Academic literature on the topic 'Australian smelt'

Freshwater fishes often exhibit high genetic population structure due to the prevalence of dispersal barriers (e.g., waterfalls) whereas population structure in diadromous fishes tends to be weaker and driven by natal homing behaviour and/or isolation by distance. The Australian smelt (Retropinnidae:Retropinna semoni) is a native fish with a broad distribution spanning inland and coastal drainages of south-eastern Australia. Previous studies have demonstrated variability in population genetic structure and movement behaviour (potamodromy, facultative diadromy, estuarine residence) across the southern part of its geographic range. Some of this variability may be explained by the existence of multiple cryptic species. Here, we examined genetic structure of populations towards the northern extent of the species’ distribution, using ten microsatellite loci and sequences of the mitochondrial cytbgene. We tested the hypothesis that genetic connectivity among rivers should be low due to a lack of dispersal via the marine environment, but high within rivers due to dispersal. We investigated populations corresponding with two putative cryptic species, SEQ-North (SEQ-N), and SEQ-South (SEQ-S) lineages occurring in south east Queensland drainages. These two groups formed monophyletic clades in the mtDNA gene tree and among river phylogeographic structure was also evident within each clade. In agreement with our hypothesis, highly significant overallFSTvalues suggested that both groups exhibit very low dispersal among rivers (SEQ-SFST= 0.13; SEQ-NFST= 0.27). Microsatellite data indicated that connectivity among sites within rivers was also limited, suggesting dispersal may not homogenise populations at the within-river scale. Northern groups in the Australian smelt cryptic species complex exhibit comparatively higher among-river population structure and smaller geographic ranges than southern groups. These properties make northern Australian smelt populations potentially susceptible to future conservation threats, and we define eight genetically distinct management units along south east Queensland to guide future conservation management. The present findings at least can assist managers to plan for effective conservation and management of different fish species along coastal drainages of south east Queensland, Australia.

Patterns of dispersal in riverine populations of Australian smelt ( Retropinna semoni ) were examined using otolith chemistry (Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) and genetic markers (allozymes, mtDNA, microsatellite DNA). During a period of prolonged low flows, young-of-year smelt were collected from 13 streams within three catchments of the southern Murray–Darling Basin, Australia. Spatial differences in otolith core and edge chemical signatures and high levels of genetic assignment to sampling locations were observed, suggesting that most recruits were retained in natal areas after spawning. Following a subsequent period of hydrological connection, the same cohort was sampled as 1-year-olds. Maximum likelihood estimation using otolith core chemistry data from these fish suggested that retention in natal areas was highly variable between years and a similar, though less pronounced, pattern was evident in genetic assignments. Partitioning of genetic variation among catchments was not significant (FCT < 0.004) and probably reflects disequilibrium between migration and genetic drift due to an historical population expansion (~270 000 years ago). Taken together, otolith chemistry and genetic analyses suggest that contemporary dispersal of smelt within these catchments is relatively restricted and may be mediated by changes in hydrological connectivity.

The smelt genus Retropinna nominally includes three small (<150 mm) freshwater fish species endemic to south-eastern Australia and New Zealand. For the two Australian species, the broad range of R. semoni (Weber) on the mainland suggests some vulnerability to isolation and genetic divergence, whereas the apparent confinement of R. tasmanica McCulloch to Tasmania is curious if, as suspected, it is anadromous. Analyses of Australian material using allozyme electrophoresis show five genetically distinct species with contiguous ranges and no evidence of genetic exchange. Three occur along the eastern seaboard (including three instances of sympatry), another in coastal and inland south-eastern Australia and Tasmania, and a fifth species in the Lake Eyre Basin. There is no indication of a simple ‘tasmanica’ v. ‘semoni’ dichotomy, but instead a complex pattern involving discrete clusters for the Upper Murray plus Darling rivers, Lower Murray, Glenelg River and Tasmanian regions, with coastal western Victorian samples having varying affinity to these groups. The overall pattern is one of deep divergences among species and strong genetic sub-structuring within and provides a strong argument for extended studies to prepare for appropriate conservation measures.

AbstractThere is a paucity of information on the diversity and occurrence of freshwater fish parasites in Australia. This study investigates the distribution and occurrence of a parasitic nematode of the genusContracaecumin freshwater fish from south-eastern Australia. Fish (n= 508) belonging to nine species and eight families were collected from eight wetlands associated with the Murrumbidgee River floodplain in the southern Murray–Darling Basin and subjected to laboratory examination. Third-stage nematode larvae were found in eight of the nine fish species. The exception was the fly-specked hardeyhead (Craterocephalus stercusmuscarum), although only one specimen of this species was examined. Nematode larvae were identified asContracaecum bancroftiusing a combined morphological and molecular approach. The parasite was most prevalent in weather loach (Misgurnus anguillicaudatus; 34.8%) and Australian smelt (Retropinna semoni; 21.4%), followed by carp (Cyprinus carpio; 9.5%), of which the former and latter are non-native species.Contracaecumprevalence differed between locations, with Two Bridges having the highest number of infected fish. This may be due to the higher number of suitable host species collected at these localities.Contracaecumspp. are parasites with low host specificity that have also been reported in Australian marine fish, humans and piscivorous birds. The high parasite prevalence in the two abundant non-native fish species in the region suggests that they act as a suitable host for this endemic parasite, resulting in the increase in the parasite population. It would be interesting to study host–parasite interactions in this area, especially if introduced fish populations declined dramatically in the attempt to eradicate them or control their population.

The early life of fishes is marked by rapid development when individuals are thought to optimise their success through ontogeny by altering ecological niches and resources. Since most fish larvae are thought to require small prey items at first feeding, competition for potentially limiting food resources may occur between species creating a juvenile bottleneck, which may, in turn, influence future recruitment strength. The diets of the early life stages of most Australian freshwater fish are poorly known. The present study investigated the ontogenetic dietary patterns of six species of fish in an Australian floodplain river. A large proportion of first-feeding larvae of three species (Murray cod, Australian smelt and carp) were able to feed externally while still retaining their yolk sac. All species demonstrated major dietary shifts from newly hatched larvae through development into juvenile stages and adulthood. Only a few minor overlaps in diet were found, with greater overlaps commonly occurring between sequential stages of the same species, reflecting subtle ontogenetic changes. Despite two co-occurrences of an introduced and a native species using the same rearing habitat as larvae, dietary preferences did not significantly overlap, suggesting that a recruitment bottleneck caused by competition for food resources is unlikely for these species.

Fish living in highly variable and unpredictable environments need to possess life-history strategies that enable them to survive environmental extremes such as floods and drought. We used the length–frequency distributions of multiple fish species in multiple seasons and highly variable hydrological conditions to infer antecedent breeding behaviour in rivers of far-western Queensland, Australia. Hypotheses tested were as follows: (1) recruitment of some or all species of fish would occur within waterholes during no-flow periods; (2) there would be seasonal recruitment responses in some fish species; (3) recruitment of some species would be enhanced by channel flows and/or flooding. Hydrology and the incidence of flooding were highly variable across the study area during 2006–2008. Flood-influenced recruitment was evident for Hyrtl's tandan, Barcoo grunter and Welch's grunter. Silver tandan, golden goby, Cooper Creek catfish and Australian smelt showed evidence of seasonal recruitment unrelated to antecedent hydrology. However, most species demonstrated continual recruitment in isolated waterholes, irrespective of antecedent flow conditions and season. Continual and seasonal recruitment capabilities have obvious advantages over flood-pulse recruitment in rivers with highly unpredictable flood regimes and underpin the persistence of many fish species in arid and semiarid rivers.

Six rivers within the upper Mumbidgee catchment were sampled for larval and juvenile fish. The rivers represented both regulated and unregulated flow regimes and varied widely in size. There was wide variation in the larval fish communities supported by each river, both in terms of the species diversity and total abundance of fish sampled. The highly regulated reach of the Mumbidgee River sampled during this study had the highest numbers of native species and native individuals of any river sampled. In the two rivers selected for further study, the Murmmbidgee and Goodradigbee, there was a high level of inter-annual consistency in the species composition within the reaches sampled, despite considerable change in the temperature and flow regimes of both rivers. This indicates that at least some spawning of those species sampled may occur each year, regardless of environmental conditions. Estimates of the relative abundance of each species sampled changed markedly between years, and it is argued, on the basis of growth information contained in the otoliths, that differential survival of larvae and juveniles was largely responsible for this shift in relative abundance. Otolith microstructure provided information on the date of spawning and early growth patterns of all species sampled in the upper Mumumbidgee catchment. In addition to determining the age and thus 'birth-date' of an individual, the effect of a particular event or series of events has on growth, and subsequent survival, is permanently recorded in the otolith microstructure. This enables accurate back-calculation and correlation to management actions or natural events. No other research tool has this ability to retrospectively assess, on a daily basis, the impacts of management actions on condition and subsequent survival of fish larvae. Species sampled could be separated into three groups based on spawning requirements; those linked with flow, those linked with temperature and generalist species that appear to have river independent cues, such as photoperiod or moon phase. Patterns in growth rate during the early life history stages enabled quantification of the consequences of variation in environmental conditions on the survival and recruitment of various species. Growth was not always highly correlated with water temperature, in fact, for mountain galaxias, high temperatures appear to negatively affect larval condition and subsequent survival. Conversely, carp exhibited a strategy more consistent with common perceptions, with growth and survival increasing with increasing temperature. The study uncovered spawning and growth patterns that were unexpected. Age analysis of western carp gudgeon demonstrated that they had undertaken a mid-winter spawning, when the water temperature in the main channel was far lower than that at which spawning was previously recorded for this species. Redfin perch from the unregulated Goodradigbee River exhibited growth rates exceeding the published upper limits for this and other closely related species. This growth could not be correlated with either temperature or flow, indicating that there are additional factors that dominate growth rates of redfin perch in the Goodradigbee River. The proportion and abundance of native species alone is not necessarily indicative of a 'healthy' or pristine system; some native species may be positively affected by river regulation, at least as juveniles. Comparison of the current larval fish community with likely pre-European fish communities does provide an indication of change to the system. The results of this study suggest that larval fish growth rates can be strongly influenced by environmental conditions, thus providing a powerful tool for monitoring future change and the factors which cause it. This study has demonstrated the value of larval and juvenile fish age and growth information, derived from otolith microstructure techniques, for many aspects of river management. Current river management priorities for which these techniques provide unique information include the determination of environmental flow regimes and the control of undesirable exotic species such as carp.

Odour plays an important role in many predator/prey interactions. In the northern hemisphere, many mammalian prey species have been shown to respond to predator odours. It is also widely assumed that mammalian predators utilise odours to locate their prey. This thesis explores the importance of odour in Australian mammalian predator/prey interactions. Responses of native Australian species to the faecal odour of two predators; the native tiger quoll Dasyurus maculatus and the introduced red fox Vulpes vulpes, were evaluated through live-trapping and focussed behavioural studies of captive animals. Tiger quoll responses to prey olfactory cues were investigated in a captive experiment. Native rodents (bush rats Rattus fuscipes, swamp rats R. lutreolus and eastern chestnut mice Pseudomys gracilicaudatus) equally avoided traps scented with either quoll or fox faeces, and in captive experiments, bush rats and swamp rats reduced their average speed in response to both predator odours. Of the marsupial species, northern brown bandicoots Isoodon macrourus and common brushtail possums Trichosurus vulpecula were captured more frequently in quoll-scented traps than unscented traps or foxscented traps, while captures of brown antechinus Antechinus stuarttii, long-nosed bandicoots Perameles nasuta and southern brown bandicoot I. obesulus were unaffected by the either predator odour. In captive experiments, brown antechinus, long-nosed and northern brown bandicoots decreased their foraging in response to both predator odours, and spent less time in areas scented with quoll faeces. Tiger quolls didn't appear to detect odour sources from a distance of >65 cm, but they did follow scent trails and spent more time in areas scented with the urine and faeces of potential prey. Chemical analysis revealed no common components in fox and quoll odour which prey species could be responding to. Therefore, these native species have evolved to respond to fox odour since foxes were introduced to Australia 130 years ago. The stronger response of native rodents to fox odour may be a legacy of their co-evolution with canid predators prior to entering Australia. A better understanding of how odour is utilised in Australian predator/prey interactions may lead to a greater ability to protect Australia's unique mammalian fauna from introduced predators.

Bees are subject to permanent threat from predators such as ants. Their nests with large quantities of brood, pollen and honey represent lucrative targets for attacks whereas foragers have to face rivalry at food sources. This thesis focused on the role of stingless bees as third party interactor on ant-aphid-associations as well as on the predatory potential represented by ants and defense mechanisms against this threat. Regular observations of an aphid infested Podocarpus for approaching stingless bees yielded no results. Another aim of this thesis was the observation of foraging habits of four native and one introduced ant species for assessment of their predatory potential to stingless bees. All species turned out to be dietary balanced generalists with one mostly carnivorous species and four species predominantly collecting nectar roughly according to optimal foraging theory. Two of the species monitored, Rhytidoponera metallica and Iridomyrmex rufoniger were considered potential nest robbers. As the name implies, stingless bees lack the powerful weapon of their distant relatives; hence they specialized on other defense strategies. Resin is an important, multipurpose resource for stingless bees that is used as material for nest construction, antibiotic and for defensive means. For the latter purpose highly viscous resin is either directly used to stick down aggressors or its terpenic compounds are included in the bees cuticular surface. In a feeding choice experiment, three ant species were confronted with the choice between two native bee species - Tetragonula carbonaria and Austroplebeia australis - with different cuticular profiles and resin collection habits. Two of the ant species, especially the introduced Tetramorium bicarinatum did not show any preferences. The carnivorous R. metallica predominantly took the less resinous A. australis as prey. The reluctance towards T. carbonaria disappeared when the resinous compounds on its cuticle had been washed off with hexane. To test whether the repulsive reactions were related to the stickiness of the resinous surface or to chemical substances, hexane extracts of bees’ cuticles, propolis and three natural tree resins were prepared. In the following assay responses of ants towards extract treated surfaces were observed. Except for one of the resin extracts, all tested substances had repellent effects to the ants. Efficacy varied with the type of extract and species. Especially to the introduced T. bicarinatum the cuticular extract had no effect. GCMS-analyses showed that some of the resinous compounds were also found in the cuticular profile of T. carbonaria which featured reasonable analogies to the resin of Corymbia torelliana that is highly attractive for stingless bees. The results showed that repellent effects were only partially related to the sticky quality of resin but were rather caused by chemical substances, presumably sesqui- and diterpenes. Despite its efficacy this defense strategy only provides short time repellent effects sufficient for escape and warning of nest mates to initiate further preventive measures
Bienen sind permanent Gefahren ausgesetzt, ihre Nester voll Brut, Pollen und Honig bieten ein ertragreiches Ziel für Räuber und auch bei der Nahrungssuche droht Konkurrenz an den Futterquellen, beispielsweise durch Ameisen. Ziel dieser Arbeit war es zu untersuchen, welche Rolle stachellose Bienen in Australien als dritter Interaktionspartner an Ameisen-Blattlaus-Assoziationen einnehmen, welcher Bedrohung sie durch räuberische Ameisen ausgesetzt sind und wie sie sich gegen diese verteidigen. Regelmäßige Beobachtungen einer von Blattläusen befallenen Steineibe auf Besuche von stachellosen Bienen blieben erfolglos, es wurden keine Anflüge erfasst. Ein weiterer Fokus dieser Arbeit lag auf der Untersuchung des Nahrungseintrags von vier heimischen, sowie einer eingeschleppten Ameisenart zur Erfassung des räuberischen Potenzials gegenüber stachellosen Bienen. Alle Ameisenarten stellten sich als Generalisten mit ausgewogenem Nahrungseintrag heraus. Eine der Arten ernährte sich hauptsächlich räuberisch, während der Eintrag von Nektar für vier Arten die Hauptressource darstellte und annäherungsweise gemäß der „optimal foraging theory“ erfolgte. Zwei der untersuchten Arten, Rhytidoponera metallica und Iridomyrmex rufoniger, wurden als potenzielle Nesträuber eingestuft. Stachellose Bienen können sich nicht durch Stiche verteidigen, sie nutzen daher andere Strategien. Pflanzenharz stellt für Bienen eine vielseitige Ressource dar, welche als Baumaterial, Desinfiziens und auch zur Verteidigung eingesetzt wird. Das Harz wird entweder in zähflüssiger Form dazu verwendet, um Angreifer zu verkleben oder die darin enthaltenen Terpene gelangen in Bestandteilen auf die Oberfläche der Bienen. In einem Futterwahl-Experiment wurden Tetragonula carbonaria und Austroplebeia australis, zwei heimische Bienenarten mit unterschiedlichen Harzsammel-Gewohnheiten und Oberflächenprofilen, drei Ameisenarten als Beute vorgelegt. Während zwei der Ameisenarten, insbesondere die eingeführte Tetramorium bicarinatum, keinerlei Präferenzen zeigte, entschieden sich die karnivoren R. metallica vorrangig für A. australis, deren Oberflächenprofil weniger Harzkomponenten aufwies. Wurden die Oberflächenbestandteile von T. carbonaria durch Waschen mit Hexan entfernt, verschwand auch die Zurückhaltung der Räuber. Um zu untersuchen ob diese Abwehrreaktion durch die Klebrigkeit der Oberfläche oder durch chemische Substanzen verursacht wurde, wurden Hexan-Extrakte der Bienenoberflächen sowie von drei Baumharzen und Nestmaterial angefertigt. Die nachfolgenden Untersuchungen richteten sich daraufhin auf die Beobachtung der Reaktion von Ameisen bei Kontakt mit Extrakt-behandelten Oberflächen. Bis auf einen der Harzextrakte zeigten alle untersuchten Substanzen unterschiedlich stark abstoßende Effekte auf Ameisen. Die eingeführte T. bicarinatum wurde jedoch nicht durch Bienenextrakt in ihrem Verhalten beeinflusst. Eine GCMS-Analyse ergab, dass einige der Harzsubstanzen auch im Oberflächenprofil von T. carbonaria zu finden waren, welches vor allem Übereinstimmungen mit dem Harz von Corymbia torelliana aufwies, einer Pflanze deren Harz für Bienen besonders attraktiv ist. Es zeigte sich, dass nicht nur die Klebrigkeit, sondern auch chemische Substanzen, vermutlich Sesqui- und Diterpene, für abstoßende Effekte verantwortlich sind. Trotz der Effektivität dieses Mechanismus sorgt er nur für eine kurzzeitige Abwehrreaktion, ermöglicht jedoch die Gelegenheit zur Flucht und Warnung von Nestgenossen, sowie zur Einleitung weiterer Gegenwehr

De nouvelles marques de commerce ont fait progressivement leur apparition, des marques qui font appel à nos cinq sens que sont la vue, l'ouïe, l'odorat, le goût ou même le touché. Ces nouvelles marques, que l'on appelle parfois les marques non traditionnelles, posent quelques difficultés pour être enregistrées. En effet, certains pays refusent leur enregistrement, d'autres sont plus réceptifs à l'arrivée de ces nouvelles marques. Notre mémoire se propose d'analyser la possibilité ou non d'enregistrer certaines de ces marques au Canada, et d'examiner également ce que d'autres pays ont prévu pour ces marques non traditionnelles. Au final, nous serons en mesure d'élaborer des recommandations pour l'intégration de ces nouvelles marques dans le droit canadien.
In recent years, new trademarks have progressively appeared: trademarks appealing to all of our five senses, sight, hearing, smell, taste or even touch. These new trademarks, sometimes called non-traditional marks, raise difficulties for registration. Indeed, some countries refuse registration, others are more open to the arrival of these new trademarks. This thesis analyses the possibility of allowing these non-traditional trademarks to be registered in Canada, and examines the conditions under which other countries accept to register them. In conclusion, our analysis will allow us to formulate recommendations on how to integrate these new trademarks into Canadian law.

<i>Abstract.</i>—We document a simple electrofishing-only monitoring program for assessing fish assemblages across large spatial extents. First, we demonstrate the justification for using only electrofishing for the monitoring. Second, we demonstrate the usefulness of having a well-designed surveillance-monitoring program in place to demonstrate the effect of landscape disturbances. Implementing electrofishing alone means that multiple sites can be sampled in a single day and there is no need to return to clear nets or traps within a sampling site. Whereas electrofishing alone does not return full species lists within sampled sites, we demonstrate that when data are aggregated up to the watershed or catchment extent, more than 90% of species are included. Analyses that do not require a census of species, such as bioassessment of river health can be readily carried out using electrofishing data. The Murray–Darling basin, Australia, was sampled with the recommended large-extent electrofishing program between 2004 and 2012, a period that saw the region subjected to large-scale variations in river flow levels spatially and temporally. We fit generalized additive models to the electrofishing data in conjunction with river flow data to document large-extent relationships between fish species occurrence and relative flow levels for the previous 3 d, 3 months, or 3 years. We found that several small-bodied species, Eastern Mosquitofish <i>Gambusia holbrooki</i>, Flathead Gudgeon <i>Philypnodon grandiceps</i>, and Australian Smelt <i>Retropinna semoni</i>, were more likely to be collected when conditions were drier in the past 3 d to 3 months, whereas common medium and large-bodied species were less likely to be collected when flow was lower over the previous 3 months to 3 years.

There are certain places on California’s Central Coast where the scent from stands of eucalyptus can penetrate your car even with the windows closed, although the smell is so inviting you are tempted to open them a bit.¹ You can have equally interesting scent experiences driving east through the California and Nevada deserts after a rain when you can inhale the pungent smell of sage and creosote bush. Or consider the fact that sometimes you can smell rain before it comes, first from the ozone in the air produced by electrical discharges, and then, especially if you are in arid regions, from the smell of geosmin released from the earth. As Cynthia Barnett points out, you can inhale an especially intense version of earth odors in some rural areas of India, West Africa, or Australia that experience the climatic extremes of months of no rain followed by stretches of monsoon. Back in 1964 two Australian scientists discovered that a major source of this odor were geosmin, a soil-dwelling bacteria, and terpenes secreted by plants. These kinds of molecules are absorbed by rock and clay during hot dry periods, building up great quantities that are then released by the sudden rise in humidity. The scientists nicknamed the smell “petrichor,” from ...