Search

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) Fundacao de Apoio a Pesquisa do Distrito Federal (FAPDF), Fundacao de Amparo a Pesquisa do Estado do Amazonas (FAPEAM), BIODIVERSA/FAPEAM, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ), Bundesministerium fuer Bildung und Forschung, Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), FAPEAM-Program POSGRAD, Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG), INPA/MCTI 465540/2014-7, Leibniz Competition 0621187/2017, Leibniz-Gemeinschaft R20F0002, Instituto Nacional de Pesquisas da Amazpnia, unidade de~pesquisa Ministerio da Ciencia, Tecnologia e Inovacoes (INPA/MCTI) 403758/2021-1, Programa Peixe Vivo of the Companhia Energetica de Minas Gerais 033W034A, Royal Society of New Zealand, Tertiary Education Commission, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), Foundation for Science and Technology, Associate LaboratoryARNET J45/2018, CEEC

Plant litter functional diversity effects on instream decomposition change across latitudes., Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.

For most passerines, nest predation has a major impact on breeding success; however, information on the identity of nest predators is scant. In 2012, we investigated the identity of nest predators that each year depredate about 50% of the nests of 21 species in a south-east coastal bird community in New South Wales, Australia. The current study is a 2-year extension of this study and shows that at this study site (a) predation accounts for at least 90% of nest failures, (b) identified nest predators comprised two reptiles, nine birds and five mammals, (c) the suite of predators changes each season, (d) the two major predators were the Eastern Whipbird (Psophodes olivaceus) and the Fan-tailed Cuckoo (Cacomantis flabelliformis), (e) the impact of the Red Fox and Feral Cat was minimal, and (f) there was a variable and complex interaction between the parasitic cuckoos and their hosts. The data show definitively the overwhelming importance of nest predation on fledgling production, and bring to light new and important data on several aspects of the suite of nest predators.

Sampling of aquatic macroinvertebrates requires techniques that are efficient and representative. Stratification of sampling units is a practical way of ensuring representative coverage of the habitat. However, efficiency of sampling devices used in the field and techniques for extraction of specimens from samples has rarely been assessed. Commonly used qualitative and quantitative samplers are described as well as the situations in which a particular device is most likely to be useful. The efficiency of these devices can be estimated using a technique known as removal sampling, whose underlying statistical theory is well understood. The laboratory examination of samples is straightforward but tedious. Flotation of specimens from inorganic material and subsampling are two methods of speeding up laboratory processing. Small cryptic species or small instars are easily obscured by detritus when picking specimens from samples under low magnification. By scanning samples twice the efficiency of extraction of specimens can be estimated.

Traits provide key ecological information that can be applied to understanding the mechanisms which drive community assembly and persistence. In recent years, trait information has provided important insights into the responses of communities to stressors including pollutants and climatic extremes. Outside of Europe and North America, the use of stream macroinvertebrate traits has generally been hindered by the lack of a national database assigning traits to taxa. Here, we present an integrated database for Australian stream macroinvertebrates, which for the first time brings together data from multiple jurisdictions to facilitate the use of traits in both theoretical and applied studies. We describe the database and discuss its applications as well as challenges and limitations of this and other trait databases. The Australian trait database provides new opportunities for research and application in freshwater management.

Dragonfly wings are of great interest to researchers investigating biomimetic designs for antiwetting and antibacterial surfaces. The waxy epicuticular layer on the membrane of dragonfly wings possesses a unique surface nanoarchitecture that consists of irregular arrays of nanoscale pillars. This architecture confers superhydrophobic, self-cleaning, antiwetting, and antibiofouling behaviors. There is some evidence available that suggests that lifestyle factors may have influenced the evolution of the wing nanostructures and, therefore, the resulting properties of the wings; however, it appears that no systematic studies have been performed that have compared the wing surface features across a range of dragonfly species. Here, we provided a comparison of relevant wing surface characteristics, including chemical composition, wettability, and nanoarchitecture, of seven species of dragonfly from three families including Libellulidae, Aeshnidae, and Gomphidae. The characteristic nanopillar arrays were found to be present, and the chemical composition and the resultant wing surface superhydrophobicity were found to be well-conserved across all of the species studied. However, subtle differences were observed between the height, width, and density of nanofeatures and water droplet bouncing behavior on the wing surfaces. The results of this research will contribute to an understanding of the physical and chemical surface features that are optimal for the design of antiwetting and antibacterial surfaces.

Dragonflies have gained much attention due to their sophisticated wing surface structure, and their associated superhydrophobic, self-cleaning and bactericidal properties. In this work, we compared and contrasted the chemical composition and surface morphology of the wing membranes of four species of dragonfly and damselfly from the Odonata family collected in 1970s (Diplacodes melanopsis and Xanthagrion erythroneurum) and 2011 (Diplacodes bipunctata, and Ischnura heterosticta). Diplacodes species are dragonflies, whilst Xanthagrion and Ischnura are damselflies. Fourier-transform infrared spectroscopy data obtained from the Australian Synchrotron were used to classify the fundamental components of all four of the insect species' wings. The spectra of all species were dominated by C H stretching, amide I and amide II and O-H stretch absorbance indicating the presence of a similar membrane composition of chitin, protein and wax in all four species. Although the samples were collected 40 years apart, there was no evidence of degradation having taken place during this time. Despite the overall similarities in spectral profile, species-specific differences were observed, most notably in the intensity of the vCH(2) peaks, which in part reflected the amount of waxes present on the wings, which appeared to be different between individual species. The surface topography also contained minor differences in the diameter and the spacial distribution of its nanopillars. It is postulated that the differences in surface wettability of the wings could be attributed to these minor differences in surface chemistry and surface topography. For example, X. erythroneurum presented the highest water contact angle (WCA) of 160 degrees whilst the D. melanopsis wings exhibited the lowest WCA (138), and the wettability of their wings was found to directly correlate with the intensity of hydrocarbon peaks found in their respective IR specta. Refereed/Peer-reviewed

Long-term studies have seldom considered the compositional stability (i.e., invariability of community composition) of stream invertebrate communities. Compositional stability could potentially be related to variations in species richness, habitat complexity, or hydrological and physicochemical conditions. Invertebrate species data were obtained for 21 sites that had been sampled over 16 to 20 years in Victoria, southern Australia. Stability of community composition at a site was measured with the mean Bray-Curtis coefficient, which was calculated for all comparisons between samples taken over the sampling period using only presence/absence data. Three datasets were compiled: one containing all species, one containing only insects, and one with family-level data. Multiple regressions demonstrated that stability at a site was related directly to species richness and habitat complexity and inversely to daily discharge; stability was not related to physicochemical conditions. The first 2 factors accounted for 45–49% of the variance while flow accounted for 9–16% but was not significant at the family level. The positive relation between stability and species richness may be due to higher variability in colonization at species-poor sites and thus lower compositional stability, while increased habitat complexity enhances stability by providing more refuges. Increased flow may result in more invertebrate drift and movement and thus lower stability, but the relationship was weak and provided little support to the idea that hydrology is an important ecological characteristic for invertebrates of southern Australian rivers.

While insect wings are widely recognised as multi-functional, recent work showed that this extends to extensive bactericidal activity brought about by cell deformation and lysis on the wing nanotopology. We now quantitatively show that subtle changes to this topography result in substantial changes in bactericidal activity that are able to span an order of magnitude. Notably, the chemical composition of the lipid nanopillars was seen by XPS and synchrotron FTIR microspectroscopy to be similar across these activity differences. Modelling the interaction between bacterial cells and the wing surface lipids of 3 species of dragonflies, that inhabit similar environments, but with distinctly different behavioural repertoires, provided the relationship between surface structure and antibacterial functionality. In doing so, these principal behavioural patterns correlated with the demands for antimicrobial efficiency dictated by differences in their foraging strategies. This work now reveals a new feature in the design elegance of natural multi-functional surfaces as well providing insights into the bactericidal mechanism underlying inherently antimicrobial materials, while suggesting that nanotopology is related to the evolutionary development of a species through the demands of its behavioural repertoire. The underlying relationship between the processes of wetting, adhesion and capillarity of the lipid nanopillars and bactericidal efficiency suggests new prospects for purely mechano-responsive antibacterial surfaces.

Summary 1. Taxonomic distinctness (or average taxonomic breadth) of a sample is a measure of diversity that has the great advantage of not being sensitive to variations in sampling effort, unlike measures of species richness. It can also be tested for departures from expectation and can thus be used to determine whether a site has suffered from a genuine loss of diversity. 2. Taxonomic distinctness or delta+ was measured using all insect species from three datasets obtained from running water habitats: reference or least disturbed sites from channel and bank habitats on rivers from the Australian state of Victoria; test sites distributed along a water quality gradient in Victoria and sites immediately below a series of dams in Victoria and New South Wales. The last two datasets comprised sites subject to a range of obvious disturbances. 3. At reference sites delta+ was generally within the range of expected values (95% confidence limits) for both habitats as would be anticipated for these essentially undisturbed sites. However, 13–14% of sites fell below the lower confidence limits. Sites in river basins with less cover of natural habitat had slightly but significantly lower delta+ values than those with more cover and these sites contributed to this anomaly. 4. Delta+ was inversely correlated with water quality (r = −0.54, P = 0.002) as measured by the first axis of a PCA of water quality variables. It was also inversely correlated with individual variables, such as turbidity and total phosphorous. 5. Delta+ was below expectation for 18 of the 19 dam sites and at 13 of these sites delta+ values were below the lower confidence limit. 6. Delta+ was a sensitive index of diversity that generally distinguished sites suffering from environmental disturbance. Only a few previous studies of river ecosystems have used delta+, which did not respond consistently to disturbance because either too few taxa at species or higher taxonomic levels were available or because longitudinal changes in species composition swamped the signal from delta+. Neither of these problems occurred with the current datasets. 7. Delta+ responded more readily to disturbance than number of species, perhaps because taxonomic distinctness reflects some of the multivariate nature of community samples, whereas number of species is blind to this aspect.

During the past decade, new biological assessment methods have been developed for use in inland waters. Less work has gone into objective testing of the individual methods and their diagnostic or other capabilities, and very little effort has been devoted to comparing methods. This special issue of Hydrobiologia brings together a number of the most recently developed bioassessment methods, or aspects of them, so readers can begin to compare their potential value and practical usefulness.

1. Sites immediately below seven dams in Victoria and 12 in southern New South Wales (NSW) were sampled for macroinvertebrates using rapid bioassessment techniques. Specimens were identified to the lowest taxonomic level. The dams had different operating and discharge regimes and thus potentially different downstream effects on this fauna. 2. The AUStralian RIVer Assessment Scheme (AUSRIVAS) predictive models for macroinvertebrate composition were applied to the families and genera observed at Victorian sites and to the families only at the NSW sites. Lists of predicted taxa, their probabilities of occurrence and ratios of observed to expected taxa (O/E scores) were obtained from these models. 3. The mean O/E score for Victoria was 0.46 at the genus level and 0.63 at the family level; for NSW the mean score at the family level was 0.62. There was no significant difference between family level scores for the two states. Thus about 40% of expected families were missing at all sites. Family level scores were highly correlated (r=0.84–0.86, P

Declining water quality and ecological condition is a typical trend for rivers and streams worldwide as human demands for water resources increase. Managing these natural resources sustainably is a key responsibility of governments. Effective water management policies require information derived from long-term monitoring and evaluation. Biological monitoring and assessment are critical for management because bioassessment integrates the biological, physical and chemical features of a waterbody. Investment in nationally coordinated riverine bioassessment in Australia has almost ceased and the foci of management questions are on more localised assessments. However, rivers often span political and administrative boundaries, and their condition may be best protected and managed under national policies, supported by a coordinated national bioassessment framework. We argue that a nationally coordinated program for the bioassessment of riverine health is an essential element of sustainable management of a nation’s water resources. We outline new techniques and research needed to streamline current arrangements to meet present-day and emerging challenges for coordinating and integrating local, regional and national bioassessment activities. This paper draws on international experience in riverine bioassessment to identify attributes of successful broad-scale bioassessment programs and strategies needed to modernise freshwater bioassessment in Australia and re-establish national broad-scale focus.

1. Quantitative samples of Agapetus pontona and Agapetus monticolus larvae were taken at two sites on each of three rivers in the catchment of the Acheron River (i.e. Little River, Steavenson River and Acheron River). Both species were univoltine with A. pontona having a 5–6-month life cycle (spring to late summer) and A. monticolus a 10-month life cycle (autumn to early summer). 2. Population densities, biomass (B), growth rates and mortality patterns derived from these field data were used to calculate secondary production (P) and turnover (P/B). At each site, these features were measured for the whole of the A. pontona life cycle, but only for the last 3 months of the A. monticolus life cycle. 3. Growth rates were highest at the sites on the Little River during summer for both species: 1.8–1.9% dry weight day−1 for A. pontona and 2.0–2.2% dry weight day−1 for A. monticolus. Turnover ratios (P/B) were also highest at the Little River sites: 3.2–6.3 for A. pontona and 1.6–1.9 for A. monticolus. Production was variable and was not significantly different among rivers for A. pontona (28.4–222.1 mg m−2 per 6 months) but was for A. monticolus (70.5–123.8 mg m−2 per 3 months for the Little River compared with 14.8–23.3 mg m−2 at the other sites). 4. Two of the rivers were subject to higher levels of rock movement during summer than the third (Little River). It was suggested that the higher growth rates (and turnover ratios) in the Little River were caused by the lower levels of rock movement causing less disruption to the feeding of the larvae. 5. Little or no larval mortality of A. pontona was observed at any site. However, mortality occurred between instar 5 and the pupal stage. This varied in a density dependent fashion, suggesting population regulation occurred: the higher the larval density the greater the mortality suffered by the pupae. No such density dependent pattern occurred for the mortality between instar 5 and the pupal stage of A. monticolus. 6. The population of A. pontona was not food limited and larval densities were low. Competition appeared to occur for pupation sites. Low and relatively constant discharges during the late summer when A. pontona pupated appeared to provide more predictable conditions than those experienced by A. monticolus in the spring when discharge was very variable resulting in the stranding (and thus death) of pupae above the water line. Such unpredictable conditions would not foster density dependent population regulation via pupal mortality.

Summary 1. Spatial scale may influence the interpretation of environmental gradients that underlie classification and ordination analyses of lotic macroinvertebrate communities. This could have important consequences for the spatial scale over which predictive models derived from these multivariate analyses can be applied. 2. Macroinvertebrate community data (identified to genus or species) from edge and main-channel habitats were obtained for sites on rivers from 25 of the 29 drainage basins in Victoria. Trends in community similarity were analysed by carrying out separate multivariate analyses on data from the edge habitats (199 sites) and the main-channel habitats (163 sites). 3. Hierarchical classification (UPGMA) showed that the edge data could be placed into 11 site groups and the main-channel data into 12 site groups. 4. Ordination analysis (hybrid multidimensional scaling) showed no sharp disjunctions between site groups in either habitat; overlap was frequent. Correlation of the ordination patterns with environmental variables showed that edge communities varied longitudinally within a drainage basin and from the east to the west of Victoria. These two trends were superimposed on one another to form a single gradient on the ordination. The taxon richness of edge communities was also related to the species richness of macrophytes at a site. Main-channel communities also displayed a longitudinal and a geographic gradient, but these two gradients were uncorrelated on the ordination. 5. Community similarity only weakly reflected geographic proximity in either habitat. A preliminary subdivision of Victoria into a series of biogeographic regions did not match the pattern of distribution of site groups for the edge habitat, illustrating the difficulties of applying to lotic communities a priori regionalizations based on terrestrial features of the landscape. 6. The longitudinal gradients in the two data sets were commonly observed in data gathered at smaller spatial scales in Victoria. The other gradients (geographic, macrophyte), however, were either not consistently repeated or not evident at smaller spatial scales. At small spatial scales (i.e. within a single drainage basin) gradients were related to variables that varied over restricted ranges, e.g. mean particle size of the substratum. 7. Species richness was very variable when plotted against river slope or distance of site from source; both of these are measures of position on the longitudinal gradients. In contrast to suggestions in the literature, species richness did not show a unimodal trend on these gradients, or any other trend. 8. Environmental gradients (apart from longitudinal gradients) that underlie predictive models of macroinvertebrate distribution are reflections of the spatial scale on which the model has been constructed and cannot be extrapolated to different scales. Models must be suited to the spatial scale over which predictions are required.

We constructed predictive models using 2 macroinvertebrate data sets (for both species and family) from bankside habitats at 49 undisturbed reference sites from 6 Victorian river basins; data were accumulated over 4 to 6 sampling occasions. Classification (by unweighted pair-group arithmetic averaging with the Bray-Curtis association measure) showed 3 site groups were evident at the species level and 4 at the family level. A subset of 5 of 22 environmental variables provided maximum discrimination (using stepwise discriminant analysis) between the 3 species site groups; these variables were: conductivity, altitude, substrate heterogeneity, distance of a site from source, and longitude. Four variables discriminated between the 4 family site groups: conductivity, catchment area upstream of site, mean annual discharge, and latitude. From the discriminant analysis, it was possible to predict the group into which an unknown site (specified only by measurements on the 4 or 5 variables just noted) would be placed and thus the probabilities of occurrence of taxa at this site. To test predictive ability, 4 sites were removed at random from the 2 data sets and the classification and discriminant models were recalculated. This process was repeated 5 times. The identity and number of taxa observed at each of these sites were compared with those predicted with a probability of occurrence >50% and the results expressed as a ratio of numbers observed to numbers expected (O/E). This ratio varied from 0.75 to 1.05 at the species level and from 0.83 to 1.12 at the family level, indicating that the fauna conformed with expectation (O/E near 1.0). To test such predictive models on independent data, O/E ratios were also calculated for family data collected in spring at 18 sites from a basin not used in the original models. Two new discriminant models based on single sets of samples from the reference sites taken in spring were constructed for this purpose. O/E ratios varied from 0.09 to 1.01 for the 18 sites and were inversely correlated (r = -0.4 to -0.8) with a range of water quality variables, the values of which increased as water quality deteriorated. The O/E ratio could thus be considered a sensitive measure of disturbance.

1. The larval life spans of twelve species of aseasonal aquatic insects (eight Trichoptera, three Ephemeroptera, one Odonata) were investigated in two tropical streams with near constant water temperatures. 2. Life spans were estimated from equations relating larval life span to the ratio between cohort production (estimated from the size–frequency technique) and annual production (estimated from regressions in the literature). 3. Life spans varied from 40 to 250 days and were positively correlated with maximum larval dry weight (r = 0.73, P < 0.001). Ephemeroptera had the shortest larval life spans (40–110 days), Trichoptera intermediate (95–185 days) and Odonata the longest (250 days).

The unique Australian monotreme, the platypus (Ornithorhynchus anatinus) potentially exerts a strong top-down influence on riverine food webs in eastern Australia. However, despite considerable interest in the evolutionary history and physiology of the platypus, little is known of its trophic relationships. To address this lack of knowledge we used stable isotope analysis, in combination with the analysis of food items stored in cheek pouches, to determine its position in a typical riverine food web. This was the essential first step in the process of designing a larger study to investigate the relative importance of top-down and bottom-up effects in rivers where the platypus occurs. We found that platypuses were feeding on a wide range of benthic invertebrates, particularly insect larvae. The similarity of δ13C and δ15N values recorded for the platypus, a native fish (Galaxias sp.) and the exotic mosquitofish (Gambusia holbrooki) indicated dietary overlap and potential competition for the same resources. Although cheek pouch studies identify most of the major groups of prey organisms, the potential for contribution of the soft-bodied organisms such as larval dipterans, is suggested by stable isotope analysis, indicating that the use of both techniques will be important in future ecological investigations.

Average taxonomic distinctness (delta+) is a measure of the mean taxonomic breadth of a sample and is thus a measure of biodiversity. It has the great advantage of not being sensitive to variations in sampling effort, unlike measures of species richness, and is thus potentially of great value for examining the effects of disturbance on biodiversity. In addition, it is possible to test delta+ for departures from expectation. The increasing level of salinity in rivers in Victoria and South Australia is a well known environmental hazard. Delta+ was calculated using all insect species or the subset of Ephemeroptera, Plecoptera and Trichoptera (EPT) species from the bank and main channel habitats at 941 and 607 sites respectively. Samples from these sites were classified into 16 salinity categories (ranging from 0.05 to 30 mS cm-1). Delta+ values for the insects showed minor change and were close to the expected value until salinity levels reached 7-14.9 mS cm-1; at higher salinities delta+ declined and became significantly different from expectation. When EPT species were used trends were less consistent and the decline at higher salinities was weaker. Feeding group diversity within each salinity category declined more or less linearly as delta+ decreased.

Widespread damage to vegetation on an isolated oceanic island (Macquarie Island), due to overgrazing (since 2002) by an expanding exotic rabbit population, could affect the nature of catchment runoff and result in changes to stream habitats and the composition of their invertebrate communities. To test this hypothesis, stream invertebrate communities that had been sampled originally in 1992 (at 15 sites when rabbit numbers were historically low), were re-sampled in 2008 (17 sites) and in 2010 (12 sites). The number of taxa recorded at each site was 25–36% lower in 2008 (7.4 taxa per site) and in 2010 (8.7 taxa) than in 1992 (11.6 taxa) and an abundance index showed a substantial decline across most taxa. Ordination indicated that composition at all sites changed markedly between years. The greatest compositional changes occurred at sites exposed to moderate or severe levels of vegetation damage, suggesting that stream invertebrates responded to habitat changes associated with increased grazing. An altered input of organic material into the streams as a result of vegetation damage may have been responsible. If communities of stream invertebrates on isolated islands are degraded, then composition may be altered permanently, unless refuges are available.

We compiled a database on a priori selected traits for South-East Australian freshwater macroinvertebrate families and used this data for the development of a biotic indicator for the detection of the effects of salinisation on freshwater communities (SPEAR(salinity)) and for the adaptation of the existing SPEAR(pesticides) index for South-East Australian taxa. The SPEAR(salinity) indicator showed a reasonably high relationship (0.38≤r(2)≤0.5) with salinity in terms of logarithmic electrical conductivity (log EC) using field biomonitoring data from 835 pools and riffle sites in Victoria and South Australia. Several other biotic indexes that were calculated for comparison purpose exhibited a lower relationship with log EC. In addition, SPEAR(salinity) was the only indicator that did not respond to other water quality variables and was therefore most selective. We used log EC data and modelled pesticide exposure for sites in Victoria in concert with SPEAR(salinity) and the existing SPEAR(pesticides) index to assess whether pesticides interacts with effects of salinity on invertebrate communities and vice versa. No interaction with pesticides was found for the effect of log EC on SPEAR(salinity), whereas EC interacted with the estimated pesticide exposure on the invertebrate communities. To foster the development of further trait-based ecological indicators, we suggest a conceptual model that predicts response traits based on the disturbance regime and disturbance mode of action of the stressor. Biotic indicators based on a priori selected traits represent a promising biomonitoring tool even for regions where ecological information is scarce.

The risk of chemicals for ecological communities is often forecast with species sensitivity distributions (SSDs) which are used to predict the concentration which will protect p% of species (PCp value). However, at the PCp value, species richness in nature would not necessary be p% less than at uncontaminated sites. The definition of species richness inherent to SSDs (contaminant category richness) contrasts with species richness typically measured in most field studies (point richness). We determine, for salinity in eastern Australia, whether these definitions of stream macroinvertebrate species richness are commensurable. There were strong relationships (r2 ≥ 0.87) between mean point species, family and Ephemeroptera, Trichoptera and Plecoptera species richness and their respective contamination category richness. Despite differences in the definition of richness used by SSDs and field biomonitoring, their results in terms of relative species loss from salinity in south-east Australia are similar. We conclude that in our system both definitions are commensurable.

SUMMARY. 1. Recolonization rates of benthic invertebrates were estimated at five sites in the catchment of the Acheron River, in spring (October) and in summer (January), The sites ranged from those that experience short floods and high shear stress at the streambed (upstream sites) to those that experience prolonged floods and low shear stress (downstream sites). We hypothesized that these differences should affect recolonization rate. 2. In October, absolute rates of recolonization of taxa (number of taxa 0.05 m−2 d−1) onto 1-m2 patches of substratum, which had been raked to remove fauna, did not vary between the three sites studied, nor did the relative rates of recolonization of taxa (absolute rate/mean number of taxa in control samples, which were taken from adjacent undisturbed patches of substratum). Absolute rates of recolonization of individuals (number of individuals 0.05 m−2 d−1) were proportional to the mean number of individuals in control samples; relative rates of recolonization of individuals (absolute rate/mean number of individuals in control samples) did not vary between sites. 3. In January, absolute rates of recolonization either of taxa or individuals were positively correlated with the mean densities of taxa or individuals in control samples; relative rates did not vary between the four sites studied. 4. We conclude that the benthic invertebrate communities at the various sites do not adapt to variations in flooding regime by altering relative recolonization rates. Absolute recolonization rates are directly proportional to the prevailing number of taxa or individuals at a site.

The platypus (Ornithorhynchus anatinus) feeds almost exclusively on benthic macroinvertebrates, yet no attempt has been made to link its energy demands with the productivity of its benthic macroinvertebrate prey. In the upper Shoalhaven River, New South Wales, we estimated macroinvertebrate production (in 2009 and 2011) from benthic samples and recorded platypus diet (2009 only) from cheek pouch samples. Ephemeroptera, Trichoptera and Chironomidae were the most numerous of six major groups in both the cheek pouches and the benthic samples. Three other groups (Odonata, Coleoptera, Sphaeriidae) were much less abundant in the benthos, but Odonata were common in the cheek pouches. In both years the Ephemeroptera, Trichoptera and Chironomidae had levels of production that were an order of magnitude higher than those of the three other groups. Rank correlation indicated that the most productive taxa were those most likely to occur in the cheek pouches. Total macroinvertebrate production for the six groups varied from 7.8gDWm–2year–1 in 2009 to 13.1gDWm–2year–1 in 2011. Previous estimates of field metabolic demand of the platypus enabled calculation of the number that could be supported by a given level of production. The observed levels of production were sufficient to support 13–27 platypuses in 2009 and 22–45 in 2011 along a 1.5-km reach of the river. Despite considerable landscape change, productive foraging habitat persists in the upper Shoalhaven River.

Details of disciplinary action taken against doctors who work abroad are often difficult to track down, so it can be tempting for doctors with something to hide to try and conceal their history. Richard Marchant offers his view on the challenges facing medical regulators

Concentration of human populations with likely impacts of climate change present major challenges for river conservation in the south-eastern coastal region of Australia. Quantitative methods for spatial prioritisation of conservation actions can play a major role in meeting these challenges. We examined how these methods may be applied to help plan for potential impacts of climate change in the region, using macroinvertebrate assemblages as surrogates of river biodiversity. Environmental gradients explaining broad-scale patterns in the composition of macroinvertebrate assemblages are well represented in protected areas; however, their effectiveness for conserving river biodiversity with climate change depends on linking management inside and outside protected areas. Projected increases in temperature and sea level may be used to prioritise conservation to counter likely major impacts in high-altitude zones and the coastal fringes, whereas elsewhere, considerable uncertainty remains in the absence of better downscaled projections of rainfall. Applying such spatial prioritisations using biodiversity surrogates could help river-focussed conservation around the world.

In marine and freshwater invertebrate populations, microscale genetic differentiation or ‘genetic patchiness’ is thought to result from variation in the abundance and genetic composition of new recruits at a particular location. In the present study, the role of the adult emergence patterns in genetic patchiness was examined using mtDNA and two microsatellite loci to compare patterns of genetic differentiation in asynchronously (subtropical) and synchronously emerging (temperate) populations of the stone-cased caddisfly Tasimia palpata. A 550 base pair region of the mitochondrial cytochrome c oxidase subunit I gene (COI) was sequenced in at least 14 individuals from each population. Genetic structure was detected only at the reach scale in the subtropical populations and no genetic differentiation was detected in temperate populations. There were more deviations from Hardy–Weinberg equilibrium (HWE) in subtropical populations than in temperate populations where 44% and 12.5%, respectively, of tests for deviations from HWE were significant. Although distinct patterns of genetic structure and deviations from HWE were observed in the subtropical and temperate populations of T. palpata, no conclusive evidence was found to suggest that the differences are caused by differences in emergence patterns. We hypothesise that genetic patchiness must be caused by post-recruitment processes, most likely the preservation of oviposition ‘hotspots’ in subtropical streams.

Regional (RSR) and local species richness (LSR) was recorded for stream invertebrate communities at reference sites in 25 drainage basins in Victoria. Regional species richness was defined as the total number of species recorded at all reference sites within a basin, and LSR as the total numbers of species recorded at a single reference site. Records were obtained from bank and channel habitats and analysed separately. Regressions between LSR and RSR indicated a proportional or linear relationship in both habitats. This applied to the whole data set and to subgroups representing Ephemeroptera, Plecoptera and Trichoptera (EPT as a group), Hemiptera, Diptera, and Coleoptera. All data sets thus represented communities in which no upper limit to LSR was observed. Multiple regressions between LSR and RSR, number of samples per site (N) and seven physical variables showed that RSR and N were nearly always significantly related to LSR. Few of the physical variables were significant except conductivity (for EPT and Coleoptera). Multidimensional scaling ordinations revealed an east-west gradient in compositional similarity of invertebrates, upon which variations in RSR had a major influence. Investigation of factors that regulate RSR will thus be necessary for a broad scale view of what regulates LSR.

Benthic macroinvertebrates are commonly used to monitor the condition of rivers and streams. Predictive models and biological objectives used in environmental policies, two tools for assessing stream condition, rely on the assumption that the communities from which the invertebrates are derived are sufficiently stable or persistent over time for valid comparisons to be made with test sites sampled years afterwards. There has only been limited testing of this in Australia and there has been no formal programme established to assess long-term changes in aquatic ecosystems. In this paper, data sets collected from the Latrobe and Yarra river systems in south-eastern Australia, sampled over periods of up to 20 years between initial and final samplings, were examined. Using multivariate analyses, it was found that stream communities were persistent at the taxonomic level of family, but significant temporal changes were apparent using species-level data. Tests of rank abundance (Friedman's and Spearman rank correlation) gave mixed results but generally lead to the same conclusions. The implications of these results are discussed with regard to changes in faunal composition, stability of rank abundances, impacts on the use of predictive models and biological objectives, and possible links to major environmental features.

The efficiency of extraction of Agapetus larvae (Glossosomatidae : Trichoptera) from quantitative benthic samples was estimated by the use of two approaches: an indirect estimate based on the probability of missing a specimen in two scans of a sample (the two-count method) and a direct estimate derived by re-picking samples. Both approaches gave similar estimates for the probability of missing a specimen of a given size and both showed that this probability increased as size decreased; losses ranged from 6% to 30%. The two-count method thus provides a reliable way to compensate for these losses. Such corrections made little difference to conclusions concerning Agapetus population density, larval growth or secondary production derived from a previous study. However, when no corrections are applied, mortality estimates may be inaccurate if early instars are picked with less efficiency than later ones.

Data on undisturbed lotic macroinvertebrate communities were assembled from a number of studies carried out in Victoria over the past 15 years; species-level information for 40 sites on nine rivers was available. Ordination (DECORANA and semi-strong hybrid multidimensional scaling) and classification (flexible UPGMA and TWINSPAN) techniques were used to assess the similarity of community composition among the sites. Correlation of environmental variables with both ordinations indicated that factors related to altitude and substratum were the most obvious gradients; a conductivity gradient was also present. The classification analyses identified four groups of sites that matched the altitudinal trends evident in the ordinations; but these techniques did not emphasize the substratum gradient. TWINSPAN also identified six groups of taxa that were characteristic of particular altitudes or regions or were widespread across all sites. The distinctiveness of the patterns from this preliminary study indicates that it would be worthwhile extending these analyses to much larger data sets from Victorian rivers.

The activity of benthic invertebrates was monitored in the water column of slowly flowing backwaters of the Acheron River during summer. Samples were taken throughout 24 h on two occasions, and densities of fauna were compared with densities in drift samples taken concurrently in the main channel. Drift densities were generally higher than those in backwaters, but not by orders of magnitude. Also, drift densities displayed significant die1 variation, whereas densities in backwaters did not consistently show such a pattern. Species composition generally differed between the two habitats. This brief study demonstrates that benthic invertebrates do swim in the water column of stream backwaters and that they may use this opportunity for colonization.

The robustness of site groupings produced by ordination (DECORANA) and classification (TWINSPAN) techniques to variations in the quality of the raw data was investigated, using two data sets on macroinvertebrate communities from the La Trobe River. Ordinations or classifications based on the presence or absence of species were not substantially different from those based on actual abundance levels. However, when taxonomic discrimination was reduced from the species (or genus) level to the family level, distortions occurred in the resulting ordinations and classifications. In addition, ordinations based on 10 replicates per sample were little different from those based on a subset of 5 or 6 of these replicates; fewer than 4 replicates did not adequately represent the patterns present in the full data set.

Benthic macroinvertebrates were quantitatively sampled at four sites, one above (T6) and three (T14A, T16, T21A) downstream of the Thomson Dam, Victoria, Australia, for three summers after completion of dam construction in 1983. Community composition was compared with that recorded previously during dam construction to determine the effects of the main environmental consequences of the dam, viz the input of fine sediment (< 2mm grain size), the temporary release of cold hypolimnetic water during summer, and altered levels of discharge. Unnaturally low summer water temperatures were only recorded at the two sites immediately downstream of the dam (in order downstream T14A and T16). After water temperatures returned to normal summer levels, species richness increased at these sites. Levels of fine sediment increased in the surface layers of the riverbed at T16 but not at T14A. By the time this study began levels at T16 had been reduced almost to pre-dam levels. At T21A levels approximately tripled after completion of construction. At T14A and T16 marked increases in species richness occurred during this study whereas at T21A species richness did not change, and was lower than that recorded during dam construction. Ordination and classification of samples clearly displayed these changes in the benthic communities downstream of the dam and the lack of change at T6 above the dam. Altered discharge resulted in some loss of habitable area and thus total standing stock at T14A only.

SUMMARY. 1 Seventeen sites were each sampled six times over 2 years for macroinvertebrates. A range of physicochemical variables was also measured to determine which factors were related to the distribution of species. 2 Numerical classification of the faunal data indicated that four groups of sites or communities were distinguishable: lowland sites; sandy upland sites; cobble upland sites from the northern catchment; cobble upland sites from the southern catchment. 3 Multiple discriminant analysis and multiple regression analysis demonstrated that particle size of the sediment, concentration of dissolved ions and altitude were the physicochemical features that were most strongly associated with changes in the faunal distribution. 4 Abundances of shredders and predators did not vary between the site groups while those of scrapers, gatherers and filterers did: scrapers were most abundant at cobble sites while gatherers and filterers were least abundant on sand and increased in abundance downstream. The distribution of the feeding groups showed some similarity with that predicted by the River Continuum Concept, but the fact that the shredders did not decrease in abundance downstream was a notable difference. 5 Abundance of the total fauna at a site was inversely related to the amount of benthic organic matter. This feature is contrary to the pattern usually reported from rivers in the northern hemisphere.

Ingestion and assimilation of the brine shrimp Parartemia zietziana were measured in the field. Populations in Pink Lake and Lake Cundare were used; both lakes are shallow ( 60°/00), and located in western Victoria; they have tow primary production. P. zietziana relies largely on organic matter in lake sediment for food. Ingestion rate was measured in situ in Pink by following the uptake of 14C from labelled sediment. The rate of faecal pellet production was measured (in both lakes) by allowing animals to defaecate for 24 h in a net suspended in the lake. Ingestion rate varied from 0.35 to 13 01 × 10–1 mg dry wt h-1 individual-1 for a range in dry weight of shrimp from 0.2 to 2.3 mg individual-1; for a similar range in weight, defaecation varied from 0.08 to 2.03 × 10-1mg dry wt h-1 individual-1. These rates were converted to joules and assimilation efficiencies of 30–60% calculated. Regressions showed that change in dry weight of shrimp accounted for > 90% of the variance in both rates.

SUMMARY. The population density of the univoltine amphipod Gammarus pseudolimnaeus was estimated monthly from April 1977 to June 1978 along a 600-m reach using a form of removal sampling at 0.5, 1.5 and 2.5 m from the bank. The probability of catching an amphipod with three sweeps over an area of 0.15 m2 was 0.95. Drift and upstream migration were measured for 24 h, also monthly. Population density varied from 1600 m−2 (newly-hatched young in July) to 26 m−2 (adults) within 3 m of the bank with 95% confidence limits of 40–60% of the mean; density was highest < 1 m from the bank and beyond 3 m it declined to insignificant levels. No significant difference could be shown between the total catches in the drift and upstream nets over a year and there appeared to be no net migration of amphipods. Mean drift was 2 amphipods day−1. Growth was estimated from the length composition of monthly samples. Annual production (P) was 29.4 kg ha−1 for one generation of the amphipod with a P/B ratio of 4.65. Egg production accounted for only 2% of this estimate. Recruitment was calculated from regressions relating female length to clutch size and egg development time to temperature in the laboratory; mean temperature was measured in the field. Mortality was greatest in July at the beginning of the generation. It was high again in September and during winter; at these later times it was suggested that starvation occurred in addition to predation. Annual consumption (C) of organic matter for the generation calculated from published data on feeding rate was 1547 kg ha−1 which results in a P/C ratio of 1.9%.

SUMMARY. Oxygen consumption of P. zietziana was measured monthly in two saline (>60‰ salinity) lakes from November 1973 to November 1975 with short (

In the Acheron River, southern Victoria, patches of riffle substratum (ca 1 m2) were disturbed every 10 days by kicking and raking. After 20 days, i.e. three disturbances, a further set of patches was disturbed once. For the next 70 days macroinvertebrate dynamics were monitored in the two sets of disturbed patches and also in contiguous control patches. There were no differences in the temporal changes in total species richness, number of species per sample, densities of individuals, or species diversity (H’) between the two disturbance regimes. The composition of the fauna colonizing each disturbance regime was similar, and after 33 days the number of species per sample was similar in disturbed and control patches. The fauna appears to be well adapted to physical disturbance and current ideas linking species richness and disturbance cannot be readily applied to stream communities at the temporal and spatial scales of this experiment.

SUMMARY. The feeding rate of G. pseudolimnaeus was measured monthly for 7 months in the field by monitoring the decline in weight of gut contents when the amphipod was starved. This decline was modelled by an exponential regression of weight on time. As the amphipods appeared to be continuous feeders, feeding rate was calculated by multiplying the dry weight of a full gut by the specific rate of emptying, i.e., the slope of the exponential regression. Specific rate of emptying was independent of animal size, but increased with temperature. Therefore, food has a longer period in which to be digested at low temperatures, which suggests that assimilation efficiency may increase. However, the assimilation efficiency of amphipods feeding on decaying maple leaves in the laboratory was only 10% and did not vary with temperature. Ingestion and egestion rates were measured in the laboratory by weighing amounts eaten and defecated. The turnover time of the contents of a full gut in the laboratory often agreed very well with turnover time measured in the field, i.e., the reciprocal of the specific rate of emptying, thus confirming the use of an exponential regression.

Twenty-five patches (1 m2) of natural stream substratum in the Acheron River, Victoria, were physically disturbed by kicking and raking during winter 1986 and summer 1987. The macroinvertebrate composition of these disturbed patches was examined at various times over the following 71 days, and compared with adjacent undisturbed control patches sampled concurrently. The disturbance did not alter the particle-size distribution (> 150 μm) of the disturbed patches. Organic material was reduced in the disturbed patches by about 70% in each season, but returned to control levels within 21 days in winter and 8 days in summer. The total number of species, and the density of species and individuals were all significantly reduced by the disturbance. Recovery of species density was complete after 21 days during winter and 8 days during summer, and the density of individuals recovered after 71 days during winter and 8 days during summer. The differences were due to the slower colonization rate of Chironomidae in winter, either because of a lower drift rate, or a slower recovery of detritus in winter. Individual species showed variations in colonization patterns, most increasing steadily at various rates, with some declining after an initial rapid increase (e.g. Baetis pp.). In the latter case, the density changes were mirrored in the control patches, emphasizing the need to take control samples concurrently with experimental samples. In each season, the species remaining immediately following the disturbance, and those subsequently colonizing the disturbed patches were in the same rank order (Spearman Rank correlation) as their occurrence in the control patches, suggesting that no taxa were differentially affected by the treatment. No evidence was found to allow the application of the Intermediate Disturbance Hypothesis to explain species diversity at the scale of this study. It appears that current hypotheses developed to explain the relationship between diversity and disturbance in sessile communities do not apply to highly mobile communities in streams.

SUMMARY. 1. The contribution of drift to macroinvertebrate colonization was studied over 10 days using pairs of substratum-filled trays, one suspended above the streambed (and thus able to be colonized by drift only) and one buried flush with the streambed (and thus open to colonization from all directions). Trays were filled with sand, gravel or stones. 2. Colonization of sand-filled trays was rapid, being completed within 24h (i.e. no subsequent change in numbers of individuals per tray); colonization of gravel or stone-filled trays was not completed by the end of the experiment. 3. Drift contributed an average of 86% of the colonizing fauna of the sand-filled trays, 36% of the fauna of the gravel-filled trays and 25% of the fauna of the stone-filled trays. The low contribution of the drift to the gravel and stones is at odds with some studies which, using similar techniques, suggest that drift is the primary source of colonizing individuals. 4. Most individual species showed low contributions by drift to colonization, with the majority having contributions under 66%. 5. Distinct differences were noted between the fauna colonizing the sand-filled trays and those colonizing the gravel or stone-filled trays (which were similar). 6. Several species common in the drift were rare in the colonizing fauna and several species which were common colonizers were absent or rare in the drift.

SUMMARY. Assimilation budgets (i.e. assimilation = respiration + excretion + production) are presented for cohorts of P. zietziana in two salt lakes. Shrimps in Pink Lake had an assimilation rate of 1631.6 kJ m−2 year −1, those in Lake Cundare 212.1 kJ m−2 year−1. In both lakes, respiration accounted for 60–80% of assimilation. Assimilation rates for individuals (derived as assimilation = ingestion minus faecal output) are also given and compared with respiratory rates of individuals. The comparisons indicated that energy was often consumed at a higher rate by respiration than it could be supplied by assimilation. Starvation due to a low assimilation efficiency was suggested as a cause of the consistent mortality, variable growth rate of individuals and unpredictable recruitment which were characteristic of the cohorts of P. zietziana in both lakes. An analysis of mortality showed that the young had the poorest survival, as predicted by a theoretical model of a starving zooplankter and a comparison of the increase with weight of ingestion and respiration. Gross growth efficiency (production: assimilation) was 15–30%, about the same as published data on Anostracans. Net growth efficiency (production : consumption) was 5–12% and generally lower than published values reflecting the difficulty P. zietziana has in balancing its budget.