ORCID Profile
0000-0002-6540-3586
Current Organisations
University of Toronto
,
University of Plymouth
,
Murray Darling Basin Authority
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Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.WATRES.2012.10.015
Abstract: Planned indirect potable reuse water treated with advanced wastewater technologies (AWWT) to remove pollutants is increasingly being used to augment drinking water and groundwater supplies. While the treatment process substantially reduces the high nitrogen (N) and phosphorus (P) concentrations typically of wastewater, both nutrients can remain at concentrations and in biologically available forms that may stimulate phytoplankton growth in nutrient-deficient systems. This study examined the short-term effect of N plus P additions, at a range of concentrations, on phytoplankton growth and species composition in mesocosm experiments in a subtropical reservoir. Nitrate (NO(3)) plus orthophosphate (PO(4)) concentrations as low as 50 and 5 μg L(-1), respectively, resulted in significant increases in phytoplankton biomass, with a 3.99 μg L(-1) increase in chlorophyll a concentration with every 10 μg L(-1) increase in N plus 1 μg L(-1) in P. The system was likely to be co-limited because the addition of N or P alone did not result in increased chlorophyll a concentrations compared with the control. However, the toxic cyanobacterium, Cylindrospermopsis raciborskii, had higher growth rates with P addition alone. This study has shown that inputs of AWWT water have the potential to increase the phytoplankton biomass in this subtropical reservoir, at least in the short term. Therefore, the effect of AWWT water on water quality in reservoirs should be further investigated before widespread application occurs.
Publisher: Wiley
Date: 22-04-2012
DOI: 10.1002/ECO.1270
Publisher: Cambridge University Press
Date: 26-03-2015
Publisher: Wiley
Date: 22-02-2019
DOI: 10.1002/AQC.3051
Publisher: Springer Science and Business Media LLC
Date: 12-1992
DOI: 10.1007/BF00006082
Publisher: Wiley
Date: 18-01-2012
DOI: 10.1002/RRA.1483
Publisher: Canadian Science Publishing
Date: 10-1989
DOI: 10.1139/F89-224
Abstract: Stable isotope analysis was used to identify the major sources of carbon utilized by fish and aquatic invertebrates in the Koroc River, a tundra river system in northern Quebec. Juvenile arctic char (Salvelinus alpinus), together with adults and juveniles of other species of fish in freshwater, obtained their carbon from either allochthonous or autochthonous sources within the river system, via the invertebrate fauna. However, adult anadromous char caught in the river clearly derived their biomass carbon from feeding at sea. Despite the limited development of riparian vegetation throughout much of the lower river catchment, terrestrial organic matter was the most likely source of energy fueling the animal communities of small tributary streams and rapids of the mainstem Koroc. In contrast, epilithic algae made a significant contribution to food chains within Alik Lake, a deep basin along the main river channel. Aquatic mosses appeared to be of, at most, tertiary importance as a source of energy to the animal communities of the lake, despite their considerable biomass.
Publisher: Springer Science and Business Media LLC
Date: 12-04-2018
DOI: 10.1007/S00442-018-4138-Y
Abstract: Mixing models have become requisite tools for analyzing biotracer data, most commonly stable isotope ratios, to infer dietary contributions of multiple sources to a consumer. However, Bayesian mixing models will always return a result that defaults to their priors if the data poorly resolve the source contributions, and thus, their interpretation requires caution. We describe an application of information theory to quantify how much has been learned about a consumer's diet from new biotracer data. We apply the approach to two ex le data sets. We find that variation in the isotope ratios of sources limits the precision of estimates for the consumer's diet, even with a large number of consumer s les. Thus, the approach which we describe is a type of power analysis that uses a priori simulations to find an optimal s le size. Biotracer data are fundamentally limited in their ability to discriminate consumer diets. We suggest that other types of data, such as gut content analysis, must be used as prior information in model fitting, to improve model learning about the consumer's diet. Information theory may also be used to identify optimal s ling protocols in situations where s ling of consumers is limited due to expense or ethical concerns.
Publisher: Michigan State University Press
Date: 04-2005
DOI: 10.1080/14634980590953211
Abstract: Intensive recreational use of oligotrophic lakes can lead to increases in epilimnetic nutrient concentrations (through direct inputs from urine or re-suspension of sediments) and the development of undesirable algal blooms. Despite these adverse ecological responses to tourist activities, many lake monitoring programs do not address tourist nutrient inputs at appropriate spatial and temporal scales. This paper presents results of investigations aimed at detecting the effects of nutrient inputs to perched dune lakes on Fraser Island, principally through within-lake comparisons of nutrient and algal variables. Nutrient concentrations and algal biomass were measured in heavily visited (disturbed) and inaccessible (reference) sites within five perched dune lakes on Fraser Island, Australia, during the summer of 1999/2000. Whilst nutrient and phytoplankton chlorophyll a concentrations did not differ between sites, periphyton chlorophyll a concentrations were occasionally significantly higher in disturbed sites than in reference sites, particularly in the very popular clear lakes, suggesting that algal growth may be enhanced by tourist activities. Experimental manipulations of nitrogen and phosphorus concentrations in algal (phytoplankton and periphyton) bioassays were undertaken in each lake over the 2000/2001 summer, to assess algal responses to nutrient additions. The response of phytoplankton communities to nutrient additions varied greatly between lakes, with evidence of limitation or co-limitation by nitrogen and phosphorus in all systems. Periphyton biomass showed similar trends to phytoplankton in some lakes, but these were not significant. Nutrients added to lakes by tourists are likely to be rapidly assimilated by littoral zone periphyton communities in these oligotrophic lakes. As a result, impacts of tourism are not likely to be detected by traditional measurements of open water nutrient and phytoplankton chlorophyll a concentrations. Instead, measurement of periphyton growth and/or biomass (chlorophyll a) in the littoral zone might be the most spatially and temporally relevant indicator of tourist impacts in these lakes.
Publisher: Wiley
Date: 07-2005
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.09.219
Abstract: Understanding the sources of sediment, organic matter and nitrogen (N) transferred from terrestrial to aquatic environments is important for managing the deleterious off-site impacts of soil erosion. In particular, investigating the sources of organic matter associated with fine sediment may also provide insight into carbon (C) and N budgets. Accordingly, the main sources of fine sediment, organic matter (indicated by total organic carbon), and N are determined for three nested catchments (2.5km
Publisher: MDPI AG
Date: 19-06-2013
DOI: 10.3390/W5020780
Publisher: Wiley
Date: 15-12-2010
Publisher: Elsevier BV
Date: 12-2013
Publisher: Wiley
Date: 03-1995
Publisher: Wiley
Date: 02-08-2013
DOI: 10.1002/HYP.9974
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/ZO9840097
Abstract: Four species of stoneflies, all Gripopterygidae, are now known from Western Australia. Riekoperla occidentalis, sp. nov., is described, together with its nymph. The nymphs of Leptoperla australica and Newmanoperla exigua are described for the first time, and sufficient descriptions and figures are given of the adults to provide for their ready identification. The adults of a poorly known species of Dinotoperla from Mingenew are also described and compared with D. bassae from Victoria, which it resembles. It is possible that this is the only species that is not endemic to Western Australia.
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/MF96055
Abstract: In-stream ecosystem processes in a tropical lowland stream in far north Queensland were studied by measuring open-system community metabolism and analysing stable isotopes. The stream catchment, like many others in this region, has been extensively cleared for the cultivation of sugar cane, and in the absence of riparian shading, aquatic and semi-aquatic plants choke the stream channel. Stream community metabolism switched between autotrophy and heterotrophy, depending on the degree of cloud cover. Successive cloudy days may be sufficient to result in anoxia in the stream, particularly in the benthos, where limited oxygen penetration into the sediments was recorded. Stable-isotope data indicated that little of the primary production from sugar cane or other C4 plants was transferred into the aquatic food web. The only significant contribution of C4 carbon was to the diets of some larger predatory fish, which must be directly dependent on terrestrial prey. In the absence of significant riparian inputs of C3 carbon, it appears that in-stream primary production supported the aquatic invertebrate community. Restoration of disturbed stream systems such as this one must include the establishment of appropriate riparian species for the reduction of excessive in-stream primary production and the supply of detritus for the maintenance of aquatic food webs.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.SCITOTENV.2011.11.022
Abstract: Little is known about the threat of mercury (Hg) to consumers in food webs of Australia's wet-dry tropics. This is despite high concentrations in similar biomes elsewhere and a recent history of gold mining that could lead to a high degree of exposure for biota. We analysed Hg in water, sediments, invertebrates and fishes in rivers and estuaries of north Queensland, Australia to determine its availability and biomagnification in food webs. Concentrations in water and sediments were low relative to other regions of Hg concern, with only four of 138 water s les and five of 60 sediment s les above detection limits of 0.1μgL(-1) and 0.1μgg(-1), respectively. Concentrations of Hg in fishes and invertebrates from riverine and wetland food webs were well below international consumption guidelines, including those in piscivorous fishes, likely due to low baseline concentrations and limited rates of biomagnification (average slope of log Hg vs. δ(15)N=0.08). A large fish species of recreational, commercial, and cultural importance (the barramundi, Lates calcarifer), had low concentrations that were below consumption guidelines. Observed variation in Hg concentrations in this species was primarily explained by age and foraging location (floodplain vs. coastal), with floodplain feeders having higher Hg concentrations than those foraging at sea. These analyses suggest that there is a limited threat of Hg exposure for fish-eating consumers in this region.
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.JENVMAN.2014.12.048
Abstract: As efforts intensify to address the issues of declining water quality and bio ersity losses in freshwater ecosystems, there have been great demands for effective methods of evaluating aquatic ecosystem health. In this study, benthic algae assemblages and water quality variables were analyzed to develop a benthic diatom-based index of biotic integrity (BD-IBI) for assessment of the aquatic environment in the upper Han River (China). Through the use of multivariate and multimetric approaches, four metrics - % prostrate in iduals, % Amphora in iduals, % polysaprob species, and diatom-based eutrophication ollution index (EPI-D) - were identified from 98 candidate metrics to develop a BD-IBI. Application of the index revealed that water quality in 11% of the 31 s led sites could be described as excellent condition, in 43% of the sites it could be described as good condition, in 25% as moderate condition, and in 21% as poor condition. The assessment further revealed that the main reason for degradation of the Han river ecosystem was nutrient enrichment through agricultural land use.
Publisher: Springer Science and Business Media LLC
Date: 31-01-2018
DOI: 10.1038/S41598-018-19918-6
Abstract: The trophic position of a top predator, synonymous with food-chain length, is one of the most fundamental attributes of ecosystems. Stable isotope ratios of nitrogen ( δ 15 N) have been used to estimate trophic position of organisms due to the predictable enrichment of 15 N in consumer tissues relative to their diet. Previous studies in crocodilians have found upward ontogenetic shifts in their ‘trophic position’. However, such increases are not expected from what is known about crocodilian diets because ontogenetic shifts in diet relate to taxonomic categories of prey rather than shifts to prey from higher trophic levels. When we analysed dietary information from the literature on the four Amazonian crocodilians, ontogenetic shifts in dietary-based trophic position (TP diet ) were minimal, and differed from those estimated using δ 15 N data (TP SIA ). Thus, ontogenetic shifts in TP SIA may result not only from dietary assimilation but also from trophic discrimination factors (TDF or Δ 15 N) associated with body size. Using a unique TDF value to estimate trophic position of crocodilians of all sizes might obscure conclusions about ontogenetic shifts in trophic position. Our findings may change the way that researchers estimate trophic position of organisms that show orders of magnitude differences in size across their life span.
Publisher: Wiley
Date: 14-11-2011
Publisher: IWA Publishing
Date: 10-2006
DOI: 10.2166/WP.2006.057
Abstract: Sustainable water resource management is constrained by three pervasive myths that societal and environmental water demands always compete with one another that technological solutions can solve all water resource management problems and that environmental solutions to protect and maintain freshwater resources are more expensive and less dependable than technological solutions. We argue that conservation and good stewardship of water resources can go a long way toward meeting societal demands and values. Furthermore, water requirements to sustain ecosystem health and bio ersity in rivers and their associated coastal systems can be well aligned with options for human use and deliver a suite of ecosystem goods and services to society. However, to achieve ecologically sustainable water management, we propose several key issues that must be addressed. The objective of this opinion paper is to stimulate discussion across traditional discipline boundaries with the aim of forging new partnerships and collaborations to meet this pressing challenge of ecologically sustainable water management.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 31-07-2015
Publisher: University of Chicago Press
Date: 12-2016
DOI: 10.1086/688667
Publisher: Wiley
Date: 20-06-2017
DOI: 10.1111/FWB.12956
Publisher: Wiley
Date: 16-05-2008
DOI: 10.1111/J.1365-2656.2008.01394.X
Abstract: 1. Lipids have more negative delta(13)C values relative to other major biochemical compounds in plant and animal tissues. Although variable lipid content in biological tissues alters results and conclusions of delta(13)C analyses in aquatic food web and migration studies, no standard correction protocol exists. 2. We compared chemical extraction and mathematical correction methods for freshwater and marine fishes and aquatic invertebrates to better understand impacts of correction approaches on carbon (delta(13)C) and nitrogen (delta(15)N) stable isotope data. 3. Fish and aquatic invertebrate tissue delta(13)C values increased significantly following extraction for almost all species and tissue types relative to nonextracted s les. In contrast, delta(15)N was affected for muscle and whole body s les from only a few freshwater and marine species and had a limited effect for the entire data set. 4. Lipid normalization models, using C : N as a proxy for lipid content, predicted lipid-corrected delta(13)C for paired data sets more closely with parameters specific to the tissue type and species to which they were applied. 5. We present species- and tissue-specific models based on bulk C : N as a reliable alternative to chemical extraction corrections. By analysing a subset of s les before and after lipid extraction, models can be applied to the species and tissues of interest that will improve estimates of dietary sources using stable isotopes.
Publisher: Public Library of Science (PLoS)
Date: 16-07-2018
Publisher: Wiley
Date: 14-06-2017
DOI: 10.1111/FWB.12952
Publisher: Wiley
Date: 06-1990
Publisher: Springer Science and Business Media LLC
Date: 10-2002
DOI: 10.1007/S00267-002-2737-0
Abstract: The flow regime is regarded by many aquatic ecologists to be the key driver of river and floodplain wetland ecosystems. We have focused this literature review around four key principles to highlight the important mechanisms that link hydrology and aquatic bio ersity and to illustrate the consequent impacts of altered flow regimes: Firstly, flow is a major determinant of physical habitat in streams, which in turn is a major determinant of biotic composition Secondly, aquatic species have evolved life history strategies primarily in direct response to the natural flow regimes Thirdly, maintenance of natural patterns of longitudinal and lateral connectivity is essential to the viability of populations of many riverine species Finally, the invasion and success of exotic and introduced species in rivers is facilitated by the alteration of flow regimes. The impacts of flow change are manifest across broad taxonomic groups including riverine plants, invertebrates, and fish. Despite growing recognition of these relationships, ecologists still struggle to predict and quantify biotic responses to altered flow regimes. One obvious difficulty is the ability to distinguish the direct effects of modified flow regimes from impacts associated with land-use change that often accompanies water resource development. Currently, evidence about how rivers function in relation to flow regime and the flows that aquatic organisms need exists largely as a series of untested hypotheses. To overcome these problems, aquatic science needs to move quickly into a manipulative or experimental phase, preferably with the aims of restoration and measuring ecosystem response.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Springer Science and Business Media LLC
Date: 29-09-2010
DOI: 10.1038/NATURE09440
Abstract: Protecting the world's freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and bio ersity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the world's population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes bio ersity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater bio ersity.
Publisher: Springer Science and Business Media LLC
Date: 28-11-2016
DOI: 10.1007/S00442-016-3786-Z
Abstract: Food web subsidies from external sources ("allochthony") can support rich biological ersity and high secondary and tertiary production in aquatic systems, even those with low rates of primary production. However, animals vary in their degree of dependence on these subsidies. We examined dietary sources for aquatic animals restricted to refugial habitats (waterholes) during the dry season in Australia's wet-dry tropics, and show that allochthony is strongly size dependent. While small-bodied fishes and invertebrates derived a large proportion of their diet from autochthonous sources within the waterhole (phytoplankton, periphyton, or macrophytes), larger animals, including predatory fishes and crocodiles, demonstrated allochthony from seasonally inundated floodplains, coastal zones or the surrounding savanna. Autochthony declined roughly 10% for each order of magnitude increase in body size. The largest animals in the food web, estuarine crocodiles (Crocodylus porosus), derived ~80% of their diet from allochthonous sources. Allochthony enables crocodiles and large predatory fish to achieve high biomass, countering empirically derived expectations for negative density vs. body size relationships. These results highlight the strong degree of connectivity that exists between rivers and their floodplains in systems largely unaffected by river regulation or dams and levees, and how large iconic predators could be disproportionately affected by these human activities.
Publisher: Canadian Science Publishing
Date: 09-2001
DOI: 10.1139/F01-113
Abstract: Dendritic channel patterns have the potential to isolate populations within drainages, depending on the relative position within the stream hierarchy of the populations. We investigated the extent of genetic sub ision in the Australian freshwater fish Pseudomugil signifer (Kner) (Pseudomugilidae) from two drainages in northern Queensland, Australia, using allozyme techniques. The drainages were adjacent and had similar channel patterns each with two major subcatchments coalesced to an estuarine confluence. Analysis of 30 sites across the two drainages revealed that although there was significant genetic variation among sites in both drainages, this was not between the two subcatchments in either case. This result did not support predictions of the stream hierarchy model (SHM), which would predict higher levels of variation among subcatchments than within them, nor did it suggest that estuarine conditions represent a significant barrier to dispersal in this species. More variation was among sites within each subcatchment. Multidimensional scaling plots revealed that, although most sites within a drainage were similar to one another, outlier sites occurred in each drainage, so correlations between genetic distance and geographic distance were weak. We suggest that the distance between sites and the probability of connectivity between sites may better explain the observed distribution of genetic ersity.
Publisher: Public Library of Science (PLoS)
Date: 06-06-2018
Publisher: Wiley
Date: 21-04-2017
DOI: 10.1111/BTP.12445
Publisher: Wiley
Date: 16-08-2007
Publisher: Wiley
Date: 08-1999
Publisher: CSIRO Publishing
Date: 1995
DOI: 10.1071/MF9951101
Abstract: Aspects of invertebrate drift were investigated in four small rainforest streams in south-eastern Queensland. Hourly s ling in two streams revealed low drift rates and no distinct diel patterns. This may have been a consequence of the low flows experienced during the study period. The drift was dominated by Simuliidae, Chironomidae and to a lesser extent Tasmanocoenis sp. (Caenidae) and Cheumatopsyche sp. 6 (Hydropsychidae). Additional studies were undertaken to examine why some in iduals of particular taxa drift while others (of the same taxa) remain in or on the substratum. Analysis of the relative gut fullness of simuliid and chironomid larvae showed that a higher proportion of non-drifting in iduals had full or nearly full guts compared with those in the drift. Hungrier in iduals of these two taxa may enter the drift as a food searching mechanism. An analysis of limb loss of hexapod nymphs indicated that a disproportionate number of in iduals in the drift had one or more limbs missing compared with those that remained in the benthos. These data support the hypothesis that invertebrates present in the drift are less fit than non-drifters.
Publisher: Wiley
Date: 19-03-2014
DOI: 10.1002/HYP.10192
Publisher: Springer Science and Business Media LLC
Date: 09-04-2006
Publisher: Wiley
Date: 20-07-2006
Publisher: Hindawi Limited
Date: 2004
Publisher: Springer Science and Business Media LLC
Date: 16-11-2020
DOI: 10.1007/S10750-020-04445-1
Abstract: The River Continuum Concept implies that consumers in headwater streams have greater dietary access to terrestrial basal resources, but recent studies have highlighted the dietary importance of high-quality algae. Algae provide consumers with physiologically important omega-3 (n-3) polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA). However, terrestrial plants and most benthic stream algae lack the long-chain (LC) n-3 PUFA docosahexaenoic acid (DHA, 22:6n-3), which is essential for neural development in fish and other vertebrates. We s led subalpine streams to investigate how the PUFA composition of neural (brain and eyes), muscle, and liver tissues of freshwater fish is related to their potential diets (macroinvertebrates, epilithon, fresh and conditioned terrestrial leaves). The PUFA composition of consumers was more similar to epilithon than to terrestrial leaves. Storage lipids of eyes most closely resembled dietary PUFA (aquatic invertebrates and algae). However, DHA and arachidonic acid (ARA, 20:4n-6) were not directly available in the diet but abundant in organs. This implies that algal PUFA were selectively retained or were produced internally via enzymatic PUFA conversion by aquatic consumers. This field study demonstrates the nutritional importance of algal PUFA for neural organs in aquatic consumers of headwater regions.
Publisher: Wiley
Date: 15-12-2010
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/MF97013
Abstract: Biffarius arenosus had a mean δ13C of –15·4 ± 0·2‰ and a mean δ15N of 5·9 ± 0·1‰ (n = 38), and Trypea australiensis had a mean δ13C of –16·3 ± 0·3 and a mean δ15N of 7·6 ± 0·1 (n = 20). The δ13C signatures of the only mangrove species present (Avicennia marina) and the most abundant saltmarsh plant (Sarcocornia quinqueflora) indicated that they were not major food sources. Seagrasses, predominantly Heterozostera tasmanica, had mean δ13C and δ15N values of –11·7 ± 0·2‰ (n = 65) and 3·9 ± 0·2‰ (n = 62), respectively. Seagrass epiphytes had mean δ13C and δ15N values of –17·9 ± 0·4‰ and 4·6 ± 0·3‰ (n = 27), respectively. A mixture of seagrasses and their epiphytes was the most likely source of organic carbon for B. arenosus. Benthic microalgae, such as diatoms, were a possible food source, but phospholipid biomarkers indicated a meagre abundance of diatoms in the sediments, and microscopy of shrimp guts revealed few or no diatom frustules. For T. australiensis, food sources were less easily distinguished than for B. arenosus, but they could include seagrass epiphytes plus the green macroalgae Enteromorpha spp. and/or the brown alga Chordaria cladisiphon.
Publisher: Cambridge University Press
Date: 11-09-2008
Publisher: Wiley
Date: 07-10-2022
DOI: 10.1111/FWB.13995
Abstract: Freshwater ecosystems are subjected to a broad range of anthropogenic threats. Understanding the responses of aquatic biota to these threats and identifying potential mitigating actions presents a major challenge for ecologists and natural resource managers. Here, we investigated the responses of fish communities to land use change at different scales. We assessed patterns of food web structure of fish across a gradient of human impacts in the Atlantic Forest ecoregion of southeast Brazil. We analysed stomach contents of fish and evaluated the response of five food web metrics to variation in land use change. We also calculated four metrics for intra‐guild comparisons in the omnivore, insectivore, and algivore–insectivore guilds. The proportional abundance of omnivores increased as temperature increased and canopy cover decreased. Food web specialisation decreased in deforested streams with higher nutrient input, suggesting higher resource sharing by those fish communities. Fish in the algivore–insectivore guild consumed fewer types of macroinvertebrates in streams with low canopy cover. The opposite pattern was observed within the insectivore guild with in iduals consuming a larger variety of prey in impacted streams. Deforestation, and increases in water temperature and nutrient input, influenced inter‐species and intra‐guild trophic interactions in fish communities in these Atlantic Forest streams, even though the richness of fish community and composition of intra‐guild species remained unchanged. Some food web metrics were sensitive to the direct and indirect effects of disturbance on these fish communities. Our study has shown that assessments of trophic interactions can detect the effects of land‐use disturbance on fish communities that may not be evident from simple measures of species richness and composition. This approach provides direct insights into the functional integrity of fish communities and should be considered for monitoring the success of programmes aimed to protect and, where necessary, restore freshwater ecosystems.
Publisher: Elsevier BV
Date: 08-2007
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09107
Abstract: Debate exists about the effects of hydrological variation on food web dynamics and the relative importance of different sources of organic carbon fuelling food webs in floodplain rivers. Stable carbon isotope analyses and ecological stoichiometry were used to determine the basal sources in dry season macroinvertebrate food webs in two floodplain river systems of Australia’s wet–dry tropics that have contrasting flow regimes. Algae, associated with phytoplankton and biofilm, were the primary food source, potentially contributing % organic carbon to the biomass of a wide range of primary and secondary consumers. However, many consumers assimilated other sources in addition to algae, e.g. detritus from local C3 riparian vegetation. Food webs were characterised by substantial flexibility in the number and types of sources identified as important, which was indicative of generalist feeding strategies. These findings suggest ‘dynamic stability’ in the food webs, which imparts resilience against natural disturbances like flow regime seasonality and variation in hydrological connectivity. This adaptation may be characteristic of macroinvertebrate assemblages in highly seasonal river systems or in those with high levels of flow variability.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF12114
Abstract: The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF10211
Abstract: Despite prior studies showing good agreement between fin and muscle isotope ratios in temperate fishes, the non-lethal method of fin s ling has yet to become a standard technique in isotopic food-web studies, and the relationship between the two tissues has never been tested in the tropics. We hypothesised that fin and muscle δ13C and δ15N would be strongly correlated in tropical fishes, thus allowing non-lethal s ling of these species. To test this hypothesis, we analysed fin and muscle tissues from 174 tropical fishes representing 27 species from the Mitchell River, Queensland, Australia. Fin tissue was a strong predictor of muscle-tissue δ13C (r2 = 0.91 for all species) and was slightly enriched in 13C (0.9‰), consistent with the results of studies on temperate species. Fin tissue was a poorer predictor of muscle-tissue δ15N (r2 = 0.56 for all species) although the mean difference between the tissues was small ( .1‰). Differences were smallest in the largest fish, possibly because the elemental composition (%N) of fin more closely resembled that of muscle. These measurements provide more impetus for increased use of fin tissue as a non-destructive means of testing hypotheses about fish food webs in the tropics and elsewhere.
Publisher: Wiley
Date: 06-05-2018
DOI: 10.1002/LNO.10818
Publisher: Wiley
Date: 30-09-2011
Publisher: Wiley
Date: 02-1986
Publisher: Wiley
Date: 05-09-2003
DOI: 10.1046/J.1365-294X.2003.01941.X
Abstract: Molecular (mitochondrial DNA, isozyme) and morphological ersity of freshwater mussels (Family Hyriidae) was examined at 21 sites encompassing four large river systems, across southwest Queensland, Australia. Evidence was found for two major morphological groups. One group, which occurred in every river system, closely matched a recognized species (Velesunio ambiguus) both morphologically and in a well-supported lineage within a mitochondrial phylogeny generated from partial cytochrome c oxidase subunit I (COI) sequences. The second group most closely matched Velesunio wilsonii in shell morphology but formed three deeply ergent mitochondrial DNA lineages. All four lineages occurred sympatrically in some areas and displayed corresponding fixed differences at nuclear allozyme loci, which suggests an absence of recent hybridization and the presence of separate species.
Publisher: Springer Science and Business Media LLC
Date: 31-05-2023
DOI: 10.1038/S41586-023-06083-8
Abstract: The stability and resilience of the Earth system and human well-being are inseparably linked 1–3 , yet their interdependencies are generally under-recognized consequently, they are often treated independently 4,5 . Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice) 4 . The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.
Publisher: Wiley
Date: 23-08-2022
DOI: 10.1002/AQC.3871
Abstract: The hydrological variability of intermittent streams means that the spatial distribution of dry‐season aquatic refuges within river networks and the temporal dynamics of hydrological connectivity between them are critical for the persistence of aquatic bio ersity. Here, a new approach is demonstrated to identify surface water bodies as priority refuges for efficient conservation management of freshwater bio ersity in intermittent stream networks. Recently developed models of surface water extent and daily streamflow were used to represent spatio‐temporal variations in hydrological connectivity and surface water persistence within river networks of eastern Australia over a 107‐yr period. Using this information, systematic conservation planning was applied to prioritize aquatic areas for conservation of 25 fish species under two scenarios. One scenario identified priority refuges to complement those already occurring in protected areas, whereas the other did not consider protected area status. The priority networks identified concentrated on the main stems of river catchments where surface water was more likely to be persistent and aquatic refuges were more likely to be connected, but also included headwaters for rare fish species. All three set conservation targets for the 25 fish species can be met in the best solution of priority networks. Although the second scenario achieved the targets with a smaller size of priority network overall, it required more new aquatic refuges and was thus less efficient than the first scenario. The newly developed datasets are useful for freshwater conservation prioritization because they account for hydrological variability of intermittent streams. The systematic prioritization approach applied is transferable to other regions and freshwater taxa to identify aquatic refuges for bio ersity conservation within intermittent stream systems.
Publisher: American Chemical Society (ACS)
Date: 02-07-2019
DOI: 10.1021/ACS.ANALCHEM.9B01697
Abstract: The analysis of circulating tumor cells (CTCs) provides a means to collect information about the evolving properties of a tumor during cancer progression and treatment. For patients with metastatic prostate cancer, noninvasive serial measurements of bloodborne cells may provide a means to tailor therapeutic decisions based on an in idual patient's response. Here, we used a high-sensitivity profiling approach to monitor CTCs in patients with metastatic castrate-resistant prostate cancer (mCRPC) undergoing treatment with abiraterone and enzalutamide, two drugs used to treat advanced prostate cancer. The capture and profiling approach uses antibody-functionalized magnetic nanoparticles to sort cells according to protein expression levels. CTCs are tagged with magnetic nanoparticles conjugated to an antibody specific for the epithelial cell adhesion molecule (EpCAM) and sorted into four zones of a microfluidic device based on EpCAM expression levels. Our approach was compared to the FDA-cleared CellSearch method, and we demonstrate significantly higher capture efficiency of low-EpCAM cells compared to the commercial method. The nanoparticle-based approach detected CTCs from 86% of patients at baseline, compared to CellSearch which only detected CTCs from 60% of patients. Patients were stratified as prostate specific antigen (PSA) progressive versus responsive based on clinically acceptable definitions, and it was observed that patients with a limited response to therapy had elevated levels of androgen receptor variant 7 (ARV7) and the mesenchymal marker, N-cadherin, expressed on their CTCs. In addition, these CTCs exhibited lower EpCAM expression. The results highlight features of CTCs associated with disease progression on abiraterone or enzalutamide, including mesenchymal phenotypes and increased expression levels of ARV7. The use of a high-sensitivity method to capture and profile CTCs provides more informative data concerning the phenotypic properties of these cells as patients undergo treatment relative to an FDA-cleared method.
Publisher: Wiley
Date: 2010
Publisher: Wiley
Date: 21-12-2018
DOI: 10.1111/FWB.13238
Publisher: Wiley
Date: 26-12-2014
DOI: 10.1002/RRA.2630
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/MF04050
Abstract: Freshwater catchments of south-east Australia possess generally rich and erse macroinvertebrate faunas, although the genetic structuring of these assemblages is poorly known. In this study, we assessed mitochondrial phylogenetic structure within four genera of macroinvertebrates from the Sydney Water Supply Catchment, south-east Australia: Euastacus (parastacid crayfish), Cheumatopsyche (hydropsychid caddisflies), Atalophlebia (leptophlebiid mayflies) and Paratya (atyid shrimp), with a view to prioritising areas of high ersity for future conservation efforts. We found extremely ergent (≈4–19%) cytochrome c oxidase subunit I (COI) lineages within all surveyed groups, many of which corresponded to recognised taxa, although there was also evidence of cryptic species within three genera Euastacus, Atalophlebia and Paratya. Distributions of these three genera were associated with high altitude streams, above dam impoundments. Our results have important implications for management of the Sydney Water Supply Catchment. Future disturbance in this region is likely to be high and priority should be directed towards preserving the ersity of fauna in these upland areas. This comparative phylogenetic approach may have value as a means to focus and direct conservation efforts in other areas supporting high bio ersity.
Publisher: Wiley
Date: 29-03-2012
DOI: 10.1890/110136
Publisher: Springer Science and Business Media LLC
Date: 10-1993
DOI: 10.1007/BF00318034
Publisher: Wiley
Date: 19-08-2021
Abstract: There is growing recognition of the importance of food quality over quantity for aquatic consumers. In streams and rivers, most previous studies considered this primarily in terms of the quality of terrestrial leaf litter and importance of microbial conditioning. However, many recent studies suggest that algae are a more nutritional food source for riverine consumers than leaf litter. To date, few studies have quantified longitudinal shifts in the nutritional quality of basal food resources in river ecosystems and how these may affect consumers. We conducted a field investigation in a subalpine river ecosystem in Austria to investigate longitudinal variations in diet quality of basal food sources (submerged leaves and periphyton) and diet source dependence of stream consumers (invertebrate grazers, shredders, filterers and predators, and fish). Fatty acid (FA) profiles of basal food sources and their consumers were measured. Our results indicate systematic differences between the FA profiles of terrestrial leaves and aquatic biota, that is periphyton, invertebrates and fish. Submerged leaves contained very low proportions of long‐chain polyunsaturated fatty acids (LC‐PUFAs), which were conversely rich in aquatic biota. While the FA composition of submerged leaves remained similar among sites, the LC‐PUFAs of periphyton increased longitudinally, which was associated with increasing nutrients from upstream to downstream. Longitudinal variations in periphyton LC‐PUFAs were reflected in the LC‐PUFAs of invertebrate grazers and shredders, and further tracked by invertebrate predators and fish. However, brown trout Salmo trutta contained a large proportion of docosahexaenoic acid (DHA, 22:6ω3), a LC‐PUFA almost entirely missing in basal sources and invertebrates. The fish accumulated eicosapentaenoic acid (EPA, 20:5ω3) from invertebrate prey and may use this FA to synthesize DHA. Our results provide a nutritional perspective for river food web studies, emphasizing the importance of algal resources to consumer somatic growth and the need to account for the longitudinal shifts in the quality of these basal resources.
Publisher: Springer Science and Business Media LLC
Date: 02-2016
Publisher: Wiley
Date: 24-09-2010
DOI: 10.1002/HYP.7853
Publisher: Wiley
Date: 17-03-2003
Publisher: Wiley
Date: 09-2001
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF11021
Abstract: Fish living in highly variable and unpredictable environments need to possess life-history strategies that enable them to survive environmental extremes such as floods and drought. We used the length–frequency distributions of multiple fish species in multiple seasons and highly variable hydrological conditions to infer antecedent breeding behaviour in rivers of far-western Queensland, Australia. Hypotheses tested were as follows: (1) recruitment of some or all species of fish would occur within waterholes during no-flow periods (2) there would be seasonal recruitment responses in some fish species (3) recruitment of some species would be enhanced by channel flows and/or flooding. Hydrology and the incidence of flooding were highly variable across the study area during 2006–2008. Flood-influenced recruitment was evident for Hyrtl's tandan, Barcoo grunter and Welch's grunter. Silver tandan, golden goby, Cooper Creek catfish and Australian smelt showed evidence of seasonal recruitment unrelated to antecedent hydrology. However, most species demonstrated continual recruitment in isolated waterholes, irrespective of antecedent flow conditions and season. Continual and seasonal recruitment capabilities have obvious advantages over flood-pulse recruitment in rivers with highly unpredictable flood regimes and underpin the persistence of many fish species in arid and semiarid rivers.
Publisher: Wiley
Date: 08-01-2020
DOI: 10.1111/FWB.13471
Publisher: Wiley
Date: 02-1998
Publisher: Wiley
Date: 03-1999
Publisher: Wiley
Date: 16-07-2003
Publisher: Wiley
Date: 02-1998
Publisher: Research Square Platform LLC
Date: 02-05-2023
DOI: 10.21203/RS.3.RS-2861426/V1
Abstract: Safe and just Earth System Boundaries (ESBs) for surface and groundwater (blue water) have been defined for sustainable water management in the Anthropocene. We evaluate where minimum human needs can be met within the surface water ESB and, where this is not possible, identify how much groundwater is required. 2.6 billion people live in catchments where groundwater is needed because they are already outside the surface water ESB or have insufficient surface water to meet human needs and the ESB. Approximately 1.4 billion people live in catchments where demand side transformations are required as they either exceed the surface water ESB or face a decline in groundwater recharge and cannot meet minimum needs within the ESB. A further 1.5 billion people live in catchments outside the ESB with insufficient surface water to meet needs, requiring both supply and demand-side transformations. These results highlight the challenges and opportunities of meeting even basic human access needs to water and protecting aquatic ecosystems.
Publisher: Frontiers Media SA
Date: 21-03-2016
Publisher: Springer Science and Business Media LLC
Date: 22-01-2014
Publisher: Wiley
Date: 29-01-2016
DOI: 10.1002/HYP.10761
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/MF07159
Abstract: Dryland rivers are characterised by highly pulsed and unpredictable flow, and support a erse biota. The present study examined the contribution of floodplain sources to the productivity of a disconnected dryland river that is a waterhole, after a major overland flood event. Rate measures of productivity were combined with stable isotope and biomass data on the food web in the waterhole and floodplain. The present study estimated that 50% of the fish carbon in the waterhole after flooding was derived from floodplain food sources. In the few months after retraction of the river to isolated waterholes, the large biomass of fish concentrated from the flooding decreased by 80%, most likely as a result of starvation. Based on the development of a carbon budget for the waterhole, mass mortality is hypothesised to be the cause of the high rates of heterotrophic production in the waterhole. The present study suggests that floodplain inputs are important for fuelling short-term production in waterholes, but via an unconventional pathway that is, fish mortality. The episodic nature of flooding in dryland rivers means that changes in flow regimes, such as water regulation or abstraction, will reduce flooding and hence floodplain subsidies to the river. This is likely to have significant impacts on river productivity.
Publisher: MDPI AG
Date: 20-12-2021
DOI: 10.3390/W13243658
Abstract: Despite advances in water resources management and planning, the São Francisco River Basin in Brazil has suffered from systematic drought problems in recent years, leading to severe human and environmental water security threats. This paper aims to track the water security for different periods and its relations with the changes in physical and natural asset conditions. The paper explores how investment planning to mitigate the water security threats and explore opportunities to increase the value of investments. The paper finds that grey infrastructure has regulated threats from increasing in the downstream of the river basin, however, continuous increase in water security threats in the upstream of the basin threatens water security downstream. This is evident from the spatial connectivity and unidirection externalities. As the capacity to further increase in grey investment is reaching its limit in the downstream, the increases in green infrastructure investment upstream, especially in the Grande River basin, could be one the way to reduce the externalities and minimise the water security risks.
Publisher: Elsevier BV
Date: 06-1999
Publisher: Elsevier BV
Date: 04-2018
Publisher: Wiley
Date: 15-05-2003
Publisher: Wiley
Date: 03-2015
DOI: 10.1890/14-0991.1
Abstract: Biotic communities are shaped by adaptations from generations of exposure to selective pressures by recurrent and often infrequent events. In large rivers, floods can act as significant agents of change, causing considerable physical and biotic disturbance while often enhancing productivity and ersity. We show that the relative balance between these seemingly ergent outcomes can be explained by the rhythmicity, or predictability of the timing and magnitude, of flood events. By analyzing biological data for large rivers that span a gradient of rhythmicity in the Neotropics and tropical Australia, we find that systems with rhythmic annual floods have higher-fish species richness, more stable avian populations, and elevated rates of riparian forest production compared with those with arrhythmic flood pulses. Intensification of the hydrological cycle driven by climate change, coupled with reductions in runoff due to water extractions for human use and altered discharge from impoundments, is expected to alter the hydrologic rhythmicity of floodplain rivers with significant consequences for both bio ersity and productivity.
Publisher: Springer Science and Business Media LLC
Date: 22-09-2017
Publisher: Springer Science and Business Media LLC
Date: 10-2002
DOI: 10.1007/S00267-002-2734-3
Abstract: We suggest that fluvial ecosystems are legitimate users of water and that there are basic ecological principles guiding the maintenance of long-term ecological vitality. This article articulates some fundamental relationships between physical and ecological processes, presents basic principles for maintaining the vitality of fluvial ecosystems, identifies several major scientific challenges and opportunities for effective implementation of the basic ecological principles, and acts as an introduction to three specific articles to follow on bio ersity, biogeochemistry, and riparian communities. All the objectives, by necessity, link climate, land, and fresh water. The basic principles proposed are: (1) the natural flow regime shapes the evolution of aquatic biota and ecological processes, (2) every river has a characteristic flow regime and an associated biotic community, and (3) aquatic ecosystems are topographically unique in occupying the lowest position in the landscape, thereby integrating catchment-scale processes. Scientific challenges for the immediate future relate to quantifying cumulative effects, linking multidisciplinary knowledge and models, and formulating effective monitoring and assessment procedures. Additionally, forecasting the ecological consequences of changing water regimes is a fundamental challenge for science, especially as environmental issues related to fresh waters escalate in the next two to three decades.
Publisher: Springer Science and Business Media LLC
Date: 16-02-2016
DOI: 10.1007/S00442-016-3573-X
Abstract: Algal polyunsaturated fatty acids (PUFA), essential for somatic growth and reproduction of aquatic animals, are influenced by ambient environmental conditions, including light and nutrients. Few studies have addressed the extent to which changes in algal PUFA can influence stream herbivore PUFA profiles and the implications for stream food webs. We manipulated subtropical stream periphyton by applying two light levels (open and shaded canopy) and two nutrient regimes (ambient and enriched) to investigate the response of PUFA and somatic growth in stream herbivores. After 6 weeks, the relative content of periphyton PUFA (%) changed distinctly and differed among treatments. Periphyton in the control treatment with open canopy showed a decline in eicosapentaenoic acid (EPA) relative to initial conditions, whereas shading increased EPA and total highly unsaturated FA (HUFA), but decreased α-linolenic acid (ALA), linoleic acid and total C18 PUFA. The interaction of open canopy and added nutrients increased periphyton ALA compared with initial conditions, while the combined effects of shading and added nutrients led to greater total HUFA. FA similarity between stream grazers (the mayfly Austrophlebioides and caddisfly Helicopsyche) and periphyton increased with periphyton HUFA content. In addition, the growth of large instars of both grazers also increased in response to increased periphyton HUFA %. Our findings show that environmental changes, associated with riparian canopy and nutrients, can lead to changes in periphyton PUFA composition that in turn affect growth and PUFA composition in stream grazers.
Publisher: Springer Science and Business Media LLC
Date: 21-09-2016
Publisher: Inter-Research Science Center
Date: 1999
DOI: 10.3354/MEPS189289
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.WATRES.2011.03.048
Abstract: This study examined the link between terrestrial and aquatic phosphorus (P) speciation in the soils and sediments of a subtropical catchment. Specifically, the study aimed to identify the relative importance of P speciation in source soils, erosion and transport processes upstream, and aquatic transformation processes as determinants of P speciation in lake sediments (Lake Wivenhoe). Using a sequential extraction technique, NH(4)Cl extractable P (NH(4)Cl-P exchangeable P), bicarbonate-dithionite extractable P (BD-P reductant soluble P), NaOH extractable P (NaOH-rP Al/Fe oxide P), HCl extractable P (HCl-P apatite-P), and residual-P (Res-P organic and residual inorganic P) fractions were compared in different soil/sediment compartments of the upper Brisbane River (UBR) catchment, Queensland, Australia. Multidimensional scaling identified two distinct groups of s les, one consisting of lake sediments and suspended sediments, and another consisting of riverbed sediments and soils. The riverbed sediments and soils had significantly higher HCl-P and lower NaOH-rP and Res-P relative to the lake and suspended sediments (P < 0.05). Analysis of the enrichment factors (EFs) of soils and riverbed sediments showed that fine grained particles (<63 μm) were enriched in all but the HCl-P fraction. This indicated that as finer particles are eroded from the soil surface and transported downstream there is a preferential export of non-apatite P (NaOH-rP, NaOH-nrP, BD-P and Res-P). Therefore, due to the preferential erosion and transport of fine sediments, the lake sediments contained a higher proportion of more labile forms of inorganic-P relative to the broader soil/sediment system. Our results suggest that a greater focus on the effect of selective erosion and transport on sediment P speciation in lakes and reservoirs is needed to better target management strategies aimed at reducing P availability, particularly in P-limited water bodies impacted by soil erosion.
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 24-06-2016
DOI: 10.1002/ECO.1757
Publisher: Elsevier BV
Date: 12-2018
Publisher: Wiley
Date: 05-10-2018
DOI: 10.1002/LNO.10673
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2014
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/MF00002
Abstract: δ15N values of plants and animals are being increasingly used to identify the flow of nitrogen through aquatic ecosystems. The δ15N values of crops, riparian trees, emergent and submerged aquatic vegetation in streams from both cleared (agricultural) and forested (rainforest) catchments were s led. Riparian and aquatic plants had similar δ15N values in forested streams,suggesting a similar source of inorganic nitrogen.In cleared catchments, however, aquatic plants had δ15N values 4–8‰ higher than adjacent riparian vegetation and aquatic plants from streams in forested catchments. The elevated δ15N values of aquatic vegetation in streams with cleared catchments suggest that these plants either have access to a different source of N than those in undisturbed catchments or that high rates of microbial decomposition and nutrient cycling in the cleared catchments influence the δ15N value of available N. This also suggests that the aquatic plants in disturbed catchments are incorporating a different source of nitrogen than the adjacent riparian vegetation. This supports the proposal that in-stream processing of N affects the δ15N value of available N in streams with cleared catchments. These results begin to identify potential pathways for nitrogen transport to streams and the effect that internal cycling may have on a stream’s nitrogen load.
Publisher: Wiley
Date: 30-06-2020
DOI: 10.1111/FWB.13581
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF12063
Abstract: Atyid shrimps are often an abundant component in undisturbed tropical streams. Studies in coastal streams in Puerto Rico and Brazil have demonstrated the importance of this group in removing periphyton and sediment from hard substrates and their effects on the composition and quantity of periphytic algae. We used experimental exclosures to investigate the influence of the small atyid Paratya australiensis on periphyton accrual on hard substrates in a coastal stream in the subtropics of Australia. We measured organic and inorganic matter, chlorophyll and algal biovolume in the presence and absence of shrimps on natural and artificial substrates. We found a 5-fold increase in the amount of organic matter on natural substrate in the absence of P. australiensis and a two to 10-fold increase in total periphyton mass on artificial substrate. The natural substrates did not show differences in biovolume of algae, however, algal biovolume on the artificial substrates was significantly higher in the exclusion treatment and diatoms were most affected. We conclude that P. australiensis can be considered a strongly-interacting element of the stream biota and an important species for monitoring and conservation.
Publisher: Elsevier BV
Date: 05-1984
DOI: 10.1016/0016-6480(84)90185-0
Abstract: The scincid lizard Tiliqua rugosa possesses a well-developed nasal gland composed of both mucoserous and salt-secreting cells. Confusion over its secretory capacities (see H. Saint- Girons , M. Lemire , and S. D. Bradshaw, 1977, Zoomorphologie 88, 277-288) has been resolved and NaCl- and KCl-injected animals can secrete a hyperosmotic fluid with an F/P ratio of about 3.6. The concentration of Na+ in the secretion varied from a mean of 434 mmol/liter when sodium loaded to 167 mmol/liter when potassium loaded. Potassium concentrations varied from 226 to 433 mmol/liter, respectively. Na:K ratios thus vary from 1.98 with NaCl loading to 0.42 with KCl loading, demonstrating the gland's capacity to vary the nature of the secretion. Rates of fluid production did not differ significantly between NaCl- and KCl-loaded in iduals and varied from 13.3 to 19.6 microliter (100 x g hr)-1. Adjacent studies on the north African agamid lizard Uromastix acanthinurus suggested that aldosterone may influence the rate and composition of the nasal gland secretions and this possibility was investigated in Tiliqua by hormone binding studies. High affinity binding for both corticosterone and aldosterone was demonstrated during the breeding season, with a Kd of 5.2 x 10(-9) and 12.9 x 10(-9) M, respectively. Binding of aldosterone to nasal gland receptors was not evident in nonbreeding animals and the binding of corticosterone was primarily nonspecific in these in iduals. These data suggest that hormone receptor concentrations and affinity vary on a seasonal basis and in concert with reproductive activity.
Publisher: Public Library of Science (PLoS)
Date: 03-03-2016
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1016/J.SCITOTENV.2017.11.199
Abstract: Water level drawdown followed by rewetting in reservoirs/lakes can shift macrophytes from a nutrient sink to a source, thus changing nutrient dynamics and causing water quality problems. However, there is limited understanding of the effect of macrophyte growth versus decomposition on nitrogen (N) and phosphorus (P) dynamics during water level fluctuations (WLFs). This study examined nutrient release versus uptake by two submerged macrophytes, the invasive Cabomba caroliniana (Cabomba) and the native Hydrilla verticillata (Hydrilla), compared to bare sediments, after drying then rewetting. Overall, we examined the nutrient dynamics in treatments comparing 1) two macrophyte species, 2) macrophyte nutrient uptake versus release, and 3) the presence of macrophytes versus bare sediments. Our study showed that Cabomba litter had a higher nutrient release rate and resulted in higher water column chlorophyll a concentrations compared with Hydrilla litter. The decomposition impact of both species on water column P concentrations was greater than that for N, and proportionally less P was assimilated than released by macrophytes compared with N. This resulted in P accumulation and a decreased N:P ratio in the water column compared to bare sediments without macrophytes. Phosphorus accumulation in the water column during macrophyte decomposition increased phytoplankton growth in our study, highlighting the potential for phytoplankton blooms, especially in P-deficient lakes. Regrown Hydrilla had a higher potential for assimilating sediment N compared to Cabomba. In contrast, regrown Cabomba was more efficient at reducing water column N compared with Hydrilla, suggesting different pathways of assimilation. Neither regrown Cabomba nor Hydrilla significantly reduced water column P concentrations. This study highlights different nutrient impacts of macrophyte beds compared to bare sediments during WLFs, and the role of regrown macrophytes in assimilating the released nutrients from macrophyte decomposition. However, the scale of their role is dependent on macrophyte species, forms of nutrients and drying-wetting regimes.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09126
Abstract: Biomagnification of mercury (Hg) leads to high concentrations in fish and subsequent health risks for fish-eaters. Despite the global concern afforded to Hg over the past 40 years, little attention has been paid to this toxic heavy metal in Australia in general, and tropical northern Australia in particular. This review examines past Hg research in Australia and explores seven hypotheses as to why so little research and monitoring has been conducted in northern rivers and estuaries. We rule out the possibility that fishing intensity (an indicator of potential Hg exposure in humans) is lower in Australia than in other countries with more intensive Hg research programs. Instead, we hypothesise that low atmospheric deposition, owing to prevailing wind direction and few local point sources, coupled with highly productive waterbodies, contributes to low Hg bioaccumulation and hence the reduced interest in measuring Hg. Outstanding questions regarding Hg in northern Australia include the assessment of atmospheric deposition rates of Hg, the trophic level and growth and food consumption rates of consumers such as large-bodied fishes, linkages between fire regimes and Hg availability, and the capacity for in situ Hg methylation in tropical systems.
Publisher: University of Chicago Press
Date: 06-1997
DOI: 10.2307/1468022
Publisher: Elsevier BV
Date: 09-2006
Publisher: Wiley
Date: 2006
DOI: 10.1002/RRA.904
Publisher: Wiley
Date: 23-11-2022
DOI: 10.1111/FWB.14022
Abstract: Variation in river flow is a strong behavioural determinant for the movement of many freshwater fish species and often is linked to key aspects of their life cycle. The alteration of natural flow regimes to meet human water demands can result in changes to this variability, and cause declines in water‐dependent biota. Environmental flows are used as a remediation tool in some regulated rivers with the intention of restoring aspects of the natural flow regime to benefit riverine species, although empirical data are required to inform the efficacy of these interventions. Using acoustic telemetry, we quantified the movement responses of two large‐bodied native fish species (freshwater catfish, Tandanus tandanus and Murray cod, Maccullochella peelii ) to variations in river flow over 4 years in two intermittent regulated rivers in the northern Murray–Darling Basin, Australia. Both rivers received periodic environmental flow releases and also there were several large natural flow events during the study period. Both species displayed a range of intra‐specific movement behaviours. Analysis of in iduals' movements revealed five distinct functional groups, which were represented in both species. We found that periods of environmental flow delivery played an important role in the movement behaviour of both species. Murray cod were more likely to move during periods of environmental flow releases, whereas freshwater catfish were less likely to move on an environmental release following higher antecedent flows. No large‐scale philopatric movements were observed, yet Murray cod were more likely to move during the breeding period, indicative of nest site selection. We also found that the likelihood of movement in both species was higher in the smaller of the two rivers for a given magnitude of flow. Our results suggest that environmental flows may benefit certain fish species by facilitating, rather than cueing breeding behaviours, allowing in iduals improved access to, and provision of, higher‐quality nesting habitats. These findings will aid water managers in creating economical and targeted environmental flow releases, timing larger flow pulses for the species with flow‐cued reproductive strategies, and providing a continuity of smaller baseflows for species whose reproduction is not dependent on flow cues but may be enhanced by greater connectivity.
Publisher: Elsevier BV
Date: 12-1996
Publisher: University of Chicago Press
Date: 03-1995
DOI: 10.2307/1467730
Publisher: University of Chicago Press
Date: 03-1995
DOI: 10.2307/1467731
Publisher: American Geophysical Union (AGU)
Date: 11-2019
DOI: 10.1029/2019WR025216
Publisher: CSIRO Publishing
Date: 1989
DOI: 10.1071/MF9890631
Abstract: At least 51 species of Trichoptera, in 10 families, are now known from south-western Australia. Larvae of the Hydrobiosidae, Philopotamidae, Hydropsychidae and some species of Ecnomidae are briefly described, and notes on their distribution and biology are presented. A key to species is also provided for the larvae of most families of Trichoptera recorded from this region.
Publisher: Wiley
Date: 26-07-2020
DOI: 10.1111/EFF.12490
Publisher: Wiley
Date: 2010
DOI: 10.1002/AQC.1072
Publisher: Wiley
Date: 24-09-2012
Publisher: Springer Science and Business Media LLC
Date: 29-06-2011
Publisher: Elsevier BV
Date: 05-1994
Publisher: Wiley
Date: 04-2021
Abstract: Algae are generally a high‐quality diet source because they provide essential compounds to aquatic consumers. In forested stream ecosystems, the availability of high‐quality algae is low compared to terrestrial organic matter, which may constrain the dietary transfer of essential compounds to consumers. However, there could be other overlooked high‐quality resource pools that provide essential compounds to consumers in river ecosystems. We conducted a field study along a subalpine river continuum in Austria to identify the nutritional role of a ‘hidden’ food resource for aquatic consumers the biofilms growing on the underside of rocks (dark biofilms). Dark and light (i.e. upper surface of rocks) biofilms and invertebrates were collected, and their fatty acid (FA) composition was analysed. Compared with light biofilms, dark biofilms contained greater proportions of bacterial FA, long‐chain saturated FA (biomarkers of terrestrial plants) and oleic acid (18:1ω9 a fungal biomarker), but a lower proportion of algal FA, especially omega‐3 polyunsaturated FA (ω3 PUFA). The ω3 PUFA composition in dark biofilms was strongly correlated with that in light biofilms. Furthermore, the overall FA profiles of dark biofilms were significantly associated with invertebrate FA profiles. Strong correlations were also observed between invertebrates and dark biofilms for bacterial FA and the ω3 PUFA eicosapentaenoic acid (EPA, 20:5ω3). Synthesis . This field study demonstrates that dark biofilms are a high‐quality resource pool for invertebrates in river ecosystems that is often overlooked. Similar to light biofilms, dark biofilms provide physiologically important FA and bacterial FA for stream invertebrates. However, these high‐quality resources are threatened by increasing human disturbances to river ecosystems. Future research is required to better understand how the quality of both dark and light biofilms changes in response to human disturbance, and how this affects dietary energy transfer to upper trophic consumers, including fish and humans.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09239
Abstract: Dryland rivers are renowned for their periods of ‘boom’ related to the episodic floods that extend over vast floodplains and fuel incredible production, and periods of ‘bust’ where the extensive channel network is restricted to the permanent refugial waterholes. Many of these river systems are unregulated by dams but are under increasing pressure, especially from water abstraction and overland flow interception for agriculture and mining. Although some aquatic organisms with desiccation-resistant life stages can utilise ephemeral floodplain habitats, the larger river waterholes represent the only permanent aquatic habitat during extended periods of low or no flow. These waterholes act as aquatic refugia in an otherwise terrestrial landscape. Variable patterns of connection and disconnection in space and time are a fundamental driver of ersity and function in these dryland river systems, and are vital for dispersal and the maintenance of erse populations, generate the spatial and temporal variability in assemblage structure for a range of different organisms and fuel the productivity that sustains higher trophic levels. Changes to natural patterns of connection and disconnection of refugial waterholes, owing to water-resource development or climate change, will threaten their persistence and diminish their functional capacity to act as aquatic refugia.
Publisher: Brill
Date: 1999
Abstract: The swimming response to flow of the freshwater shrimp Paratya australiensis Kemp, 1917, was examined in a small recirculating laboratory stream. On three occasions during 1993 larvae, juveniles, small and large adults, and ovigerous females were collected from headwater populations and tested in the laboratory at current speeds of 10 and 30 cm s-1. Juvenile and adult shrimps showed the same strong positive rheotactic response at velocities of 10 and 30 cm s-1. However, large adults moved upstream more rapidly than juveniles and small adults. This response was not influenced by the time of year of collection or time of day tested (day/night). Ovigerous females showed a weak response to flow and tended to maintain position rather than move into the current. Early stage larvae (stages III and IV) were not able to maintain position at the lowest velocities. The positive rheotactic response of shrimps, particularly large adults, is seen as an adaptation to compensate for downstream movement of larvae by drift and juvenile and adult displacement during high discharge events. La nage en reponse au courant chez la crevette d'eau douce Paratya australiensis Kemp, 1917, a ete examinee en laboratoire dans un petit courant continu d'eau. A trois reprises durant l'annee 1993, des larves, des juveniles, de petits et grands adultes, ainsi que des femelles ovigeres ont ete collectes dans populations situees en amont et testes au laboratoire a des vitesses de courant de 10 a 30 cm s-1. Les crevettes juveniles et adultes ont repondu par une forte rheotaxie positive aux vitesses de 10 a 30 cm s-1. Cependant, les adultes de grande taille se sont deplaces vers l'amont plus rapidement que les juveniles et les petits adultes. Cette reponse n'a pas ete influencee par le moment du prelevement, que ce soit au cours de l'annee ou de la journee (jour/nuit). Les femelles ovigeres ont donne une faible reponse au courant et tendaient a maintenir leur position plutot qu'a se deplacer dans le courant. Les jeunes larves (stades III et IV) n'etaient pas capables de maintenir leur position aux vitesses les plus basses. La rheotaxie positive des crevettes, en particulier des grands adultes, est consideree comme une adaptation pour compenser le mouvement des larves entrainees vers l'aval par le courant et le deplacement des jeunes et des adultes au moment des hautes eaux.
Publisher: Wiley
Date: 21-11-2011
DOI: 10.1111/J.1365-2656.2011.01925.X
Abstract: 1. Despite implications for top-down and bottom-up control and the stability of food webs, understanding the links between consumers and their diets remains difficult, particularly in remote tropical locations where food resources are usually abundant and variable and seasonal hydrology produces alternating patterns of connectivity and isolation. 2. We used a large scale survey of freshwater biota from 67 sites in three catchments (Daly River, Northern Territory Fitzroy River, Western Australia and the Mitchell River, Queensland) in Australia's wet-dry tropics and analysed stable isotopes of carbon (δ(13) C) to search for broad patterns in resource use by consumers in conjunction with known and measured indices of connectivity, the duration of floodplain inundation, and dietary choices (i.e. stomach contents of fish). 3. Regression analysis of biofilm δ(13) C against consumer δ(13) C, as an indicator of reliance on local food sources (periphyton and detritus), varied depending on taxa and catchment. 4. The carbon isotope ratios of benthic invertebrates were tightly coupled to those of biofilm in all three catchments, suggesting assimilation of local resources by these largely nonmobile taxa. 5. Stable C isotope ratios of fish, however, were less well-linked to those of biofilm and varied by catchment according to hydrological connectivity the perennially flowing Daly River with a long duration of floodplain inundation showed the least degree of coupling, the seasonally flowing Fitzroy River with an extremely short flood period showed the strongest coupling, and the Mitchell River was intermediate in connectivity, flood duration and consumer-resource coupling. 6. These findings highlight the high mobility of the fish community in these rivers, and how hydrological connectivity between habitats drives patterns of consumer-resource coupling.
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/MF04068
Abstract: Tourists can adversely influence the ecology of oligotrophic lakes by increasing algal production via direct nutrient inputs and/or re-suspension of sediments. To assess the influence of tourists on food web dynamics, we used the natural abundance of stable isotopes of carbon and nitrogen to calculate the relative importance of autochthonous and allochthonous carbon sources to littoral zone food webs across five variously visited perched dune lakes on Fraser Island, Australia. The relative importance of autochthonous (phytoplankton and periphyton) carbon to littoral zone consumers was highly variable across taxa and lakes. Despite the potential influence of algal biomass, ambient nutrient concentrations and tannin concentrations on the contribution of autochthonous carbon to littoral zone food webs, none of these variables correlated to the per cent contribution of autochthonous carbon to consumer diets. Instead, autochthonous sources of carbon contributed more to the diets of aquatic consumers in heavily visited lakes than in less visited lakes, suggesting that tourist activities might drive these systems towards an increased reliance on autochthonous carbon. The assessment of the contribution of autochthonous carbon to littoral zone food webs may represent a more robust indicator of the impact of tourists in oligotrophic lakes than standard measures of nutrient concentrations and/or algal biomass.
Publisher: Wiley
Date: 10-2004
Publisher: Elsevier
Date: 2008
Publisher: Wiley
Date: 04-2016
DOI: 10.1111/FWB.12755
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.JENVMAN.2013.11.021
Abstract: River rehabilitation aims to protect bio ersity or restore key ecosystem services but the success rate is often low. This is seldom because of insufficient funding for rehabilitation works but because trade-offs between costs and ecological benefits of management actions are rarely incorporated in the planning, and because monitoring is often inadequate for managers to learn by doing. In this study, we demonstrate a new approach to plan cost-effective river rehabilitation at large scales. The framework is based on the use of cost functions (relationship between costs of rehabilitation and the expected ecological benefit) to optimize the spatial allocation of rehabilitation actions needed to achieve given rehabilitation goals (in our case established by the Swiss water act). To demonstrate the approach with a simple ex le, we link costs of the three types of management actions that are most commonly used in Switzerland (culvert removal, widening of one riverside buffer and widening of both riversides) to the improvement in riparian zone quality. We then use Marxan, a widely applied conservation planning software, to identify priority areas to implement these rehabilitation measures in two neighbouring Swiss cantons (Aargau, AG and Zürich, ZH). The best rehabilitation plans identified for the two cantons met all the targets (i.e. restoring different types of morphological deficits with different actions) rehabilitating 80,786 m (AG) and 106,036 m (ZH) of the river network at a total cost of 106.1 Million CHF (AG) and 129.3 Million CH (ZH). The best rehabilitation plan for the canton of AG consisted of more and better connected sub-catchments that were generally less expensive, compared to its neighbouring canton. The framework developed in this study can be used to inform river managers how and where best to spend their rehabilitation budget for a given set of actions, ensures the cost-effective achievement of desired rehabilitation outcomes, and helps towards estimating total costs of long-term rehabilitation activities. Rehabilitation plans ready to be implemented may be based on additional aspects to the ones considered here, e.g., specific cost functions for rural and urban areas and/or for large and small rivers, which can simply be added to our approach. Optimizing investments in this way will ultimately increase the likelihood of on-ground success of rehabilitation activities.
Publisher: Wiley
Date: 10-1986
Publisher: Wiley
Date: 08-2006
DOI: 10.1890/1051-0761(2006)016[1311:TCOPEF]2.0.CO;2
Abstract: Accounting for natural differences in flow variability among rivers, and understanding the importance of this for the protection of freshwater bio ersity and maintenance of goods and services that rivers provide, is a great challenge for water managers and scientists. Nevertheless, despite considerable progress in understanding how flow variability sustains river ecosystems, there is a growing temptation to ignore natural system complexity in favor of simplistic, static, environmental flow "rules" to resolve pressing river management issues. We argue that such approaches are misguided and will ultimately contribute to further degradation of river ecosystems. In the absence of detailed empirical information of environmental flow requirements for rivers, we propose a generic approach that incorporates essential aspects of natural flow variability shared across particular classes of rivers that can be validated with empirical biological data and other information in a calibration process. We argue that this approach can bridge the gap between simple hydrological "rules of thumb" and more comprehensive environmental flow assessments and experimental flow restoration projects.
Publisher: Wiley
Date: 15-03-2017
DOI: 10.1111/FWB.12909
Publisher: Informa UK Limited
Date: 05-03-2021
Publisher: Elsevier BV
Date: 09-1997
Publisher: Springer Science and Business Media LLC
Date: 09-10-2011
DOI: 10.1007/S00442-011-2148-0
Abstract: High levels of hydrological connectivity during seasonal flooding provide significant opportunities for movements of fish between rivers and their floodplains, estuaries and the sea, possibly mediating food web subsidies among habitats. To determine the degree of utilisation of food sources from different habitats in a tropical river with a short floodplain inundation duration (~2 months), stable isotope ratios in fishes and their available food were measured from three habitats (inundated floodplain, dry season freshwater, coastal marine) in the lower reaches of the Mitchell River, Queensland (Australia). Floodplain food sources constituted the majority of the diet of large-bodied fishes (barramundi Lates calcarifer, catfish Neoarius graeffei) captured on the floodplain in the wet season and for gonadal tissues of a common herbivorous fish (gizzard shad Nematalosa come), the latter suggesting that critical reproductive phases are fuelled by floodplain production. Floodplain food sources also subsidised barramundi from the recreational fishery in adjacent coastal and estuarine areas, and the broader fish community from a freshwater lagoon. These findings highlight the importance of the floodplain in supporting the production of large fishes in spite of the episodic nature and relatively short duration of inundation compared to large river floodplains of humid tropical regions. They also illustrate the high degree of food web connectivity mediated by mobile fish in this system in the absence of human modification, and point to the potential consequences of water resource development that may reduce or eliminate hydrological connectivity between the river and its floodplain.
Publisher: Elsevier BV
Date: 07-1983
Publisher: Wiley
Date: 10-1996
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/MF99112
Abstract: This paper reviews research on fluxes of carbon in Australian floodplain rivers. Except where cover is absent, and in-stream gross primary production is gC m–2 day–1 and ratios of production to respiration are , riparian sources dominate carbon pools in catchment streams. On floodplains, primary production by river red gum (Eucalyptus camaldulensis) forests is ~600 gC m–2 year–1. Total primary production by aquatic macrophytes and biofilms in floodplain wetlands is gC m–2 year–1 and gC m–2 year–1, respectively. Large pools of particulate organic carbon (POC) exist on floodplains as litter ( gC m–2) and coarse woody debris (~6 kgC m–2). Floods may release 50 gDOC m–2 from leaf litter. Export of this DOC (dissolved organic carbon) may be substantial relative to autochthonous production in river channels. Sediments deposited on floodplains during large floods represent a substantial sink of riverine POC (up to 280 gC m–2). Bacteria are responsible for rapid decomposition of DOC and POC in floodplain wetlands (sediment respiration and methanogenesis, both ~1 gC m–2 day–1). Flow and its interaction with geomorphology control carbon fluxes in rivers. Decreased inputs of floodplain carbon, following river regulation and physical disturbances to catchments and floodplains, may have resulted in many Australian rivers being dominated by algal production.
Publisher: CSIRO Publishing
Date: 1988
DOI: 10.1071/MF9880785
Abstract: Life history patterns of thirteen species of invertebrates from streams of the northern jarrah forest were examined over a 1-year period. Five species had univoltine cycles with a single cohort and demonstrated a high degree of synchrony of larval development and a restricted period of adult emergence. Two species of Leptophlebiidae also had univoltine cycles but showed the more typical pattern of Australian mayflies, with extended recruitment, multiple overlapping cohorts and a long period of adult emergence. Uroctena sp., a small gammarid, had a generation time of 1 year but showed considerable spatial variation in the degree of synchrony of development. This appeared to be a result of differences in the constancy of stream discharge and was not attributable to differences in the temperature regime of the streams. At least three species demonstrated cohort splitting which resulted in an apparently bivoltine cycle. A life-history pattern of alternating long and short development times is described which, on average, would produce two generations every 3 years. This is considered to be a highly adaptive strategy for Australian stream insects with slow life cycles and can explain the extended periods of recruitment and adult emergence so often observed. Streams of the northern jarrah forest are depauperate compared with other Australian streams, despite predictable temperature and discharge regimes. The insular nature of the south-west Bassian region and its long period of isolation may be the principle cause of this reduced ersity. The invertebrate community of these streams is simple in structure and has a high degree of seasonality that is atypical of the temperate streams of Australia and New Zealand.
Publisher: Elsevier BV
Date: 02-2016
Publisher: The Royal Society
Date: 04-2022
Abstract: Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ 13 C and δ 15 N in bones of crocodiles s led 40 to 55 years ago (small population) with bones from contemporary in iduals (large population). We found that δ 13 C and δ 15 N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
Publisher: Elsevier BV
Date: 05-2016
Publisher: Wiley
Date: 22-09-2015
DOI: 10.1002/HYP.10311
Publisher: Wiley
Date: 12-01-2009
Publisher: Wiley
Date: 16-02-2018
DOI: 10.1111/GCB.14050
Abstract: Phenological responses to climate change have been widely observed and have profound and lasting effects on ecosystems and bio ersity. However, compared to terrestrial ecosystems, the long-term effects of climate change on species' phenology are poorly understood in aquatic ecosystems. Understanding the long-term changes in fish reproductive phenology is essential for predicting population dynamics and for informing management strategies, but is currently h ered by the requirement for intensive field observations and larval identification. In this study, a very low-frequency s ling of juveniles and adults combined with otolith measurements (long axis length of the first annulus LAFA) of an endemic Tibetan Plateau fish (Gymnocypris selincuoensis) was used to examine changes in reproductive phenology associated with climate changes from the 1970s to 2000s. Assigning in idual fish to their appropriate calendar year class was assisted by dendrochronological methods (crossdating). The results demonstrated that LAFA was significantly and positively associated with temperature and growing season length. To separate the effects of temperature and the growing season length on LAFA growth, measurements of larval otoliths from different sites were conducted and revealed that daily increment additions were the main contributor (46.3%), while temperature contributed less (12.0%). Using constructed water-air temperature relationships and historical air temperature records, we found that the reproductive phenology of G. selincuoensis was strongly advanced in the spring during the 1970s and 1990s, while the increased growing season length in the 2000s was mainly due to a delayed onset of winter. The reproductive phenology of G. selincuoensis advanced 2.9 days per decade on average from the 1970s to 2000s, and may have effects on recruitment success and population dynamics of this species and other biota in the ecosystem via the food web. The methods used in this study are applicable for studying reproductive phenological changes across a wide range of species and ecosystems.
Publisher: CSIRO Publishing
Date: 1994
DOI: 10.1071/MF9940875
Abstract: Two main approaches have been mooted for the management of fresh waters to prevent or control cyanobacterial blooms: a 'bottom-up' approach in which the supply of essential nutrients is restricted, and a 'top-down' or 'biomanipulation' approach in which attempts are made to restructure the food web to maximize consumption of noxious cyanobacteria by herbivorous zooplankton. In this review, the published literature is examined to gauge whether the common zooplankton of Australian fresh waters have the capacity to control cyanobacterial blooms, especially of toxic forms, and thus whether the biomanipulation approach might be applied successfully in Australia. As zooplankton assemblages in Australian inland waters are quite different in composition from those of the Northern Hemisphere, they are unlikely to respond to manipulations of trophic structure in a similar way. The most common zooplankters in Australian inland waters, calanoid copepods and rotifers, have less potential for controlling cyanobacterial blooms than do large cladocerans. The latter are common in the Northern Hemisphere and are considered requisite for the control of cyanobacterial blooms. Toxic cyanobacteria, which cause the most severe environmental problems, have well documented detrimental effects on zooplankton. The few reports of zooplankton grazing on cyanobacteria in Australian fresh waters do not indicate that native zooplankton can consume noxious cyanobacteria at the rates required for control of algal blooms. There may, therefore, be grounds for strong reservations about the likely success of programmes proposed to control cyanobacterial blooms by the manipulation of trophic structure in Australian fresh waters.
Publisher: Springer Science and Business Media LLC
Date: 05-1988
DOI: 10.1007/BF00016669
Publisher: Springer Science and Business Media LLC
Date: 05-1988
DOI: 10.1007/BF00016668
Publisher: Wiley
Date: 19-04-2023
DOI: 10.1111/FWB.14088
Abstract: Organisms at the base of stream food webs are typically poor in long‐chain polyunsaturated fatty acids (LC‐PUFA), especially in docosahexaenoic acid (DHA), whereas consumers at higher trophic levels are often rich in LC‐PUFA. For ex le, fish tissues, especially the brain, are DHA‐rich. This obvious mismatch between consumer LC‐PUFA and their basal dietary supply may result from selective retention and/or endogenous conversion of dietary precursors to LC‐PUFA. To determine which is more likely, we investigated compound‐specific carbon stable isotopes in PUFA ( δ 13 C PUFA ) of potential basal resources (stream epilithon, leaf litter) and consumers (invertebrates, European bullhead, and two salmonid species and their brain, eye, liver, and muscle tissues). We predicted that consumer‐PUFA, depleted in 13 C values relative to their dietary sources, would indicate internal de novo PUFA synthesis. Alternatively, higher consumer‐ δ 13 C PUFA values would imply selective retention of aquatic (epilithon and conditioned leaves) rather than terrestrial resources or internal production, irrespective of trophic levels. Invertebrate grazers and predators resembled δ 13 C values of essential fatty acids ( δ 13 C EFA ) of benthic algae, while shredder‐ δ 13 C EFA values reflected those of conditioned rather than fresh leaves. Lower eye‐ δ 13 C EFA values of salmonids than in livers indicated high retention of dietary PUFA sources (invertebrates and epilithon). Stable isotope values of eicosapentaenoic acid suggest that all consumers retained algal EPA, while insectivorous fish produced DHA in their liver. There is no further evidence from carbon stable isotopes for local PUFA conversion within neural tissues. Our study demonstrates that δ 13 C PUFA can be used to track sources of these highly functional molecules in aquatic consumers and highlights the importance of algal derived‐PUFA for these consumers in oligotrophic headwater streams.
Publisher: Wiley
Date: 02-2001
Publisher: Springer Science and Business Media LLC
Date: 23-11-2019
Publisher: Wiley
Date: 14-02-2017
DOI: 10.1111/FWB.12904
Publisher: Wiley
Date: 10-01-2013
DOI: 10.1002/RRA.2554
Publisher: Wiley
Date: 12-2012
DOI: 10.1890/11-1792.1
Abstract: Catchment and riparian degradation has resulted in declining ecosystem health of streams worldwide. With restoration a priority in many regions, there is an increasing interest in the scale at which land use influences stream ecosystem health. Our goal was to use a substantial data set collected as part of a monitoring program (the Southeast Queensland, Australia, Ecological Health Monitoring Program data set, collected at 116 sites over six years) to identify the spatial scale of land use, or the combination of spatial scales, that most strongly influences overall ecosystem health. In addition, we aimed to determine whether the most influential scale differed for different aspects of ecosystem health. We used linear-mixed models and a Bayesian model-averaging approach to generate models for the overall aggregated ecosystem health score and for each of the five component indicators (fish, macroinvertebrates, water quality, nutrients, and ecosystem processes) that make up the score. Dense forest close to the survey site, mid-dense forest in the hydrologically active near-stream areas of the catchment, urbanization in the riparian buffer, and tree cover at the reach scale were all significant in explaining ecosystem health, suggesting an overriding influence of forest cover, particularly close to the stream. Season and antecedent rainfall were also important explanatory variables, with some land-use variables showing significant seasonal interactions. There were also differential influences of land use for each of the component indicators. Our approach is useful given that restoring general ecosystem health is the focus of many stream restoration projects it allowed us to predict the scale and catchment position of restoration that would result in the greatest improvement of ecosystem health in the regions streams and rivers. The models we generated suggested that good ecosystem health can be maintained in catchments where 80% of hydrologically active areas in close proximity to the stream have mid-dense forest cover and moderate health can be obtained with 60% cover.
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 25-10-2002
Publisher: Wiley
Date: 16-08-2007
Publisher: Frontiers Media SA
Date: 07-04-2017
Publisher: Springer Science and Business Media LLC
Date: 18-12-2013
DOI: 10.1007/S11356-012-1343-9
Abstract: Diatoms have been regularly used as bioindicators to assess water quality of surface waters. However, diatom-based indices developed for a specific geographic region may not be appropriate elsewhere. We s led benthic diatom assemblages in the upper Han River, a subtropical river in China, to evaluate applicability of 14 diatom-based indices used worldwide for water quality assessment. A total of 194 taxa from 31 genera were identified in the dry season and 139 taxa from 23 genera in the wet season. During the dry season, significant relationships were found for all but one of the diatom-based indices (Index Diatom Artois-Picardie) with one or more physical and chemical variables including nutrients and ion concentrations in river waters. The Biological Diatom Index (IBD) and diatom-based eutrophication ollution index (EPI-D) were strongly related to trophic status and ionic content, while Watanabe's Index was related to organic pollution and conductivity. Yet, the diatom indices showed weak relationships with physical and chemical variables during the wet season. It suggests that diatom-based indices developed in Europe can be applied with confidence as bioindicators of water quality in subtropical rivers of China, at least during base-flow conditions.
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/MF97003
Abstract: Aspects of the life history and population dynamics of Paratya australiensis were examined in headwater streams of the Conondale Range, south-eastern Queensland, particularly in relation to spatial and temporal variation in temperature and flow dynamics. Breeding period and population structure at nine sites in three subcatchments were examined during three years of monthly s ling using a non-destructive, photographic method. Breeding was restricted to the warmer months of late spring and summer. Peak abundances of ovigerous females and release of larvae occurred earlier at warmer, lower-altitude sites than at cooler, upper-altitude sites. This is consistent with the general trend for seasonal breeding in temperate and subtropical species of atyids, and perennial breeding in tropical species, and suggests that the summer breeding period of P. australiensis was strongly influenced by temperature. In subtropical, south-eastern Queensland, larvae were released just before and during the wet season. Although populations were quite resilient, disturbance from high-flow events also shaped the life history. Hydrology modified the breeding period by influencing overall abundance and recruitment success and by favouring the early release of larvae before peak flows. The reasonably well defined seasonal cycle and synchronized development appear to result from the combined effects of temperature and hydrology.
Publisher: Wiley
Date: 16-11-2012
DOI: 10.1111/FWB.12058
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/MF04120
Abstract: Summer field observations in five 2nd order streams (width 1–2 m, depth 5–15 cm, velocity 5–10 cm s–1) in Western Australia and south-east Queensland showed that daily maximum temperatures changed by ±4°C over distances of 600–960 m (travel time 2–3 h) immediately downstream from 40–70% step changes in riparian shade. There was a strong linear relationship between the rate of change of daily maximum temperature and the change of shade such that downstream from a 100% change of shade the heating/cooling rates are ±4°C h–1 and ±10°C km–1 (upper bound ±6°C h–1 and ±15°C km–1) respectively. These high rates only apply over short distances and travel times because downstream water temperatures adjust to the new level of shade and reach a dynamic equilibrium. Shade was too patchy in the study streams to measure how long water takes to reach equilibrium, however, using an existing computer model, we estimate that this occurs after ~1200 m (travel time 4 h). Further modelling work is desirable to predict equilibrium temperatures under given meteorological, flow and shade conditions. Nevertheless, landowners and regulators can use this information to determine whether the presence/absence of certain lengths of bankside shade are likely to cause desirable/undesirable temperature decreases/increases.
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/MF06142
Abstract: Little is known about ecosystem processes in dryland rivers, despite the global distribution of these systems. Those in Australia are characterised by long periods of no flow in which they persist for many months as series of isolated, often turbid, waterholes. We assessed benthic and pelagic primary production, respiration, and bacterial production in one of these waterholes to determine the metabolic balance of the waterhole and resolve the relative importance of autochthonous and allochthonous sources of organic carbon. Despite a photic zone depth of only 0.25 m, three lines of evidence suggested that autochthonous sources of organic carbon were important for fuelling bacterial production under no-flow conditions: the metabolic balance of the waterhole was not indicative of large allochthonous inputs rates of gross primary production were great enough to meet a substantial fraction of estimated bacterial carbon demand and pathways for allochthonous carbon to enter the waterhole were limited. These results suggest that models of lake metabolism based on temperate ecosystems can be expanded to include dryland river waterholes, which group with eutrophic lakes owing to their high levels of inorganic nutrients, low allochthonous inputs and autotrophic metabolic balance.
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/MF04084
Abstract: The tropical rivers of northern Australia have received international and national recognition for their high ecological and cultural values. Unlike many tropical systems elsewhere in the world and their temperate Australian counterparts, they have largely unmodified flow regimes and are comparatively free from the impacts associated with intensive land use. However, there is growing demand for agricultural development and existing pressures, such as invasive plants and feral animals, threaten their ecological integrity. Using the international literature to provide a conceptual framework and drawing on limited published and unpublished data on rivers in northern Australia, we have derived five general principles about food webs and related ecosystem processes that both characterise tropical rivers of northern Australia and have important implications for their management. These are: (1) the seasonal hydrology is a strong driver of ecosystem processes and food-web structure (2) hydrological connectivity is largely intact and underpins important terrestrial–aquatic food-web subsidies (3) river and wetland food webs are strongly dependent on algal production (4) a few common macroconsumer species have a strong influence on benthic food webs and (5) omnivory is widespread and food chains are short. The implications of these ecosystem attributes for the management and protection of tropical rivers and wetlands of northern Australian are discussed in relation to known threats. These principles provide a framework for the formation of testable hypotheses in future research programmes.
Publisher: Frontiers Media SA
Date: 14-10-2016
Publisher: Wiley
Date: 26-06-2006
Publisher: FapUNIFESP (SciELO)
Date: 2023
DOI: 10.1590/1982-0224-2022-0044
Abstract: Abstract The Amazon River basins present distinct natural and anthropogenic characteristics that influence the structure of stream habitats and their associated biota. The influence of these characteristics can be evaluated through different spatial scales. We aimed to assess the influence (with and without the effect of spatial-geographical factors) of local, macroscale, and land-use variables in the structure of stream fish assemblages of Amazonian catchments with different deforestation levels. A partial redundancy analysis and a reduced metrics model were used to assess these influences. With geographic-spatial effects, we verified that the macroscale and local variables explained the variation in fish composition, and, without the effects, land use also explained the variation in this composition. In the forested catchments, the biota was associated with streams with natural characteristics (e.g., leaf banks). In the deforested catchments, it was associated with land use, sandy catchments with higher soil density (higher capacity of degradation), and less complex streams (fewer leaf banks, more sand). The associated fish have life features linked to these characteristics (e.g., Gymnorh hichthys rondoni associated with sand). This configuration seems to be a result of both the impact of land use in the catchment (i.e., increased erosion, increased sedimentation) and the naturally sandy constitution of the catchment as well, reflecting the sandy substrate.
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/MF06025
Abstract: Fish in dryland rivers must cope with extreme variability in hydrology, temperature and other environmental factors that ultimately have a major influence on their patterns of distribution and abundance at the landscape scale. Given that fish persist in these systems under conditions of high environmental variability, dryland rivers represent ideal systems to investigate the processes contributing to and sustaining fish bio ersity and recruitment in variable environments. Hence, spatial and temporal variation in fish assemblage structure was examined in 15 waterholes of the Warrego River between October 2001 and May 2003. Fish assemblages in isolated waterholes were differentiated at the end of the dry 2001 winter but were relatively similar following high summer flows in January 2002 as a consequence of high hydrological connectivity among waterholes. Small, shallow waterholes supported more species and higher abundances than large-deep waterholes. Large, deep waterholes provided important refuge for large-bodied fish species such as adult yellowbelly, Macquaria ambigua, and the eel-tailed catfish, Tandanus tandanus. Recruitment patterns of bony bream (Nematalosa erebi), Hyrtl’s tandan (Neosilurus hyrtlii) and yellowbelly were associated with high flow events and backwater inundation however recruitment of yellowbelly and bony bream was also evident following a zero-flow period. Departures from typical flood-induced seasonal spawning patterns may reflect opportunistic spawning behaviours appropriate to the erratic patterns of flooding and dry spells in dryland rivers.
Publisher: Wiley
Date: 12-2005
Publisher: Springer Science and Business Media LLC
Date: 16-07-1998
Abstract: Headwater populations of the common shrimp Paratya australiensis were s led to examine the factors influencing egg and clutch size. Much of the spatial variation in these reproductive traits was associated with differences in altitude, with upper sites having larger eggs and smaller clutches. Mean egg size at high-altitude sites was higher than that previously reported for this species. Temporal variation in egg and clutch size was also observed, with significant increases in egg size during the breeding season. At most sites, this increase was accompanied by a decrease in clutch size. The combined effect of the reciprocal patterns in egg volume and clutch size resulted in relatively little spatial and temporal variation in reproductive effort. In a field experiment, using a unique genetic marker, shrimps were translocated between two sites with significantly different egg sizes. After one generation (18 months), the mean egg size of translocated females was the same as that of females from the `source' population. In contrast, clutch size changed towards that of the resident females. This suggests that egg size is under strong genetic control, while clutch size is influenced by the environment.
Publisher: Cambridge University Press
Date: 2015
Publisher: Informa UK Limited
Date: 1989
Publisher: Springer Science and Business Media LLC
Date: 12-2000
DOI: 10.1046/J.1365-2540.2000.00782.X
Abstract: Recent studies of the genetic structure of stream-dwelling organisms have suggested that fine-scale patterns are the consequence of patchy recruitment from a small number of matings and limited in-stream dispersal. Predictions of this hypothesis were tested by spatial and temporal analysis of the genetic structure of populations of a stream mayfly (Bungona sp: Baetidae) in subtropical streams in south-eastern Queensland. Significant departures from Hardy-Weinberg proportions occurred more often than would be predicted by chance alone and no consistent pattern was observed across sites, loci or s ling times. As in previous studies, the largest differentiation was observed at the smallest spatial scale (reaches within streams) on most s ling occasions. These data provide additional support for a patchy recruitment hypothesis. Despite the fine-scale population structure, there was evidence of widespread adult dispersal across the study region, especially between streams and subcatchments within the same block of continuous dense forest.
Publisher: American Geophysical Union (AGU)
Date: 04-2021
DOI: 10.1029/2020EF001866
Abstract: Keeping the Earth system in a stable and resilient state, to safeguard Earth's life support systems while ensuring that Earth's benefits, risks, and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a “safe and just corridor” that meets these goals. Although “safe” and “just” Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.
Publisher: Wiley
Date: 23-04-2015
DOI: 10.1111/FWB.12578
Publisher: Wiley
Date: 22-03-2013
Publisher: Wiley
Date: 05-2005
Publisher: Springer Science and Business Media LLC
Date: 15-12-1997
Publisher: Wiley
Date: 18-09-2002
Publisher: Wiley
Date: 17-03-2003
Publisher: Springer Science and Business Media LLC
Date: 04-1990
DOI: 10.1007/BF00028418
Publisher: Wiley
Date: 05-1995
Publisher: Springer Science and Business Media LLC
Date: 22-02-2006
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/MF13110
Abstract: Providing flows for biota and environmental processes is a challenging water management issue. For society the ability and willingness to allocate water to sustain the environment is increasingly competitive due to escalating demand and as a consequence of climate change. In response, an array of environmental flow (E-flow) methods have developed. Our view is that few E-flows have been implemented and even fewer evaluated in a research and management context. Much of our science effort in E-flows has been directed primarily at method development, with less attention being given to monitoring, evaluation and subsequent revision of E-flow strategies. Our objectives are to highlight the lack of connection between current trends in E-flow literature and theory with assessment of the efficacy and practical application of these methods. Specifically, effective E-flows need to be explicit about flow-ecology relationships to adequately determine the amount and timing of water required. We briefly outline the historical development of E-flows and discuss how serial development of methods and techniques has restricted implementation, evaluation and revision. We highlight areas where methods are lacking, such as incorporation of data on flow-ecology relationships into operational use of E-flow methods. We suggest four initial steps that will improve the applicability, implementation and ultimate success of E-flows.
Publisher: Frontiers Media SA
Date: 02-07-2018
Publisher: IWA Publishing
Date: 07-2007
DOI: 10.2166/WS.2007.044
Abstract: The waterways of South East Queensland, Australia, represent unique and complex ecosystems that have a high conservation value and support major recreational and commercial fisheries. The agricultural districts of the region also contribute significantly to the regional economy and, together with the growing urban areas, are heavily reliant on good quality water supplies. However, the human footprint of these activities has led to significant changes in catchment hydrology and sediment delivery, declining water quality and loss of aquatic bio ersity. Predicted population increases in the region are likely to further impact on the ecological and economic health of its waterways and catchments, and there are growing community expectations to reverse the decline in water quality and ecosystem health. In response to these concerns, government, industry and community stakeholders have worked in close cooperation to develop a whole-of-government, whole-of-community approach to understanding and managing the region's waterways. This paper provides an overview of the experience gained through development of the SEQ Healthy Waterways Partnership and highlights some of the key factors we believe have contributed to its success.
Publisher: Public Library of Science (PLoS)
Date: 12-06-2013
Publisher: University of Chicago Press
Date: 12-2016
DOI: 10.1086/688092
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/MF99011
Abstract: Caridina sp. is an atyid shrimp occupying coastal streams in south-eastern Queensland and northern New South Wales. Shrimps from two geographic regions in south-eastern Queensland were examined. An analysis of 7 allozyme loci showed very high levels of genetic differentiation among catchments (F ST = 0.65) with much lower levels within catchments. This indicates extremely limited dispersal among catchments with greater levels within catchments. The levels of genetic differentiation were even greater than previously reported for two other atyid shrimp species occurring in upland rainforest streams. Populations from the Noosa River were more similar to those from the Glasshouse Mountains than to those from the geographically closer Tin Can Bay streams. This pattern was remarkably similar to that of a fish species occurring in the same streams and may reflect a recent confluence of streams from the Glasshouse Mountains and the Noosa River regions.
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/MF9840261
Abstract: Three of the six permanent hypersaline lakes on Rottnest Island become meromictic 'hot lakes' during winter and spring. An important factor contributing to this transient stratification is a surface input of fresh water from seepages around the lakes, which overlays the existing hypersaline layer. Heat penetrates to the monimolimnion of these clear-water lakes and is trapped by the insulating effect of the overlying less-saline water. The disappearance of the stratification at the onset of summer is thought to be due to reduced freshwater input and evaporation of the less-saline mixolimnion.
Publisher: Springer Science and Business Media LLC
Date: 05-05-2006
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Stuart Bunn.