Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-his... more Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-history strategies of freshwater fish in relation to environmental variation across Australian river basins and (2) to identify key life-history traits associated with species extinction risk in order to determine how fish communities and extinction-prone species may respond to future environmental change.
Planning for the remediation of multiple threats is crucial to ensure the long term persistence o... more Planning for the remediation of multiple threats is crucial to ensure the long term persistence of biodiversity. Limited conservation budgets require prioritizing which management actions to implement and where. Systematic conservation planning traditionally assumes that all the threats in priority sites are abated (fixed prioritization approach). However, abating only the threats affecting the species of conservation concerns may be more cost-effective. This requires prioritizing individual actions independently within the same site (independent prioritization approach), which has received limited attention so far. We developed an action prioritization algorithm that prioritizes multiple alternative actions within the same site. We used simulated annealing to find the combination of actions that remediate threats to species at the minimum cost. Our algorithm also accounts for the importance of selecting actions in sites connected through the river network (i.e., connectivity). We applied our algorithm to prioritize actions to address threats to freshwater fish species in the Mitchell River catchment, northern Australia. We compared how the efficiency of the independent and fixed prioritization approach varied as the importance of connectivity increased. Our independent prioritization approach delivered more efficient solutions than the fixed prioritization approach, particularly when the importance of achieving connectivity was high. By spatially prioritizing the specific actions necessary to remediate the threats affecting the target species, our approach can aid cost-effective habitat restoration and land-use planning. It is also particularly suited to solving resource allocation problems, where consideration of spatial design is important, such as prioritizing conservation efforts for highly mobile species, species facing climate change-driven range shifts, or minimizing the risk of threats spreading across different realms.
Understanding the biogeographic and phylogenetic basis to interspecifi c diff erences in species ... more Understanding the biogeographic and phylogenetic basis to interspecifi c diff erences in species ' functional traits is a central goal of evolutionary biology and community ecology. We quantify the extent of phylogenetic infl uence on functional traits and life-history strategies of Australian freshwater fi sh to highlight intercontinental diff erences as a result of Australia ' s unique biogeographic and evolutionary history. We assembled data on life history, morphological and ecological traits from published sources for 194 Australian freshwater species. Interspecifi c variation among species could be described by a specialist -generalist gradient of variation in life-history strategies associated with spawning frequency, fecundity and spawning migration. In general, Australian fi sh showed an affi nity for life-history strategies that maximise fi tness in hydrologically unpredictable environments. We also observed diff erences in trait lability between and within life history, morphological and ecological traits where in general morphological and ecological traits were more labile. Our results showed that life-history strategies are relatively evolutionarily labile and species have potentially evolved or colonised in freshwaters frequently and independently allowing them to maximise population performance in a range of environments. In addition, reproductive guild membership showed strong phylogenetic constraint indicating that evolutionary history is an important component infl uencing the range and distribution of reproductive strategies in extant species assemblages. For Australian freshwater fi sh, biogeographic and phylogenetic history contribute to broad taxonomic diff erences in species functional traits, while fi ner scale ecological processes contribute to interspecifi c diff erences in smaller taxonomic units. Th ese results suggest that the lability or phylogenetic relatedness of diff erent functional traits aff ects their suitability for testing hypothesis surrounding community level responses to environmental change.
Biotic communities are shaped by adaptations from generations of exposure to selective pressures ... more 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 diversity. We show that the relative balance between these seemingly divergent 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 biodiversity and productivity.
Conservation planning is sensitive to a number of scale-related issues, such as the spatial exten... more Conservation planning is sensitive to a number of scale-related issues, such as the spatial extent of the planning area, or the size of units of planning. An extensive literature has reported a decline in efficiency of conservation outputs when planning at small spatial scales or when using large planning units. However, other key issues remain, such as the grain size used to represent the spatial distribution of conservation features. Here, we evaluate the effect of grain size of species distribution data versus size of planning units on a set of performance measures describing efficiency (ratio of area where species are represented/total area needed), rate of commission errors (species erroneously expected to occur), representativeness (proportion of species achieving the target) and a novel measure of overall conservation uncertainty (integrating commission errors and uncertainty in the actual locations where species occur). We compared priority areas for the conservation of freshwater fish in the Daly River basin (northern Australia). Our study demonstrates that the effect of grain size of species distribution data was more important than planning unit size on conservation planning performance, with an increase in commission errors up to 80% and conservation uncertainty over 90% when coarse data were used. This was more pronounced for rare than common species, where the mismatch between coarse representations of biodiversity patterns and the smaller areas of actual occupancy of species was more evident. Special attention should be paid to the high risk of misallocation of limited budgets when planning in heterogeneous or disturbed environments, where biodiversity is patchily distributed, or when planning for conservation of rare species.
Dense tropical rainforest, waterfalls and shallow riffle-run-pool sequences pose challenges for r... more Dense tropical rainforest, waterfalls and shallow riffle-run-pool sequences pose challenges for researcher access to remote reaches of streams for surveying aquatic fauna, particularly when using capture-based collecting techniques (e.g. trapping, backpack and boat electrofishing). We compared the detection of aquatic species (vertebrates and invertebrates .1 cm in body length) within pool habitats of a rainforest stream obtained by two visual techniques during both the wet and dry season: active visual survey by snorkelling and baited remote underwater video stations (BRUVSs). Snorkelling detected more species than a single BRUVS at each site, both within and among seasons. Snorkelling was most effective for recording the presence and abundance of diurnally active small-bodied species (adult size ,150 mm total length), although both techniques were comparable in detecting large-bodied taxa (turtles, fish and eels). On the current evidence, snorkelling provides the most sensitive and rapid visual technique for detecting rainforest stream fauna. However, in stream sections dangerous to human observers (e.g. inhabited by crocodiles, entanglement, extreme flows), we recommend a stratified deployment of multiple BRUVSs across a range of stream microhabitats within each site.
Aim Refugia play a key ecological role for the persistence of biodiversity in areas subject to na... more Aim Refugia play a key ecological role for the persistence of biodiversity in areas subject to natural or human disturbance. Temporary freshwater ecosystems regularly experience dry periods, which constrain the availability of suitable habitats. Current and future threats (e.g. water extraction and climate change) can exacerbate the negative effects of drying conditions. This could compromise the persistence of a large proportion of global freshwater biodiversity, so the identification and protection of refugia seems an urgent task.
Current methods underpinning environmental flow (eFlow) decisions often lack transparency, do not... more Current methods underpinning environmental flow (eFlow) decisions often lack transparency, do not adequately consider uncertainties and rarely include adaptive management principles. We report the development and application of an eFlow Bayesian Network (BN) model that links four flow components with an ecological model to predict the spawning and recruitment of two important native fish species, the Australian Grayling and River Blackfish, in the highly regulated and flow-stressed lower Latrobe River in Victoria, Australia. Autumn high flows, in conjunction with low stream temperature, are critical for Grayling spawning. The BN model was used to predict the probability of spawning and recruitment of these two native fish species for four flow scenarios. Quantitative data, flow simulation models and expert judgement were used to parameterize the BN model. The model results showed clearly that currently, and into the future, there is a very low likelihood of spawning and recruitment of Australian Grayling in the lower Latrobe. River Blackfish are minimally affected by the predicted reductions in flow and increased stream temperatures. Management scenarios aimed at modifying flows and stream temperatures to increase the likelihood of successful spawning and recruitment of Australian Grayling were assessed. Self-sustaining populations of Australian Grayling could conceivably be achieved in the upper reaches of this river if fish passage was provided through an on-stream reservoir. A major benefit in building and applying an eFlow BN model is that it can facilitate meaningful analysis and discussion of the ecological effects of particular eFlow regimes.
Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-his... more Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-history strategies of freshwater fish in relation to environmental variation across Australian river basins and (2) to identify key life-history traits associated with species extinction risk in order to determine how fish communities and extinction-prone species may respond to future environmental change.
Planning for the remediation of multiple threats is crucial to ensure the long term persistence o... more Planning for the remediation of multiple threats is crucial to ensure the long term persistence of biodiversity. Limited conservation budgets require prioritizing which management actions to implement and where. Systematic conservation planning traditionally assumes that all the threats in priority sites are abated (fixed prioritization approach). However, abating only the threats affecting the species of conservation concerns may be more cost-effective. This requires prioritizing individual actions independently within the same site (independent prioritization approach), which has received limited attention so far. We developed an action prioritization algorithm that prioritizes multiple alternative actions within the same site. We used simulated annealing to find the combination of actions that remediate threats to species at the minimum cost. Our algorithm also accounts for the importance of selecting actions in sites connected through the river network (i.e., connectivity). We applied our algorithm to prioritize actions to address threats to freshwater fish species in the Mitchell River catchment, northern Australia. We compared how the efficiency of the independent and fixed prioritization approach varied as the importance of connectivity increased. Our independent prioritization approach delivered more efficient solutions than the fixed prioritization approach, particularly when the importance of achieving connectivity was high. By spatially prioritizing the specific actions necessary to remediate the threats affecting the target species, our approach can aid cost-effective habitat restoration and land-use planning. It is also particularly suited to solving resource allocation problems, where consideration of spatial design is important, such as prioritizing conservation efforts for highly mobile species, species facing climate change-driven range shifts, or minimizing the risk of threats spreading across different realms.
Understanding the biogeographic and phylogenetic basis to interspecifi c diff erences in species ... more Understanding the biogeographic and phylogenetic basis to interspecifi c diff erences in species ' functional traits is a central goal of evolutionary biology and community ecology. We quantify the extent of phylogenetic infl uence on functional traits and life-history strategies of Australian freshwater fi sh to highlight intercontinental diff erences as a result of Australia ' s unique biogeographic and evolutionary history. We assembled data on life history, morphological and ecological traits from published sources for 194 Australian freshwater species. Interspecifi c variation among species could be described by a specialist -generalist gradient of variation in life-history strategies associated with spawning frequency, fecundity and spawning migration. In general, Australian fi sh showed an affi nity for life-history strategies that maximise fi tness in hydrologically unpredictable environments. We also observed diff erences in trait lability between and within life history, morphological and ecological traits where in general morphological and ecological traits were more labile. Our results showed that life-history strategies are relatively evolutionarily labile and species have potentially evolved or colonised in freshwaters frequently and independently allowing them to maximise population performance in a range of environments. In addition, reproductive guild membership showed strong phylogenetic constraint indicating that evolutionary history is an important component infl uencing the range and distribution of reproductive strategies in extant species assemblages. For Australian freshwater fi sh, biogeographic and phylogenetic history contribute to broad taxonomic diff erences in species functional traits, while fi ner scale ecological processes contribute to interspecifi c diff erences in smaller taxonomic units. Th ese results suggest that the lability or phylogenetic relatedness of diff erent functional traits aff ects their suitability for testing hypothesis surrounding community level responses to environmental change.
Biotic communities are shaped by adaptations from generations of exposure to selective pressures ... more 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 diversity. We show that the relative balance between these seemingly divergent 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 biodiversity and productivity.
Conservation planning is sensitive to a number of scale-related issues, such as the spatial exten... more Conservation planning is sensitive to a number of scale-related issues, such as the spatial extent of the planning area, or the size of units of planning. An extensive literature has reported a decline in efficiency of conservation outputs when planning at small spatial scales or when using large planning units. However, other key issues remain, such as the grain size used to represent the spatial distribution of conservation features. Here, we evaluate the effect of grain size of species distribution data versus size of planning units on a set of performance measures describing efficiency (ratio of area where species are represented/total area needed), rate of commission errors (species erroneously expected to occur), representativeness (proportion of species achieving the target) and a novel measure of overall conservation uncertainty (integrating commission errors and uncertainty in the actual locations where species occur). We compared priority areas for the conservation of freshwater fish in the Daly River basin (northern Australia). Our study demonstrates that the effect of grain size of species distribution data was more important than planning unit size on conservation planning performance, with an increase in commission errors up to 80% and conservation uncertainty over 90% when coarse data were used. This was more pronounced for rare than common species, where the mismatch between coarse representations of biodiversity patterns and the smaller areas of actual occupancy of species was more evident. Special attention should be paid to the high risk of misallocation of limited budgets when planning in heterogeneous or disturbed environments, where biodiversity is patchily distributed, or when planning for conservation of rare species.
Dense tropical rainforest, waterfalls and shallow riffle-run-pool sequences pose challenges for r... more Dense tropical rainforest, waterfalls and shallow riffle-run-pool sequences pose challenges for researcher access to remote reaches of streams for surveying aquatic fauna, particularly when using capture-based collecting techniques (e.g. trapping, backpack and boat electrofishing). We compared the detection of aquatic species (vertebrates and invertebrates .1 cm in body length) within pool habitats of a rainforest stream obtained by two visual techniques during both the wet and dry season: active visual survey by snorkelling and baited remote underwater video stations (BRUVSs). Snorkelling detected more species than a single BRUVS at each site, both within and among seasons. Snorkelling was most effective for recording the presence and abundance of diurnally active small-bodied species (adult size ,150 mm total length), although both techniques were comparable in detecting large-bodied taxa (turtles, fish and eels). On the current evidence, snorkelling provides the most sensitive and rapid visual technique for detecting rainforest stream fauna. However, in stream sections dangerous to human observers (e.g. inhabited by crocodiles, entanglement, extreme flows), we recommend a stratified deployment of multiple BRUVSs across a range of stream microhabitats within each site.
Aim Refugia play a key ecological role for the persistence of biodiversity in areas subject to na... more Aim Refugia play a key ecological role for the persistence of biodiversity in areas subject to natural or human disturbance. Temporary freshwater ecosystems regularly experience dry periods, which constrain the availability of suitable habitats. Current and future threats (e.g. water extraction and climate change) can exacerbate the negative effects of drying conditions. This could compromise the persistence of a large proportion of global freshwater biodiversity, so the identification and protection of refugia seems an urgent task.
Current methods underpinning environmental flow (eFlow) decisions often lack transparency, do not... more Current methods underpinning environmental flow (eFlow) decisions often lack transparency, do not adequately consider uncertainties and rarely include adaptive management principles. We report the development and application of an eFlow Bayesian Network (BN) model that links four flow components with an ecological model to predict the spawning and recruitment of two important native fish species, the Australian Grayling and River Blackfish, in the highly regulated and flow-stressed lower Latrobe River in Victoria, Australia. Autumn high flows, in conjunction with low stream temperature, are critical for Grayling spawning. The BN model was used to predict the probability of spawning and recruitment of these two native fish species for four flow scenarios. Quantitative data, flow simulation models and expert judgement were used to parameterize the BN model. The model results showed clearly that currently, and into the future, there is a very low likelihood of spawning and recruitment of Australian Grayling in the lower Latrobe. River Blackfish are minimally affected by the predicted reductions in flow and increased stream temperatures. Management scenarios aimed at modifying flows and stream temperatures to increase the likelihood of successful spawning and recruitment of Australian Grayling were assessed. Self-sustaining populations of Australian Grayling could conceivably be achieved in the upper reaches of this river if fish passage was provided through an on-stream reservoir. A major benefit in building and applying an eFlow BN model is that it can facilitate meaningful analysis and discussion of the ecological effects of particular eFlow regimes.
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