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: The traditional North American Relative Stock D density (RSD) and Proportional Stock Density (PSD) indices are adapted to brown trout populations in Central Italy by means of two methods to provide insight into the population structures of brown trout.
Abstract: The purpose of this study was to provide reference data on the growth and population structure of brown trout Salmo (trutta ) trutta Linnaeus, in Central Italy. Standards for growth (percentiles and a standard growth model) were developed from the von Bertalanffy growth model by using length-at-age data obtained from 122 sampling sites in the River Tiber basin. Length-frequency indices provide a numeric estimation for deviations of the population structure from a balanced population. We adapted the traditional North American Relative Stock Density (RSD) and Proportional Stock Density (PSD) indices to brown trout populations in Central Italy by means of two methods. In the first method, the benchmarks of length categories were established by using percentages applied to the largest individual in the dataset. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from 263 sampling sites in the River Tiber basin. The results showed that the PSD calculated by the first method provided a better insight into the population structures of brown trout.These results provide tools that will help ichthyologists and fish managers to compare the growth and population structure of brown trout throughout Central Italy.
11 citations
Cites background from "Native and exotic fish species in t..."
...More detailed information on the characteristics of the River Tiber basin and its fish populations is available in Lorenzoni et al. (2006)....
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TL;DR: The results of gill-nets selectivity gave important information to design a plan to control this species and confirmed that the use of suitable fishing techniques could be useful to manage the population of this alien species in Piediluco lake as well as in other similar environments.
Abstract: Key-words: growth, gill-net selectivity, alien species, euthrophic lake, fisheries management The analysis of catch selectivity of fishing equipment is a crucial step for the management of alien species in freshwater ecosystems. Roach Rutilus rutilus was introduced in many waterways in Italy often becoming the dominant species of the fish community and it is now considered potential pest. In Piediluco lake the species was first found in 2004 and its abundance has increased at a level that creates concern for the other fish species present in the lake. The growth of R. rutilus and the selectivity of gill-nets on its population were examined in Piediluco lake by analysing the selectivity of gill-nets of different mesh size. Sampling was conducted from January 2011 to October 2012 by means of gill-nets of differentsized mesh (8, 10, 12.5, 15.5, 19.5, 24, 28, 35, 45 and 55 mm). The results showed that R. rutilus in Piediluco lake had a growth faster and higher than in many other lake environments. The results of gill-nets selectivity gave important information to design a plan to control this species and confirmed that the use of suitable fishing techniques could be useful to manage the population of this alien species in Piediluco lake as well as in other similar environments.
10 citations
Cites background from "Native and exotic fish species in t..."
...Linnaeus, 1758 can be considered extinct (Lorenzoni et al., 2006); the remaining 11 are all introduced (Lorenzoni et al....
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...This ecological trait of roach represents a threat for this environment, as this could lead to a further worsening of water quality through predation of R. rutilus on zooplankton (Lorenzoni et al., 2006)....
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...…in water quality and the gradual transition toward a eutrophic status has led to a drastic change in the native fish communities of Piediluco lake (Lorenzoni et al., 2006): only 6 species of the original community (Table I) are still present [eel Anguilla anguilla (Linnaeus, 1758) Southern pike…...
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...The change in water quality and the gradual transition toward a eutrophic status has led to a drastic change in the native fish communities of Piediluco lake (Lorenzoni et al., 2006): only 6 species of the original community (Table I) are still present [eel Anguilla anguilla (Linnaeus, 1758) Southern pike Esox cisalpinus Bianco and Delmastro, 2011, brown trout Salmo trutta Linnaeus,1758, Italian rudd Scardinius hesperidicus Bonaparte, 1845, cavedano chub Squalius squalus (Bonaparte, 1837) and tench Tinca tinca (Linnaeus, 1758)] while Italian roach Rutilus rubilio (Bonaparte, 1837) and three-spined stickleback Gasterosteus aculeatus...
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...…(Bonaparte, 1837) and tench Tinca tinca (Linnaeus, 1758)] while Italian roach Rutilus rubilio (Bonaparte, 1837) and three-spined stickleback Gasterosteus aculeatus 07p3 Linnaeus, 1758 can be considered extinct (Lorenzoni et al., 2006); the remaining 11 are all introduced (Lorenzoni et al., 2012)....
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TL;DR: The purposes of this paper were to analyze dietary composition of the two species, determine the degree of overlap in their diets and investigate the feeding ecology of P. nigricans in terms of absence and presence of the alien species.
Abstract: The Arno goby Padogobius nigricans is an endemic species to Central Italy. The populations of this species are in sharp decline due to habitat modifications and potentially competition with Padanian goby Padogobius bonelli, an endemic species to Northern Italy, introduced in some watercourses of Central Italy. The purposes of this paper were to analyze dietary composition of the two species, determine the degree of overlap in their diets and investigate the feeding ecology of P. nigricans in terms of absence and presence of the alien species. Specimens were collected from the Aggia River, a tributary of Tiber River. Gut contents were analyzed and prey items were identified to the lowest recognizable taxa and counted. All the obtained results showed that P. nigricans and P. bonelli in the Aggia River share a similar diet. Both species fed extensively on Chironomids and no statistically significant ontogenetic changes in feeding habits were found. A high degree of diet overlap was observed. Diet of P. nigricans and P. bonelli also included fish and where the species live in syntopy, individuals belonging to Padogobius genus were found in stomach, suggesting that mutual predation may occur.
10 citations
Cites background from "Native and exotic fish species in t..."
...(405 km) river in Italy and the second for watershed (17,375 km(2)) (Lorenzoni et al., 2006)....
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...Study area The Aggia River (43 2408.5700N, 12 12040.3400E) is a right tributary of the Tiber River, the third-longest (405 km) river in Italy and the second for watershed (17,375 km2) (Lorenzoni et al., 2006)....
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...It has successfully colonized the upper and middle sectors of Tiber over the last years (Lorenzoni et al., 2006), and now it is spreading in the tributaries (Lorenzoni et al., 2010)....
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...It has successfully colonized the upper and middle sectors of Tiber over the last years (Lorenzoni et al., 2006), and now it is spreading in the tributaries (Lorenzoni et al....
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TL;DR: In this paper, a spatial multicriteria analysis is proposed to analyze the opportunities of nature-based tourism development in N2K in Umbria, one of the Regions of central Italy, which consists of 102 sites.
9 citations
TL;DR: Amur sleeper (Perccottus glenii) is currently one of the most invasive fish species in Europe as mentioned in this paper, and its occurrence, abundance, population size structure and impact on indicators of diversity were examined in oxbow lakes of both rivers.
Abstract: Amur sleeper (Perccottus glenii) is currently one of the most invasive fish species in Europe. This inspired our research to identify potential channels of emigration in two rivers, the Vistula and the Wieprz. Amur sleeper occurrence, abundance, population size structure and impact on indicators of diversity were examined in oxbow lakes of both rivers. Amur sleeper was recorded for the first time in floodplain areas located between two rivers, which may serve as main travel corridors. Amur sleeper was noted in four out of six oxbow lakes in each river. Its relative abundance varied depending on the oxbow lake, ranging from 0.002 to 1.60 ind. m−2 in the basin of the Vistula River and from 0.04 to 0.35 ind. m−2 in the basin of the Wieprz River. Percentage share in the dominance structure ranged from 2.42 to 100 % and from 40 to over 67 % in the oxbow lakes of the Vistula River and Wieprz River, respectively. The size structure of the Amur sleeper populations was dominated by young individuals (Tl < 50 mm), which is characteristic of developing populations. The presence of Amur sleeper did not significantly affect biodiversity indicators. Its occurrence was related to the amount of vegetative cover.
9 citations
Cites background from "Native and exotic fish species in t..."
...Evaluation of the impact of invasive species on ecosystems is extremely difficult and often requires knowledge of the ecosystem existing before the occurrence of the invasive species and a long observation period after its appearance (Lorenzoni et al. 2006; Gaygusuz et al. 2007)....
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References
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Book•
01 Jan 1992
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!
78,324 citations
TL;DR: It is hypothesized that producer and consumer communities characteristic of a given river reach become established in harmony with the dynamic physical conditions of the channel.
Abstract: From headwaters to mouth, the physical variables within a river system present a continuous gradient of physical conditions. This gradient should elicit a series of responses within the constituent...
9,145 citations
"Native and exotic fish species in t..." refers background in this paper
...Fish assemblage composition varied along the Tiber River according to environmental variables, a common feature of stream fish communities (HUET, 1949, 1954, 1962; VANNOTE et al., 1980; MINSHALL et al., 1985; CHANGEUX, 1995)....
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...Habitat controls the longitudinal distribution of fish, and changes in habitat characteristics are often associated with changes in the composition of the fish assemblage (HUET, 1949, 1954, 1962; VANNOTE et al., 1980; MINSHALL et al., 1985; MORIN and NAIMAN, 1990; CHANGEUX, 1995; BELLIARD et al., 1999; ARUNACHALAM, 2000; BUNN and DAVIES, 2000)....
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...…of fish, and changes in habitat characteristics are often associated with changes in the composition of the fish assemblage (HUET, 1949, 1954, 1962; VANNOTE et al., 1980; MINSHALL et al., 1985; MORIN and NAIMAN, 1990; CHANGEUX, 1995; BELLIARD et al., 1999; ARUNACHALAM, 2000; BUNN and DAVIES, 2000)....
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TL;DR: Alkalinity measurements are used in the interpretation and control of water and wastewater treatment processes and can be interpreted in terms of specific substances only when the chemical composition of the sample is known.
Abstract: 1. Discussion Alkalinity of a water is its acid-neutralizing capacity. It is the sum of all the titratable bases. The measured value may vary significantly with the end-point pH used. Alkalinity is a measure of an aggregate property of water and can be interpreted in terms of specific substances only when the chemical composition of the sample is known. Alkalinity is significant in many uses and treatments of natural waters and wastewaters. Because the alkalinity of many surface waters is primarily a function of carbonate, bicarbonate, and hydroxide content, it is taken as an indication of the concentration of these constitutents. The measured values also may include contributions from borates, phosphates, silicates, or other bases if these are present. Alkalinity in excess of alkaline earth metal concentrations is significant in determining the suitability of a water for irrigation. Alkalinity measurements are used in the interpretation and control of water and wastewater treatment processes. Raw domestic wastewater has an alkalinity less than, or only slightly greater than, that of the water supply. Properly operating anaerobic digesters typically have supernatant alkalinities in the range of 2000 to 4000 mg calcium carbonate (CaCO3)/L. 1
7,510 citations
TL;DR: Given their current scale, biotic invasions have taken their place alongside human-driven atmospheric and oceanic alterations as major agents of global change and left unchecked, they will influence these other forces in profound but still unpredictable ways.
Abstract: Biotic invaders are species that establish a new range in which they proliferate, spread, and persist to the detriment of the environment. They are the most important ecological outcomes from the unprecedented alterations in the distribution of the earth's biota brought about largely through human transport and commerce. In a world without borders, few if any areas remain sheltered from these im- migrations. The fate of immigrants is decidedly mixed. Few survive the hazards of chronic and stochastic forces, and only a small fraction become naturalized. In turn, some naturalized species do become invasive. There are several potential reasons why some immigrant species prosper: some escape from the constraints of their native predators or parasites; others are aided by human-caused disturbance that disrupts native communities. Ironically, many biotic invasions are apparently facilitated by cultivation and husbandry, unintentional actions that foster immigrant populations until they are self-perpetuating and uncontrollable. Whatever the cause, biotic invaders can in many cases inflict enormous environmental damage: (1) Animal invaders can cause extinctions of vulnerable native species through predation, grazing, competition, and habitat alteration. (2) Plant invaders can completely alter the fire regime, nutrient cycling, hydrology, and energy budgets in a native ecosystem and can greatly diminish the abundance or survival of native species. (3) In agriculture, the principal pests of temperate crops are nonindigenous, and the combined expenses of pest control and crop losses constitute an onerous "tax" on food, fiber, and forage production. (4) The global cost of virulent plant and animal diseases caused by parasites transported to new ranges and presented with susceptible new hosts is currently incalculable. Identifying future invaders and taking effective steps to prevent their dispersal and establishment con- stitutes an enormous challenge to both conservation and international commerce. Detection and management when exclusion fails have proved daunting for varied reasons: (1) Efforts to identify general attributes of future invaders have often been inconclusive. (2) Predicting susceptible locales for future invasions seems even more problematic, given the enormous differences in the rates of arrival among potential invaders. (3) Eradication of an established invader is rare, and control efforts vary enormously in their efficacy. Successful control, however, depends more on commitment and continuing diligence than on the efficacy of specific tools themselves. (4) Control of biotic invasions is most effective when it employs a long-term, ecosystem- wide strategy rather than a tactical approach focused on battling individual invaders. (5) Prevention of invasions is much less costly than post-entry control. Revamping national and international quarantine laws by adopting a "guilty until proven innocent" approach would be a productive first step. Failure to address the issue of biotic invasions could effectively result in severe global consequences, including wholesale loss of agricultural, forestry, and fishery resources in some regions, disruption of the ecological processes that supply natural services on which human enterprise depends, and the creation of homogeneous, impoverished ecosystems composed of cosmopolitan species. Given their current scale, biotic invasions have taken their place alongside human-driven atmospheric and oceanic alterations as major agents of global change. Left unchecked, they will influence these other forces in profound but still unpredictable ways.
6,195 citations
"Native and exotic fish species in t..." refers background 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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TL;DR: In this article, a new multivariate analysis technique, called canonical correspondence analysis (CCA), was developed to relate community composition to known variation in the environment, where ordination axes are chosen in the light of known environmental variables by imposing the extra restriction that the axes be linear combinations of environmental variables.
Abstract: A new multivariate analysis technique, developed to relate community composition to known variation in the environment, is described. The technique is an extension of correspondence analysis (reciprocal averaging), a popular ordination technique that extracts continuous axes of variation from species occurrence or abundance data. Such ordination axes are typically interpreted with the help of external knowledge and data on environmental variables; this two—step approach (ordination followed by environmental gradient identification) is termed indirect gradient analysis. In the new technique, called canonical correspondence analysis, ordination axes are chosen in the light of known environmental variables by imposing the extra restriction that the axes be linear combinations of environmental variables. In this way community variation can be directly related to environmental variation. The environmental variables may be quantitative or nominal. As many axes can be extracted as there are environmental variables. The method of detrending can be incorporated in the technique to remove arch effects. (Detrended) canonical correspondence analysis is an efficient ordination technique when species have bell—shaped response curves or surfaces with respect to environmental gradients, and is therefore more appropriate for analyzing data on community composition and environmental variables than canonical correlation analysis. The new technique leads to an ordination diagram in which points represent species and sites, and vectors represent environmental variables. Such a diagram shows the patterns of variation in community composition that can be explained best by the environmental variables and also visualizes approximately the "centers" of the species distributions along each of the environmental variables. Such diagrams effectively summarized relationships between community and environment for data sets on hunting spiders, dyke vegetation, and algae along a pollution gradient.
5,689 citations