Box Hill South, Australia
Box Hill South, Australia

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Whiterod N.S.,Murray Darling Freshwater Research Center | Whiterod N.S.,Charles Sturt University
Ecology of Freshwater Fish | Year: 2013

This study documented the swimming capacity of a large ambush predator, Murray cod Maccullochella peelii, endemic to the Murray-Darling Basin, Australia. It was evident that the species is a swimming generalist, maintaining moderate ability across all aspects of the swimming capacity parameters that were investigated. For instance, the species was capable of prolonged swimming performance (critical swimming speed, Ucrit: absolute, 0.26-0.60 m·s-1, relative, 1.15-2.20 BL s-1) that was inferior to active fish species, but comparable with other ambush predators. The species had low energetic demands, maintaining a low mass-specific standard (21.3-140.3 mg·h-1 kg-1) and maximum active metabolic rate (75.5-563.8 mg·h-1 kg-1), which lead to a small scope for activity (maximum active metabolic rate-standard metabolic rate; 1.4-5.9). They were reasonably efficient swimmers (absolute and relative optimal swimming speed, 0.17-0.61 m·s-1 and 0.77-1.93 BL·s-1, respectively) and capable of repeat bouts of prolonged performance (recovery ratio = 0.99). Allometric changes in aspects of swimming capacity were realised with body mass, whereas broad swimming capacity was maintained across a wide range of temperatures. The swimming capacity demonstrated by M. peelii reflects a sit-and-wait foraging strategy that seeks to conserve energy characteristic of ambush predators, but with distinct features (e.g., lack of fast-start ability) that may reflect their evolution in some of the world's most hydrologically and thermally variable rivers. © 2012 John Wiley & Sons A/S.

Lawson L.L.,University of Florida | Hill J.E.,University of Florida | Vilizzi L.,Murray Darling Freshwater Research Center | Hardin S.,Florida Fish And Wildlife Conservation Commission | And 3 more authors.
Risk Analysis | Year: 2013

The initial version (v1) of the Fish Invasiveness Scoring Kit (FISK) was adapted from the Weed Risk Assessment of Pheloung, Williams, and Halloy to assess the potential invasiveness of nonnative freshwater fishes in the United Kingdom. Published applications of FISK v1 have been primarily in temperate-zone countries (Belgium, Belarus, and Japan), so the specificity of this screening tool to that climatic zone was not noted until attempts were made to apply it in peninsular Florida. To remedy this shortcoming, the questions and guidance notes of FISK v1 were reviewed and revised to improve clarity and extend its applicability to broader climatic regions, resulting in changes to 36 of the 49 questions. In addition, upgrades were made to the software architecture of FISK to improve overall computational speed as well as graphical user interface flexibility and friendliness. We demonstrate the process of screening a fish species using FISK v2 in a realistic management scenario by assessing the Barcoo grunter Scortum barcoo (Terapontidae), a species whose management concerns are related to its potential use for aquaponics in Florida. The FISK v2 screening of Barcoo grunter placed the species into the lower range of medium risk (score = 5), suggesting it is a permissible species for use in Florida under current nonnative species regulations. Screening of the Barcoo grunter illustrates the usefulness of FISK v2 as a proactive tool serving to inform risk management decisions, but the low level of confidence associated with the assessment highlighted a dearth of critical information on this species. © 2012 Society for Risk Analysis.

Tricarico E.,University of Florence | Vilizzi L.,Murray Darling Freshwater Research Center | Gherardi F.,University of Florence | Copp G.H.,Salmon and Freshwater Fisheries Team | Copp G.H.,Bournemouth University
Risk Analysis | Year: 2010

The Freshwater Invertebrate Invasiveness Scoring Kit (FI-ISK) is proposed as a screening tool for identifying potentially invasive freshwater invertebrates. FI-ISK was adapted from the Fish Invasiveness Scoring Kit (FISK) of Copp, Garthwaite, and Gozlan, which is an adapted form of the Weed Risk Assessment (WRA) of Pheloung, Williams, and Halloy. Initial assessments using FI-ISK, which include confidence (certainty/uncertainty) rankings by the assessor to each response, were calibrated to determine the most appropriate score thresholds for classifying nonnative species into low-, medium-, and high-risk categories, using both the original medium-to-high risk threshold scores for the WRA (i.e., ≥6) and for FISK (i.e., ≥19). Patterns of the assessor's confidence, when making the responses during the FI-ISK assessments, were also examined. Using receiver operating characteristic (ROC) curves, FI-ISK was shown to distinguish accurately (and with statistical confidence) between potentially invasive and noninvasive species of nonnative crayfish (Decapoda: Astacidae, Cambaridae, Parastacidae), with the statistically appropriate threshold score for high-risk species scores being ≥16. FI-ISK represents a useful and viable tool to aid decision- and policymakers in assessing and classifying freshwater invertebrates according to their potential invasiveness. © 2009 Society for Risk Analysis.

Vilizzi L.,Murray Darling Freshwater Research Center | Copp G.H.,Salmon and Freshwater Team | Copp G.H.,Trent University | Britton J.R.,Bournemouth University
Knowledge and Management of Aquatic Ecosystems | Year: 2013

Suspected of being in decline, the European barbel Barbus barbus population of the River Lee, a heavily-modified river in South East England, has been the subject of investigations to identify factors associated with perceived population decreases. Population surveys between 1995 and 1999 captured a total of 912 individuals, and standard length (SL) frequency analyses between years suggested that the population decline was not related to juvenile recruitment but rather to a recruitment bottleneck in fish 300-340 mm SL. This bottleneck probably results from insufficient available habitat suitable to this size class. Of the sampled fish, scales were removed from 764 and were used in a scale ageing exercise among three researchers. Analyses of their independent age estimates revealed variable interpretations, which arose from uncertainties relating to the difficulty of analysing scale patterns from relatively large, slow-growing fish. Nevertheless, error was within published acceptable margins, and age estimates revealed B. barbus in the river to age 10 years, lower than in many UK rivers. The SL-at-age growth curve was characterised by very fast growth in the initial years of life. Thus, the causal factors in the decline of this B. barbus population appear to have been in the adult life-stage habitat and were likely related to the loss of longitudinal connectivity, mainly due to the presence of water retention structures. River and aquatic ecosystem remediation strategies should therefore focus on enhancing longitudinal connectivity in conjunction with the ongoing improvement of water quality and ecosystem integrity. © ONEMA, 2013.

Copp G.H.,Center for Environment | Copp G.H.,Bournemouth University | Vilizzi L.,Murray Darling Freshwater Research Center | Gozlan R.E.,Murray Darling Freshwater Research Center
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010

1. The contamination of fish consignments (for stocking or aquaculture) is a major pathway by which non-native organisms, including fish, are introduced to new areas. One of the best examples of this is the topmouth gudgeon Pseudorasbora parva, which was accidentally imported into Romania and then throughout Europe in consignments of Asian carp species. 2. The introduction and spread of topmouth gudgeon in the UK has been linked to imports and movements of the ornamental variety (golden orfe) of ide Leuciscus idus. To examine this hypothesis, relationships between authorized movements of both native and non-native fish species (in particular ide) and the occurrence in England of topmouth gudgeon were tested at the 10 × 10 km scale. 3. Topmouth gudgeon occurrence in the wild was significantly correlated with the trajectories of movements of ornamental fish species (ide/orfe, sunbleak Leucaspius delineatus) as well as a few non-ornamental fish species (European catfish Silurus glanis, Atlantic salmon Salmo salar and grass carp Ctenopharyngodon idella). 4. These results highlight the mechanism by which non-native fish species disperse from the point of first introduction, and especially that movements of fish within the country represent an important mechanism for accidental introductions of non-native species. © Crown copyright 2010.

Dillon S.,CSIRO | McEvoy R.,La Trobe University | Baldwin D.S.,Murray Darling Freshwater Research Center | Baldwin D.S.,CSIRO | And 4 more authors.
PLoS ONE | Year: 2014

As an increasing number of ecosystems face departures from long standing environmental conditions under climate change, our understanding of the capacity of species to adapt will become important for directing conservation and management of biodiversity. Insights into the potential for genetic adaptation might be gained by assessing genomic signatures of adaptation to historic or prevailing environmental conditions. The river red gum (Eucalyptus camaldulensis Dehnh.) is a widespread Australian eucalypt inhabiting riverine and floodplain habitats which spans strong environmental gradients. We investigated the effects of adaptation to environment on population level genetic diversity of E. camaldulensis, examining SNP variation in candidate gene loci sampled across 20 climatically diverse populations approximating the species natural distribution. Genetic differentiation among populations was high (FST = 17%), exceeding previous estimates based on neutral markers. Complementary statistical approaches identified 6 SNP loci in four genes (COMT, Dehydrin, ERECTA and PIP2) which, after accounting for demographic effects, exhibited higher than expected levels of genetic differentiation among populations and whose allelic variation was associated with local environment. While this study employs but a small proportion of available diversity in the eucalyptus genome, it draws our attention to the potential for application of wide spread eucalypt species to test adaptive hypotheses. © 2014 Dillon et al.

Whitworth K.L.,La Trobe University | Whitworth K.L.,Murray Darling Freshwater Research Center | Baldwin D.S.,Murray Darling Freshwater Research Center | Baldwin D.S.,CSIRO
Environmental Chemistry | Year: 2011

The accumulation of reduced sulfur species in the sediments of salinised inland waterways poses a serious environmental risk to many historically freshwater environments. Here the effects of salinity (and associated sulfate concentration), organic carbon load and temperature on reduced sulfur accumulation and speciation in closed microcosms containing sediments from a wetland that had not previously been salinised are examined. At conductivities of up to 10 000 μS cm -1, extant sediment carbon was sufficient to allow reduction of the entire sulfate load. Sulfate reduction was carbon limited at higher salinities. The rate of sulfate reduction approximately tripled with an increase in temperature from 20 to 30°C. Speciation studies showed that elemental sulfur and an unidentified sulfur species - probably reduced organic sulfur - were the dominant reduced sulfur species present during the early stages of sulfate reduction. By the end of the incubation period (226 days), reactive forms of S (elemental sulfur and acid-volatile sulfide) dominated. In the low conductivity treatments (0 and 1000 μS cm -1) reduced sulfur was approximately equally distributed between the two forms; acid volatile sulfide comprised ∼75% of the reduced sulfur at higher salinities. Formation of less reactive di-sulfide minerals was inconsequential over the timescale of this experiment. © CSIRO 2011.

Whiterod N.,Murray Darling Freshwater Research Center | Sherman B.,CSIRO
River Research and Applications | Year: 2012

The 60-km-long pool created by the Mildura weir exhibits pronounced physical, chemical and biological gradients along its length. As the river deepens and widens downstream along the weir pool, the flow velocity decreases and the potential for thermal stratification (intensity and duration of stratification) increases. Most nutrient concentrations (TN, NOx, FRP) as well as the euphotic depth increased in the downstream direction whereas TP and turbidity decreased. The increase in bioavailable nutrients co-occurred with an increase in electrical conductivity suggesting the presence of relatively more saline groundwater inflows to the weir pool. Throughout the summer (12 December 2003-18 March 2004), with the exception of 8days, the water column throughout the weir pool mixed completely on a diurnal basis in the deeper sections and was continuously mixed in the shallower upstream sections. This mixing substantially reduced the mean irradiance experienced by the phytoplankton near the weir. Maximum cyanobacteria concentrations were observed in the mid-weir pool where the range of conditions was most suitable. Diatom abundance increased along the most downstream 20km of the pool where the water column was deeper and slower flowing yet still mixed completely on a diurnal basis. Peaks in cyanobacteria biomass are not expected in the lower weir pool until lower discharges promote persistent thermal stratification and increase the mean irradiance in the surface mixed layer. © 2011 John Wiley & Sons, Ltd.

Baldwin D.S.,Murray Darling Freshwater Research Center | Baldwin D.S.,CSIRO | Mitchell A.,Murray Darling Freshwater Research Center | Mitchell A.,CSIRO
Water Research | Year: 2012

The impact of sulfate pollution is increasingly being seen as an issue in the management of inland aquatic ecosystems. In this study we use sediment slurry experiments to explore the addition of sulfate, with or without added carbon, on the anaerobic biogeochemical cycles in a wetland sediment that previously had not been exposed to high levels of sulfate. Specifically we looked at the cycling of S (sulfate, dissolved and particulate sulfide - the latter measured as acid volatile sulfide; AVS), C (carbon dioxide, bicarbonate, methane and the short chain volatile fatty acids formate, acetate, butyrate and propionate), N (dinitrogen, ammonium, nitrate and nitrite) and redox active metals (Fe(II) and Mn(II)). Sulfate had the largest effects on the cycling of S and C. All the added S at lower loadings were converted to AVS over the course of the experiment (30 days). At the highest loading (8mmol) less than 50% of consumed S was converted to AVS, however this is believed to be a kinetic effect. Although sulfate reduction was occurring in sediments with added sulfate, dissolved sulfide concentrations remained low throughout the study. Sulfate addition affected methanogenesis. In the absence of added carbon, addition of sulfate, even at a loading of 1mmol, resulted in a halving of methane formation. The initial rate of formation of methane was not affected by sulfate if additional carbon was added to the sediment. However, there was evidence for anaerobic methane oxidation in those sediments with added sulfate and carbon, but not in those sediments treated only with carbon. Surprisingly, sulfate addition had little apparent impact on N dynamics; previous studies have shown that sulfide can inhibit denitrification and stimulate dissimilatory nitrate reduction to ammonia. We propose that because most of the reduced sulfur was in particulate form, levels of dissolved sulfide were too low to interfere with the N cycle. © 2011.

Vilizzi L.,Murray Darling Freshwater Research Center
Fundamental and Applied Limnology | Year: 2012

Temporal variability in flow is central to the functioning of river ecosystems, with current conceptual models emphasising the importance of flow events, namely overbank flood pulses and in-channel flow pulses, in enhancing riverine fish production. However, whilst the benefits of flood pulses have been widely documented, there is an overall dearth of information with regard to the role of flow pulses in enhancing fish spawning and recruitment. To test the validity of applicable conceptual models of floodplain fish production in response to alternating low-flow and flow-pulse years in the absence of a flood pulse, fish larvae were sampled every three to five weeks from 2002 to 2007 in an anabranch system of the highly-regulated and semi-arid lower Murray River (southeastern Australia). Small-bodied native fish (mainly, un-specked hardyhead, carp gudgeon, flathead gudgeon and Australian smelt) spawned successfully in every year irrespective of hydrological conditions, with Australian smelt being particularly abundant in two of the three low-flow years following a flow-pulse event. However, spawning in the majority of these small-bodied species was enhanced by the two flow pulses. On the contrary, large-bodied silver perch and golden perch only spawned during one of the two spring flow pulses, emphasising the importance of both timing and duration of a flow pulse along with its coupling with temperature. The findings of the present study support recent views that a combination of conceptual models of floodplain fish production is likely to apply in temperate to semi-arid floodplain rivers. Management measures aimed at the benefit of native fish communities should account for both flow and flood pulses through the release of environmental water, and this should be supported by long-term studies able to span the components of a river's flow history. © 2012 E. Schweizerbart'sche Verlagsbuchhandlung.

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