Are alien fish disadvantaged by extremely variable flow regimes in arid-zone rivers?

2010 ◽  
Vol 61 (8) ◽  
pp. 857 ◽  
Author(s):  
J. F. Costelloe ◽  
J. R. W. Reid ◽  
J. C. Pritchard ◽  
J. T. Puckridge ◽  
V. E. Bailey ◽  
...  

The proliferation of alien fish in dryland rivers potentially obstructs the maintenance of river health. Modified flow regimes are hypothesised to facilitate invasions by alien fish but in unregulated dryland rivers, large floods provide a recruitment advantage for native over alien species whereas droughts favour alien species. We tested these hypotheses by using data from a 3-year study (2000–2003) of fish populations in the unmodified rivers of the Lake Eyre Basin (LEB) of Australia. Results from a lower reach of Cooper Creek were compared with those of an earlier study (1986–1992). During both periods, large floods occurred, with return periods ranging from >1 in 5 to >1 in 25 years. In the lower Cooper, decreases in the abundance of alien species relative to native species, and dramatic increases in recruitment of native species, were observed during a 1–3-year period following large floods. In two other rivers in 2000–2003, there was no statistically significant change in the already low abundances of alien species. We suggest that the naturally variable hydrological regimes and native-dominant fish assemblages of the unregulated LEB rivers afford some resistance to the establishment and proliferation of alien fish through flood and drought conditions.

2017 ◽  
Vol 68 (4) ◽  
pp. 629 ◽  
Author(s):  
Serena H. Hamilton ◽  
Carmel A. Pollino ◽  
Keith F. Walker

Regionalisations based on species assemblages are a useful framework for characterising ecological communities and revealing patterns in the environment. In the present study, multivariate analyses are used to discern large-scale patterns in fish assemblages in the Murray–Darling Basin, based on information from the Murray–Darling Basin Authority’s first Sustainable Rivers Audit (SRA), conducted in 2004–2007. The Basin is classified into nine regions with similar historical fish assemblages (i.e. without major human intervention), using data that combine expert opinion, museum collections and historical records. These regions are (1) Darling Basin Plains, (2) Northern Uplands, (3) Murray Basin Plains, (4) Northern Alps, (5) Central East, (6) Avoca Lowland, (7) Southern Slopes, (8) Southern Alps and (9) South-Western Slopes. Associations between assemblages and physical variables (catchment area, elevation, hydrology, precipitation, temperature) are identified and used to reinforce the definitions of regions. Sustainable Rivers Audit data are compared with the historical assemblages, highlighting species whose range and abundance have changed since the early 19th century. Notable changes include declines in native species such as silver perch, river blackfish, mountain galaxias, Macquarie perch, trout cod and freshwater catfish, and the advent of alien species including common carp, eastern gambusia, goldfish, redfin perch, brown trout and rainbow trout. Less significant declines are evident for native carp gudgeons, golden perch, two-spined blackfish, bony herring and flathead gudgeon. Changes are evident even in regions where habitats have been little disturbed in the past 200 years.


PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0227169
Author(s):  
Katia Sánchez-Ortiz ◽  
Kara J. M. Taylor ◽  
Adriana De Palma ◽  
Franz Essl ◽  
Wayne Dawson ◽  
...  

Island species and habitats are particularly vulnerable to human disturbances, and anthropogenic changes are increasingly overwriting natural island biogeographic patterns. However, quantitative comparisons of how native and alien assemblages respond to human disturbances are scarce. Using data from 6,242 species of vertebrates, invertebrates and plants, from 7,718 sites on 81 islands, we model how land-use change, human population density and distance to the nearest road affect local assemblages of alien and native species on islands. We found that land-use change reduces both richness and abundance of native species, whereas the number and abundance of alien species are high in plantation forests and agricultural or urban sites. In contrast to the long-established pattern for native species (i.e., decline in species number with island isolation), more isolated islands have more alien species across most land uses than do less isolated islands. We show that alien species play a major role in the turnover of island assemblages: our models show that aliens outnumber natives among the species present at disturbed sites but absent from minimally-disturbed primary vegetation. Finally, we found a homogenization pattern for both native and alien assemblages across sites within most land uses. The declines of native species on islands in the face of human pressures, and the particular proneness to invasions of the more remote islands, highlight the need to reduce the intensity of human pressures on islands and to prevent the introduction and establishment of alien species.


<em>Abstract</em>.—Riverine fish assemblages on the North American plains continue to change as native species’ distributions shrink and become increasingly fragmented due to impoundment, changes in the quantity and quality of water, and negative interactions of introduced species. To identify important changes to fish assemblages and their environment, long-term data are needed. I used fish assemblage and discharge data from 22 plains river localities across nearly 20 years to identify potential covariation between fish assemblages and the flow regime. I also obtained data on water use at the watershed scale to determine its potential effects on flow regimes and fish assemblages. A modified time series analysis indicated that directional change was occurring for many of the fish assemblages, though the strength of this change was highly variable among localities. Directional change was strongly and positively associated with change in flow regime, and change in flow regime was positively associated with human modification of the landscape, including number of wastewater facilities and returns. These results illustrate how demands on our water resources can ultimately influence riverine fish assemblages, largely by disrupting natural flow regimes. As population growth continues, the integrity of plains fish assemblages and their riverine environment will likely continue to decline, further exacerbating the fragmentation and reduction of species’ geographic ranges.


Author(s):  
Katia Sánchez-Ortiz ◽  
Kara J. M. Taylor ◽  
Adriana De Palma ◽  
Franz Essl ◽  
Wayne Dawson ◽  
...  

AbstractIsland species and habitats are particularly vulnerable to human disturbances, and anthropogenic changes are increasingly overwriting natural island biogeographic patterns. However, quantitative comparisons of how native and alien assemblages respond to human disturbances are scarce. Using data from 6,242 species of vertebrates, invertebrates and plants, from 7,718 sites on 81 islands, we model how land-use change, human population density and distance to the nearest road affect local assemblages of alien and native species on islands. We found that land-use change reduces both richness and abundance of native species, whereas the number and abundance of alien species are high in plantation forests and agricultural or urban sites. In contrast to the long-established pattern for native species (i.e., decline in species number with island isolation), more isolated islands have more alien species across most land uses than do less isolated islands. We show that alien species play a major role in the turnover of island assemblages: our models show that aliens outnumber natives among the species present at disturbed sites but absent from minimally-disturbed primary vegetation. Finally, we found a homogenization pattern for both native and alien assemblages across sites within most land uses. The declines of native species on islands in the face of human pressures, and the particular proneness to invasions of the more remote islands, highlight the need to reduce the intensity of human pressures on islands and to prevent the introduction and establishment of alien species.


2021 ◽  
Vol 41 (3) ◽  
pp. 358-366
Author(s):  
Peter B. Banks

Distinguishing between whether a species is alien or native can be problematic, especially for introduced species that are long-established in new areas outside of their natural range. Transport by humans is the criterion for alien status used by many definitions, whereas arbitrary time since arrival to a location is often used to define native status. Here I propose an eco-evolutionary approach to distinguish between alien and native status and use this to resolve uncertainty in the status of the dingo in Australia. Dingoes were transported to mainland Australia by humans, but more than 4000 years ago, and dingoes now interbreed with feral domestic dogs. Legally, this mix of events has the dingo classified as native in some jurisdictions and alien in others. I suggest that native status for introduced species should be based on (1) whether the species has evolved in their new environment; (2) whether local species recognise and respond to them as they do towards deep endemic native species, and; (3) whether their impacts benchmark against those of a native species or are exaggerated like those of other alien species. Dingoes are behaviourally, reproductively and morphologically different to close ancestors from south-east Asia, and this difference has a genetic basis indicative of evolution in Australia. There is abundant evidence that native prey species on mainland Australia recognise and respond to them as a dangerous predator, which they are. But there is strong evidence that dingo impacts on prey are not exaggerated, with effect sizes from mensurative experiments similar to those of experiments on native predators rather than alien predators. These three lines of evidence suggest dingoes should be considered native to mainland Australia. I suggest this eco-evolutionary approach to defining native status can be helpful in resolving the often-heated debates about when an alien species becomes native.


2017 ◽  
Vol 10 (2) ◽  
pp. 26 ◽  
Author(s):  
Milton Goncalves Silva Junior ◽  
Antonio Carlos Leal Castro ◽  
Ulrich Saint-Paul

The northern coast of Brazil has more than 30 estuaries distributed along 650 km of coastline. These conditions favor the presence of relatively large fish communities in estuarine environments, but published information on the fish fauna in tidal creeks in northern Brazil is only available for some mangrove systems, and comparative studies between fish estuarine communities in different tidal creeks are less common. The choice of the study area was based on the fact that it has been poorly investigated with regard to estuarine fish fauna in comparison in mangrove tidal creeks using the same fishing gear. The objective of the present study was to compare the composition of the relative biomass of taxonomic, functional and ecological guilds of fish assemblages occurring in estuarine systems along the northern coast of Brazil. The study area of the present comparative analysis extended from the southeastern edge of the Marajoara Gulf to the western edge of the Maranhense Gulf. A comparative analysis among different estuarine systems was performed using data from other studies. The abundance of juveniles was greater in the Caeté, Curuçá and Cururuca estuaries than other estuaries. Cluster analysis separated the estuaries into two distinct groups and significant differences between these groups only exist in relation to geographical proximity. The present investigation indicates that the coastal region between the states of Pará and Maranhão is characterized by high dynamics and environmental heterogeneity, particularly with regard to changes in river discharge and tidal fluctuations. The present results underscore the importance of ecological information on ichthyofauna in tropical estuaries in order to include appropriate descriptors in conservation or restoration processes of marine communities and habitats.


Author(s):  
Andersonn Silveira Prestes

The establishment and spread of exotic species is a contemporary major concern. Alien species may become invasive in their new habitat, leading to both/either environmental and/or economic impacts. I briefly reviewed the literature in the last decade about the relationship of exotic species and native communities. I identified that professionals usually approach the subject in two main points of view: (1) researchers tend to point out the impacts of alien species on entire communities, evaluating if the relationship is positive, negative or neutral; (2) they focus on the eco-evolutionary processes involved in the introductions, the dynamics of invasion, and individual study cases. When evaluating the response of introductions to entire communities, evidence seems to be ambiguous and may support positive, negative or neutral relationship, especially depending on the scale approached. The unique eco-evolutionary pathways of each introduction may be a great shortcoming in the searching for generalities. On the other hand, advances have been made in understanding the dynamics of invasion on different lineages through a more selective/individualized approach. I suggest that the dynamics of invasion might be studied through a perspective in which different eco-evolutionary processes, levels of organization (from gene to entire communities), the history of the organism(s) and time are taken into account. Individual cases might be compared in attempt to understand how the relationship exotic and native works and in the search for generalities.


2020 ◽  
Vol 47 (2) ◽  
pp. 89-99
Author(s):  
Peter Urban ◽  
Nuno Guimarães ◽  
Jozef Bučko

AbstractThis summary provides an overview of the golden jackal (Canis aureus) categorization in Europe with particular focus on its presence in Slovakia. The distribution range of this species in Europe has been expanding in recent decades. Currently, European population is in constant and fast increase, widening their ranges towards Central and Eastern Europe and more recently in some western countries. All over Europe, the categorization of the golden jackal status is discussed with some controversial. A recent genetic study helped to determine that golden jackals do not meet the established three criteria, which categorize a species as an invasive alien species. In Slovakia, golden jackals’ numbers grown considerably in the last decade and with an increasing of their distribution through the country it became a permanent species of the Slovak fauna. The only internal status is the hunting Act no. 274/2009, which classifies it as, game species. The fast adaptation and dispersion through Slovakia can be considered similar to the behaviour of an invasive species, as suggested in previous studies in Hungary. Based on widely accepted definitions, agreed under international legal instruments, it is quite clear that the term ‘Invasive Alien Species’ only encompasses non-native species specifically introduced by humans (intentionally or accidentally). Following this Invasive Alien Species terminology, golden jackals cannot be categorized as such in Slovakia. The natural expansion, the growing ranges, and the increase in numbers of the golden jackal in Slovakia in the last decades points to a need to improve the knowledge of the species.


Botanica ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 115-123
Author(s):  
Pēteris Evarts-Bunders ◽  
Gunta Evarte-Bundere

Abstract Evarts-Bunders P., Evarte-Bundere G., 2018: New knowledge about species of the genus Chaerophyllum (Apiaceae) in Latvia. - Botanica, 24(2): 115-123. The genus Chaerophyllum belongs to the Apiaceae family, which is one of the most complicated and difficult to identify in Latvia. There are five species verified by herbarium materials known in Latvia: Chaerophyllum aromaticum - native species, rather frequent in all regions in forests, parks and shrublands, C. aureum - anthropophyte, known only from one locality in Daugavpils city along the railway, C. bulbosum - anthropophyte, earlier grown as a root vegetable and now found rarely in parks, at roadsides, waste places, along fences and under canopy of trees close to human settlements, C. hirsutum - native species, known from several localities only in south-eastern part of Latvia, mostly in the Daugava valley - forested ravines, slopes of broad-leaved forests, and C. temulum - alien species, known only from few localities - waste places, railway sides and old manor parks in the whole territory of Latvia. The most striking results are related to the distribution of C. hirsutum in Latvia. The literature sources and herbarium material of Anthriscus nitida, previously known and collected in Latvia, after our critical revision are considered as Chaerophyllum hirsutum, whereas Anthriscus nitida at least in the Latvian flora has not been identified yet and has been removed from the flora lists by mistake.


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