Native and exotic fish species in the tiber river watershed (umbria - italy) and their relationship to the longitudinal gradient
TL;DR: The preliminary results suggest that characteristics of fish community alterations depend on the type of river sector involved; the small rivers of the basin are a refuge zone for the native community and are currently of fundamental importance for maintaining biodiversity.
Abstract: In this study we examine the spatial variations in the fish communities in the Tiber River watershed, including both native and exotic species. Its main objectives were to assess the quality of fish communities of this area and to verify if factors of fish community disturbance are constant over the basin or if they change along the river gradient. The level of degradation was evaluated according to the ratio between the number of native fish species and total number of species (ZIC = Zoogeographic Integrity Coefficient). A total of 37 fish species was found, 13 native and 24 exotic (64.86%). Cyprinid is the prevailing family with 15 species (7 native, 8 exotic). The species most frequently introduced are cyprinids, followed by salmonids (4 species) and gobids (3 species). Of the 24 exotic species only 11 (45.83%) can be considered intentionally introduced by man: the proportion of intentionally introduced transplanted species (66.67%) is considerably higher than the translocated species (33.33%). There is a correlation between the longitudinal gradient of the river, the morphological evolution of the riverbed and decline in water quality. High ZIC values were related to higher elevation, greater slope and better water quality. As the size of the river increases the fish communities appear to be ever-more dominated by species of exotic origin, whose number progressively increases with the worsening of the water quality and downstream movement. The number of native species is the greatest in the middle reaches of the rivers, and decreases both upstream and downstream. Compared to the introduced species, the native species tend to stay upstream and are often the only species found in the headwaters. The number of introduced species increases downstream. We have also found differences among translocated and transplanted species: the first ones tend to favor the middle reaches of the rivers, while transplanted species seem to prefer the downstream sectors. In almost all cases, the sampling station immediately below an impoundment has the lowest ZIC values in comparison to the river stretches above the dam. Our preliminary results suggest that characteristics of fish community alterations depend on the type of river sector involved; the small rivers of the basin are a refuge zone for the native community and are currently of fundamental importance for maintaining biodiversity.
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TL;DR: It is concluded that reservoirs promote taxonomic homogenization at multiple spatial scales, while the community-level effects of species introductions and local extinctions within river basins have been sparsely analyzed.
Abstract: Most studies analyzing patterns in biotic homogenization of fish communities have used large-scale approaches, while the community-level effects of species introductions and local extinctions within river basins have been sparsely analyzed. In this article, we examine patterns in freshwater fish α- and β-diversity in relation to the presence of reservoirs in a Mediterranean river (Guadiana river; Iberian Peninsula). We used fish samples from 182 river localities and 59 reservoir ones to address two main questions: (i) do reservoirs favor the establishment of invasive fish species?; and (ii) do reservoirs bear taxonomically homogenized fish communities? Although total species richness was not different between rivers and reservoirs, the latter had more invasive species and less native ones. Fish species found in reservoirs tended to be larger ones, but invasive species of any size showed higher preferences for reservoirs. Native species that were rare or absent in reservoirs were those that showed higher sensitivity to invasive species in rivers. Reservoir fish communities were taxonomically homogenized in relation to river ones, both when considering all fish species and using only natives or only invasive ones. Our results suggest that invasive species occupying reservoirs constitute an ecological filter excluding most native species from such systems. Invasive species in the study area are often widely introduced elsewhere, while native species found in reservoirs are congeneric and ecologically similar to those found in other Iberian studies. Thus, we conclude that reservoirs promote taxonomic homogenization at multiple spatial scales, while could also be promoting the functional homogenization of Iberian fish communities.
106 citations
Cites background from "Native and exotic fish species in t..."
...For example, most of the invasive species listed in Table 1 are frequently found in homogenized rivers in Italy (Lorenzoni et al. 2006) or North America (Moyle and Mount 2007)....
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05 May 2015
TL;DR: There is no consensus on the reasons for the absence of self-sustaining populations of rainbow trout across much of Europe, but knowledge of the mechanisms involved is limited, while the data collected here shed new light on the invasion biology of the species.
Abstract: The rainbow trout (Oncorhynchus mykiss) is probably the most widely introduced fish species in the world. Since the first translocation outside of the range of its natural distribution, the species has been introduced into at least 99 countries and has established reproducing populations in many different parts of the world. The present review aims to synthesize the existing information on these translocations, with special emphasis on self-sustaining populations in Europe, where continuous introductions have in general not led to naturalization. Our survey produced a list of more than 130 confirmed or potential self-sustaining populations across 16 European countries. The highest abundance of such populations was observed in the Alpine foothills of central Europe where naturalization is not limited to modified waters less suitable for native salmonids but also occurs commonly in pristine and near-natural waters. There is no consensus on the reasons for the absence of self-sustaining populations of rainbo...
82 citations
TL;DR: Findings show that T-RFLP of 16S rRNA genes can be used to compare vaginal microbial communities and gain information about the numerically dominant populations that are present, and are largely invariant over time.
Abstract: To define and monitor the structure of microbial communities found in the human vagina, a cultivation-independent approach based on analyses of terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes was developed and validated. Sixteen bacterial strains commonly found in the human vagina were used to construct model communities that were subsequently used to develop efficient means for the isolation of genomic DNA and an optimal strategy for T-RFLP analyses. The various genera in the model community could best be resolved by digesting amplicons made using bacterial primers 8f and 926r with HaeIII; fewer strains could be resolved using other primer-enzyme combinations, and no combination successfully distinguished certain species of the same genus. To demonstrate the utility of the approach, samples from five women that had been collected over a 2-month period were analyzed. Differences and similarities among the vaginal microbial communities of the women were readily apparent. The T-RFLP data suggest that the communities of three women were dominated by a single phylotype, most likely species of Lactobacillus. In contrast, the communities of two other women included numerically abundant populations that differed from Lactobacillus strains whose 16S rRNA genes had been previously determined. The T-RFLP profiles of samples from all the women were largely invariant over time, indicating that the kinds and abundances of the numerically dominant populations were relatively stable throughout two menstrual cycles. These findings show that T-RFLP of 16S rRNA genes can be used to compare vaginal microbial communities and gain information about the numerically dominant populations that are present.
57 citations
TL;DR: The main results of this study indicated that: (i) the genetic diversity of brown trout in central Italy is very complex and (ii) its conservation is seriously threatened by genetic introgression phenomena still ongoing.
Abstract: Mediterranean brown trout is subject to several serious threats such as pollution, water abstraction, habitat alteration and especially genetic introgression with domestic strains used for stocking activities. Despite this latter issue has largely been debated by scientists, local managers and stakeholders for decades, official stocking practices with domestic trout still persists in several countries (Italy included), even if there are laws explicitly prohibiting introduction of organisms of non-local origin. Probably, the last opportunity to conserve native brown trout populations is represented by protected areas. Therefore, in the present study, we aimed to verify the role of the Nature 2000 network and a national park as valid tools to guarantee the survival of native brown trout in the Apennines. Partial mitochondrial DNA control region sequence analysis and genotyping of the locus LDH-C1* and 11 microsatellites were used to investigate the genetic diversity of three rivers from central Italy. For all rivers investigated a temporal analysis of introgression was also carried out. The genetic diversity of three domestic stocks was included in the sampling design for comparison. The main results of this study indicated that: (i) the genetic diversity of brown trout in central Italy is very complex and (ii) its conservation is seriously threatened by genetic introgression phenomena still ongoing. The only samples showing no introgression or a decrease in genetic introgression were those isolated by the presence of natural and/or artificial barriers to fish movements rather than protected by inhabiting rivers within the Natura 2000 network. This observation prompts an important reflection on issues concerning fluvial continuity restoration and suggests that barrier removal should be undertaken with caution in order to avoid the concrete risk of domestic trout spreading that could promote additional loss of native brown trout biodiversity.
34 citations
TL;DR: In this paper, the authors used relative weight (W r ), a condition index which allows evaluation of fish well-being, as a tool to investigate the impact of the presence of non-native species (NNS) on the condition of the key native species (NS) of the Tiber River basin (Italy): Barbus tyberinus Bonaparte, Leuciscus cephalus (Linnaeus), Leucisus lucumonis Bianco, Rutilus rubilio (Bonaparte) and Telestes muticellus (Bon
Abstract: The aim of the research was to test relative weight (W r ), a condition index which allows evaluation of fish well-being, as a tool to investigate the impact of the presence of non native species (NNS) on the condition of the key native species (NS) of the Tiber River basin (Italy): Barbus tyberinus Bonaparte, Leuciscus cephalus (Linnaeus), Leuciscus lucumonis Bianco, Rutilus rubilio (Bonaparte) and Telestes muticellus (Bonaparte). By means of Canonical Correlation Analysis, data from 130 sampling sites, distributed throughout Tiber River basin, were examined. W r of NS was related to densities of NNS and to environmental variables. Moreover, the correlation between W r of NS and density of NNS was investigated through linear regression analysis and covariance analysis. Preliminary results encourage the use of W r as a tool to assess the relationship between NS and ecological factors (such as the presence of NNS) and to explain the changes that occur along the longitudinal gradient of a river.
30 citations
References
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TL;DR: In this paper, a study of fish communities in the upper Danube was carried out at 19 localities in 1976 and 1984, yielding 24 samples with over 23,000 specimens.
Abstract: A study of fish communities in the upper Danube was carried out at 19 localities in 1976 and 1984, yielding 24 samples with over 23 000 specimens. Forty-two species — 8 of them new for this part of the Danube — and 6 cyprinid hybrids were identified. Two distinct regions, above and below Ulm, were recognized for the upper Danube on the basis of both abiotic (distance from source, elevation, river gradient) and biotic (species richness, species distribution) characters of the localities. Nine species were distributed over most of the upper Danube, while 10 and 23 species were limited mostly to the upriver and downriver sections, respectively. A factor analysis of ecomorphological attributes for 28 dominant species revealed a generalist-specialist pattern among their swimming behavior and feeding modes. The proportions of swimming and feeding specialists differed significantly between the upriver and downriver communities. Potential species for invasion into the North Sea system, when the Rhein-Main-Donau canal opens, were identified, and the danger of a reverse invasion by both sea lamprey and eel into the Black Sea system is explained. Although an experience with other large ship canals - Erie. Welland and Suezseems to indicate that serious changes may be delayed for about half a century, these changes are predicted and warned against.
95 citations
"Native and exotic fish species in t..." refers background in this paper
...In fact, in temperate rivers the species richness progressively increases from mountain to valley (SHELDON, 1968; SCHLOSSER, 1982; BALON et al., 1986; MORIN and NAIMAN, 1990; PONT et al., 1995; BELKESSAM et al., 1997; CHANGEUX, 1995; PETERSON and RABENI, 2001) and this pattern surely characterized the autochthonous populations in the Tiber River in the past (BIANCO, 1990a; BIANCO and KEITMAIER, 2001)....
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...In fact, in temperate rivers the species richness progressively increases from mountain to valley (SHELDON, 1968; SCHLOSSER, 1982; BALON et al., 1986; MORIN and NAIMAN, 1990; PONT et al., 1995; BELKESSAM et al., 1997; CHANGEUX, 1995; PETERSON and RABENI, 2001) and this pattern surely characterized…...
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TL;DR: The establishment of exotic monogenean populations on Australian native fishes via host-switching is considered less likely than for other parasitic groups due to the generally high host-specificity of monogeneans, combined with the phylogenetic dissimilarity of native and exotic fishes.
84 citations
"Native and exotic fish species in t..." refers background in this paper
...…resources (LEVEQUE, 1997), predation (JACKSON and WILLIAMS, 1980; LEVEQUE, 1997), parasitism or the introduction of pathogenic agents (BLANC, 1997; DOVE and ERNST, 1996; LODGE et al., 2000); hybridisation and modification of the environment should also be included as possible harmful effects…...
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...The pre-existing fish community may be changed greatly as a result of competition for food or other resources (LEVEQUE, 1997), predation (JACKSON and WILLIAMS, 1980; LEVEQUE, 1997), parasitism or the introduction of pathogenic agents (BLANC, 1997; DOVE and ERNST, 1996; LODGE et al., 2000); hybridisation and modification of the environment should also be included as possible harmful effects resulting from the introduction of exotic species....
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01 Jan 2000
TL;DR: A narrow window of opportunity exists to protect the function of North American aquatic ecosystems, their fish- eries, and the unique biodiversity of crayfishes that they contain.
Abstract: North America harbors about 390 native species of crayfishes, 75% of the world's total. In this arti- cle, we highlight the threats posed by nonindigenous crayfishes to freshwater ecosystem function, fisheries, and the biodiversity of native crayfishes; draw some lessons for North American freshwa- ter conservation from the experience with nonindigenous crayfishes in Europe; and review existing regulations that address the introduction of nonindigenous crayfishes. Most North American cray- fishes have naturally small ranges in the southeastern United States, rendering them very vulnera- ble to environmental change. In contrast, Europe has only five, broadly distributed, native crayfish- es, all of which have been greatly affected by environmental changes, especially the introduction of nonindigenous crayfishes (mostly from North America). In response, many European governments have adopted strict regulations to protect native crayfishes. The loss of thousands of populations of native European crayfishes and the political responses to it offer useful guidance to efforts to pro- tect North American freshwater biodiversity and ecosystems. As in Europe, the most important threat to native North American crayfish biodiversity is nonindigenous crayfishes (many from with- in North America). In several well-documented cases, nonindigenous crayfishes have greatly altered North American lake and stream ecosystems, harmed fisheries, extirpated many popula- tions of native crayfishes, and contributed to the global extinction of at least one native crayfish species. However, most species are still relatively unaffected, but the smaller ranges of most North American crayfishes make them more vulnerable than European crayfishes. Thus, a narrow win- dow of opportunity exists to protect the function of North American aquatic ecosystems, their fish- eries, and the unique biodiversity of crayfishes that they contain.
72 citations
"Native and exotic fish species in t..." refers background or result in this paper
...Another problem is the introduction of exotic species, which is considered as one of the most important but least studied factors that disrupt aquatic ecosystems (MILLS et al., 1993; LEACH, 1995; LODGE et al., 2000; MACK et al., 2000; BYERS et al., 2002)....
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...Literature regarding the impact of exotic species reports numerous examples of the extinction of native species (COWX, 1997; LODGE et al., 2000; MACK et al., 2000)....
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...The pre-existing fish community may be changed greatly as a result of competition for food or other resources (LEVEQUE, 1997), predation (JACKSON and WILLIAMS, 1980; LEVEQUE, 1997), parasitism or the introduction of pathogenic agents (BLANC, 1997; DOVE and ERNST, 1996; LODGE et al., 2000); hybridisation and modification of the environment should also be included as possible harmful effects resulting from the introduction of exotic species....
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...…predation (JACKSON and WILLIAMS, 1980; LEVEQUE, 1997), parasitism or the introduction of pathogenic agents (BLANC, 1997; DOVE and ERNST, 1996; LODGE et al., 2000); hybridisation and modification of the environment should also be included as possible harmful effects resulting from the…...
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...These results seem to support the hypothesis that exotic species have a greater impact when environmental degradation is high and water quality declines (McKINNEY and LOCKWOOD, 1999; GODINHO and FERREIRA, 2000; LODGE et al., 2000)....
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TL;DR: The lower Guadiana fish community changed in space from assemblages characterized by the high relative abundances of Leuciscus pyrenaicus, smaller size-classes of Barbus spp.
Abstract: — A survey of fish assemblages (composition and spatial organization) was made in the lower Guadiana basin (southern Iberia) during the summer of 1994. A total of 6937 specimens belonging to 18 species were collected in 44 channel units and 30 sites (i. c. a series of channel units), comprising all the freshwater species previously recorded in the area except the exotic Esox lucius and the endemic endangered cyprinid Anaecypris hispanica. The endemic cyprinids Chondrostoma lemmingii and Barbus sclateri were rarely encountered, whereas the exotic Lepomis gibbosus was the predominant species found. The lower Guadiana fish community changed in space from assemblages characterized by the high relative abundances of Leuciscus pyrenaicus, smaller size-classes of Barbus spp. and Tropidophoxinellus alburnoides (all Iberian endemisms), to assemblages characterized by the high relative abundances of L. gibbosus, Micropterus salmoides, Cichlasoma facetum (all exotic species) and the larger size-classes of Barbus comiza and Barbus microcephalus. The former assemblages used smaller (i. e., narrow and shallow) sites and channel units, usually in tributaries and closer to headwaters, with smaller L. pyrenaicus being dominant in sites located in the tributaries discharging to the brackish Guadiana. This group was also related to channel units rich in emergent macropthytes. The latter assemblages were related to the largest sites and channel units, typically found in the main river or in tributary sites far from the source. Besides these two groups, some species were associated to noticeable environmental conditions; Blennius fluviatilis to channel units with current velocity and heterogeneous substrate, typically found in the main river, and Cobitis paludica to channel units with heterogeneous substrate.
59 citations
"Native and exotic fish species in t..." refers background or result in this paper
...Although studies on the environmental organization of freshwater fish communities in Italy are still limited, some of the trends revealed by our analysis have been described for other geographic areas (AADLAND, 1991; BELKESSAM et al., 1997; LOBB and ORTH, 1991; SCOPPETTONE, 1993; COLLARES-PEREIRA et al., 1995; GODINHO et al., 1997; GODINHO and FERREIRA, 2000)....
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...…fish communities in Italy are still limited, some of the trends revealed by our analysis have been described for other geographic areas (AADLAND, 1991; BELKESSAM et al., 1997; LOBB and ORTH, 1991; SCOPPETTONE, 1993; COLLARES-PEREIRA et al., 1995; GODINHO et al., 1997; GODINHO and FERREIRA, 2000)....
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TL;DR: In this paper, a hierarchical channel-unit-based habitat classification system for warmwater streams was proposed to evaluate fishes in 11 channel units in both headwater and downstream reaches of an Ozark stream during summer and winter.
Abstract: To evaluate a hierarchical channel-unit-based habitat classification system for warmwater streams, we sampled fishes in 11 channel units in both headwater and downstream reaches of an Ozark stream during summer and winter. There was significantly greater species richness (total number of species) at the downstream reach and greater biomass at the upstream reach, as revealed by multifactor analyses of variance. There were significant differences in both species richness and biomass among channel units and seasons and significant channel unit × season interactions, which together suggest that fish changed habitat use between summer and winter. Cross-validation procedures indicated that the fish assemblages in channel units at the headwater site, which had an average channel unit classification accuracy of 47%, were less predictable than those of downstream reaches, which averaged 61% accuracy. These differences were attributed to differences in habitat specialization between fishes of the headwater...
56 citations
"Native and exotic fish species in t..." refers background in this paper
...In fact, in temperate rivers the species richness progressively increases from mountain to valley (SHELDON, 1968; SCHLOSSER, 1982; BALON et al., 1986; MORIN and NAIMAN, 1990; PONT et al., 1995; BELKESSAM et al., 1997; CHANGEUX, 1995; PETERSON and RABENI, 2001) and this pattern surely characterized the autochthonous populations in the Tiber River in the past (BIANCO, 1990a; BIANCO and KEITMAIER, 2001)....
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...…to valley (SHELDON, 1968; SCHLOSSER, 1982; BALON et al., 1986; MORIN and NAIMAN, 1990; PONT et al., 1995; BELKESSAM et al., 1997; CHANGEUX, 1995; PETERSON and RABENI, 2001) and this pattern surely characterized the autochthonous populations in the Tiber River in the past (BIANCO, 1990a; BIANCO…...
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