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Vilizzi L.,Murray Darling Freshwater Research Center | Vilizzi L.,Ichth Oz Environmental Science Research | Thwaites L.A.,South Australian Research And Development Institute | Smith B.B.,Level Inc | And 2 more authors.
Marine and Freshwater Research | Year: 2014

Common carp, Cyprinus carpio, is a highly invasive fish species across freshwater systems of south-eastern Australia, and especially in semi-arid floodplain wetlands. However, multi-component, large-scale experimental studies on carp effects on such ecosystems are scarce. This is in spite of demands to prioritise management and control of carp for the rehabilitation of habitats across the Murray-Darling Basin. A 2-year, large-scale field experiment in a terminal wetland of the lower River Murray (South Australia) evaluated the effects of free-ranging carp on water transparency, aquatic macrophytes (biomass and cover), zooplankton density, benthic invertebrates (density, richness and diversity) as well as native fish. Within 1 year since artificial inundation, transparency sharply decreased and this was accompanied by a decrease in aquatic macrophyte biomass and cover, a fluctuation in zooplankton density, and a decrease in benthic invertebrate richness and diversity. Also, the decreases in transparency and benthic invertebrate richness were significantly related to carp biomass, which averaged 68.0kgha-1 and induced a shift from clear- to turbid-water state. Following a flood event, increased connectivity caused carp to further access the newly inundated areas. © CSIRO 2014.

Vilizzi L.,Murray Darling Freshwater Research Center | Vilizzi L.,Ichth Oz Environmental Science Research | Thwaites L.A.,South Australian Research And Development Institute | Smith B.B.,Level Inc
Transactions of the Royal Society of South Australia | Year: 2014

Common carp Cyprinus carpio are a declared pest fish throughout the Murray-Darling Basin. Successful management of this highly-invasive species aimed at mitigating its detrimental effects on aquatic ecosystems is therefore a priority issue for wetland restoration and rehabilitation programmes for the benefit of native fish communities. As part of a large-scale, field-based experiment on carp impacts, a population of carp was extensively sampled from 2009 to 2011 at Brenda Park wetland (lower River Murray South Australia) under both drought and flooding conditions. A consistent young-of-year (YoY) cohort was present in the 2009-10 breeding season, indicating successful spawning within the wetland. However, the same cohort appeared not to leave the wetland later in the season, possibly as a result of drought-induced low-flow conditions. Conversely there was no evidence for within-wetland spawning in 2010-11 and 2011-12. Following a major flood event in Summer/Autumn2011, a consistent stock-size (210-440 mmTL) component was present in the carp population. Despite one successful spawning event out of the three breeding seasons of sampling, it cannot be ruled out that Brenda Park can act as a recruitment hot-spot for carp, especially in light of the large-scale population dynamics of this species. Measures for wetland rehabilitation should account for this and rely on a combination of flow regulation practices, enhancement of native fish passage and integrated carp management/control measures involving use of selective traps or exclusion screens, removal programmes and, whenever feasible, water draw-downs.

Tarkan A.S.,Mugla University | Guler Ekmekci F.,Hacettepe University | Vilizzi L.,Ichth Oz Environmental Science Research | Copp G.H.,Salmon and Freshwater Team | And 2 more authors.
Journal of Applied Ichthyology | Year: 2014

The aim of the present study was to assess the invasive potential of introduced non-native and translocated fishes in Turkey (Anatolia and Thrace) by applying the Fish Invasiveness Screening Kit (FISK), a risk identification tool for freshwater fishes. From independent evaluations by two assessors of 35 species, calibration of FISK for Turkey identified a threshold score of 23, which reliably distinguished between potentially invasive (high risk) and potentially non-invasive (medium to low risk) fishes for Anatolia (Asia) and Thrace (Europe). No species was categorized as 'low risk', 18 species were categorized as 'medium risk' and 17 as 'high risk' (two being 'moderately high risk', nine 'high risk', and six 'very high risk'). The highest scoring species was gibel carp Carassius gibelio, whereas the lowest scoring species was Caucasian dwarf goby Knipowitschia caucasica, a translocated species. Assessor certainty in their responses averaged overall between 'mostly uncertain' and 'mostly certain', with red piranha Pygocentrus nattereri and topmouth gudgeon Pseudorasbora parva achieving the lowest and highest certainty values, respectively, and with overall significant differences in certainty between assessors. The results of the present study indicate that FISK is a useful and viable tool for identifying potentially invasive non-native fishes in Turkey, a country characterized by natural biogeographical frontiers. © 2013 Blackwell Verlag GmbH.

Vilizzi L.,Ichth Oz Environmental Science Research | Ekmekci F.G.,Hacettepe University | Tarkan A.S.,Mugla University | Jackson Z.J.,U.S. Fish and Wildlife Service
Ecology of Freshwater Fish | Year: 2015

Common carp Cyprinus carpio occurs in several non-native areas worldwide, where it is generally regarded as either naturalised or invasive. Anatolia (Turkey) represents a unique region for evaluating common carp growth, due both to its location at the southernmost range of expansion of the species' wild form and to most of its water bodies having been stocked with domesticated strains. Based on a review of length-at-age data for common carp stocks from 45 water bodies sampled between 1953 and 2007, regional patterns in growth across climates, water body types, scalation variants and sexes, along with altitudinal gradients in growth performance and mortality, were investigated. Growth rates were lower in cold and arid relative to temperate climates, and also under hot or dry summers; this was true also of the mirror relative to the scale variant, males to females, but not of water body types (i.e., man-made reservoirs, natural lakes, water courses). Growth performance and mortality decreased with increasing altitude and decreasing temperature, likely due to optimisation of resource allocation between growth and reproduction. Growth rate of common carp from Anatolia was consistently lower compared to its native (Eurasian) and, especially, invasive (North American) counterparts, which reflected an opportunistic life-history strategy. Lower growth rates in Anatolia were ascribed to lower resilience of the widespread mirror variant together with limited habitat for spawning in man-made reservoirs. Better knowledge of common carp growth in Anatolia will improve stock management and conservation efforts. Further studies will help clarify the mechanisms responsible for evolutionary genotype-phenotype inter-relationships. © 2014 John Wiley & Sons A/S.

Mccarthy B.,Murray Darling Freshwater Research Center | Mccarthy B.,La Trobe University | Zukowski S.,Murray Darling Freshwater Research Center | Zukowski S.,La Trobe University | And 9 more authors.
Austral Ecology | Year: 2014

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 1800km 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. © 2014 Ecological Society of Australia.

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