Do invasive eastern gambusia (Gambusia holbrooki) shape wetland fish assemblage structure in south-eastern Australia?

2012 ◽  
Vol 63 (8) ◽  
pp. 659 ◽  
Author(s):  
Jed I. Macdonald ◽  
Zeb D. Tonkin ◽  
David S. L. Ramsey ◽  
Andrew K. Kaus ◽  
Alison K. King ◽  
...  
Keyword(s):  
Native Species ◽  
Ecological Impacts ◽  
Life History Strategies ◽  
Ecological Niches ◽  
Gambusia Holbrooki ◽  
Fish Assemblage Structure ◽  
South Eastern ◽  
Eastern Australia ◽  
Specialist Species ◽  
South Eastern Australia

Defining the ecological impacts conferred by invasive fishes provides a framework for evaluating the feasibility of control efforts in invaded waterways, and for predicting the consequences of future incursions. Eastern gambusia (Gambusia holbrooki) is a remarkably successful invader of freshwater systems worldwide, with the capacity to detrimentally impact native fishes both directly (e.g. competition, predation, agonistic interactions) and indirectly (e.g. triggering trophic cascades). Here, we modelled the influence of eastern gambusia and several environmental covariates on fish species diversity, abundance and condition based on quantitative survey data collected from 93 wetlands in south-eastern Australia. We predicted that small-bodied, wetland specialist species sharing dietary- and habitat-niches with eastern gambusia would be most severely impacted, and that environmental stressors associated with wetland drying during late summer would magnify these impacts. Eastern gambusia influenced the occurrence, abundance and/or body condition of most common wetland species; however, the direction and level of impact appeared dependent on both biotic and environmental forces. From these results, we postulate that generalist life-history strategies that permit niche-segregation may release some native species from competitive/predatory pressures, allowing coexistence with eastern gambusia in resource-limited, environmentally harsh habitats, whilst specialist species that occupy narrower ecological niches may be less resistant.

scholarly journals Ophyiulus in Victoria: results of millipede surveys from south-eastern Australia

2015 ◽  
Vol 127 (2) ◽  
pp. 69
Author(s):  
Briony A. Norton ◽  
Linda J. Thomson ◽  
Michael A. Nash
Keyword(s):  
Species Identification ◽  
Preliminary Data ◽  
Native Species ◽  
South Eastern ◽  
Eastern Australia ◽  
The Future ◽  
South Eastern Australia

The composition and ecology of the millipede fauna of Victoria remain poorly understood. We collected millipedes as part of a series of ecological arthropod surveys across south-eastern Australia, focusing mainly on Victoria. These samples almost exclusively contained millipedes from the introduced order Julida. We pursued species identification of the julids when it became apparent there were species other than the well-recorded Ommatoiulus moreleti (Lucas, 1860) (Portuguese millipede) in the samples. The majority of specimens were O. moreleti, but we also detected at least one species of Cylindroiulus Verhoeff, 1894, as well as an Ophyiulus Berlese, 1884, species, specimens of which have been identified as Ophyiulus cf. targionii. These are the first Ophyiulus records for Victoria to our knowledge. We present preliminary data on the abundance through the year of Ophyiulus. This is the first study to examine this species in Victoria and little is currently known about its likely impact on agriculture or on native species. Monitoring and research of the species in the future is therefore warranted.

Dung burial by native and introduced dung beetles (Scarabaeidae)

1994 ◽  
Vol 45 (8) ◽  
pp. 1799 ◽  
Author(s):  
M Tyndale-Biscoe
Keyword(s):  
Introduced Species ◽  
Native Species ◽  
Dry Weight ◽  
Dung Beetle ◽  
Dung Beetles ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

The quantity of dung buried and shredded by dung beetles at four sites in south-eastern Australia was found to be positively correlated with the dry weight (biomass) of beetles in the pads. Each of the four sites has two abundant native species of dung beetles, and one to five well-established introduced species present. At Uriarra, where only one introduced species is common, a mean of 7 . 2 l � 1.94% (1990-91) and 6.01�1.31% (1991-92) of the dung was buried per week. At Fyshwick, with two common introduced species of dung beetles, 22.27� 4.03% (1990-91) and 12 04�2 72% (1991-92) of the dung was buried per week. Braidwood, with four introduced species, had a mean of 15.81� 2.82% (1991-92) weekly dung buried, and Araluen, with five introduced species, had 30.18�8- 73% (1992-93) dung buried per week. Dung beetle numbers were low at all sites during the first half of 1991-92 season due to a drought throughout the region. Dung shredding averaged less than 12% over the seasons at all sites, but fluctuated from 0 to 70%, depending mainly on beetle numbers in the dung pads on individual occasions. Increasing numbers of exotic dung beetles throughout the pastoral areas of Australia should result in increased amounts of dung buried and shredded, with correspondingly increased benefits to Australian agriculture.

Genetic structure and diversity of introduced eastern mosquitofish (Gambusia holbrooki) in south-eastern Australia

2012 ◽  
Vol 63 (12) ◽  
pp. 1206 ◽  
Author(s):  
Renae M. Ayres ◽  
Vincent J. Pettigrove ◽  
Ary A. Hoffmann
Keyword(s):  
Published Data ◽  
Gambusia Holbrooki ◽  
Historical Records ◽  
Genetic Structuring ◽  
South Eastern ◽  
Introduced Range ◽  
Eastern Australia ◽  
Eastern Mosquitofish ◽  
Microsatellite Diversity ◽  
South Eastern Australia

The closely related eastern mosquitofish (Gambusia holbrooki) and western mosquitofish (Gambusia affinis) have been introduced into many countries and collectively represent the most widely distributed freshwater fish in the world. We investigated genetic patterns associated with the spread of G. holbrooki in its introduced range in south-eastern Australia, by sampling 60 G. holbrooki populations (n = 1771) from major regions where G. holbrooki was initially introduced into Australia, and characterising the genetic diversity and population structure of G. holbrooki, using five polymorphic nuclear microsatellite loci and sequences from two mitochondrial genetic markers. Results were compared with published data on American and European Gambusia samples and historical records. Low microsatellite diversity and strong population genetic structuring were found within G. holbrooki in south-eastern Australia. Observed heterozygosity and allelic richness declined regionally in the order Sydney, Brisbane, Canberra, Melbourne and Adelaide. Microsatellite variation in Australia was reduced compared with native populations. Two mitochondrial DNA haplotypes of G. holbrooki were found; one was common, whereas the other was detected in one Sydney population and one Melbourne population. Cytochrome b sequence diversity was reduced compared with native and European ranges, and sequences were identical to two haplotypes previously identified. Microsatellite diversity of G. holbrooki in south-eastern Australia validates historical records of its spread, beginning north and moving south. Mitochondrial sequencing confirms that G. holbrooki is present in Australia, but the origins of Australian G. holbrooki populations remain unclear.

Condition of fenced and unfenced remnant vegetation in inland catchments in south-eastern Australia

2008 ◽  
Vol 56 (7) ◽  
pp. 590 ◽  
Author(s):  
Sue V. Briggs ◽  
Nicola M. Taws ◽  
Julian A. Seddon ◽  
Bindi Vanzella
Keyword(s):  
Species Richness ◽  
Native Species ◽  
Public Investment ◽  
Grazing Pressure ◽  
South Eastern ◽  
Remnant Vegetation ◽  
Vegetation Condition ◽  
Eastern Australia ◽  
Native Species Richness ◽  
South Eastern Australia

Considerable areas of remnant native vegetation have been fenced in the last decade to manage grazing by domestic stock. This study investigated vegetation condition in comparative fenced and unfenced remnant vegetation in the mid–upper Murrumbidgee and Lachlan catchments in south-eastern Australia. Native species richness, native groundcover and overstorey regeneration were higher at fenced than at unfenced sites. Area of bare ground was lower at fenced sites. Exotic groundcover did not differ between fenced and unfenced sites. Native species richness was higher at sites fenced for longer and with no stock grazing; neither native nor exotic groundcover at fenced sites was related to time since fencing or stock grazing pressure. Some tree species regenerated at both fenced and unfenced sites (Blakely’s red gum, Eucalyptus blakelyi; tumbledown gum, E. dealbata, long-leaved box, E. goniocalyx; red stringbark, E. macrorhyncha), some regenerated at few fenced and few unfenced sites (white box, E. albens; yellow box, E. melliodora) and some regenerated at fenced sites but not at unfenced sites (grey box, E. microcarpa; mugga ironbark, E. sideroxylon; white cypress pine, Callitris glaucophylla). Although less robust than pre- and postfencing monitoring, the comparisons reported here provide a logistically feasible and relatively inexpensive assessment of effects of the sizeable public investment in fencing on vegetation condition.

Temporal change in fish assemblages in the lower Goulburn River, south-eastern Australia: comment on Pollino et al. (2004)

2006 ◽  
Vol 57 (3) ◽  
pp. 303 ◽  
Author(s):  
David A. Crook ◽  
Wayne M. Koster
Keyword(s):  
Survey Data ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Recent Analysis ◽  
Stressed Condition ◽  
Fish Assemblage Structure ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

A recent analysis of fish assemblages in the Goulburn River, south-eastern Australia, used fish survey data collected between 1970 and 2002 to examine spatial patterns in the compositions and relative abundances of fish assemblages in the catchment. Based on this analysis, it was concluded that the native fish fauna of the Goulburn River is in a stressed condition and that introduced species dominate the fish assemblages. Fish survey data collected in 1982–1983 are compared with data collected in 2003–2004 to examine whether fish assemblages in the lower Goulburn River were stable at the temporal scale at which the data were aggregated in the previous analysis. The results show significant differences in fish assemblage composition between the two surveys, suggesting that fish assemblage structure in the lower Goulburn River did not remain stable between 1982–1983 and 2003–2004. The aggregation of data collected over several decades has the potential to confound analysis of spatial variations in fish assemblages and is unlikely to provide a reliable means of assessing their current condition.

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