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MDFRC item.Risk assessments are crucial for identifying and mitigating impacts from biological invasions. The Fish Invasiveness Scoring Kit (FISK) is a risk identification (screening) tool for freshwater fishes consisting of two subject areas: biogeography/history and biology/ecology. According to the outcomes, species can be classified under particular risk categories. The aim of this study was to apply FISK to the Iberian Peninsula, a Mediterranean climate region highly important for freshwater fish conservation due to a high level of endemism. In total, 89 fish species were assessed by three independent assessors. Results from receiver operating characteristic analysis showed that FISK can discriminate reliably between noninvasive and invasive fishes for Iberia, with a threshold of 20.25, similar to those obtained in several regions around the world. Based on mean scores, no species was categorized as “low risk,” 50 species as “medium risk,” 17 as “moderately high risk,” 11 as “high risk,” and 11 as “very high risk.” The highest scoring species was goldfish Carassius auratus. Mean certainty in response was above the category “mostly certain,” ranging from tinfoil barb Barbonymus schwanenfeldii with the lowest certainty to eastern mosquitofish Gambusia holbrooki with the highest level. Pair-wise comparison showed significant differences between one assessor and the other two on mean certainty, with these two assessors showing a high coincidence rate for the species categorization. Overall, the results suggest that FISK is a useful and viable tool for assessing risks posed by non-native fish in the Iberian Peninsula and contributes to a “watch list” in this region.

MDFRC item.Prolonged flooding in 2010/11 ended a decade of drought and produced a large-scale hypoxic blackwater event across the southern Murray-Darling Basin, Australia. The hypoxic conditions caused fish kills and Murray crayfish Euastacus armatus to emerge from the water onto the river banks to avoid the poor water quality. This study examined the medium-term impact of this blackwater event on Murray crayfish populations in the Murray River, where approximately 1800 km of the main channel were affected by hypoxia. Murray crayfish populations were surveyed in July 2012, along a 1100-km section of the Murray River at 10 sites affected by hypoxic blackwater and six sites that were not affected, and data were compared with surveys of the same sites undertaken in July 2010, four months before the hypoxic blackwater event (before-after-control-impact experimental design). Murray crayfish abundance in 2012 (post-blackwater) was significantly lower at blackwater affected sites (81% reduction from 2010), but not at non-affected sites. The hypoxic blackwater impacted Murray crayfish of both sexes and all size-classes in a similar manner. The results demonstrate that prolonged periods of hypoxia can markedly impact populations of the long-lived and slow-growing Murray crayfish despite the species ability to emerge from hypoxic water. The findings highlight important challenges for the management of both the recreational fishery for this species and riverine flows in relation to hypoxic blackwater events.

Murray-Darling Freshwater Research CentreMDFRC item.An overall lack of generality still exists in relationships between degree of flow modification and ecological/geomorphological response, important for better understanding and management of freshwater resources. Here, we model direct and indirect effects in flow-habitat-biota relationships in the littoral zone of a 230 km stretch of the lower River Murray (Victoria, Australia), a large and highly-regulated lowland river. We rely on a novel (to lotic ecology) statistical method called the 'd-sep test'. A number of theory-laden (including PHABSIM-based) competitive models were assessed, and model reliability further evaluated against alternative models. The model of choice was one with flow directly affecting all abiotic (substratum composition) and biotic (aquatic vegetation, zooplankton abundance, fish abundance) components. The latter were in turn linked in a bottom-up series, with inclusion of a direct effect of aquatic vegetation on fish abundance. However, an alternative model with a direct effect of substratum composition on fish abundance was also partly supported by the data. We discuss the ecological significance of the proposed model(s), along with their value, relevance, and implications in (fish) habitat assessment studies.

"September 2008".Project Number: Living Murray Monitoring 2005 – 2009 - M/BUS/87-2,3.MDFRC item.142 pages. 1 of 8 reports associated with project see (Part A The Living Murray Initiative: Lindsay-Mulcra-Wallpolla Islands and Hattah Lakes Icon Sites condition monitoring program design), (Part B The Living Murray Initiative: Lindsay-Mulcra-Wallpolla Islands and Hattah Lakes Icon Sites 2006-7 condition monitoring program data), (The Living Murray Initiative: Lindsay-Mulcra-Wallpolla Islands and Hattah Lakes Icon Sites 2006-7 condition monitoring program data), (The Living Murray Condition Monitoring of Lindsay, Mulcra and Wallpolla Islands 2007/08), (The Living Murray Initiative: Lindsay-Mulcra- Wallpolla Islands Icon Site 2006-7 intervention monitoring program data), (The Living Murray Initiative: Monitoring within the Mallee CMA region 2005-06) and (The Living Murray Initiative: Monitoring within the Mallee CMA region 2005-06).No abstract available.

MDFRC item.The climatic conditions of north temperate countries pose unique influences on the rates of invasion and the potential adverse impacts of non-native species. Methods are needed to evaluate these risks, beginning with the pre-screening of non-native species for potential invasives. Recent improvements to the Fish Invasiveness Scoring Kit (FISK) have provided a means (i.e., FISK v2) of identifying potentially invasive non-native freshwater fishes in virtually all climate zones. In this study, FISK is applied for the first time in a north temperate country, southern Finland, and calibrated to determine the appropriate threshold score for fish species that are likely to pose a high risk of being invasive in this risk assessment area. The threshold between “medium” and “high” risk was determined to be 22.5, which is slightly higher than the original threshold for the United Kingdom (i.e., 19) and that determined for a FISK application in southern Japan (19.8). This underlines the need to calibrate such decision-support tools for the different areas where they are employed. The results are evaluated in the context of current management strategies in Finland regarding non-native fishes.

Murray-Darling Freshwater Research CentreMDFRC item.Data on the diel density and dispersal of young-of-the-year (0+) fishes in the River Lee(Hertfordshire) at Holwell Bridge were examined in August 1998 to determine whetherpatterns in this stretch with no fencing along the banks were similar to those observed inAugust 1996 in a nearby, downstream stretch (Woolmer’s Park), where the river is fencedoff. Although the numbers of 0+ fish captured (both overall and for most fish species)was higher at night or dawn, similar to Woolmer’s Park, the differences were notstatistically significant, probably due to low sample number.

"October 2006".Project Number: Threatened aquatic species management: Age structure and food source availability of the Murray Hardyhead – M/BUS/80-2,3; Native Fish Recruitment and Flood Pulse Water Quality Monitoring on Lindsay Island – M/BUS/83-2,3; Protecting Murray Hardyhead – M/BUS/80.4.MDFRC item.1 of multiple reports associated with project see- M/BUS/80-2,3; M/BUS/83-2,3 and M/BUS/80.4.No abstract available.

"June 2007".Project Number: Threatened aquatic species management: Age structure and food source availability of the Murray Hardyhead – M/BUS/80-2,3; Native Fish Recruitment and Flood Pulse Water Quality Monitoring on Lindsay Island – M/BUS/83-2,3; Protecting Murray Hardyhead – M/BUS/80.4.MDFRC item.1 of multiple reports associated with project see- M/BUS/80-2,3; M/BUS/83-2,3 and M/BUS/80.4.No abstract available.

MDFRC item.Article first published online: 4 OCT 2012 - Correction added after online publication on October 4, 2012: In the title, “Scoring” was changed to “Screening”.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.

"September 2008".Project Number: The impact of drought on aquatic communities in the lower Darling River - M/BUS/241.MDFRC item.62 pages.It is generally anticipated that river pools are core habitat for native fish and that during droughts isolated deep pools function as key refugia for aquatic communities, yet there is considerable pressure placed on these pools for irrigation, stock and domestic supply. The overarching objective of the project was to address the distinct lack of knowledge on how these systems function, and of their relative importance as refugia during drought periods by investigating the ecology of river pools as they become isolated, and subsequently reconnect due to regulated releases. Understanding processes that occur within these pools during periods of low- and no- flow, and during periods when flow is reinstated is vital to maintaining sustainable ecosystems. The project monitored conditions in three distinct, deep (>5m) pools situated above Harcourt and below Pooncarie (within and downstream of the areas involved in the 2004 lower Darling River Fish Kill respectively) between December 2006 and May 2008. The project has captured a summer-autumn low flow (250MLday-1), autumn-winter cease to flow, late winter reinstatement of low flow ( 6°C) occur at the downstream sites during both summer and autumn at this flow band. During stratified periods, conditions in the bottom section of the water column were frequently either hypoxic (low dissolved oxygen) or anoxic (no dissolved oxygen) for extended periods of time (>100 days). In contrast, hypoxic conditions were rarely recorded in the surface layer. Taking into account balancing the needs for maintaining security of supply, summer base-flows should be established and maintained that are sufficient to prevent the onset of persistent thermal stratification and subsequent anoxia at depth in refuge pools and weir pools for the entire reach of the lower Darling.The observation that robust fish communities exist in the sampled reaches, despite a combination of high temperatures and hypoxic and anoxic conditions at depth within the pools suggests that sufficient habitat is available to sustain native fish in these pools during droughts. However, the fish community is highly susceptible to disturbances. For example, the data associated with the re-instatement of flow following a summer no-flow period demonstrated that hypoxic conditions were present throughout the water column in the deep pools prior to and immediately following the arrival of the flow front. Periods such as this when the entire water column becomes deoxygenated pose a significant threat to aquatic communities and suggest that a tipping point for onset of anoxia throughout the water column was approached if not narrowly avoided. If it is necessary to reinstate flows during summer, extreme care should be taken in order to minimise the risk of extensive fish deaths.

"March 2011".Project Number: 2009-10 Condition Monitoring at Lindsay-Mulcra-Wallpolla Islands - M/BUS/87-2,3,4 BW283.MDFRC item.This report details the condition monitoring undertaken at Lindsay, Mulcra and Wallpolla (LMW) Islands as part of the 2009/10 Living Murray Condition Monitoring Program. Icon Site condition monitoring has been developed to: Determine the change in environmental condition of individual assets resulting from water application and the implementation of works programs under The Living Murray (TLM). Assess whether sustainable native fish, bird and vegetation communities are being maintained across the Icon Sites. The Outcomes Evaluation Framework stipulates that measurable targets be created to unambiguously assess whether a pre-determined level of condition has been achieved. At the time of writing, such targets had not been developed for LMW. In the absence of defined targets, this report focuses upon Icon Site specific objectives. Icon Site specific objectives presented in the Outcomes Evaluation Framework have been further refined as part of the Lindsay-Mulcra-Wallpolla Environmental Management Plan. Together these objectives form the basis for condition monitoring at Lindsay-Mulcra-Wallpolla of which there are six vegetation components and one fish component. River Red Gum The ecological objectives for River Red Gum (RRG) at Lindsay, Mulcra and Wallpolla are: Current area maintained. Maintain current condition and extent of River Red Gum communities to sustain species assemblages and processes typical of such woodland. Large scale mapping at regular intervals is required to quantify changes in the distribution and areal extent of River Red Gum at LMW. Currently there is no such mapping program underway, so it is not possible to know if current area of RRG is being maintained. Significant increases in Crown Condition scores between the sampling events of 2008/09 and 2009/10 suggest changes in the conditions favourable for tree growth on the LMW floodplain. This is attributed to environmental watering at Mulcra Horseshoe Lagoon and a break in drought conditions. However, with the notable exception of the relatively small area of extant Red Gum with Flood Tolerant Understorey (RGFTU) at Mulcra Island, the recent improvement observed for RRG trees at LMW represents a change in the previous downward trend in condition rather than a return to acceptable condition. Stand condition modelling conducted by Cunningham et al.(2009) reports that the extent of severely degraded stands was higher in the Mallee (Hattah, Chowilla and LMW) than at other TLM Icon Sites, that the majority of stands were in a stressed condition in 2003 and that this had increased by 4% by 2009. Recruitment must keep pace with mortality for a population to remain sustainable and this must occur within the current spatial context if the present distribution is to be maintained (i.e. ecological objectives are to be met). Size-class frequency distributions for Fringing Red Gum Woodland (FRGW) indicate a relative abundance of trees within the smaller size classes suggesting sustainable recruitment. However, despite indications of recent improvement in the condition of trees on average, population viability assessments suggest there are long-term sustainability concerns for Red Gum Forest (RGF) communities at LMW. Black Box The ecological objectives for Black Box (BB) at LMW are: At least 20% of the original area of Black Box vegetation maintained. Improve condition to sustain species assemblages and processes typical of Black Box woodland. Ecological Vegetataion Class (EVC) mapping conducted in 2005 provides the most accurate and up to date information about the areal extent of Black Box at LMW and is therefore the logical choice for a BB areal standard. However, in the absence of an ongoing program mapping the distribution of Black Box at the Icon Site scale, it is not possible to know what proportion of the original area of Black Box is being maintained. Size-class distributions for Black Box communities do not approximate inverse J-shaped curves indicative of sustainable populations. Further, between 2008/09 and 2009/10 there was a reduction in the relative proportion of Diameter at Breast Hight (DBH) 16 ds/m, DPI 2008) and an increase in abundance could be indicative of an increase in site salinity. It is recommended that soil salinity testing be undertaken at the LMW Icon Site. Of concern are the appearances and/or incr

"June 2009".Project Number: Impacts of drought on distribution of fish communities in the Mullaroo Creek - Lindsay River Complex - M/BUS/255.MDFRC item.This study was initiated and designed in response to a protracted period of low flows predicted to occur in the lower River Murray region as a result of extreme drought, low inflow conditions and imposed water management strategies across the Murray-Darling catchment during 2007. Previous research has demonstrated that the Lindsay Island anabranch complex in north-western Victoria supports robust populations of native and exotic fish species. The Mullaroo Creek, an anabranch of the River Murray that dissects Lindsay Island is of particular importance to management of Murray cod in the lower Murray region as it supports what is considered to be a robust self sustaining population that is important to sustainability of Murray cod at the broader regional level. During the predicted ‘Low Flow’ period, the River Murray at Lock 7 ceased to flow for a total of 166 days and average daily flow decreased by 87% as compared to the preceding five year or 'Base Flow' period. Despite prevailing low flows and protracted periods of zero flow in the Murray River at Lock 7 during 2007 and 2008, flow into the Mullaroo Creek, with its off-take 2 km upstream from Lock 7, did not cease to flow. During the Low Flow period, average daily flow in the Mullaroo Creek was reduced by 16.5% compared to the average daily flow recorded during the Base Flow period. There was an opportunity to combine five years of existing fish assemblage data (2002 – 2006) compiled by the MDFRC for the Lindsay Island anabranch complex at Base Flows, with two years of data gathered during the protracted period of Low Flow (2007 - 2008), to enable examination of changes in the spatial distribution, assemblage structure, abundance and population size structure of native and exotic fish species in response to the influence of the protracted Low Flow period. Distributing the analysis of fish sampling effort across Base Flow and Low Flow periods revealed that there was no significant change to the composition of the large bodied fish assemblage (all species combined) relative to flow conditions across Lindsay Island during this study. However, there were significant changes regarding the abundance of particular species at particular reaches. The relative abundance of Murray cod in the Upper Mullaroo Creek increased during the Low Flow period as compared to the Base Flow period. The most important consideration here is that the relative abundance of Murray cod in the Mullaroo Creek did not decrease during the Low Flow period and there are several potential explanations to explain this observation. Unlike Murray cod, the relative abundance of golden perch decreased during the Low Flow period, potentially result of a lack of observable recruitment across the study reaches since 2005. In the context of decision making regarding the alteration of flow regimes and therefore the flow habitats of fish at TLM Icon sites, consideration should be given to the findings of this project. Examination of the length-frequency distribution of Murray cod in the Mullaroo Creek highlights the significant impact result of recreational harvest upon the population structure of Murray cod in the Mullaroo Creek. We consider recreational harvest to be the single most eminent threat to the status of Murray cod in the Mullaroo Creek and as a consequence, the broader region. We recommend that anglers be denied access to the Mullaroo Creek, from its off-take on the Murray River, to its confluence with the Lindsay River via the creation of a fisheries conservation zone, consistent with provisions existing within the Victorian Fisheries Act (1995).

MDFRC item.Predictions of future climate change include shifts in patterns of precipitation, evapotranspiration and water run-off, resulting in increased periods of drought as well as variability and intensity of rainfall events. In the United Kingdom, the non-native North American sunfish, pumpkinseed Lepomis gibbosus (L.), is expected to benefit from these changes. We examine how hydrological variability induced by predicted changes in climate will affect the dispersal and spread of pumpkinseed in England by: (i) determining the relationship between discharge regime and pumpkinseed propagule pressure; (ii) examining a newly-established pumpkinseed population following a flood event in 2007; and (iii) comparing the growth and life-history traits of this new population with fish collected from the source population to demonstrate how the pumpkinseed's life-history plasticity contributes to its success as a coloniser. Using Bayesian modelling, we determined that the number of pumpkinseed escapees is likely to increase with increasing discharge. The newly-established pumpkinseed population showed fast juvenile growth, early age at maturity and small size at maturity. These traits differed significantly from the source population, specifically total length (TL) means at ages 1 and 2 were significantly greater in the new population, whereas TL at age 4 was significantly greater in the source population, and a significantly higher proportion of mature females were found at smaller size classes in the newly established pumpkinseed population. This study demonstrates the potential link between hydrological variability (current and future) and the dispersal of non-native pumpkinseed, leading to the establishment of new populations.

Murray-Darling Freshwater Research CentreMDFRC item.Amongst passive collecting gear types, light traps have been used extensively to sample the larvae and juveniles of fish in both marine and freshwater environments, and especially so in structurally complex habitats. Although a number of modifications have been proposed to increase efficiency, no account has hitherto been made of the possible loss of trapped larvae and juveniles as a result of within-trap predation by piscivorous fish. To address this issue, we evaluated the efficiency of modified light traps by the addition of mesh (3 mm knot-to-knot wrapped around the entrance chambers), by combining results from a long-term monitoring study with those from a designed field experiment. Abundance of larvae and juveniles collected during the monitoring program was higher in the years following mesh application (hence, beyond monthly variation), and this was supported by the experiment. Based on the latter, light/mesh traps consistently caught only larvae/juveniles, hence excluding adults; whereas the opposite was true of the light/no-mesh trap combination. Also, mesh/no-light traps did not capture any fish, unlike no-mesh/no-light traps, which sampled only adults. Our findings suggest that in situ predation on larvae and juveniles within light traps should not be overlooked. The occurrence of piscivorous and cannibalistic behaviour in Hypseleotris spp. is also discussed.

MDFRC item.First published online 2012.1. Floodplain wetlands are areas of high biodiversity and conservation value, including those in semi-arid regions. River regulation has resulted in disconnection from the main river channel of several ephemeral wetland systems, with profound modifications to their natural wetting/drying cycles that have contributed to the decline in diversity, distribution and abundance of native fish. 2. From 2005 to 2011, a series of managed inundation events through pumping followed by natural inundation allowed assessment and comparison of the fish assemblage developing in Hattah Lakes, a semi-arid wetland system of the regulated Murray River (Victoria, Australia). 3. As a result of one-way pumping from the main channel to Hattah Lakes, a ‘filtered’ fish assemblage consisting mainly of small-bodied native species and very low numbers of non-native species fully developed within 2 years. After disconnection from the main river channel in the absence of pumping, within-system recruitment also occurred, but later drying of all water bodies caused the entire fish assemblage to perish. Conversely, following two-way flooding by natural inundation a more diverse fish assemblage developed, including large-bodied native species but also non-native species, some of which were previously unrecorded. 4. Managed inundation through pumping in Hattah Lakes represents a viable option for the creation of fish habitat, for promoting recruitment, and as a measure of rehabilitation. However, the absence of connectivity back to the main river channel means that future measures should be implemented to maintain a refuge water pool until the next inundation event. Long-term monitoring is a key component of the integrated wetland conservation framework adopted by the Ramsar Wetland Convention, and this is especially relevant to the conservation of semi-arid wetlands world-wide including Hattah Lakes.

"April 2009".Project Number: Implications of pumping water on the ecology of Hattah Lakes - M/BUS/210.MDFRC item.1 of 2 reports associated with project see (Implications of pumping and ponding water on water quality and the development of diverse aquatic ecosystems: Intervention Monitoring of the Hattah Lakes Icon Site 2006/07).This report details the intervention monitoring undertaken at Hattah Lakes by the Murray-Darling Freshwater Research Centre in 2007/08 as part of The Living Murray program. The project investigated the ecological responses of river red gum, water quality, wetland vegetation and fish to the pumping of water to Hattah Lakes. The Hattah Lakes is part of the 48,000 ha Hattah-Kulkyne National Park located in the north west of Victoria. It contains 18 freshwater lakes (12 of which are Ramsar-listed) connected by a series of floodplain channels fed by the Murray River during periods of high flow. River regulation has threatened the ecological values of Hattah Lakes due to changes in the timing, duration and frequency of wet and dry phases in the lake system. Storage and extraction of water from the Murray River upstream of Hattah Lakes has resulted in the mean discharge in the Murray River near Hattah Lakes being ≈ 50% of natural. Natural overbank flooding has occurred on only one occasion in the past 11 years. Due to the reduced frequency of flooding, pumping has become a necessary management intervention to achieve inundation of the lakes in the current regulated and drought conditions. The pumping of water into Hattah Lakes from the Murray River occurred on four occasions during the period April 2005 to December 2006. It is expected to remain a long-term management intervention to maintain ecological values at the Hattah Lakes Icon Site. River red gum The greatest increase in river red gum (RRG) crown density (and condition) occurred in the ≈ 6-month period following pumping at Lake Mournpall (treatment), Brockie (treatment) and Yelwell (experimental control that did not receive pumped water). At least part of the increase across all lakes was attributed to the well-above-average rainfall during this period. For the ≈ 6-12 month and ≈ 12-18 month periods following pumping, mean crown densities of RRG have generally been maintained or have decreased at all three lakes. This was not expected, as the environmental watering was predicted to generate increases in crown densities at Lakes Mournpall and Lake Brockie for a longer period. Statistical analysis of the crown density profiles showed significant differences between the lakes that received pumped water and the control lake. These differences were due to a significantly lesser decline in crown density at Lakes Mournpall and Brockie during the ≈ 12-18 month period than occurred at the control Lake Yelwell. The lower rate of decrease in crown density at the treatment lakes may be due to these lakes receiving pumped water. However, it may in part be attributed to the control Lake Yelwell having a RRG population in poorer condition than the treatment lakes at the commencement of the study. Analysis of RRG response with distance from the water edge revealed that the greatest increases in crown density occurred for RRG located upon the lakebeds of the treatment lakes in the 12-month period following inundation. The bases of these trees were directly inundated from the pumped water. In contrast, the RRG located at higher elevations that were not directly inundated responded to a lesser degree. The findings suggest that RRG fringing the lakebeds may require direct inundation to achieve a greater increase in crown condition from environmental watering events. Water quality Water levels at Lakes Mournpall, Hattah, Bulla and Arawak decreased over the study period and held maximum water depths of ≈ 0.3 – 0.5m in mid-September 2008. As water levels decreased, turbidity increased and became more variable due to the increased susceptibility of the lakebed sediments to re-suspension from wind and wave action. This influenced euphotic depth in the lakes which typically ranged from 0.2 – 0.8m across the lakes. Electrical conductivity increased within the lakes as dissolved salts become more concentrated through evaporation but were less than 1,500 μS.cm-1 at the end of the study period. Surface water temperatures remained within the range of 10 – 30oC. Phytoplankton blooms comprising blue-green algae species were present at all four lakes during the study period. Total chlorophyll pigment exceeded 250 μg.L-1 and blue green algae counts exceeded 1 million cells.mL-1 at all lakes for at least one sampling occasion. The blue-green algae communities of each lake remained distinct to one another over the study period with communities changing in a cyclic manner most likely due to seasonal influences. A total of 20 blue-green algae taxa were identified within Hattah Lakes, with four potentially toxic species sampled including (in decreasing abundance) Microcystis aeruginosa, Anabaena spiroides f. spiroides, Cylindrospermopsis raciborskii and Anabaena circinalis. The water quality variables of pH and dissolved oxygen were variable and influenced by the photosynthesis within the water column. Day-time dissolved oxygen concentrations were typically supersaturated (>100% saturation) and pH was elevated (peak of 10.29) when phytoplankton and submerged macrophyte biomass was high. Wetland vegetation The lakebed vegetation communities of Lakes Brockie (treatment that received pumped water) and Lake Boich (control that did not receive pumped water) were monitored over a ≈ 21 month period to determine the effects of pumping upon lakebed vegetation communities. A total of 91 plant species were recorded at Lakes Brockie and Boich during the sampling period; of these 69 were indigenous (76%) and 22 were exotic (24%). These plant species were from ≈ 21 families, with Chenopodiaceae and Asteraceae containing considerably greater numbers of taxa than the other families. Before intervention, 31 plant species were recorded at Lake Brockie and 13 plant species were recorded at Lake Boich. After intervention, the number of plant species recorded at Lakes Brockie and Boich across all four sampling times was 53 and 58, respectively. Statistically significant differences in vegetation community between the two lakes at the High and Medium elevations were measured. However, no statistically significant difference was observed between the lakes over time. This contrasts with the analysis of only the Before and After 1 survey as reported in EPA and MDFRC (2008) and is due to the influence of the three additional After surveys in the 2007/08 analysis. Whilst statistically significant results were not recorded between lakes as a result of Lake Brockie receiving pumped water, there have been notable changes in the vegetation communities at Lakes Brockie and Boich. This is particularly evident when considering the plant functional groups at the lakes. The lakebed vegetation community at Lake Brockie changed from being predominantly terrestrial before inundation to one dominated by flood-responsive species, returning to a predominantly terrestrial lakebed community ≈ 19 months after pumping. A total of 15 flood-tolerant and one aquatic/semi-aquatic species were recorded at this lake following pumping. In contrast, the vegetation community at Lake Boich consisted of predominantly terrestrial species at four or the five sampling times. A total of two flood-responsive species were sampled at this control lake following pumping. Fish The series of pumping interventions at Hattah Lakes has resulted in the development of a significant fish community within the lakes contrary to initial expectations. However, the mismatch between the fish communities of the lakes (e.g. very low abundances of common carp, bony bream and absence of eastern gambusia) and the Murray River indicates that pumping has acted as a screen upon the fish community. In March 2008, a total of 8,248 fish representing four native (golden perch, carp gudgeon, flathead gudgeon and Australian smelt) and two non-native (goldfish and common carp) species were sampled from the four lakes. In June 2008, a total of 2,994 fish representing three native (carp gudgeon, flathead gudgeon, Australian smelt) and one non-native (goldfish) species were sampled from these same lakes using the standard fyke netting technique. The additional use of two gill nets in June 2008 at Lakes Mournpall and Hattah also sampled common carp (n = 17), golden perch (n = 9) and silver perch (n = 1). Native fish comprised 98.8% and 99.9% of the sampled fish in March 2008 and June 2008, respectively. Three small-bodied native fish consisting of carp gudgeon, Australian smelt and flathead gudgeon together comprised over 98% of the total catch for each time. The results of this study were compared with those from five earlier surveys following the commencement of pumping at Hattah Lakes. Whilst relative fish abundance has consistently increased between the first five surveys, the two surveys of 2008 demonstrate a decrease in both abundance and diversity of fish within the Hattah Lakes. This decrease is attributed to the reduction in aquatic habitat as the lakes become shallow and increased vulnerability of the fish community to predation by birds. Fish currently remaining in the lakes will perish by February 2009 if the lakes dry completely as expected. This will mark the third consecutive occasion since 1996 that fish communities have developed within Hattah Lakes but have not had an opportunity to move back to the Murray River and contribute to fish populations more broadly. The near-annual reconnection of Hattah Lakes with the Murray River under natural flow scenarios highlights the changed role of Hattah Lakes for fish due to river regulation and extraction. Management recommendations Based on the results of this project, the autho

Murray-Darling Freshwater Research CentreMDFRC item.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.

MDFRC item.1. Floodplain wetlands are productive components of lowland rivers and are thought to be important habitat and nurseries for many fish species. Fish assemblages inhabiting floodplain wetlands vary considerably through space and time and are largely shaped by wetting ⁄drying cycles, although there is little understanding how many aspects of flooding (e.g. magnitude, timing, duration, frequency) influence the fish assemblages. As a consequence, decisions on flooding of wetlands by managers aimed at restoring native fish assemblages are often based on limited knowledge. 2. This study examined the importance of total duration of flooding on the temporal and spatial dynamics of wetland fish assemblages in the Murray River, in south-eastern Australia. The study examined: (i) how the abundance of 0+ and 1+ fish varied with wetland, season and the duration of wetland filling; (ii) how environmental parameters, including food production changed in relation to the duration of wetland filling; (iii) changes in condition indices for the most abundant species and (iv) changes in species richness and total abundance over time. 3. The 0+ fish assemblage varied more through space and time than the 1+ assemblage. Longer cumulative river–wetland filling was associated with greater total abundances of newly recruited (0+) fish; this was particularly true for common carp (Cyprinus carpio, alien) and carp gudgeon (Hypseleotris spp., native). The body condition of carp gudgeon also increased with the duration of filling, even though static measures of food production declined. The small flooding events that occurred as part of this study did not translate into measurable improvements in the fish assemblage over the longer term (3 years), but did prevent wetlands from drying and thus maintained these habitats as refuges.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.We studied movement and abundance of barbel, Barbus barbus, over three years (October 1995 to September 1998) in two stretches (Woolmer's Park, Holwell Bridge) of a section of the River Lee (Hertfordshire, England) delimitated by water retention structures. Of 349 tagged individuals (168 at Woolmer's Park: 181 at Holwell Bridge), 51.8 % and 13.3 % respectively were recaptured at least once, with a much higher rate of multiple recaptures at Woolmer's Park, where monitoring of movements was over a longer period, than at Holwell Bridge, where too few recaptures were made for further movement analysis. At Woolmer's Park, 77.1 % of the barbel showed limited (i.e. resident component) and the rest greater betweencapture movements (i.e. mobile component). There was no preferential directional movement across size classes. Based on the available recapture data, population size (estimated through a Bayesian method) first increased moderately (1995-96) and then sharply (1996-97) at Woolmer's Park, and even further later at Holwell Bridge (1998-99). This may reflect a recovery phase in the local population, or possibly a rising part of a cyclic recruitment pattern, such as reported for barbel elsewhere and for other cyprinids in the UK. Habitat enhancement is recommended over stocking, given the adequate abundance of barbel in areas with suitable habitat. However, it remains unclear whether fencing-off of the banks from livestock will enhance 0+ barbel numbers, which appear to be low relative to some European rivers of similar width and depth.

"March 2008".Project Number: Implications of pumping water on the ecology of Hattah Lakes - M/BUS/210.MDFRC item.1 of 2 reports associated with project see (Implications of pumping water on the ecology of Hattah Lakes).The Hattah-Kulkyne Lakes is one of six Living Murray icon sites, located in Hattah-Kulkyne National park in the north west of Victoria. The lakes complex consists of 18 freshwater lakes, 12 of which are Ramsar listed. These lakes periodically fill during high flow events fed by Chalka Creek, an anabranch of the Murray River. The lakes and surrounds contain significant river red gum communities and support a diverse range of waterfowl, native fish and invertebrates during wet phases, making them a significant ecological asset. River regulation and drought have threatened the values of the Hattah Lakes. In particular, the absence of overbank flooding since 2000 led to serious concern regarding the health of river red gum communities. This prompted the delivery of environmental water into the Hattah Lakes from the Murray River as an emergency measure to maintain existing river red gum communities. Approximately 25GL of water was pumped and ponded in Chalka Creek and nine lakes from a series of four pumping events undertaken between April 2005 and December 2006. The Murray Darling Basin Commission (MDBC) engaged the Murray-Darling Freshwater Research Centre (MDFRC) and EPA Victoria to monitor the ecological response of the lakes to pumping and ponding for the 2006/07 period. The project aimed to determine whether pumping is a viable option to meet The Living Murray objectives. The study specifically focused on (i) assessing the response of river red gum condition to the flooding, (ii) identifying water quality threats that may prevent diverse aquatic ecosystems from developing and (iii) monitoring the response of fish, invertebrates and macrophytes by surveying newly filled lakes and those filled for over one year. Key findings from this study are: River red gum trees at inundated lakes (Lakes Mournpall and Brockie) improved their condition (measured as crown density) to a significantly greater degree than at a control lake (Lake Yelwell) that did not receive pumped water. This increase in tree condition is attributed to the pumped watering event. In addition, there was an increase in tree condition at the control lake (to a lesser extent than for the lakes receiving water) and this is attributed to above average rainfall during the study period. Due to a build up of organic matter loads on dry lakebeds, some lakes experienced a brief period of low dissolved oxygen following inundation. Extensive algal blooms also developed over summer, causing large diel fluctuations in dissolved oxygen and pH. These factors were identified as being potential threats to the development of aquatic communities, particularly for macrophyte establishment. An abundant and relatively diverse native fish community has developed within the Hattah Lakes. A total of 16,291 fish representing six native and two exotic fish species were sampled from six lakes and Chalka Creek. Because the lakes were completely dry prior to the first pumping event in April 2005, this community has developed from fish larvae, eggs or juveniles pumped into the lakes. The sampling of only two exotic fish species (goldfish and only one common carp) demonstrates that pumping is a filter upon the fish community, with common carp and eastern gambusia in particular being excluded with this water delivery mode. Macrophyte seed bank trials demonstrated that there is a high potential for diverse native macrophyte communities to develop at most lakes and therefore achieve the objectives listed in the Hattah Lakes Environmental Management Plan. Macrophytes were able to establish on the lakebeds under the managed flooding regime, although with varying levels of success between lakes. A total of 115 macrophyte taxa belonging to 34 families were identified. Distinct macrophyte communities occurred at each studied lake. The highest abundance and diversity of macrophytes occurred at elevations +30 and +60cm above the waterline. These elevations occurred in areas that were initially inundated following managed flooding but were exposed as lake water levels lowered. Aquatic macrophyte establishment at or below the waterline was initially quite poor at most lakes, however, macrophyte cover increased over the sampling period. It is difficult to ascertain whether the patterns in macrophyte development are a function of water quality (e.g. low dissolved oxygen, high turbidity) or the time since inundation. Despite some water quality concerns (e.g. blue-green algal blooms), pumping and ponding allowed diverse and abundant macroinvertebrate and zooplankton communities to develop and be sustained in the longer term, which will aid in achieving The Living Murray objectives. Sediment assessments at eight lakes and Chalka Creek showed a low risk of sulfidic sediments posing a management problem within the Hattah Lakes system. Overall, the managed flooding event achieved by the pumping and ponding of water has been a successful management intervention for improving river red gum health and allowing diverse aquatic ecosystems to develop at the Hattah Lakes icon site. In the current drought period, this has created a productive wetland system that is providing important ecosystem services as a drought refuge. The lake ecosystems are dynamic and both water quality and the condition and composition of biological communities will continue to change as the lakes dry. Intervention monitoring will occur in 2007/08 for continued investigation of river red gums, lakebed macrophytes, fish and some water quality variables. This additional intervention monitoring will complement the existing data by allowing the communities within the Hattah Lakes system to be monitored over a longer term. In the likely absence of seasonal flooding or further pumping of environmental water at the Hattah Lakes in 2007/08, this monitoring will occur as the lakes undergo their drying phase Macroinvertebrate have life histories linked to the natural flow regime and the loss of this will interfere with their lifecycle and habitat requirements.

"April 2007".Project Number: Develop and submitted a standardised wetland assessment protocol for assessing the suitability of permanent wetlands for disconnection and development of an ongoing monitoring programme for disconnected wetlands - M/BUS/232 XA225.MDFRC item.As agreed by First Ministers, a number of measures including the disconnection of wetlands have been progressively implemented over recent months. Additional wetlands in South Australia and NSW have been identified as having the potential to return relatively high yields in evaporative savings (Murray-Darling Basin, Dry Inflow Contingency Planning Overview Report to First Ministers April 2007). The restoration of the natural wetting and drying regimes is typically expected to improve habitat availability for indigenous flora and fauna. However, within the current management context there are a number of site specific conditions that may expose wetlands to long-term or irreversible damage. These conditions include acidification potential, shallow groundwater, and the role of the wetland as critical drought refugia for threatened or rare species persistence. Both these factors will be considered in the proposed assessment. It is recommended that these wetlands undergo ecological assessment to ensure that long-term or permanent ecological damage will not be sustained, before commencement of construction of works to disconnect them. Sites that are identified as supporting threatened species are likely to require assessments under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act). The States have agreed in MDBC Out-of-Session Resolution 138 that the Environmental Watering Group (EWG) will consider and provide advice to the MDBC on a standardised rapid flora and fauna assessment protocol and an ongoing wetland monitoring programme identifying environmental trigger points to guide the management of the closure and reopening of wetlands. The monitoring program will enable a clear evaluation of both short term and long term impacts of drying on the ecology of the wetland.

First published online 2012.MDFRC item.The Fish Invasiveness Scoring Kit (FISK) is currently one of the most popular pre-screening tools for freshwater fishes. A recent upgrade has ensured its wider climatic relevance to countries with subtropical regions. This enhancement is of particular importance to Australia, which encompasses tropical, arid, and temperate zones, and where the introduction of nonnative fish species poses a significant risk to biodiversity. In this study, 55 fish species previously evaluated in a U.K.-based calibration of FISK are reassessed for their potential invasiveness in the Murray-Darling Basin (MDB; southeastern Australia), the continent's largest catchment encompassing arid and temperate climates. Approximately half of the species were classed as "medium risk" and the other half as "high risk," and the ≥19 threshold previously identified from the calibration study was confirmed. The three highest scoring species (common carp Cyprinus carpio carpio, goldfish Carassius auratus, and eastern mosquitofish Gambusia holbrooki) were those already present and invasive in the area, whereas nearly half of the tropical and subtropical species had lower scores compared to U.K. assessments, possibly because of climate change predictions of drier conditions across the MDB. There were some discordances between FISK and two Australian-based assessment protocols, one of which is qualitative and the other represents a simplified version of FISK. Notably, the Australian origins of FISK should provide for an additional reason for further applications of the tool in other RA areas (i.e., drainage basins) of the continent, ultimately encouraging adoption as the country's reference screening tool for management and conservation purposes.