ORCID Profile
0000-0001-6047-031X
Current Organisation
James Cook University
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Publisher: Oxford University Press (OUP)
Date: 29-08-2014
DOI: 10.1111/BIJ.12363
Publisher: Wiley
Date: 28-07-2011
Publisher: Springer Science and Business Media LLC
Date: 25-07-2012
DOI: 10.1038/NATURE11318
Abstract: The rapid disruption of tropical forests probably imperils global bio ersity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their bio ersity. A critical constraint in addressing this question has been that data describing a broad array of bio ersity groups have been unavailable for a sufficiently large and representative s le of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of bio ersity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious bio ersity declines.
Publisher: Wiley
Date: 16-01-2017
DOI: 10.1111/FWB.12884
Publisher: Springer Science and Business Media LLC
Date: 04-10-2021
DOI: 10.1007/S10750-021-04703-W
Abstract: Leaf litter decomposition is a key process in stream ecosystems, the rates of which can vary with changes in litter quality or its colonization by microorganisms. Decomposition in streams is increasingly used to compare ecosystem functioning globally, often requiring the distribution of litter across countries. It is important to understand whether litter sterilization, which is required by some countries, can alter the rates of decomposition and associated processes. We examined whether litter sterilization with gamma irradiation (25 kGy) influenced decomposition rates, litter stoichiometry, and colonization by invertebrates after weeks of instream incubation within coarse-mesh and fine-mesh litterbags. We used nine plant species from three families that varied widely in litter chemistry but found mostly consistent responses, with no differences in decomposition rates or numbers of invertebrates found at the end of the incubation period. However, litter stoichiometry differed between irradiated and control litter, with greater nutrient losses (mostly phosphorus) in the former. Therefore, the effects of irradiation on litter chemistry should be taken into account in studies focused on stoichiometry but not necessarily in those focused on decomposition rates, at least within the experimental timescale considered here.
Publisher: Wiley
Date: 08-02-2011
DOI: 10.1111/J.1461-0248.2010.01578.X
Abstract: The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.
Publisher: Wiley
Date: 14-12-2010
DOI: 10.1111/J.1095-8649.2010.02862.X
Abstract: The diets of 21 terapontid species from freshwater environments in northern Australia were investigated to determine the similarity and dissimilarity among species and the extent of any ontogenetic shifts. Distinct ontogenetic dietary shifts occurred in all species for which sufficient data were available, with many species passing through several discrete trophic categories during their life histories. Diets of all juvenile terapontids were similar, mainly comprising aquatic insects and zooplankton. Larger size classes of terapontids erged into a broad spectrum of feeding groups comprising carnivorous dietary modes (including piscivory and lepidophagy), omnivory (including frugivory and consumption of allochthonous prey), herbivory and detritivory. The results indicate that the terapontids represent Australia's most trophically erse freshwater fish family.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09202
Abstract: In Australia’s Wet Tropics rivers, perennial base flows punctuated by wet season floods drive instream responses across a range of spatial and temporal scales. We combined gut-content and stable-isotope analyses to produce preliminary webs depicting trophic links between fish, their main prey items and basal productivity sources. We then used these webs to test the applicability of general food web principles developed in other tropical systems. Although a range of sources appeared to underpin fish productivity, a large portion of total energy transfer occurred through a subset of trophic links. Variability in food web structure was negatively correlated with spatial scale, being seasonally stable at river reaches and variable at smaller scales. Wet Tropics rivers are similar to those in other tropical areas, but exhibit some unique characteristics. Their high degree of channel incision improves longitudinal connectivity, thereby allowing fish to move between mesohabitats and target their preferred prey items, rather than shifting their diet as resources fluctuate. However, this also inhibits lateral connectivity and limits terrestrial energy inputs from beyond the littoral zone.
Publisher: Public Library of Science (PLoS)
Date: 06-10-2011
Publisher: Wiley
Date: 09-2011
DOI: 10.1890/10-2244.1
Abstract: Most hypotheses explaining the general gradient of higher ersity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of ersity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global ersity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder ersity and abundance in the tropics, which contrasts with ersity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and erse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expected latitudinal pattern and showed that shredder distribution (abundance, ersity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more erse in particular biogeographic realms). In contrast to our hypothesis, shredder ersity was unrelated to leaf toughness, but it was inversely related to litter ersity. Our findings markedly contrast with global trends of ersity for most taxa, and with the general rule of higher consumer ersity at higher levels of resource ersity. Moreover, they highlight the emerging role of temperature in understanding global patterns of ersity, which is of great relevance in the face of projected global warming.
Publisher: Wiley
Date: 11-11-2006
Publisher: Wiley
Date: 17-12-2019
DOI: 10.1111/FWB.13459
Publisher: The Royal Society
Date: 22-05-1997
Publisher: Elsevier BV
Date: 12-1975
Publisher: University of Chicago Press
Date: 06-2009
DOI: 10.1899/08-118.1
Publisher: Wiley
Date: 16-08-2018
DOI: 10.1111/FWB.13172
Publisher: Schweizerbart
Date: 31-08-2006
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/MF12251
Abstract: We investigated the biophysical environment, invertebrate fauna and ecosystem health of lagoons on the Tully–Murray floodplain in the Queensland Wet Tropics bioregion. These wetlands are biologically rich but have declined in area and condition with agricultural development and are poorly protected, despite being located between two World Heritage areas. Lagoons varied in size, habitats and water quality, with increasing signatures of agriculture (e.g. elevated nutrient concentrations) from the upper to lower floodplain. Zooplankton were abundant, but not erse, and correlated variously with environmental variables, so were not useful in assessing lagoon condition. Benthic macroinvertebrates were abundant and erse and correlated strongly with riparian condition, habitats, water quality and degree of agriculture in the catchment, but gradients in assemblage structure were not strong because the flow regime, with multiple annual floods, maintains higher water quality than in some tropical systems. The absence of pristine reference lagoons and the limited availability of replicate sites h er the development of monitoring systems. Nevertheless, we show that appropriate s ling, analysis and knowledge of comparable systems allow inferences to be drawn regarding ecological condition. This is important because environmental managers need best available and timely advice whatever the opportunities for rigorous study design.
Publisher: Springer Science and Business Media LLC
Date: 10-1987
DOI: 10.1007/BF00007209
Publisher: American Association for the Advancement of Science (AAAS)
Date: 26-03-2021
Abstract: Plant litter functional ersity effects on instream decomposition change across latitudes.
Publisher: Wiley
Date: 18-11-2012
DOI: 10.1002/HYP.8364
Publisher: Wiley
Date: 23-04-2012
DOI: 10.1111/J.1420-9101.2012.02504.X
Abstract: The ecological opportunities associated with transitions across the marine-freshwater interface are regarded as an important catalyst of ersification in a range of aquatic taxa. Here, we examined the role of these major habitat transitions and trophic ersification in a radiation of Australasian fishes using a new molecular phylogeny incorporating 37 Terapontidae species. A combined mitochondrial and nuclear gene analysis yielded a well-supported tree with most nodes resolved. Ancestral terapontids appear to have been euryhaline in habitat affiliation, with a single transition to freshwater environments producing all Australasian freshwater species. Mapping of terapontid feeding modes onto the molecular phylogeny-predicted carnivorous dietary habits was displayed by ancestral terapontids, which subsequently ersified into a range of additional carnivorous, omnivorous, herbivorous and detritivorous dietary modes upon transition to freshwater habitats. Comparative analyses suggested that following the freshwater invasion, the single freshwater clade has exhibited an increased rate of ersification at almost three times the background rate evident across the rest of the family. The marine-freshwater transition within Terapontidae appears to have resulted in substantial dietary radiation in freshwater environments, as well as increased lineage ersification rates relative to euryhaline-marine habitats.
Publisher: Springer Science and Business Media LLC
Date: 28-09-2020
Publisher: Springer Science and Business Media LLC
Date: 08-06-2006
DOI: 10.1007/S00442-006-0454-8
Abstract: The threat posed by predation varies among predator species and with environmental context, and prey species often adjust their responses accordingly. We investigated such effects within an insect assemblage from a tropical Australian stream. These systems are frequently subjected to catastrophic floods, often suggested to reduce the importance of predation in streams, and invertebrate faunas are characterised by relatively broad environmental tolerances. Impacts of the hunting predator Australopelopia prionoptera (Diptera: Chironomidae) and an undescribed ambush predator from the Polycentropodidae (Trichoptera) on survival and development of two species of tubicolous Chironomidae, Echinocladius martini (Orthocladiinae) and Polypedilum australotropicus (Chironominae), were assessed in laboratory microcosms. A further experiment investigated how impacts of Australopelopia varied over a broad range of temperatures, exceeding that experienced annually by the studied populations. Neither predator impacted survivorship for E. martini, but the presence of the polycentropodid caused E. martini to spend longer as larvae and reduced adult longevity, and adult females were smaller-sized and had smaller oocytes. In contrast, both predators reduced survivorship of P. australotropicus, but only Australopelopia affected its development, causing reductions in pupal duration and oocyte size. The observed non-lethal impacts of predation reflect the threat each predator is known to pose to each prey species in situ. Impacts of predation varied little with temperature, reflecting the broad thermal tolerances of all study species. The predator-specific responses of the prey species imply that predation is a significant selective force in tropical Australian streams, although fluctuation in intensity of predation associated with flooding may limit its importance for community structure and prey ersity at larger scales. Our results indicate a more limited scope for environmental modification of predator-prey relationships in faunas characterised by broad physiological tolerances.
Publisher: Wiley
Date: 12-12-2013
DOI: 10.1111/FWB.12080
Publisher: University of Chicago Press
Date: 09-2012
DOI: 10.1899/11-068.1
Publisher: Public Library of Science (PLoS)
Date: 22-09-2014
Publisher: Wiley
Date: 09-10-2014
DOI: 10.1002/HYP.10065
Publisher: Elsevier BV
Date: 04-2016
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/MF04023
Abstract: In temperate regions of the northern hemisphere, where stream thermal regimes fluctuate seasonally and predictably, temperature has a role in niche segregation and maintenance of patterns of lotic ersity and distribution, as described by the ‘Thermal Equilibrium Hypothesis’. In Australia, the role of temperature in regulating patterns of ersity and distribution has been obscure, as seasonal variation in stream temperatures can be exceeded by stochastic fluctuation in flow. The thermal responses of five lotic Chironomidae (Diptera) species, contrasting in biogeographic (evolutionary) history, from warm tropical and cool temperate Australian populations, were investigated. All species, including postulated cool-stenotherms, showed broadly eurythermic developmental and morphological responses, and maintained both survivorship and oocyte production at elevated temperatures despite reductions in overall body size. There were subtle differences among species according to biogeographic affinity, with tolerances of Gondwanan species, which were narrower than those of cosmopolitan species, best characterised as ‘mesothermic’, but there was little ergence between populations. These results have implications for the understanding of ersity and distribution of Australian chironomids, and indicate that applicability of the Thermal Equilibrium Hypothesis to Australian lotic faunas may be limited.
Publisher: Wiley
Date: 09-2009
Publisher: Springer Science and Business Media LLC
Date: 14-09-2013
Publisher: University of Chicago Press
Date: 06-2012
DOI: 10.1899/11-103.1
Publisher: Cambridge University Press
Date: 13-01-2005
Publisher: University of Chicago Press
Date: 06-2009
DOI: 10.1899/08-146.1
Publisher: Wiley
Date: 09-2020
DOI: 10.1002/AQC.3339
Publisher: EDP Sciences
Date: 2012
DOI: 10.1051/LIMN/2012013
Publisher: Wiley
Date: 2000
Publisher: Public Library of Science (PLoS)
Date: 23-01-2014
Publisher: Wiley
Date: 27-03-2008
Publisher: Wiley
Date: 10-11-2009
Publisher: University of Chicago Press
Date: 03-2014
DOI: 10.1086/674632
Publisher: Wiley
Date: 03-07-2006
Publisher: University of Chicago Press
Date: 06-2004
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF11190
Abstract: In freshwater systems, dissolved oxygen (DO) saturation frequently fluctuates, falling at night and rising during the day in response to respiration and photosynthesis, respectively, of aquatic biota. Low DO (hypoxia) is a common cause of fish kills in freshwater systems around the world. Laboratory studies on responses of fish to fluctuating DO are currently limited, and require techniques that produce a realistic cycle of DO depletion and replacement. Artificial DO-depletion mechanisms frequently used for hypoxia studies may underestimate the field effects of hypoxia on fish because of the lack of the naturally occurring synergistic effect of lower pH, and seldom allow fish to employ behavioural adaptations to hypoxia, such as aquatic surface respiration. We demonstrate proof-of-principle for an alternative method of creating fluctuating hypoxia in an experimental environment, using the natural rhythms of photosynthesis and respiration of aquatic plants to create realistic conditions. A range of volumes of aquatic macrophytes were used alone and in combination with fish to lower DO saturation in sealed freshwater aquaria, and achieved DO saturations as low as 1.3%. This cost-effective method can be deployed over long periods with minimal effort in comparison to traditional methods of DO reduction.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF11105
Abstract: With the covariation between fish form and function of long-standing interest to fish biologists, ecomorphological research provides a framework for assessing the interaction between the morphology of an organism and their ecology. Whereas ecomorphological studies of Australian fishes are rare, the terapontid grunters are an ideal candidate for study because of their ersity of dietary habits. We examined the morphological correlates of the diet of 21 species of northern Australia’s terapontids and their constituent ontogenetic trophic units. Preliminary analyses focusing on morphology identified the role of allometric growth – in characters such as intestinal length, maxilla length and mouth width – as driving considerable ontogenetic ergence in interspecific morphological trajectories. A significant relationship was identified between diet and morphology across species, although morphology explained only half of the observed dietary variation. Body size, and its relationship to allometric development of several morphological parameters, appears to constrain the trophic habits expressed by many terapontids at different life-history stages. Many of the diet–morphology relationships evident within the Terapontidae parallel those seen in other studies, providing substantial corroboration for the ecomorphological approach. This demonstrates that selective pressures have driven morphology in terapontids to converge morphologically with other ecologically comparable fishes across the globe.
Publisher: Wiley
Date: 23-04-2008
Publisher: Wiley
Date: 23-05-2012
Publisher: Wiley
Date: 15-10-2017
DOI: 10.1111/FWB.13036
Publisher: Springer Science and Business Media LLC
Date: 09-07-2013
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/MF08055
Abstract: Wet-season flooding causes dietary shifts in tropical freshwater fish by regulating instream productivity, habitat structure and food availability. These dynamics have been comprehensively documented worldwide, but data are limited for Australia’s Wet Tropics rivers. The aim of the present study was to extend our earlier fish–habitat model for these systems by examining the role of trophic dynamics in determining fish assemblage composition. Chlorophyll a and phaeophytin concentrations, benthic and littoral invertebrates and fish were collected at four sites in the lower Mulgrave River under a range of flow conditions. Wet-season flooding caused significant reductions in instream productivity, whereas habitat disturbance reduced densities and abundances of littoral and benthic invertebrates. However, volumetric gut contents of 1360 fish, from 36 species, revealed seasonal shifts in guild membership by only two species, with fish moving between sites to target their preferred prey items – largely irrespective of differences in habitat structure. As a result, the food consumed by the fish community present at each site closely reflected the seasonal availability of food resources. The present paper questions whether fish community composition in small tropical rivers can be accurately predicted from habitat surrogates alone and encourages consideration of constraints imposed by the trophic dynamics and reproductive ecology of fish.
Publisher: MDPI AG
Date: 05-12-2014
DOI: 10.3390/D6040771
Publisher: Wiley
Date: 18-04-2012
Publisher: Springer Science and Business Media LLC
Date: 06-1991
DOI: 10.1007/BF00323785
Publisher: Springer Science and Business Media LLC
Date: 17-06-2021
DOI: 10.1038/S41467-021-23930-2
Abstract: The relationship between detritivore ersity and decomposition can provide information on how biogeochemical cycles are affected by ongoing rates of extinction, but such evidence has come mostly from local studies and microcosm experiments. We conducted a globally distributed experiment (38 streams across 23 countries in 6 continents) using standardised methods to test the hypothesis that detritivore ersity enhances litter decomposition in streams, to establish the role of other characteristics of detritivore assemblages (abundance, biomass and body size), and to determine how patterns vary across realms, biomes and climates. We observed a positive relationship between ersity and decomposition, strongest in tropical areas, and a key role of abundance and biomass at higher latitudes. Our results suggest that litter decomposition might be altered by detritivore extinctions, particularly in tropical areas, where detritivore ersity is already relatively low and some environmental stressors particularly prevalent.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/MF19343
Abstract: Waterholes that remain in the dry season in intermittent dryland rivers are important biotic refugia, but detailed ecological descriptions of these habitats and their plankton are scarce. We aimed to determine spatial and temporal variation in phytoplankton assemblages in a tropical Australian dryland river system, their main environmental determinants and the potential of the phytoplankton for ecosystem monitoring. We s led nine sites in three rivers over 2 years using standard methods. Water quality and phytoplankton assemblages varied considerably among sites, rivers and seasons, reflecting lithology, hydrology, bathymetry and local catchment influences. Major environmental drivers included conductivity, pH, temperature and species of N and P. We analysed several derived versions of the original dataset by using density and presence–absence data, eliminating rarer species and grouping species into higher taxa. We found substantial consistency among analyses in environmental drivers, identified using distance-based linear modelling, and in variability among systems, identified using nested permutational multivariate analysis of variance (PERMANOVA). Responsiveness of the algal assemblages to environmental drivers and consistency among analyses, even using subs les at low taxonomic resolution, suggests potential for ecosystem monitoring and optimising of s le throughput, although variability among systems requires substantial effort to determine the range of reference conditions.
Publisher: Wiley
Date: 14-04-2011
DOI: 10.1002/RRA.1505
Publisher: Wiley
Date: 10-04-2008
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/MF20067
Abstract: There is limited information available on the ecology of planktonic invertebrate assemblages of small tropical lowland rivers, despite zooplankton being a vital resource for larval fish. Herein we describe the spatial patterns and temporal dynamics of invertebrate zooplankton at 8 locations over a 25-month period in the lowland section of a short coastal river in the Australian Wet Tropics. Zooplankton were more abundant in slack than flowing waters and assemblages were dominated by Copepoda, but contained many less numerous taxa, including freshwater invertebrates at the more upstream sites. Taxonomic richness, total density and the densities of the most abundant taxa were greatest in the most downstream sites. Seasonal patterns in the density of zooplankton did not differ between the 2 years. Distance-based linear modelling of assemblages identified distance downstream and associated variables, such as salinity, as the most important environmental effects on zooplankton. The zooplankton assemblage in the lower Mulgrave River is strongly influenced by the incised nature of the river, perennial flows, the presence of slack waters, wet season floods and estuarine incursion. Zooplankton dynamics differ from the typical pattern of tropical floodplain systems in that their maximum proliferation occurs during the benign but productive late dry season.
Publisher: University of Chicago Press
Date: 06-2009
DOI: 10.1899/07-161.1
Publisher: Wiley
Date: 08-2022
DOI: 10.1002/ECO.2457
Abstract: The critical role of hydrology in tropical floodplain river systems is well established, but there is limited information on the drivers of larval and juvenile recruitment of freshwater fishes in small tropical rivers. Herein, we describe the patterns of occurrence and abundance of fish larvae, juveniles and adults in the lower reaches of a short, deeply incised coastal river of the Australian Wet Tropics. We expected that several environmental factors, including site proximity to the coast and flow and salinity regimes, would influence the life‐history strategies, distribution and abundance of larval and juvenile fishes. Study sites contained the larval stages of 23 of the 38 native species present, including nine species for which there are no previous larval records from Wet Tropics rivers or elsewhere. Larvae and juvenile fishes of most species exhibited maximum abundance in the benign but productive dry season, but some diadromous species showed peak abundance in tidal riverine/estuarine waters during the wet season. Most species exhibited peak larval abundance during the same months of Years 1 and 2 under similar hydrological, physicochemical water quality and habitat conditions in both years. These results are summarised in a conceptual model depicting how seasonal hydrology interacts with channel and habitat characteristics to influence life‐history strategies and hence spatial and temporal variations in larval fish abundance in Wet Tropics rivers. Our results highlight the importance of seasonal contrasts in flow, habitat structure, water quality and food resources in supporting the variety of life‐history strategies in the fish assemblages.
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/MF07129
Abstract: Strong relationships between seasonal flooding, instream habitat structure and fish assemblages have been well documented in large tropical rivers (e.g. the flood pulse concept). However, the mechanics of these relationships are likely to differ substantially in smaller coastal rivers, such as those in Costa Rica, south-east Brazil and Australia’s Wet Tropics. These systems typically feature steep upland streams with short, deeply incised lowland channels and poorly connected floodplains. This hypothesis was investigated by documenting spatial and temporal variation in fish-habitat relationships in the Mulgrave River, north-east Queensland. S ling was conducted at four lowland sites under a range of flow conditions, from dry-season baseflows to a one-in-ten-year flood. Longitudinal environmental gradients and fine-scale habitat patches were important in regulating fish assemblage structure during the dry season. However, high wet-season flows, constrained by the deep channel, acted as disturbances rather than gentle flood-pulses. In particular, the mobilisation of bed sediments led to scouring of aquatic vegetation and a dramatic reduction in habitat heterogeneity. Seasonal movements of fish led to significant changes in assemblage structure – from a community dominated by Neosilurus ater, Hypseleotris compressa, Awaous acritosus and Redigobius bikolanus during the dry season, to one dominated by Nematalosa erebi, Ambassis agrammus and Glossamia aprion during the wet season. Based on these observations, together with information from the literature, a conceptual model of fish-habitat dynamics is presented that is better suited to small tropical rivers than those developed in larger systems with expansive floodplains.
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/MF02038
Abstract: A method of preparing and interpreting the microstructure of otoliths of the eastern rainbowfish, Melanotaenia splendida splendida, was developed and used to validate the periodicity of increment formation. Otoliths were collected from laboratory-reared M. s. splendida of known age. The sagittal otolith was preferred for ageing because resolving the earliest increments was easier than in the lapillus during an early slow-growth period, up to 15 days after hatching. Increments formed in the sagittae before hatching, and a distinct discontinuity was visible in the otolith sections at a time corresponding to hatching. Another discontinuity occurred at the time of yolk-sac absorption, when larvae became completely reliant on exogenous feeding. After this, increments were clear, regularly spaced and easily resolved. Linear relationships were found between fish size and sagittal length, breadth and perimeter. Observations of the otolith sections confirmed that the increments in sagittae of M. s. splendida were laid down daily. The information provided here enables growth and mortality rates of M. s. splendida to be measured, providing a useful tool for monitoring the impacts of contaminants in tropical Australian waters.
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/MF02037
Abstract: This paper describes the ontogeny and morphogenesis of the eastern rainbowfish, Melanotaenia splendida splendida, including details on reproduction and the conditions required for laboratory breeding and rearing. M. s. splendida is easily bred under standard laboratory conditions using readily available commercial foods. Aquaria with two males and three females can produce between 40 and 200 eggs daily. They can be induced to spawn daily throughout the year through manipulation of light and temperature conditions. The eggs, which ranged in size from 0.93 to 1.20 mm, had a homogeneous yolk and a clear, uniform chorion, making observation of developmental stages possible. Development was telolecithical and ision was meroblastic. Development of M. s. splendida was similar to that of other Melanotaenia species. At 28°C, hatching occurred between 4 and 8 days, with an average larval length of 3.7 mm standard length. Growth was rapid and the fish reached sexual maturity within approximately 90 days. Knowledge of the developmental stages of M. s. splendida is important in enabling further work, such as bioassays and environmental monitoring, to be carried out, investigating the ways in which changes in the environment, such as pollution, will impact on Australia's freshwater fishes. Melanotaenia splendida splendida is an ideal species for this purpose in the north-eastern tropics of Australia.
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Wiley
Date: 11-2013
DOI: 10.3732/AJB.1200614
Abstract: Sprouting in woody plants promotes persistence in the face of disturbance, ultimately influencing population structure. Different disturbance regimes drive variable population responses, but there have been few direct tests of the relative differences in population structure to specific drivers. We measured population structure as genotypic ersity (clonality) as a function of hydrological regime for a riverine tree, Melaleuca leucadendra, a major structural component in flood landscapes in the Australian dry tropics. We estimated clonality, genotypic richness, and population allelic ersity. The relationship among disturbance, genetic estimates of clonality, and population distinctiveness was compared with flood regime, characterized by return frequencies and hydrological stress at in idual river reaches. Two contrasting patterns of genotypic structure were detected and corresponded to order-of-magnitude differences in flood regime between sites. At mainstem locations characterized by greatest flood intensity, sprouting generated clonal structure to 17 m (30% ramets clonal). By contrast, clonality was atypical at lower-disturbance tributaries (0% clonal). Population allelic distributions showed extensive genetic exchange among mainstem locations, but strong genetic differentiation between mainstem and tributaries. Population structure and distinctiveness in riverine Melaleuca are determined by differences in sprouting and recruitment responses that depend on localized hydrological regime. Sprouting contributes to population persistence via localized clonal growth. Resprouting following disturbance in M. leucadendra may help explain its numerical dominance in tropical river systems. This study, although preliminary, suggests that flood ecosystems may represent excellent experimental systems to develop a better understanding of whole-organism responses to environmental drivers.
Publisher: Public Library of Science (PLoS)
Date: 31-07-2013
Publisher: Informa UK Limited
Date: 20-12-2017
Publisher: Wiley
Date: 23-04-2008
Publisher: Wiley
Date: 04-2005
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/MF05052
Abstract: The structure of stream communities is typically thought to be driven by stochastic events such as floods, in contrast with communities in many other systems in which biotic interactions have a major role. However, it is possible that biotic interactions are important in some situations in streams, especially where resources are limited and physical influences are stable for substantial periods. Leaf litter – the main energy source and a distinct habitat in forest streams – constitutes a patchy resource where biotic interactions among and within consumer species are likely to occur. The intraspecific interference in four leaf-eating species (shredders), common in Australian tropical streams, was experimentally examined – Anisocentropus kirramus (Trichoptera : Calamoceratidae), Lectrides varians and Triplectides gonetalus (Trichoptera : Leptoceridae) and Atalophlebia sp. (Ephemeroptera : Leptophlebiidae). All four species showed some degree of intraspecific interference, indicated by lowered leaf breakdown rates when density increased. Breakdown rates per capita decreased exponentially for all species with increased density, with slight differences among species. These differences were more evident when body size was taken into account, with breakdown rates depressed at lower densities for the two species with larger body sizes, T. gonetalus and Atalophlebia sp. Overall breakdown rates did not always increase with higher densities, because they were compensated for by depressed in idual breakdown rates. Our results indicate that intraspecific interference can be an important mechanism regulating leaf breakdown in streams.
Publisher: Springer Science and Business Media LLC
Date: 25-09-2019
Publisher: Elsevier
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 31-07-2007
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09132
Abstract: Comparisons of leaf-litter processing in streams suggest that tropical streams have fewer leaf shredders than temperate streams and that insect shredders might be replaced by other taxa such as Crustacea in tropical systems. Australian wet-tropical streams have abundant insect shredders, and also abundant crayfish, which may contribute to litter processing. We monitored litter input and retention in a Queensland rainforest stream to determine availability of litter in different seasons, and we conducted experiments to test the hypothesis that crayfish were important contributors to litter processing. Litter fall peaked in the late dry season and litter accumulated steadily in pools, whereas in riffles, the standing crop was maintained at a threshold level. All accumulated litter was washed from the stream during a flood. The crayfish, Cherax cairnsensis, readily fed on leaves. Its processing rate was related negatively to leaf toughness and positively to leaf nitrogen content. The crayfish assimilated up to 28.5% of the material processed at 24°C, and none at 11°C. These results confirm that there are alternatives to insect shredders in tropical streams, even when insect shredders are abundant.
Publisher: Elsevier
Date: 2008
Publisher: Elsevier BV
Date: 10-2011
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/ZO07040
Abstract: The structure and dynamics of fish assemblages were studied in two small coastal streams in the seasonal tropics of northern Queensland. The study encompassed two consecutive wet seasons of contrasting flood magnitudes. Flooding had substantial effects on physical habitats by shifting sediments and removing aquatic macrophytes, and short-term changes in the fish assemblages reflected these habitat changes. Changes were of higher magnitude following a one-in-eighteen-year flood than a one-in-one-year flood however, in both cases return to prior assemblage structure occurred as the dry season progressed, but with more rapid recovery after the smaller event. The stream fish assemblages showed high resilience to the flood disturbance at magnitudes seen in this study.
Publisher: Springer Science and Business Media LLC
Date: 19-09-2007
DOI: 10.1007/S00244-006-0215-Z
Abstract: Lethal and sublethal effects of ammonia toxicity to juvenile barramundi (Lates calcarifer) were investigated under laboratory conditions following the OECD guidelines for testing of chemicals. Acute toxicity was tested in a static nonrenewal system at pH 9.0 and temperature around 29 degrees C. The 24-, 48-, and 96-h LC(50) values for barramundi were 3.89, 3.67, and 3.31 mg total ammonia N L(-1) and 1.59, 1.47, and 1.3 mg nonionized ammonia N L(-1), respectively. Estimated lethal concentrations indicated a relatively high sensitivity to acute ammonia toxicity for barramundi and equaled the 25th percentile most sensitive North American fish species with regard to the species mean acute value (USEPA 1999). A 3-week postexposure experiment on surviving in iduals from the acute toxicity test, in clean water, indicated that exposure to acute concentrations up to 1.16 mg nonionized ammonia N L(-1) did not have any significant effects on growth.
Publisher: Wiley
Date: 29-08-2010
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF14120
Abstract: Hypoxia in freshwater ecosystems of the Australian wet tropics occurs naturally, but is increasing as a result of anthropogenic influences. Diel cycling of dissolved oxygen (DO) concentration (fluctuating hypoxia) is common in the region. Laboratory experiments sought to identify relationships between severity of fluctuating hypoxia and sublethal effects on ventilation, feeding and growth for juvenile barramundi (Lates calcarifer), eastern rainbowfish (Melanotaenia splendida splendida) and sooty grunter (Hephaestus fuliginosus). Fish continued to feed and grow under daily exposure to severe fluctuating hypoxia treatments for several weeks. Ventilation rates increased in a significant direct quadratic relationship with the severity of hypoxia treatments and increasing hypoxia caused ventilatory behaviour changes in all species. Barramundi and rainbowfish attempted aquatic surface respiration and were more tolerant of severe hypoxia than was sooty grunter barramundi and rainbowfish are also more likely to experience hypoxia in the wild. There was a significant quadratic relationship between growth and minimum DO saturation for barramundi. Although all three species were tolerant of hypoxia, anthropogenic stressors on tropical Australian aquatic ecosystems may increase the frequency and severity of hypoxic conditions causing a concomitant increase in fish kill events.
Publisher: CSIRO Publishing
Date: 02-05-2022
DOI: 10.1071/MF21287
Abstract: We argue for improved conservation of freshwater ecosystems at catchment or eco-regional scales by explicit assignment of values to all river sections and wetlands, recognising current disturbance, and aiming for ‘no further harm’ to the commons. The need is indicated by the global deterioration of bio ersity and ecosystem services of rivers and wetlands, increasing demands on water and land resources, and climate change. Regional pressures include multiple jurisdictions, competing demands, piecemeal management, pollution and habitat impacts. Effective resource and conservation management needs to integrate multiple uses via governance of activities of stakeholders, recognising hydrogeomorphic, water quality and ecological properties of ecosystems. Complete ecological protection is impractical amidst water-resource and land-use development, but we suggest that all river reaches and wetlands be given a conservation rating based on habitat, bio ersity and connectivity values. We present a straightforward approach to spatial conservation rating of freshwaters, using hydrogeomorphic typology and assignment of conservation values on the basis of available information and expert elicitation. We illustrate the approach by using the large Burdekin River catchment in north-eastern Australia. This approach is complementary to more spatially focused conservation prioritisation and could greatly improve management for sustainability, reduce further decline in conservation values, and facilitate rehabilitation.
Publisher: Wiley
Date: 07-08-2012
Publisher: Wiley
Date: 10-10-2007
Publisher: Cambridge University Press (CUP)
Date: 03-2007
DOI: 10.1017/S0266467406003920
Abstract: Consumption of terrestrial leaf litter by stream invertebrates is an important process, but little attention has been paid to the influence of leaf ersity on the process. Tropical forests are known to have much greater ersity of plant species than their temperate counterparts, but studies of litter processing in tropical streams have not explicitly addressed this issue. This paper documents the streambed leaf litter composition and ersity of an Australian tropical rain-forest stream and the leaf preferences of consumers in the stream. We hypothesized that there would be high ersity of litter in the stream and that the shredders would have broad preferences, given that litterfall of any one species would occur over a restricted period. Leaf litter was characterized by high species ersity (81 species from one stream reach s led on two occasions). Leaf consumers (‘shredders’) were associated with a relatively broad suite of leaf species (38 species) and did not indicate clear leaf preferences. However, in a laboratory feeding experiment, using the three most common shredder species and some of the most abundant leaf species in the stream, all shredder species exhibited clear preference for a single leaf species ( Endiandra bessaphila ). Preference for this and other species was affected by the conditioning age of leaves (i.e. the length of time leaves were exposed to leaching and microbial colonization), with conditioned leaves usually being preferred, and previously non-selected leaves becoming more palatable with conditioning. Thus, different successional stages were more important than the identity of leaf species in determining the distribution of shredders among the leaves.
Publisher: EDP Sciences
Date: 16-08-2010
DOI: 10.1051/LIMN/2010019
Publisher: Wiley
Date: 02-2005
Publisher: Springer Science and Business Media LLC
Date: 07-1987
DOI: 10.1007/BF00006609
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Richard Pearson.