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Context. The Murray--Darling Basin -- Australia's largest river system -- is heavily dominated by alien fish. Native fish species have suffered numerous localised extinctions and ~47% are listed on federal and/or state threatened species lists. Aims. This paper explores the hypothesis that alien fish and alien fish stockings can be the primary cause of decline and localised extinction of large-bodied native fish species, as opposed to habitat degradation and river regulation. The Lower Goodradigbee River, which is unregulated, in excellent instream health over the great majority of its course, and replete with high quality habitat, is utilised as a case study. Methods. I investigated the hypothesis by synthesising historical records with contemporary scientific research and recent field observations. The role of alien fish species, particularly alien trout species (Oncorhynchus mykiss and Salmo trutta) and constant stockings of them, were closely examined. Results. Data support the hypothesis that domination by alien trout species and their continual stocking have lead to historical declines and localised extinctions of large-bodied native fish species. Continued alien trout stockings, along with more recent invasions of alien carp (Cyprinus carpio) and alien redfin perch (Perca fluviatilis), are inhibiting native fish recovery. A suspected field sighting of the alien fish pathogen atypical Aeromonas salmonicida is reported, and the status of the declining native crayfish Murray cray (Euastacus armatus), and potential alien fish impacts upon them, are examined. Conclusions. The impacts of alien fish and alien fish stocking in Australia require major re-evaluation and dedicated research. Implications. It is strongly recommended that stocking of alien trout into the Lower Goodradigbee River for angling cease in order to conserve surviving native fish and Murray cray populations. Conservation stockings to effect a Murray cod (Maccullochella peelii) recovery in the Lower Goodradigbee River are warranted. [ABSTRACT FROM AUTHOR]

Solanum elaeagnifolium Cav (silverleaf nightshade) is a deep‐rooted, multi‐stemmed, perennial, herbaceous woody plant that has been observed to threaten agricultural and native biodiversity worldwide. It is widely agreed that without efficient integrated management, S. elaeagnifolium will continue to cause significant economic and environmental damage across multiple scales. It is estimated that the annual economic impact of S. elaeagnifolium in Australia exceeds AUD $62 million, with this figure likely to be much higher in other countries invaded by this plant. It can also tolerate a high level of abiotic stress and survive in a range of temperatures (below freezing point to 34°C) and areas with an average yearly rainfall between 250 and 600 mm. Its extensive deep taproot system is capable of regenerating asexually and with its many seed dispersal mechanisms; it can quickly spread and establish itself within a region. This makes containment and management of the species especially challenging. Previous management has largely been focused on biological control, competition, essential oils, grazing pressure, herbicide application and manual removal. Despite the large range of available management techniques, there has been little success in the long‐term control of S. elaeagnifolium, and only a handful of methods such as essential oils and herbicide application have shown reasonable success for controlling this weed. Therefore, this review aims to synthesise the identified and potentially useful approaches to control S. elaeagnifolium that have been recorded in the literature which deal with its biology, distribution and management. It also explores previous and current management techniques to ascertain the research gaps and knowledge required to assist in the effective and economically sustainable management of this invasive weed. [ABSTRACT FROM AUTHOR]

Summary: Invasive species such as vertebrate herbivores cause threats to native ecosystems through causing changes to vegetation composition and structure, competition, ecosystem engineering, impacts on soil, and through spreading disease. In the mountainous country of Australia, Sambar Deer (Rusa unicolor) are becoming an increasing threat to fragile and endangered ecosystems, which are also facing other significant threats such as climate change. Methods for ameliorating these impacts are currently limited to lethal control programmes through shooting or fencing key areas. Fencing is not a viable option for large areas and can have large logistical costs as well as negative ecological outcomes. This study aimed to compare two shooting methods (ground shooting vs thermally assisted aerial culling with thermal image operator) for controlling sambar at low densities in a mountainous area. This programme was the first to use this specific thermal technique for deer in mountainous country in Australia. We found that thermally assisted aerial culling was more effective for removing Sambar than ground shooting. Thermally assisted aerial culling removed more Sambar in total, shot more animals per hour, covered a larger search area, was cheaper per hectare covered, and had very high "seen", "targeted", and "shot" ratios. Ground shooting sessions were lower in cost overall, but the cost per hectare was higher and rate of Sambar shot was lower than that of thermally assisted aerial culling. Ground shooting did remove more Sambar per hectare as ground shooting focuses on a smaller area, but this advantage is outweighed by the fact that thermally assisted shooting also allowed the concurrent removal of Feral Pigs. This work indicates that thermally assisted aerial culling is the preferred method for effective management of Sambar in an alpine environment. Ground shooting may be beneficial when Sambar are concentrated in key areas or to complement initial knock down by thermally assisted aerial culling. [ABSTRACT FROM AUTHOR]

Live animal smuggling presents a suite of conservation and biosecurity concerns, including the introduction of invasive species and diseases. Yet, understanding why certain species are smuggled over others, and predicting which species will be smuggled, remains relatively unexplored. Here, we compared the live reptile species illegally smuggled to Australia (75 species) to the legal trade of live reptile species in the United States. Almost all smuggled species were found in the legal US pet market (74 species), and we observed an average time lag of 5.6 years between a species first appearing in the United States and its subsequent detection in Australia. Using a Bayesian regression model, species popularity in the United States, and internationally, were positively associated with smuggling probability to Australia. Our findings give insight to the drivers of illegal wildlife trade and our predictive modelling approach provides a framework for anticipating future trends in wildlife smuggling. [ABSTRACT FROM AUTHOR]

Globalisation has increased the occurrence of species being introduced outside of their natural range. The African carder bee, Pseudoanthidium (Immanthidium) repetitum (Hymenoptera: Megachilidae), is one such species. P. repetititum was first recorded in Australia in 2000 in Queensland (north-east Australia), and rapidly spread down the east coast of Australia, and by 2015 was reported to be a common component of bee assemblages in urban community gardens in Victoria (southern Australia). Here, I report the first occurrences of this species in Western Australia, on the other side of the continent, representing a major expansion of the distribution of the species. Thus far there are three confirmed and one unconfirmed localities where this species has been seen, all localised to the Mandurah region in residential areas of Western Australia. Female specimens were collected from a garden in Halls Head, where it was observed to be abundant. Other bees, both native and the introduced European honeybee, were foraging alongside it. The occurrence of P. repetitum represents a major expansion in its distribution. It remains rare and localised; however, given known negative impacts of introduced species on native fauna and flora, especially in Australia, vigilance is required to monitor this species. The African carder bee, Pseudoanthidium (Immanthidium) repetitum (Hymenoptera: Megachilidae), is an introduced species in Australia. It was first reported in 2000 and rapidly spread across the east coast. This paper reports the first observations of P. repetitum on the other side of the continent in Western Australia, representing a major range expansion. Potential impacts on native fauna and flora of this species are discussed. [ABSTRACT FROM AUTHOR]

Globally, freshwater fishes are declining at an alarming rate. Despite much evidence of catastrophic declines, few Australian species are listed as threatened under national legislation. We aim to help redress this by identifying the Australian freshwater fishes that are in the most immediate risk of extinction. For 22 freshwater fishes (identified as highly threatened by experts), we used structured expert elicitation to estimate the probability of extinction in the next ~20 years, and to identify key threats and priority management needs. All but one of the 22 species are small (<150 mm total length), 12 have been formally described only in the last decade, with seven awaiting description. Over 90% of these species were assessed to have a >50% probability of extinction in the next ~20 years. Collectively, the biggest factor contributing to the likelihood of extinction of the freshwater fishes considered is that they occur in small (distributions ≤44 km2), geographically isolated populations, and are threatened by a mix of processes (particularly alien fishes and climate change). Nineteen of these species are unlisted on national legislation, so legislative drivers for recovery actions are largely absent. Research has provided strong direction on how to manage ~35% of known threats to the species considered, and, of these, ~36% of threats have some management underway (although virtually none are at the stage where intervention is no longer required). Increased resourcing, management intervention and social attitudinal change is urgently needed to avert the impending extinction of Australia's most imperilled freshwater fishes. Australian freshwater fishes have typically been neglected in conservation planning, despite evidence of catastrophic declines. Here we use structured expert elicitation to identify the Australian freshwater fishes in imminent risk of extinction. All 22 species considered had moderate to high (>40%) likelihoods of extinction in the next two decades. Using conservation progress metrics, we identify priority management needs for averting future extinctions. [ABSTRACT FROM AUTHOR]

Alien species have invaded worldwide and altered native biodiversity and ecosystem functions. In Lake Biwa, Japan, Micrasterias hardyi—considered an endemic species in Australia—has become one of the major dominant species since 2016. To evaluate long-term and seasonal variations in M. hardyi, we analyzed 20 years of plankton samples from the northern basin of Lake Biwa. The presence of this species was first confirmed in February 2015, and increased for long periods from November 2015 (4.2 cells cm−2) to December 2016 (2.3 × 105 cells cm−2) and from September 2017 (2.0 × 102 cells cm−2) to January 2019 (5.7 × 104 cells cm−2). Particles similar to chytrid zoosporangia were observed and attached to M. hardyi cells. However, the infection rate was low (up to 22.5%), and the infection did not seem to be a major lethal factor. We estimated that M. hardyi was introduced in the early 2000s by simple linear regression of abundance. This result indicates the existence of long time lag from introduction to detection. Moreover, as the propagule pressure to nearby water systems has been high, it is highly probable that M. hardyi has spread to other lakes and ponds via Lake Biwa. [ABSTRACT FROM AUTHOR]

Over a period of 34 years (1954-1987), a total of 11.9 million glass eels were stocked all over Austria to improve the yields of commercial fishermen and to make the lakes more attractive for anglers. Nearly half (48%) of the imported glass eels were introduced into natural, previously eel-free Alpine lakes until stocking ceased in 1988. Twenty-five years later, their occurrence could be verified in 56% ( N = 22) of the Austrian Alpine lakes larger than 50 ha and mean body length had increased to 66 cm. Eels from seven selected Austrian Alpine lakes exhibited a yearly mean increase in length between 0.6 and 1.5 cm, indicating a comparatively poor growth compared with the majority of eel populations from within their natural distribution range. At the same time, high expectations in developing a flourishing eel fishery were not met. In all but one lake, the harvest remained below 3% of the total yearly catch and salmonids remained the dominant target species. During peak harvest in the 1980s, it exceeded 8% in mesotrophic Wallersee (2600 kg). Simulations of stock development indicated that the yield could have been improved, but contrary to earlier expectations eels never became important for local cuisine and catches remained too low for the development of a profitable export business. On the other hand, eels may have contributed to the loss of small-bodied fish taxa. [ABSTRACT FROM AUTHOR]

Most nominal fan worm species belonging to the genus Parasabella Bush, 1905, and Sabellomma Nogueira, Fitzhugh & Silva-Rossi, 2010 (Sabellidae, Annelida) lack unique morphological diagnostic features. Species diagnoses rely on a combination of attributes, often making reference to characters that are qualitatively or quantitatively continuous. This, together with a lack of knowledge about phenotypic intraspecific variation in most species, suggests that the sole use of morphological features is insufficient to identify and characterize some of these species. Examination of collections revealed that Parasabella is a common and diverse group of sabellids along the Australian coastline, although it had only been recorded here twice. The genus Sabellomma is here reported in Australia for the first time. Comparison of morphological data and nuclear (internal transcribed spacer) and mitochondrial (cytochrome oxidase I) DNA sequence data of 30 terminals in a range of analyses allowed us to assess the monophyly of Parasabella and its sister-group relationship with Sabellomma and to examine some of the species boundaries and genetic diversity within lineages. The combined sequence data results indicate the presence of seven distinct genetic Parasabella lineages in Australia, four of which are assigned to previously described species (three are new records for Australia), and two are considered as a complex of species sharing a unique combination of characters, one of which is described as new. Another Parasabella species with distinct atypical radiolar eyes and a species of Sabellomma are also described as new. [ABSTRACT FROM AUTHOR]

Distributional records of non-native fish species were identified in the Wet Tropics region, Far North Queensland, Australia, through a compilation of published records and expert knowledge. A total of 1106 records were identified comprising 346 presence and four uncertain records for at least 13 species, and 756 absence records. All current presence records consist of six species from the families Cichlidae and Poeciliidae with established self-sustaining populations in the region, probably affecting the highly diverse native fish fauna. [ABSTRACT FROM AUTHOR]

The cane toad ( Rhinella marina) is one of the most successful invasive species worldwide, and has caused significant negative impacts on Australian fauna. Experimental work in the laboratory and in mesocosms has shown that tadpoles of native frogs can affect survival, size at metamorphosis and duration of larval period of cane toad tadpoles. To test if these effects occur in nature, we conducted a field experiment using two temporary ponds where we set up enclosures with tadpoles of native green tree frogs ( Litoria caerulea) and cane toads in treatments with a range of densities and combinations. The presence of green tree frog tadpoles significantly decreased the growth rate of toad tadpoles and increased the duration of their larval period in both ponds; in one pond, frog tadpoles also significantly reduced the body length and mass of metamorph toads. Toad tadpoles did not have any significant negative effects on green tree frog tadpoles, but there was strong intraspecific competition within the latter species: increased frog tadpole density resulted in increased larval period and reduced survival, growth rate and size at metamorphosis for frogs at one or both ponds. Our results are encouraging for the possibility of using native frogs as one component of an integrated approach to the biological control of cane toads. [ABSTRACT FROM AUTHOR]

Disentangling the effects of prey limitation (bottom-up) and predation (top-down) processes on natural populations is difficult, but the perturbations introduced by an invasive species can provide pseudo-experimental evidence on this issue., In tropical Australia, keelbacks ( Tropidonophis mairii) and slatey-grey snakes ( Stegonotus cucullatus) experience little direct cost or benefit from the arrival of toxic invasive cane toads ( Rhinella marina), because they rarely eat toads and if they do, are relatively resistant to the toads' toxins. Nonetheless, these snakes could be affected indirectly by toad-induced decreases in the availability of prey (native frogs) and/or by fatal poisoning of the snakes' predators (large varanid lizards). The former (bottom-up) effect predicts decreases in snake body condition, feeding and growth rates after toads arrive, whereas the latter (top-down) effect predicts increases in survival., Our mark-recapture studies on these snakes in tropical Australia (for 7 years before and 7 years after toad arrival) reveal bottom-up effects both on an anurophagous dietary specialist (keelbacks) and a generalist feeder (slatey-grey snakes)., Top-down effects of toad arrival were seen in keelbacks but not in slatey-grey snakes, perhaps reflecting the latter's larger body size., Indirect effects coinciding with the timing of toad invasion thus were mediated through changes in food supply for both native species and in rates of predation for one species. [ABSTRACT FROM AUTHOR]

Sagittal otoliths were used to age the samples of Tilapia mariae collected from a coastal river and an impoundment. Validation of sagittae checks was achieved using both quantitative marginal increment analysis and by tetracycline marking of the otoliths of fish kept in tanks and in a farm dam. The annulus pattern on the otoliths was generally clear and their formation appeared to be temperature related and largely completed in the Austral spring around September and October. Male T. mariae grow faster and larger than females and the maximum ages of fish from the coastal river and impoundment was 9+ and 4+ years, respectively. Past fish surveys and the absence of older age classes in the impoundment population would suggest that this population was only very recently established. [ABSTRACT FROM AUTHOR]

Attempts to manipulate species abundances can have unforeseen consequences. Our studies suggest that community-group efforts to cull cane toads ( Rhinella marina) invading Australia may interfere with the toad's local enemies. Abundance of the toad parasite Rhabdias pseudosphaerocephala and the ant Iridomyrmex reburrus (a toad predator) may decrease when community groups spray antiseptic (Dettol) at pond edges to kill toads. Our trials show that Dettol kills parasitic larvae and repels predatory ants; thus, community-group control efforts may reduce natural toad regulation. Conversely, volunteer 'toad-busters' traversing isolated localities to collect toads may spread parasitic larvae via muddy footwear. Our trials show that larvae can remain alive in muddy boot-treads for at least a week, and our field data reveal changed parasite dynamics in areas where community groups are most active. Thus, the impacts of culling activities on this invasive species may be exacerbated or undermined by inadvertent interference with host-parasite and predator-prey interactions. [ABSTRACT FROM AUTHOR]

Oreochromis mossambicus (Peters 1852) are native to the eastward flowing rivers of central and southern Africa but from the early 1930s they have been widely distributed around the world for aquaculture and for biological control of weeds and insects. While O. mossambicus are now not commonly used as an aquaculture species, the biological traits that made them a popular culture species including tolerance to wide ranging ecological conditions, generalist dietary requirements and rapid reproduction with maternal care have also made them a 'model' invader. Self-sustaining populations now exist in almost every region to which they have been imported. In Australia, since their introduction in the 1970s, O. mossambicus have become established in catchments along the east and west coasts and have the potential to colonise other adjacent drainages. It is thought that intentional translocations are likely to be the most significant factor in their spread in Australia. The ecological and physical tolerances and preferences, reproductive behaviour, hybridization and the high degree of plasticity in the life history traits of O. mossambicus are reviewed. Impacts of O. mossambicus on natural ecosystems including competitive displacement of native species, habitat alteration, predation and as a vector in the spread of diseases are discussed. Potential methods for eradicating or controlling invasive populations of O. mossambicus including physical removal, piscicides, screens, environmental management and genetic technologies are outlined. [ABSTRACT FROM AUTHOR]

Cane Toads (Rhinella marina; hereafter 'toads') are large, toxic American anurans that were introduced to Australia in 1935. Research on their ecological impact has focussed on the lethal ingestion of toxic toads by native frog-eating predators. Less attention has been paid to the potential impacts of Cane Toads as predators, although these large anurans sometimes eat vertebrates, such as nestling birds and bird eggs. We review published and unpublished data on interactions between Cane Toads and Australian ground-nesting birds, and collate distributional and breeding information to identify the avian taxa potentially at risk of having eggs or chicks eaten by Cane Toads. Cane Toads are currently sympatric with 80 ground-nesting bird species in Australia, and five additional species of bird occur within the predicted future range of the toad. Although many species of bird are potentially at risk, available data suggest there is minimal impact of Cane Toads on ground-nesting species. Future research could usefully address both direct and indirect impacts of the invasion by Cane Toads, ideally with detailed field observations of these impacts on nesting success and of changes in bird breeding success as a function of invasion by toads. [ABSTRACT FROM AUTHOR]

Predicting which species will be affected by an invasive taxon is critical to developing conservation priorities, but this is a difficult task. A previous study on the impact of invasive cane toads (Bufo marinus) on Australian snakes attempted to predict vulnerability a priori based on the assumptions that any snake species that eats frogs, and is vulnerable to toad toxins, may be at risk from the toad invasion. We used time-series analyses to evaluate the accuracy of that prediction, based on >3600 standardized nocturnal surveys over a 138- month period on 12 species of snakes and lizards on a floodplain in the Australian wet-dry tropics, bracketing the arrival of cane toads at this site. Contrary to prediction, encounter rates with most species were unaffected by toad arrival, and some taxa predicted to be vulnerable to toads increased rather than declined (e.g., death adder Acanthophis praelongus; Children's python Antaresia childreni). Indirect positive effects of toad invasion (perhaps mediated by toad-induced mortality of predatory varanid lizards) and stochastic weather events outweighed effects of toad invasion for most snake species. Our study casts doubt on the ability of a priori desktop studies, or short-term field surveys, to predict or document the ecological impact of invasive species. [ABSTRACT FROM AUTHOR]

Although invasive species are viewed as major threats to ecosystems worldwide, few such species have been studied in enough detail to identify the pathways, magnitudes, and timescales of their impact on native fauna. One of the most intensively studied invasive taxa in this respect is the cane toad (Bufo marinus), which was introduced to Australia in 1935. A review of these studies suggests that a single pathway--lethal toxic ingestion of toads by frog-eating predators--is the major mechanism of impact, but that the magnitude of impact varies dramatically among predator taxa, as well as through space and time. Populations of large predators (e.g., varanid and scincid lizards, elapid snakes, freshwater crocodiles, and dasyurid marsupials) may be imperilled by toad invasion, but impacts vary spatially even within the same predator species. Some of the taxa severely impacted by toad invasion recover within a few decades, via aversion learning and longer-term adaptive changes. No native species have gone extinct as a result of toad invasion, and many native taxa widely, imagined to be at risk are not affected, largely as a result of their physiological ability to tolerate toad toxins (e.g., as found in many birds and rodents), as well as the reluctance of many native anuran-eating predators to consume toads, either innately or as a learned response. Indirect effects of cane toads as mediated through trophic webs are likely as important as direct effects, but they are more difficult to study. Overall, some Australian native species (mostly large predators) have declined due to cane toads; others, especially species formerly consumed by those predators, have benefited. For yet others, effects have been minor or have been mediated indirectly rather than through direct interactions with the invasive toads. Factors that increase a predator's vulnerability to toad invasion include habitat overlap with toads, anurophagy, large body size, inability to develop rapid behavioral aversion to toads as prey items, and physiological vulnerability to bufotoxins as a result of a lack of coevolutionaty history of exposure to other bufonid taxa. [ABSTRACT FROM AUTHOR]

Abstract: Members of the general public interact with wildlife in many ways, and an inability to distinguish between species can have significant implications for conservation. For example, attempts by environmentally-concerned private citizens to control invasive species may cause collateral damage unless people can reliably distinguish native fauna from the invader. We tested the Australian public’s ability to distinguish invasive cane toads (Bufo marinus) from native frogs at egg, tadpole, subadult and adult life-history stages. Errors were common, especially for eggs and tadpoles (27–31% error rates) and less so for subadult and adult toads and frogs (5–43% error rates). Accuracy of identification was higher in people living in areas where toads occur (compared to other parts of Australia or overseas), and similar in men and women (but with a decrease in older men). Ability to identify anurans was increased by toad-identification awareness programs and membership of “toad-busting” community groups, but direct killing of cane toads by the general public may inflict substantial “friendly fire” on native frogs. In the absence of any clear evidence for ecological benefits from toad-killing, we suggest that such collecting activities should be conducted only in areas where toads are known to occur, and under the supervision of trained personnel (to identify any anuran before it is killed), rather than as an ad hoc activity pursued independently by local residents. More generally, conservation activities that involve public participation should carefully evaluate the potential rates and consequences of species misidentification by well-intentioned but untrained people. [Copyright &y& Elsevier]

1. The invasion of carp ( Cyprinus carpio L.) in Australia illustrates how quickly an introduced fish species can spread and dominate fish communities. This species has become the most abundant large freshwater fish in south-east Australia, now distributed over more than 1 million km2. 2. Carp exhibit most of the traits predicted for a successful invasive fish species. In addition, degradation of aquatic environments in south-east Australia has given them a relative advantage over native species. 3. Derivation of relative measures of 13 species-specific attributes allowed a quantitative comparison between carp and abundant native fish species across five major Australian drainage divisions. In four of six geographical regions analysed, carp differed clearly from native species in their behaviour, resource use and population dynamics. 4. Climate matching was used to predict future range expansion of carp in Australia. All Australian surface waters appear to be climatically suitable for carp. 5. This assessment strongly reinforces the need for immediate management of carp in Australia to include targeted control of human-assisted dispersal, such as use of carp as bait by anglers, distribution to new locations by anglers and the use of the ‘Koi’ strain in the aquarium industry. 6. Given their historical spread, dispersal mechanisms and ecological requirements, the expansion of carp across most of the remainder of Australia is to be expected. [ABSTRACT FROM AUTHOR]