ORCID Profile
0000-0002-9608-4151
Current Organisation
University of Melbourne
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Evolutionary Impacts of Climate Change | Life Histories | Evolutionary Biology
Ecosystem Adaptation to Climate Change | Wild Caught Fin Fish (excl. Tuna) |
Publisher: The Royal Society
Date: 06-2016
Abstract: Humans are altering the environment at an unprecedented rate. Although behavioural plasticity has allowed many species to respond by shifting their ranges to more favourable conditions, these rapid environmental changes may cause ‘evolutionary traps’, whereby animals mistakenly prefer resources that reduce their fitness. The role of evolutionary traps in influencing the fitness consequences of range shifts remains largely unexplored. Here, we review these interactions by considering how climate change may trigger maladaptive developmental pathways or increase the probability of animals encountering traps. We highlight how traps could selectively remove some phenotypes and compromise population persistence. We conclude by highlighting emerging areas of research that would improve our understanding of when interactions between evolutionary traps and range shifts are likely to be most detrimental to animals.
Publisher: Wiley
Date: 25-01-2023
DOI: 10.1111/REC.13869
Abstract: Outcomes from restoration and reintroduction programs can be enhanced by understanding the habitat use of animals, and how likely they are to move and why? River blackfish are native to southeastern Australia where their range and abundance have declined. We reintroduced 27 river blackfish into two sites, one where rehabilitation had been undertaken (with more vegetation, instream woody habitat, and undercut banks) and an unmanipulated control site. We monitored fish for 9 months after release to assess site occupancy, habitat use, and drivers of movement. We modeled the likelihood of fish remaining at either site, their habitat use, and predictors of movement (site type, habitat, time, and river discharge). While more fish remained at the treatment site, this difference was not statistically significant. Future trials incorporating increased numbers of fish and replicate treatment and control release sites would allow a more detailed test of whether fish are more likely to remain at restored sites. Fish spent more time in deeper areas with more riparian vegetation. Habitat, flow, and time since release were significant predictors of fish movement, with fish more likely to move from release sites with less suitable habitat, during rainfall events, and during the initial stages of our study. Our results illustrate that blackfish are a suitable candidate for translocations, retaining their largely sedentary behavior and should be easily measurable if restoration has provided suitable habitat and their presence is an indicator of success. Our work is also a useful case study for translocation of other nonmigratory fish worldwide.
Publisher: Wiley
Date: 15-10-2020
DOI: 10.1111/GCB.15363
Publisher: Springer Science and Business Media LLC
Date: 20-01-2023
DOI: 10.1007/S10641-022-01381-Y
Abstract: The impacts of mine contaminants on ecological connectivity in rivers and streams are poorly documented globally. We used acoustic telemetry to evaluate and refine conceptual models of fish movement in Magela Creek, a stream in the wet-dry tropics of Australia. This creek receives wastewater discharge from a nearby uranium mine, and a secondary objective was to describe behavioural responses of fish to one such discharge event. Of 55 fish (black bream Hephaestus fuliginosus , saratoga Scleropages jardinii , sharp-nose grunter Syncomistes butleri ) tagged in dry season refuge pools 18 km upstream of the mine lease area (RPA [Ranger Project Area]), 16 (29%) moved downstream after the first wet season flows, using the RPA as habitat for 3–5 months before moving upstream to their previous locations as flows receded. Of 39 fish (spangled perch Leiopotherapon unicolor , barred grunter Amniataba percoides , black catfish Neosilurus ater ) tagged ~ 8–12 km downstream of the RPA in the late wet season, only two were subsequently detected in the RPA. Direct and camera-based observations of 12 species of upstream-migrating fish during mine-water discharge in the late wet season showed no evidence of mine-water avoidance. Our results demonstrate that Magela Creek provides wet season habitat for fish within the RPA and acts as a migration pathway that connects lowland reaches and floodplains to upstream dry season refuges. Use by fish of waterbodies within the RPA highlights the need to manage the site to ensure that future contaminant egress and water quality do not adversely affect fish migration and habitat suitability.
Publisher: Wiley
Date: 04-01-2017
DOI: 10.1111/FWB.12888
Publisher: Wiley
Date: 12-07-2017
DOI: 10.1002/ECM.1264
Publisher: Wiley
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 11-01-2022
DOI: 10.1038/S42003-021-02960-Y
Abstract: Marine fish populations commonly exhibit low-frequency fluctuations in biomass that can cause catch volatility and thus endanger the food and economic security of dependent coastal societies. Such variability has been linked to fishing intensity, demographic processes and environmental variability, but our understanding of the underlying drivers remains poor for most fish stocks. Our study departs from previous findings showing that sea surface temperature (SST) is a significant driver of fish somatic growth variability and that life-history characteristics mediate population-level responses to environmental variability. We use autoregressive models to simulate how fish populations integrate SST variability over multiple years depending on fish life span and trophic position. We find that simulated SST-driven population dynamics can explain a significant portion of observed low-frequency variability in independent observations of fisheries landings around the globe. Predictive skill, however, decreases with increasing fishing pressure, likely due to demographic truncation. Using our modelling approach, we also show that increases in the mean and variance of SST could lify biomass volatility and lessen its predictability in the future. Overall, biological integration of high-frequency SST variability represents a null hypothesis with which to explore the drivers of low-frequency population change across upper-trophic marine species.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MF17388
Abstract: Understanding the influence of river hydrology and connectivity on the migration and recruitment of diadromous fishes is fundamental for species management and conservation. We investigated the downstream catadromous spawning migration of adult female congolli (Pseudaphritis urvillii) using acoustic telemetry, and subsequent juvenile recruitment, in the lower reaches of the River Murray, Australia, in 2009–2011. The years 2009 and 2010 were characterised by diminished freshwater flow, closure of tidal barrages, and disconnection of freshwater and estuarine habitats however, a navigation lock was operated to facilitate downstream fish passage in 2010. In both years, % of in iduals tagged upstream undertook downstream migrations, in association with day-of-the-year (June–July) and moonphase (full), and accumulated upstream of the tidal barrages. In 2009, fish were unable to pass the barrages and remained upstream, but in 2010, an estimated in iduals passed through the navigation lock, including 40% of in iduals tagged upstream. These transitioned rapidly ( h) through the estuary and into the ocean. In association, abundances of upstream migrant juveniles in spring–summer 2010–2011 were up to 180 times greater than in spring–summer 2009–2010. Our study illustrates the potential impact of tidal barriers on migrations and population dynamics of catadromous fish, and the importance of understanding species-specific migration ecology.
Publisher: Wiley
Date: 06-09-2020
DOI: 10.1111/OIK.07332
Publisher: Wiley
Date: 15-11-2018
DOI: 10.1002/LOM3.10291
Publisher: Wiley
Date: 12-09-2013
DOI: 10.1002/ECE3.757
Publisher: Wiley
Date: 12-09-2016
DOI: 10.1111/FAF.12156
Publisher: Wiley
Date: 21-10-2010
DOI: 10.1111/J.1420-9101.2010.02149.X
Abstract: Visual signals play a vital role in many animal communication systems. Signal design, however, often varies within species, raising evolutionarily important questions concerning the maintenance of phenotypic ersity. We analysed nuptial colour variation within and among nine populations of southern pygmy perch (Nannoperca australis Günther) along an environmental light gradient. Within populations, larger males were redder and blacker, and better-condition males were blacker. Among populations, red colour was positively correlated with the amount of orange-red light present, suggesting that males are likely optimizing signal conspicuousness by producing proportionally larger and redder patches in broad spectrum environments with more orange-red light. Signal contrast, in this regard, is maximized when red colour, appearing bright because of the prevalence of red wavelengths, is viewed against the water-column background. Together, our results are concordant with the sensory drive hypothesis selection favours signal adaptations or signal plasticity to ensure communication efficacy is maximized in different light environments.
Publisher: Wiley
Date: 27-01-2021
DOI: 10.1111/GCB.15490
Abstract: Fisheries harvest has pervasive impacts on wild fish populations, including the truncation of size and age structures, altered population dynamics and density, and modified habitat and assemblage composition. Understanding the degree to which harvest‐induced impacts increase the sensitivity of in iduals, populations and ultimately species to environmental change is essential to ensuring sustainable fisheries management in a rapidly changing world. Here we generated multiple long‐term (44–62 years), annually resolved, somatic growth chronologies of four commercially important fishes from New Zealand's coastal and shelf waters. We used these novel data to investigate how regional‐ and basin‐scale environmental variability, in concert with fishing activity, affected in idual somatic growth rates and the magnitude of spatial synchrony among stocks. Changes in somatic growth can affect in idual fitness and a range of population and fishery metrics such as recruitment success, maturation schedules and stock biomass. Across all species, in idual growth benefited from a fishing‐induced release of density controls. For nearshore snapper and tarakihi, regional‐scale wind and temperature also additively affected growth, indicating that future climate change‐induced warming and potentially strengthened winds will initially promote the productivity of more poleward populations. Fishing increased the sensitivity of deep‐water hoki and ling growth to the Interdecadal Pacific Oscillation (IPO). A forecast shift to a positive IPO phase, in concert with current harvest strategies, will likely promote in idual hoki and ling growth. At the species level, historical fishing practices and IPO synergized to strengthen spatial synchrony in average growth between stocks separated by 400–600 nm of ocean. Increased spatial synchrony can, however, increase the vulnerability of stocks to deleterious stochastic events. Together, our in idual‐ and species‐level results show how fishing and environmental factors can conflate to initially promote in idual growth but then possibly heighten the sensitivity of stocks to environmental change.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/MF20206
Abstract: Stock enhancement is an important tool used to rebuild depleted fish populations or enhance recreational fishing. Hatchery-reared in iduals can express trait differences, such as growth, which may affect later survival. However, there is little understanding of how early life growth variation affects stocking success. We examined early life growth of golden perch Macquaria ambigua and assessed how growth within hatcheries affects the survival of stocked fish. We measured daily otolith increment widths at 10, 20 and 30 days after hatching, but before stocking into lakes in south-eastern Australia. Mean growth decreased with age, but variation in growth increased. We then compared the early life growth of these in iduals to those recaptured after 2 years at liberty (age-2+). Faster in idual growth between 20 and 30 days was positively correlated with increased length at stocking. Mean growth between 20 and 30 days of age-2+ fish was higher than that of young-of-year fish, but among-in idual variation in growth did not differ between the two groups. These results suggest that in iduals with fast hatchery growth have increased survival to 2 years. We propose that enhancing growth within hatcheries may increase the survival of stocked fish, and thus the cost-effectiveness of fish stocking.
Publisher: Canadian Science Publishing
Date: 09-2020
Abstract: Analysis of growth increments in the hard parts of animals (e.g., fish otoliths) can be used to assess how organisms respond to variability in environmental conditions. In this study, mixed-effects models were applied to otolith data simulated for two hypothetical fish populations with assumed biological parameters and known growth response to environmental variability. Our objective was to assess the sensitivity of environment–growth relationships derived from otolith biochronologies when challenged with a range of realistic ageing errors and s ling regimes. We found that the development of a robust biochronology and the precision of environmental effect estimates can be seriously h ered by insufficient s le size. Moreover, the introduction of even moderate ageing error into the data can cause substantial underestimation of environmental sources of growth variation. This underestimation diminished our capacity to correctly quantify the known environment–growth relationship and more generally will lead to overly conservative conclusions concerning the growth response to environmental change. Careful study design, reduction of ageing errors, and large s le sizes are critical prerequisites if robust inferences are to be made from biochronological data.
Publisher: Springer Science and Business Media LLC
Date: 27-11-2012
DOI: 10.1038/NCLIMATE1616
Publisher: Oxford University Press (OUP)
Date: 12-02-2018
Abstract: European plaice (Pleuronectes platessa) is a commercially important flatfish species in the North Sea. Yet, the environmental factors that affect the growth of plaice remain unresolved. Here we examine the drivers of plaice growth variation by using a large archive of otoliths from female plaice collected in the northeastern part of the North Sea from 1993 to 2015, providing growth data over the period 1985–2014. We developed a series of increasingly complex mixed-effect models to explore intrinsic (within in idual) and extrinsic (environmental factors: bottom temperature and plaice density) sources of growth variation. We analysed juvenile (0 and 1 year) and (sub)adult (≥2 years) growth separately due to different habitat utilization across life stages. Juvenile growth was positively correlated with bottom temperature, whereas growth of adults was negatively correlated with bottom temperature. Correlations for both were strongest during autumn (September to October). For juveniles, the temperature–growth relationship likely reflects a response to growing season length while for adults it could reflect temperature-dependent changes to metabolic rate or food availability. For both juveniles and adults, we also found inverse relationship between population density and growth. We suggest that the approach used in this study can find a much wider application in European waters.
Publisher: Springer Science and Business Media LLC
Date: 26-01-2021
DOI: 10.1038/S41598-021-81727-1
Abstract: The relationship between growth and sexual maturation is central to understanding the dynamics of animal populations which exhibit indeterminate growth. In sequential hermaphrodites, which undergo post-maturation sex change, the size and age at which sex change occurs directly affects reproductive output and hence population productivity. However, these traits are often labile, and may be strongly influenced by heterogenous growth and mortality rates. We analysed otolith microstructure of a protandrous (i.e., male-to-female) fish (barramundi Lates calcarifer ) to examine growth in relation to in idual variation in the timing of sex change. Growth trajectories of in iduals with contrasting life histories were examined to elucidate the direction and extent to which growth rate influences the size and age in iduals change sex. Then, the relationships between growth rate, maturation schedules and asymptotic maximum size were explored to identify potential trade-offs between age at female maturity and growth potential. Rapid growth was strongly associated with decreased age at sex change, but this was not accompanied by a decrease in size at sex change. In iduals that were caught as large females grew faster than those caught as males, suggesting that fast-growing in iduals ultimately obtain higher fitness and therefore make a disproportionate contribution to population fecundity. These results indicate that in idual-level variation in maturation schedules is not reflective of trade-offs between growth and reproduction. Rather, we suggest that conditions experienced during the juvenile phase are likely to be a key determinant of post-maturation fitness. These findings highlight the vulnerability of sex-changing species to future environmental change and harvest.
Publisher: Springer Science and Business Media LLC
Date: 18-08-2020
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF10308
Abstract: Freshwater environments and their fishes are particularly vulnerable to climate change because the persistence and quality of aquatic habitat depend heavily on climatic and hydrologic regimes. In Australia, projections indicate that the rate and magnitude of climate change will vary across the continent. We review the likely effects of these changes on Australian freshwater fishes across geographic regions encompassing a ersity of habitats and climatic variability. Commonalities in the predicted implications of climate change on fish included habitat loss and fragmentation, surpassing of physiological tolerances and spread of alien species. Existing anthropogenic stressors in more developed regions are likely to compound these impacts because of the already reduced resilience of fish assemblages. Many Australian freshwater fish species are adapted to variable or unpredictable flow conditions and, in some cases, this evolutionary history may confer resistance or resilience to the impacts of climate change. However, the rate and magnitude of projected change will outpace the adaptive capacities of many species. Climate change therefore seriously threatens the persistence of many of Australia’s freshwater fish species, especially of those with limited ranges or specific habitat requirements, or of those that are already occurring close to physiological tolerance limits. Human responses to climate change should be proactive and focus on maintaining population resilience through the protection of habitat, mitigation of current anthropogenic stressors, adequate planning and provisioning of environmental flows and the consideration of more interventionist options such as managed translocations.
Publisher: Wiley
Date: 26-12-2020
Abstract: Natural river floodplains are among the Earth's most biologically erse and productive ecosystems but face a range of critical threats due to human disturbance. Understanding the ecological processes that support bio ersity and productivity in floodplain rivers is essential for their future protection and rehabilitation. Fish assemblage structure on tropical river floodplains is widely considered to be driven by dispersal limitation during the wet season and by environmental filtering and interspecific interactions during the dry season. However, the in idual-level movement behaviours (e.g. site attachment, nomadism, homing) that regulate dispersal of fish on floodplains are poorly understood. We combined radiotelemetry and remote sensing to examine the movement behaviour of two large-bodied fishes (barramundi Lates calcarifer, forktail catfish Neoarius leptaspis) over the flood cycle in a tropical river-floodplain system in northern Australia to: (a) quantify movement responses in relation to dynamic habitat resources at a landscape scale and (b) determine the extent of spatial 'reshuffling' of in idual fish following the wet season. Both species altered their behaviour rapidly in response to changes in the availability and distribution of aquatic habitat, with most in iduals undertaking extensive movements (up to ~27 km from the tagging location) on the inundated floodplain during the wet season. Although there was considerable in idual variation in movement patterns, overall barramundi distributions closely tracked the extent of floodplain primary productivity, whereas catfish distributions were most closely associated with the extent of flooded area. Most in iduals of both species exhibited homing back to previously occupied dry season refugia during the wet-to-dry transition, even though other potential refugia were available in closer proximity to wet season activity areas. We postulate that homing behaviour modulates temporal variation in fish assemblage composition and abundance and limits the transfer of aquatic-derived energy and nutrients into terrestrial food webs by reducing fish mortality on drying floodplains. Our study demonstrates the importance of quantifying in idual-level behaviour across the three stages of dispersal (emigration, inter-patch movement, immigration) for our understanding of how animal movement influences energetic subsidies and other large-scale ecosystem processes.
Publisher: Wiley
Date: 30-05-2022
DOI: 10.1111/FME.12559
Abstract: Estuaries are dynamic environments and often support rich bio ersity and important fisheries. Linking environmental drivers or events to observed biological changes in these systems provides critical information that can facilitate their management. Historical fish and fisheries data for Western Port, a large embayment in south‐east Australia that supports rich bio ersity, were collated, including catch records, recruitment indices and two novel growth time series. Dynamic factor analysis (DFA) identified three common patterns associated with the biological time‐series data, which in turn were related to both local and regional environmental drivers. On a local scale, nitrogen loads and chlorophyll a concentration affected fish metrics, potentially through the food web and via changes to critical seagrass habitat. On a regional scale, offshore sea surface temperature in Bass Strait was important. Step changes (change points) in the three common patterns were predominantly associated with significant El Niño and La Niña events and, to a lesser extent, recruitment pulses and the cessation of commercial netting.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Wiley
Date: 16-11-2019
DOI: 10.1111/GEB.12847
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/ZO13054
Abstract: The Macquarie perch (Macquaria australasica) is a threatened fish species that inhabits rivers and impoundments in south-eastern Australia. Previous studies have shown that Macquarie perch in impoundments exhibit synchronised upstream spawning migrations to shallow, fast-flowing habitats in the lower reaches of inflowing streams. There has been little study of movement behaviours of entirely riverine populations of Macquarie perch despite this being the species’ natural habitat. Here, radio-telemetry is used to test the hypothesis that riverine populations exhibit synchronised migrations during the spawning season. Thirty Macquarie perch in the Yarra River, Victoria, a translocated population outside of the species’ natural range, were radio-tagged before the late spring–early summer spawning season and their movements followed over a 10-month period (May 2011 to February 2012). Tagged fish typically occupied restricted reaches of stream ( m). Sixteen of the fish undertook occasional upstream or downstream movements (~250–1000 m) away from their usual locations, particularly associated with large flow variations during the spawning season. There was no evidence of synchronised migratory behaviour or movement of multiple fish to specific locations or habitats during the spawning season. Whilst further research over more years is needed to comprehensively document the spawning-related behaviours of riverine Macquarie perch, our study demonstrates that management of riverine populations of this threatened species cannot necessarily be based on the model of spawning behaviour developed for lacustrine populations.
Publisher: Elsevier BV
Date: 11-2019
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/MF15398
Abstract: Detailed understanding of flow-ecology requirements for aquatic biota underpins the use of environmental flows as an effective restoration tool in regulated rivers. However, flow recommendations are often overly simplistic and insufficient to provide the necessary environmental requirements for these biota. This is often due to failure to gain and integrate information on in idual species ecology and, by using coarse generalisations, about flow-ecology responses. To inform more effective delivery of environmental flows, we investigated spawning responses of the threatened Australian grayling (Prototroctes maraena) to environmental flows over 2 years in three coastal rivers. Spawning activity was highest during within-channel flow pulses, especially during periods of environmental flow delivery. Peak spawning occurred in late autumn and was positively related to flow duration. This result has important implications for environmental flows management in regions where water is scarce and there is potential conflict among multiple users because, for Australian grayling, it is not necessarily the volume of water released that is important, but how the flow is delivered. Our study demonstrated the importance of quantifying flow-ecology relationships via targeted monitoring and research so as to develop appropriate flow regimes, and should encourage managers to examine more critically the logic behind generalised environmental flow objectives.
Publisher: Wiley
Date: 29-08-2017
DOI: 10.1002/AQC.2808
Publisher: Proceedings of the National Academy of Sciences
Date: 26-04-2021
Abstract: The synergistic impacts of rapid climatic warming and fisheries harvest are threatening the sustainability of wild fisheries. Their collective impact on fish recruitment—a key process underpinning stock abundance—remains poorly understood. We experimentally exposed fish populations to realistic warming and fishing-selection regimes over multiple generations and found that warmed populations experienced a severe decline in recruitment rate. This warming-induced decline was exacerbated by size-selective fishery harvest. Once warming and size-selective fishing were relaxed, recruitment rates rapidly recovered. Our results suggest that synergistic impacts of fishing and warming can have delayed effects on stock resilience and that preserving fish body size ersity will help to increase their resilience to global warming.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MF17173
Abstract: Flow regimes have been fundamentally altered in many of the world’s river systems. There is a need to restore components of natural flow variability to protect freshwater bio ersity. The Australian bass is a long-lived, catadromous percichthyid endemic to coastal drainages of south-eastern Australia. Little is known of the timing and magnitude of flows considered important for recruitment and growth of in iduals in southern latitudes of the species range. Herein we generate nearly 50 years of otolith-derived recruitment and growth histories for Australian bass and relate these to hydrologic, climatic and demographic variables. We found that younger Australian bass grew fastest in years following a cooler spring, whereas the growth of older fish exhibited little response to temperature. Australian bass year class strength was positively related to high flows in spring and in a negative curvilinear way to spring temperature. A lack of suitable natural flows in spring may be responsible for little to no recruitment of Australian bass in the Genoa River over the past two decades. Based on our findings, the continuing trend of lower rainfall and higher temperatures, coupled with river regulation in some systems in the region, will likely result in depressed juvenile growth and prolonged periods of recruitment failure over the medium to longer term, with significant implications for the viability of populations.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2019
DOI: 10.1007/S00442-019-04460-7
Abstract: Diadromy is a form of migration where aquatic organisms undergo regular movements between fresh and marine waters for the purposes of feeding and reproduction. Despite having arisen in independent lineages of fish, gastropod molluscs and crustaceans, the evolutionary drivers of diadromous migration remain contentious. We test a key aspect of the 'productivity hypothesis', which proposes that diadromy arises in response to primary productivity differentials between marine and freshwater habitats. Otolith chemistry and biochronology data are analysed in a facultatively catadromous tropical fish (barramundi, Lates calcarifer) to determine the effect of freshwater residence on growth rates. In iduals that accessed freshwater grew ~ 25% faster on average than estuarine residents in the year following migration, suggesting that catadromy provides a potential fitness advantage over non-catadromous (marine/estuarine) life histories, as predicted by the productivity hypothesis. Although diadromous barramundi exhibited faster growth than non-diadromous fish, we suggest that the relative reproductive success of diadromous and non-diadromous contingents is likely to be strongly influenced by local environmental variability such as temporal differences in river discharge, and that this may facilitate the persistence of erse life history strategies within populations.
Publisher: Inter-Research Science Center
Date: 28-06-2018
DOI: 10.3354/MEPS12234
Publisher: Public Library of Science (PLoS)
Date: 02-07-2015
Publisher: Elsevier BV
Date: 08-2019
Publisher: American Geophysical Union (AGU)
Date: 20-02-2014
DOI: 10.1002/2013GL058638
Publisher: Wiley
Date: 16-01-2022
DOI: 10.1111/FWB.13878
Abstract: Restoration projects often rely on the assumption that a local intervention will restore diminished populations, without fully understanding the constraints that limit the target species in the first place. In rivers, one common restoration technique is to place large structures, such as wood and boulders, on the bed, with the assumption that fish will subsequently arrive and use them. Nonetheless, providing large habitat structure may not overcome demographic or resource constraints on fish populations, and thus may not aid recovery. We aimed to test if resource constraints (food and cover) are limiting local densities of fishes in a degraded stream by experimentally alleviating these constraints. If the abundance of one or more species is constrained by resource availability, then local numbers of these species should increase following an increase in resources. To test our prediction, we increased the availability of food and microhabitat complexity (cover) at sites in Hughes Creek, a degraded stream in south‐east Australia that has extensive accumulations of sand and limited in‐stream structure. At treatment sites, we hammered pairs of wooden stakes (25 cm apart) into the stream bed so that the ends of stakes protruded just above the water surface at moderate flows. Stakes effectively trapped passing sticks and leaves, which increased local detrital densities and, subsequently, invertebrate densities, hence providing food and cover for fish. Over the course of a year, we compared the changes in fish abundances at treatment sites to unmanipulated control sites. Fish responded quickly to enhanced retention of detritus, with assemblage differences observed between treatment and control sites. We caught more river blackfish ( Gadopsis marmoratus ), southern pygmy perch ( Nannoperca australis ), Macquarie perch ( Macquaria australasica ), and mountain galaxias ( Galaxias olidus ) at treatment sites on some occasions, indicating that these species may be subject to resource constraints in this stream. The magnitude of observed positive fish responses was influenced by the life‐stage of in iduals and local stream conditions. Importantly, treatment effects varied through time and were no longer observed after a large flood affected the study stream. Our results show that resource constraints limit local species abundances and demonstrate a novel method of overcoming these constraints in a small, degraded stream. This is a necessary first step but future work is needed to examine whether increases in abundance are due to the provided resources increasing growth rates, survivorship, or reproduction. This work also highlights the importance of understanding species’ life histories, the broader landscape setting, and the disturbance regime when undertaking site scale restoration.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/MF18299
Abstract: Understanding the influence of extrinsic factors such as hydrology and hydraulics on recruitment provides essential insight to inform management of fish populations. The critically endangered silver perch Bidyanus bidyanus is a long-lived, potamodromous pelagophil endemic to Australia’s Murray–Darling Basin. Declines of this species are often attributed to river regulation, although quantitative studies linking hydrology and hydraulics to key aspects of its life cycle are sparse. We used a multidecadal age-structured dataset collected from a locally abundant population of silver perch to quantify the relative importance of different abiotic drivers on year-class strength (recruitment). Silver perch recruited across highly variable hydrological conditions. The strongest year classes were associated with a combination of low to average river discharge (i.e. within channel) and high water temperatures over the peak spawning period, followed in the next year by extended high flows and widespread flooding that promoted survival of age-1+ juvenile fish. We suggest that conditions affecting the growth and dispersal of juvenile fish, in addition to the spawning period, are critical in governing recruitment dynamics. This highlights the need for multiyear flow plans for freshwater fish populations.
Publisher: Inter-Research Science Center
Date: 16-03-2015
DOI: 10.3354/MEPS11147
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MF17367
Abstract: Because fish are sensitive indicators of flow alteration, a detailed knowledge of the response of fish to flows is crucial to the sound management of regulated river systems. Estuary perch are a catadromous, long-lived, estuarine-dependant percichthyid. Here, we relate otolith-derived recruitment and growth histories of in iduals of the species in the highly regulated river to hydrologic, climatic and demographic variables. Year class strength was positively related to high flows over the spawning season and in a negative curvilinear way to flows in the austral winter, in addition to cooler annual temperatures in general. Flows benefiting recruitment of estuary perch are best timed to occur in austral winter in addition to the spawning season. Without a substantial increase in the volume of environmental water, large recruitment events will remain dependent on sizable natural catchment-generated inflows. On the basis of our findings, climate change predictions of lower rainfall and higher temperatures in south-east Australia may result in prolonged periods of recruitment failure in the region, and have significant implications for the viability of not only the population of estuary perch in the Snowy River, but also southern populations of the species in general.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2011
Publisher: Oxford University Press (OUP)
Date: 16-03-2018
Publisher: Wiley
Date: 04-01-2011
Publisher: Wiley
Date: 15-04-2014
DOI: 10.1111/FWB.12376
Publisher: Cold Spring Harbor Laboratory
Date: 28-03-2018
DOI: 10.1101/290387
Abstract: Female ornaments are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade-off resources related to reproduction to promote ornament expression. Here, we investigate the potential trade-off between female ornamentation and fecundity in the sex-role reversed, wide-bodied pipefish, Stigmatopora nigra . We measured two components of the female ornament, body width and stripe thickness, and tested the relationship between these ornaments and female fecundity and the mean egg size. Both body width and stripe thickness were strongly and positively related to female body size. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus a greater relative fitness advantage. However, larger females suffered a slight decrease in egg size, consistent with a potential trade-off between egg size and body size, although no relationship between egg size and ornaments was observed. Our results suggest that larger S. nigra females accurately advertise their reproductive value to males, and underscore the importance of investigating the potential mechanisms that promote and maintain honesty of female ornaments.
Publisher: MDPI AG
Date: 06-03-2022
Abstract: (1) Background: This paper aims to present and discuss the most significant challenges encountered by STEM professionals associated with remote working during the COVID-19 lockdowns. (2) Methods: We performed a qualitative analysis of 921 responses from professionals from 76 countries to the open-ended question: “What has been most challenging during the lockdown for you, and/or your family?” (3) Findings: Participants reported challenges within the immediate family to include responsibilities for school, childcare, and children’s wellbeing and the loss of social interactions with family and friends. Participants reported increased domestic duties, blurred lines between home and work, and long workdays. Finding adequate workspace was a problem, and adaptations were necessary, especially when adults shared the same setting for working and childcare. Connectivity issues and concentration difficulties emerged. While some participants reported employers’ expectations did not change, others revealed concerns about efficiency. Mental health issues were expressed as anxiety and depression symptoms, exhaustion and burnout, and no outlets for stress. Fear of becoming infected with COVID-19 and uncertainties about the future also emerged. Pressure points related to gender, relationship status, and ethnicities were also evaluated. Public policies differed substantially across countries, raising concerns about the adherence to unnecessary restrictions, and similarly, restrictions being not tight enough. Beyond challenges, some benefits emerged, such as increased productivity and less time spent getting ready for work and commuting. Confinement resulted in more quality time and stronger relationships with family. (4) Interpretation: Viewpoints on positive and negative aspects of remote working differed by gender. Females were more affected professionally, socially, and personally than males. Mental stress and the feeling of inadequate work efficiency in women were caused by employers’ expectations and lack of flexibility. Working from home turned out to be challenging, primarily due to a lack of preparedness, limited access to a dedicated home-office, and lack of previous experience in multi-layer/multi-scale environments.
Publisher: Wiley
Date: 12-04-2014
DOI: 10.1111/GCB.12545
Abstract: How in iduals respond to environmental change determines the strength and direction of biological processes like recruitment and growth that underpin population productivity. Ascertaining the relative importance of environmental factors can, however, be difficult given the numerous mechanisms through which they affect in iduals. This is especially true in dynamic and complex estuarine environments. Here, we develop long-term otolith-based indices of recruitment and growth for estuary perch Percalates colonorum (Bemm River, Australia), to explore the importance of intrinsic (in idual, demographic) and extrinsic (hydrologic, climatic, density-dependent) factors in driving estuarine fish productivity. Analyses involved a novel zero-inflated specification of catch curve regression and mixed effects modelling. The 39 years of recruitment and 46 years of growth data, spanning a period of environmental change including severe drought, displayed considerable inter-annual variation. Recruitment success was strongly related to high freshwater inflows during the spawning season, suggesting that these conditions act as spawning cues for adults and potentially provide favourable conditions for larvae. In iduals displayed age-dependent growth, with highest rates observed at younger ages in years characterized by warm temperatures, and to a lesser degree, greater magnitude base inflow conditions. We detected systematic among-year-class growth differences, but these were not attributable to year class strength, suggesting that environmental conditions experienced by in iduals as juveniles can have long-lasting effects of greater importance to population productivity than density-dependent growth responses. The primacy of temperature in driving growth variation highlights that under-appreciated climatic variation can affect estuarine fish productivity through direct physiological and indirect food web mechanisms. We predict that climatic warming will promote in idual growth in southerly populations of P. colonorum but concurrently limit recruitment due to forecast reductions in spawning season river discharge. Disparate trait responses are likely in other fishes as they respond to multiple and changing environmental drivers, making predictions of future population productivity challenging.
Publisher: CSIRO Publishing
Date: 10-01-2023
DOI: 10.1071/MF22213
Abstract: Many migratory species are under threat globally. Management actions to conserve these species require a quantitative understanding of their life-history requirements, such as cues for migration. Migrations to spawn are a critical component of the life-cycle of diadromous fishes but are often poorly understood. Downstream migration patterns of common galaxias (Galaxias maculatus) were investigated in the Bunyip–Tarago River system, southern Australia, using passive integrated transponder technology. Fish undertook rapid (typically 1–3 days) downstream migration (up to 50 km) from the upper reaches to the lowland reaches near the estuary. Migration occurred from March to May during the known spawning period, with peak movement between late April and mid-May. Migration was also related to increased river discharge, with fish being more likely to migrate on days when flow was high compared with the previous 2 days, and a waxing moon (i.e. increasing illumination). Our results fill an important knowledge gap in the life history of this widely distributed diadromous species. Importantly, the knowledge about the likely drivers of movement can inform management actions such as providing environmental flows in austral autumn and at appropriate moon phases to trigger the downstream migration of adult common galaxias from freshwater reaches to estuarine spawning areas.
Publisher: Wiley
Date: 02-2015
DOI: 10.1890/13-2355.1
Publisher: Wiley
Date: 06-02-2012
DOI: 10.1111/J.1365-2656.2012.01961.X
Abstract: 1. Maternal reproductive investment is thought to reflect a trade-off between offspring size and fecundity, and models generally predict that mothers inhabiting adverse environments will produce fewer, larger offspring. More recently, the importance of environmental unpredictability in influencing maternal investment has been considered, with some models predicting that mothers should adopt a ersified bet-hedging strategy whilst others a conservative bet-hedging strategy. 2. We explore spatial egg size and fecundity patterns in the freshwater fish southern pygmy perch (Nannoperca australis) that inhabits a ersity of streams along gradients of environmental quality, variability and predictability. 3. Contrary to some predictions, N. australis populations inhabiting increasingly harsh streams produced more numerous and smaller eggs. Furthermore, within-female egg size variability increased as environments became more unpredictable. 4. We argue that in harsh environments or those prone to physical disturbance, sources of mortality are size independent with offspring size having only a minor influence on offspring fitness. Instead, maternal fitness is maximized by producing many small eggs, increasing the likelihood that some offspring will disperse to permanent water. We also provide empirical support for ersified bet-hedging as an adaptive strategy when future environmental quality is uncertain and suggest egg size may be a more appropriate fitness measure in stable environments characterized by size-dependent fitness. These results likely reflect spatial patterns of adaptive plasticity and bet-hedging in response to both predictable and unpredictable environmental variance and highlight the importance of considering both trait averages and variance. 5. Reproductive life-history traits can vary predictably along environmental gradients. Human activity, such as the hydrological modification of natural flow regimes, alters the form and magnitude of these gradients, and this can have both ecological and evolutionary implications for biota adapted to now non-existent natural environmental heterogeneity.
Publisher: Springer Science and Business Media LLC
Date: 03-04-2017
DOI: 10.1007/S00267-017-0853-0
Abstract: The development of effective strategies to restore the biological functioning of aquatic ecosystems with altered flow regimes requires a detailed understanding of flow-ecology requirements, which is unfortunately lacking in many cases. By understanding the flow conditions required to initiate critical life history events such as migration and spawning, it is possible to mitigate the threats posed by regulated river flow by providing targeted environmental flow releases from impoundments. In this study, we examined the influence of hydrological variables (e.g., flow magnitude), temporal variables (e.g., day of year) and spatial variables (e.g., longitudinal position of fish) on two key life history events (migration to spawning grounds and spawning activity) for a threatened diadromous fish (Australian grayling Prototroctes maraena) using data collected from 2008 to 2015 in the Bunyip-Tarago river system in Victoria. Our analyses revealed that flow changes act as a cue to downstream migration, but movement responses differed spatially: fish in the upper catchment showed a more specific requirement for rising discharge to initiate migration than fish in the lower catchment. Egg concentrations peaked in May when weekly flows increased relative to the median flow during a given spawning period. This information has recently been incorporated into the development of targeted environmental flows to facilitate migration and spawning by Australian grayling in the Bunyip-Tarago river system and other coastal systems in Victoria.
Publisher: Wiley
Date: 13-04-2011
Publisher: Wiley
Date: 11-01-2023
DOI: 10.1002/ECY.3918
Abstract: Large‐scale, climate‐induced synchrony in the productivity of fish populations is becoming more pronounced in the world's oceans. As synchrony increases, a population's “portfolio” of responses can be diminished, in turn reducing its resilience to strong perturbation. Here we argue that the costs and benefits of trait synchronization, such as the expression of growth rate, are context dependent. Contrary to prevailing views, synchrony among in iduals could actually be beneficial for populations if growth synchrony increases during favorable conditions, and then declines under poor conditions when a broader portfolio of responses could be useful. Importantly, growth synchrony among in iduals within populations has seldom been measured, despite well‐documented evidence of synchrony across populations. Here, we used century‐scale time series of annual otolith growth to test for changes in growth synchronization among in iduals within multiple populations of a marine keystone species (Atlantic cod, Gadus morhua ). On the basis of 74,662 annual growth increments recorded in 13,749 otoliths, we detected a rising conformity in long‐term growth rates within five northeast Atlantic cod populations in response to both favorable growth conditions and a large‐scale, multidecadal mode of climate variability similar to the East Atlantic Pattern. The within‐population synchrony was distinct from the across‐population synchrony commonly reported for large‐scale environmental drivers. Climate‐linked, among‐in idual growth synchrony was also identified in other Northeast Atlantic pelagic, deep‐sea and bivalve species. We hypothesize that growth synchrony in good years and growth asynchrony in poorer years reflects adaptive trait optimization and bet hedging, respectively, that could confer an unexpected, but pervasive and stabilizing, impact on marine population productivity in response to large‐scale environmental change.
Publisher: Wiley
Date: 07-08-2021
Abstract: Directional or stabilising selection should drive the expression of a dominant movement phenotype within a population. Widespread persistence of multiple movement phenotypes within wild populations, however, suggests that in iduals that move (movers) and those that do not (residents) can have commensurate performance. The costs and benefits of mover and resident phenotypes remain poorly understood. Here, we explored how the presence and timing of movements are correlated with annual somatic growth rates, a useful proxy for performance because it is easily measured and rapidly reflects environmental changes. We used otolith growth measurements and stable isotope analyses to recreate growth and among‐reach movement histories of a partially migrating, long‐lived freshwater fish, golden perch Macquaria ambigua . We compared the association between movement and growth at two temporal scales: (a) short‐term (annual) differences in growth, in the years preceding, during or following movement and (b) long‐term (lifetime) differences in growth. Overall, 59% of in iduals performed at least one among‐reach movement, with these in iduals subsequently more likely to move repeatedly throughout their lives. Movers grew faster than residents, with this difference most pronounced in the juvenile and early adult stages, when most movements occurred. Annual growth did not, however, change immediately prior to or following a specific movement event. Among‐in idual variation in growth was initially higher for residents than for movers but decreased with age, at a faster rate for residents than for movers, such that levels conformed after 5 years of age. Our results indicate that lifetime movement is linked to faster growth in the early years of a fish's life. These faster growing movers are likely to be larger at a given age, leading to numerous potential benefits. However, the persistence of resident phenotypes suggests that there is likely a cost–benefit trade‐off to moving. The presence of multiple movement phenotypes may contribute to the resilience of populations by buffering against naturally and anthropogenically exacerbated environmental variability.
Publisher: Wiley
Date: 10-04-2022
DOI: 10.1002/EAP.2563
Abstract: Fisheries and natural water resources across the world are under increasing pressure from human activity, including fishing and irrigated agriculture. There is an urgent need for information on the climatic/hydrologic drivers of fishery productivity that can be readily applied to management. We use a generalized linear mixed model framework of catch curve regression to resolve the key climatic/hydrological drivers of recruitment in Barramundi Lates calcarifer using biochronological (otolith aging) data collected from four river-estuary systems in the Northern Territory, Australia. These models were then used to generate estimates of the year class strength (YCS) outcomes of different water abstraction scenarios (ranging from 10% to 40% abstraction per season/annum) for two of the rivers in low, moderate, and high discharge years. Barramundi YCS displayed strong interannual variation and was positively correlated with regional monsoon activity in all four rivers. River-specific analyses identified strong relationships between YCS and several river-specific hydrology variables, including wet and dry season discharge and flow duration. Water abstraction scenario models based on YCS-hydrology relationships predicted reductions of >30% in YCS in several cases, suggesting that increased water resource development in the future may pose risks for Barramundi recruitment and fishery productivity. Our study demonstrates the importance of the tropical monsoon as a driver of Barramundi recruitment and the potential for detrimental impacts of increased water abstraction on fishery productivity. The biochronological and statistical approaches we used have the potential to be broadly applied to inform policy and management of water resource and fisheries.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/MF10284
Abstract: Applying uniform population models and management strategies to widespread species can be ineffective if populations exhibit variable life histories in response to local conditions. Galaxias maculatus, one of the world’s most widely distributed fish species, occurs in a broad range of habitats and is highly adaptable, making it an ideal species for examining variation in life history traits across large geographic scales. Here, we examine the spawning biology and early life history of diadromous G. maculatus in coastal rivers in Victoria, Australia, and compare them to other populations throughout its range. We predicted that traits associated with these critical life stages, especially those that respond to environmental conditions that vary geographically, such as seasonal cues and temperature, are likely to vary across large spatial scales. We found that spawning occurs later in Victoria than in New Zealand (NZ) and South America, but migration back to rivers occurs at the same time in Victoria and NZ, but not South America. G. maculatus returning to rivers are also smaller and younger in Victoria than those in NZ. Other traits, like some attributes of spawning schools and spawning habitats, did not vary across large scales. Researchers and managers should be cautious when making broad assumptions about the biology of widely distributed species.
Publisher: IEEE
Date: 2009
Publisher: Wiley
Date: 29-08-2018
DOI: 10.1002/ECE3.4459
Publisher: Wiley
Date: 23-05-2019
Abstract: Fishing and climate change are profoundly impacting marine biota through unnatural selection and exposure to potentially stressful environmental conditions. Their effects, however, are often considered in isolation, and then only at the population level, despite there being great potential for synergistic selection on the in idual. We explored how fishing and climate variability interact to affect an important driver of fishery productivity and population dynamics: in idual growth rate. We projected that average growth rate would increase as waters warm, a harvest-induced release from density dependence would promote adult growth, and that fishing would increase the sensitivity of somatic growth to temperature. We measured growth increments from the otoliths of 400 purple wrasse (Notolabrius funicola), a site-attached temperate marine reef fish inhabiting an ocean warming hotspot. These were used to generate nearly two decades of annually resolved growth estimates from three populations spanning a period before and after the onset of commercial fishing. We used hierarchical models to partition variation in growth within and between in iduals and populations, and attribute it to intrinsic (age, in idual-specific) and extrinsic (local and regional climate, fishing) drivers. At the population scale, we detected predictable additive increases in average growth rate associated with warming and a release from density dependence. A fishing-warming synergy only became apparent at the in idual scale where harvest resulted in the 50% reduction of thermal growth reaction norm ersity. This phenotypic change was primarily caused by the loss of larger in iduals that showed a strong positive response to temperature change after the onset of size-selective harvesting. We speculate that the dramatic loss of in idual-level biocomplexity is caused by either inadvertent fisheries selectivity based on behaviour, or the disruption of social hierarchies resulting from the selective harvesting of large, dominant and resource-rich in iduals. Whatever the cause, the removal of in iduals that display a positive growth response to temperature could substantially reduce species' capacity to adapt to climate change at temperatures well below those previously thought stressful.
Publisher: Wiley
Date: 09-03-2022
DOI: 10.1111/ELE.13989
Abstract: Fish and other ectotherms living in warmer waters often grow faster as juveniles, mature earlier, but become smaller adults. Known as the temperature-size rule (TSR), this pattern is commonly attributed to higher metabolism in warmer waters, leaving fewer resources for growth. An alternative explanation focuses on growth and reproduction trade-offs across temperatures. We tested these hypotheses by measuring growth, maturation, metabolism and reproductive allocation from zebrafish populations kept at 26 and 30°C across six generations. Zebrafish growth and maturation followed TSR expectations but were not explained by baseline metabolic rate, which converged between temperature treatments after a few generations. Rather, we found that females at 30°C allocated more to reproduction, especially when maturing at the smallest sizes. We show that elevated temperatures do not necessarily increase baseline metabolism if sufficient acclimation is allowed and call for an urgent revision of modelling assumptions used to predict population and ecosystem responses to warming.
Location: No location found
Start Date: 06-2019
End Date: 12-2022
Amount: $343,000.00
Funder: Australian Research Council
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