were of two basic types—coastal and continental. There is evidence of the former evolving biologically into the later, and for some lakes to be still in transition. There is also evidence of increasing salinity in recent decades and already two lakes exhibit severe secondary salinity. Like other salt lakes in Australia the fauna is regionally distinctive. [ABSTRACT FROM AUTHOR]

Subterranean or groundwater estuaries occur in porous and cavernous substrates where groundwater abuts the ocean. Like surface estuaries, they are strongly stratified, temporally and hydrochemically heterogeneous environments that support complex hydrogeochemical and biological processes and ecological communities. Here, we contend that groundwater estuaries also occur where groundwater flow approaches salt lakes and provide evidence in the context of groundwater (valley or phreatic) calcretes in palaeovalleys of the arid western plateau of Australia. The calcrete groundwater estuaries display marked and complex physico-chemical gradients along, across and through the groundwater flow path. From the first principles and the density differences between water bodies, we may expect the form and dynamics of the saltwater front to mimic that of marine estuaries but with the dynamic and temporal response to changing hydrology heavily dampened, and driven by the episodic groundwater recharge and lake filling typical of arid regions. The calcrete aquifers support diverse biological communities of obligate groundwater animals, largely endemic to a given calcrete body. These communities comprise both macro and microinvertebrates, predominantly a suite of crustacean higher taxa, and a great diversity of diving beetles (Dytiscidae) isolated in the calcrete aquifers between ca. 5 and 8 million years ago. [ABSTRACT FROM AUTHOR]

Patterns and dynamics of the salt marsh vegetation that surrounds many of the salt lake systems of arid/semi-arid Australia are poorly known. Lake Austin is a very large salt lake with extensive areas of fringing salt marsh; it is located in the arid Yilgarn Region of Western Australia. In this study, the changes in this vegetation over a 4-year period (1998–2002), during which both a major flooding event and addition of hypersaline groundwater from a nearby mining operation occurred, are reported. The monitoring program, based on Before-After-Control-Impact (BACI) principles, was designed to detect impacts of discharging hypersaline water into the lake; however, the flooding event, the result of above average rainfall in early 2000, complicated the results. The rains of 2000 and subsequent inundation of the vegetation immediately fringing the lake bed and major inlet channels resulted in dramatic changes to the species composition of annual and short-lived species and growth of perennial species. Flooding resulted in substantial death and damage to perennial shrubs (particularly Halosarcia fimbriata) due most likely to a combination of several weeks/months of inundation and smothering by macroalgae and Ruppia, with smaller plants and those closer to the lake bed impacted upon to a greater degree. Seed germination and recruitment of new Halosarcia plants was substantial as floodwaters receded with the majority of these seedlings surviving some 2 years after flooding despite the severe drought that followed the flood. Growth rates of seedlings differed substantially and were linked to subtle differences in micro-topography. Recruitment following flooding was also demonstrated in in vitro experiments involving inundated soil cores, provided water was relatively non-saline (conductivity <30 mS cm−1). A conceptual model is proposed to explain changes in fringing vegetation in response to frequency, depth, period and salinity of flooding in relation to micro-topography. Despite the profound effect of flooding, impacts of discharge were identified, with changes in topsoil pH and salinity greater in areas closer to the discharge than those further away. Impacts on vegetation characteristics were not detected. [ABSTRACT FROM AUTHOR]

Stable isotope signatures (δ13C and δ15N) were used to compare trophic linkages between epilithic periphyton and three families of macroinvertebrates (Baetidae, Leptophlebiidae and Gripopterygidae) in riffles of two rivers with developed catchments (including agriculture, urbanization, impoundment and flow regulation) and two with undeveloped catchments (native forest with no major impoundments) in the Murrumbidgee River system, New South Wales, Australia. Periphyton had much higher average δ15N values and lower average C:N ratios in the developed rivers than in the undeveloped rivers, probably because of the combined effects of nutrient enrichment, upstream impoundment and alteration of riparian vegetation. The invertebrates were generally slightly depleted in 13C and 15N relative to expected values if they were assimilating whole periphyton alone, which suggests that they were assimilating periphyton components selectively or also consuming other foods. The match in isotope signatures between periphyton and invertebrates was only slightly weaker in the developed than in the undeveloped rivers, suggesting that development did not greatly disrupt trophic linkages between periphyton and these invertebrates. [ABSTRACT FROM AUTHOR]

Relationships between key phytoplankton attributes including Chl a-specific light absorption, pigment composition and concentration, photosynthesis, primary production and community structure were studied in two open shallow nutrient-poor coastal systems receiving similar amounts of sewage water. Both systems were significantly nitrogen limited. However, differences in wastewater treatment (primary vs secondary) and sewage dilution (50%) between the two systems caused a greater difference between systems than locally around the outflows. For both systems, water at the outlet had significantly lower water transparency caused by a 20% higher absorption by coloured dissolved organic matter. Nutrient concentrations were also elevated, gradually decreasing with distance north (governing current) of the outflows, causing higher abundance of nano-sized phytoplankton, higher content of carotenoid pigments, 20–50% higher Chl a-specific absorption coefficients and higher photosynthetic capacity. Although maximum rates of Chl a-normalised photosynthesis were strongly related to nitrate availability, no effects were found on the derived areal primary production or algal biomass suggesting that photosynthetic and optical parameters are more sensitive indicators of nutrient enrichment than biomass or productivity. [ABSTRACT FROM AUTHOR]

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 <1 to <100 seedlings m−2 day−1, and showed a peak in the summer–autumn period. Regression analysis showed a significant negative correlation ( r 2 = 0.738) between the number of M. ericifolia emergents and water depth. Water depth and salinity were negatively correlated ( r 2 = 0.819), and increases in the number of M. ericifolia emergents as water levels fell were also associated with high salinities. Increasing air temperature and vapour pressure deficit also stimulated seed release during periods of drying. This study is one of the first to demonstrate the importance of aerial seed banks for sexual recruitment in woody wetland plants and the release of seed in relation to environmental factors. Aerial seed banks warrant consideration alongside soil seed banks for the establishment and long-term survival of woody plants in wetlands. [ABSTRACT FROM AUTHOR]