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Mountain galaxias

About: Mountain galaxias is a research topic. Over the lifetime, 11 publications have been published within this topic receiving 392 citations.

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Journal ArticleDOI
TL;DR: This work explores the significance and extent of so-called "hyper-cryptic" species complexes, using the Australian freshwater fish Galaxias olidus as a proxy for any organism whose taxonomy ought to be largely finalized when compared to those in little-studied or morphologically undifferentiated groups.
Abstract: Several recent estimates of global biodiversity have concluded that the total number of species on Earth lies near the lower end of the wide range touted in previous decades. However, none of these recent estimates formally explore the real "elephant in the room", namely, what proportion of species are taxonomically invisible to conventional assessments, and thus, as undiagnosed cryptic species, remain uncountable until revealed by multi-gene molecular assessments. Here we explore the significance and extent of so-called "hyper-cryptic" species complexes, using the Australian freshwater fish Galaxias olidus as a proxy for any organism whose taxonomy ought to be largely finalized when compared to those in little-studied or morphologically undifferentiated groups. Our comprehensive allozyme (838 fish for 54 putative loci), mtDNA (557 fish for 605 bp of cytb), and morphological (1963-3389 vouchers for 17-58 characters) assessment of this species across its broad geographic range revealed a 1500% increase in species-level biodiversity, and suggested that additional taxa may remain undiscovered. Importantly, while all 15 candidate species were morphologically diagnosable a posteriori from one another, single-gene DNA barcoding proved largely unsuccessful as an a priori method for species identification. These results lead us to draw two strong inferences of relevance to estimates of global biodiversity. First, hyper-cryptic complexes are likely to be common in many organismal groups. Second, no assessment of species numbers can be considered "best practice" in the molecular age unless it explicitly includes estimates of the extent of cryptic and hyper-cryptic biodiversity. [Galaxiidae; global estimates; hyper-diverse; mountain galaxias; species counts; species richness.].

147 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the response of fish populations to wood addition to two streams in southeastern Australia that have been impacted by sand slugs, and they concluded that in streams subjected to frequent disturbance, restoring refugia may be as, if not more, important as restoring what we term residential habitat.
Abstract: Human-induced erosion regularly delivers massive quantities of fine sediments into streams and rivers forming large static bodies of sediment known as sand slugs, which smother in-stream habitat, alter community structure, and decrease biodiversity. Sand slugs are widespread in parts of southeastern Australia as well as in many other parts of the world, and there is now considerable interest in restoring such affected streams. The reintroduction of large timber is widely suggested as a strategy for restoring habitat complexity, but this has rarely been tested in sand slug‐ affected streams. We examined the response of fish populations to wood addition to two streams in southeastern Australia that have been impacted by sand slugs. Manipulated sites (three per treatment) had either one or four timber structures added, and these sites were compared with (three) unmanipulated (control) sites before and after the manipulation occurred. Despite a supraseasonal drought during the study, we observed short-term increases in the abundance of Mountain galaxias (Galaxias olidus) at the four-structure sites, while both the fourstructure and the one-structure treatments appeared to buffer against drought-induced declines in two other species, River blackfish (Gadopsis marmoratus) and Southern pygmy perch (Nannoperca australis), relative to controls. However, drought eventually caused the complete loss of surface water from these streams and the loss of fish from both manipulated and unmanipulated sites. Thus, although the study supports the use of timber structures as a means of increasing local fish abundances, these beneficial effects were, in these streams, contingent upon permanency of flow. Because sedimentation has depleted the number of permanent refuge pools in these creeks, recovery rates of the fauna (i.e., resilience) are likely to be slow. We therefore conclude that in streams subjected to frequent disturbance, restoring refugia may be as, if not more, important as restoring what we term residential habitat.

112 citations

Journal ArticleDOI
TL;DR: The introduced salmonid Oncorhynchus mykiss was eradicated by use of the piscicide rotenone from a section of small montane stream upstream of an impassable barrier, and colonization of the stream by the native Galaxias olidus was monitored annually for four successive years.
Abstract: The introduced salmonid Oncorhynchus mykiss was eradicated by use of the piscicide rotenone from a section of small montane stream upstream of an impassable barrier. Recolonization of the stream both above and below the barrier by the native Galaxias olidus was monitored annually for four successive years. Following trout eradication, G. olidus recolonized the trout-free stream section above the barrier but was never detected below the barrier where trout still occurred. Initial colonization was by juvenile G. olidus but a successful breeding population had established three years after trout eradication. The implications of the use of barriers and targeted eradication programmes are discussed for the management of small, threatened fish species.

108 citations

Journal ArticleDOI
TL;DR: In this article, the authors conducted laboratory swim trials to determine and compare the dispersal capabilities of two native Australian fish, mountain galaxias (Galaxias olidus, Family Galaxiidae) and southern pygmy perch (Nannoperca australis), that maintain populations in hydrologically variable and intermittently flowing streams in south-east Australia.
Abstract: Animal movement is an important process connecting habitats in heterogeneous landscapes, and can play a key role in population persistence. Laboratory swim trials were conducted to determine and compare the dispersal capabilities of two native Australian fish, mountain galaxias (Galaxias olidus, Family Galaxiidae) and southern pygmy perch (Nannoperca australis, Family Nannopercidae) that maintain populations in hydrologically variable and intermittently flowing streams in south-eastern Australia. These experiments showed that G. olidus had significantly greater swimming endurance under a range of flow velocities. Concurrent field surveys were used to establish whether swimming abilities observed in laboratory studies were consistent with patterns of inferred movement from distribution and abundance patterns observed in the field. Data collected at multiple sites from headwater to lowland reaches along multiple streams revealed substantial temporal changes in the distribution of young-of-year (0+) G. olidus, with spawning occurring at upland sites in winter, followed by downstream larval migration and subsequent upstream movement in late spring. Observed spatial and temporal patterns in G. olidus abundances were consistent with a source-sink population structure, which may be disrupted by prolonged cease-to-flow periods during drought years. In contrast, results for N. australis suggested limited dispersal, with restricted local populations that persist at sites with permanent surface water. These field and laboratory findings complement our understanding of the spatial population structure of these two species in intermittent streams, and highlight the importance of understanding the role of dispersal in species conservation and habitat restoration.

29 citations

01 Jan 2003
TL;DR: Rotenone has been used for sampling stream fish assemblages in Australia for many years but there have been only two instances where it was used to eradicate trout populations from streams or sections of streams.
Abstract: Rotenone has been used for sampling stream fish assemblages in Australia for many years but there have been only two instances where it has been used to eradicate trout populations from streams or sections of streams. In 1992, rainbow trout Oncorhynchus mykiss was removed from c. 2.4 km of Lees Creek, a small montane stream in the Australian Capital Territory. A barrier at the downstream end of the treated section was augmented to prevent trout reinvasion, and the recolonisation of the native species mountain galaxias Galaxias olidus was monitored. The shortterm effects of the rotenone treatment on the aquatic macroinvertebrate fauna was also investigated. In 1994 and 1995 a total of 20 km of stream length in seven small streams in the Goulburn River catchment in Victoria were treated with rotenone to remove O. mykiss and brown trout Salmo trutta. This catchment contains some of the only remaining populations of the nationally endangered species barred galaxias Galaxias fuscus which was threatened by predation from invading trout. Barriers to prevent trout reinvasion were first constructed, trout were removed by ichthyocide treatment and the downstream recolonisation by G. fuscus of rehabilitated sites was monitored. The methodology and results for the two projects are presented along with lessons learnt and future directions. 1 . I N T R O D U C T I O N Trout form the basis of a highly valued recreational fishery in southeastern Australia. However in some areas, the impact of trout on native fish species is severe and control of trout populations is required. Exotic salmonids have had deleterious effects on small native fish of the family Galaxiidae in Australia and New Zealand (Frankenberg 1966, 1974; McDowall 1968, 1990; Cadwallader 1978, 1996; Fletcher 1979, 1986; Jackson & Williams 1980; Jackson 1981; McIntosh et al. 1992, 1994). Both brown trout Salmo trutta L. and rainbow trout Oncorhynchus mykiss (Richardson) were introduced to Australian waters more than a century ago, before accurate distribution or abundance data had been collected for native fish species. Consequently, much of the evidence of

22 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20191
20181
20171
20142
20131
20081