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 introduced goby Padogobius bonelli has established abundant populations in the River Tiber basin (Central Italy) and its expansion coincided with the decrease of the endemic P. nigricans populations.
Abstract: The introduced goby Padogobius bonelli has established abundant populations in the River Tiber basin (Central Italy) and its expansion coincided with the decrease of the endemic P. nigricans. P. bonelli exhibits a more aggressive behaviour than P. nigricans, but other biological attributes may advance its colonization success. To test this hypothesis, some reproductive parameters (gonado-somatic index, age at maturity, egg size, absolute and relative fecundity) of a long-time established non-native population of P. bonelli were analysed and compared to a population from the native area as well as to those of P. nigricans inhabiting the same river. As a result, no differences between non-native and native populations of P. bonelli were observed. On the contrary, non-native P. bonelli showed higher values of gonado-somatic index for both sexes, a more protracted spawning season and produced a greater number of eggs than P. nigricans. These results indicated a greater reproductive output of P. bonelli that can enhance its invasion process and favour the expansion outside of its native range, causing further decline of P. nigricans populations.
4 citations
Cites background from "Native and exotic fish species in t..."
...The survival of endemic fishes is threatened by several factors such as pollution, habitat modification, dam construction (Lorenzoni et al., 2006; Cucherousset & Olden, 2011; Ribeiro & Leunda, 2012; Franchi et al., 2014) and introduction of non-native species, that is widely counted as the second…...
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TL;DR: Evidence of growth differences between sexes was found, with males living longer and reaching larger sizes and condition was lower in females than in males, especially during the breeding period due to the strain of high reproduction.
Abstract: Summary
In this study, data of Padogobius nigricans, a species endemic to Central Italy, were used to assess the age, growth parameters and condition of this species. Length–weight relationships are also provided and represent the first available reference in the literature for the Arno goby. Data were collected in the Aggia River, a tributary of the Tiber River, by monthly samplings. A total of 780 specimens ranging in size from 1.5 to 9.2 cm were analyzed. Age was assessed by examination of scales, with the maximum age of 4+ years observed in males and 3+ in females. Previous growth was determined by back-calculation of scale measurements. The von Bertalanffy growth parameters were estimated separately for sexes (males: L∞ = 9.759 cm, k = 0.505, t0 = 0.025, Ф′ = 1.682; females: L∞ = 8.989, k = 0.458, t0 = 0.028; Ф′ = 1.599). Evidence of growth differences between sexes was found, with males living longer and reaching larger sizes. Using the relative condition factor, condition was lower in females than in males, especially during the breeding period due to the strain of high reproduction. Competition with the congeneric P. bonelli, a species endemic to Northern Italy that was introduced in Central Italy, seems not to have been disadvantaged directly by the growth of P. nigricans in the Aggia River, since no selective size-mortality occurred in the population.
2 citations
Cites background from "Native and exotic fish species in t..."
...34′′E) is a small right tributary of the Tiber River, which is the third-longest (405 km) river in Italy and second in watershed area (17 375 km(2)) (Lorenzoni et al., 2006)....
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...The Aggia River (43°2408.57″N; 12°12040.34″E) is a small right tributary of the Tiber River, which is the third-longest (405 km) river in Italy and second in watershed area (17 375 km2) (Lorenzoni et al., 2006)....
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01 Jan 2010
TL;DR: It is demonstrated that the various fishing techniques can be effectively combined with the aim of controlling the goldfish population in Lake Trasimeno by analysing the selectivity of the equipment used to control this invasive species.
Abstract: Key-words: gill-net selectivity, invasive species, electrofishing, CPUEs The fishery biology of the goldfish Carassius auratus was studied in Lake Trasimeno by analysing the selectivity of the equipment that can be used to control this invasive species. Sampling was conducted monthly from February 2003 to January 2004 by means of electrofishing, fyke-nets and gill-nets of different-sized mesh (22, 25, 28, 35, 40, 50, 70 and 80 mm). The average value of the CPUEs of goldfish caught was 10175.48 g·10 −2 ·m −2 for gill-nets, 246.97 g·h −1 for fyke-nets and 606.50 g·min −1 for electrofishing. The efficiency of electrofishing was not uniform in all periods of the year, the mean CPUEs being highest in spring, when specimens of reproductive age were preferentially caught. Gill-nets yielded abundant catches of goldfish in all seasons, and displayed good sampling efficiency even in winter. With regard to the selectivity of gill-nets, estimated optimum selection lengths for each mesh size were: 11.92 cm, 13.55 cm, 15.18 cm, 18.97 cm, 21.68 cm, 27.10 cm, 37.94 cm and 43.36 cm. The results of this research demonstrate that the various fishing techniques can be effectively combined with the aim of controlling the goldfish population in Lake Trasimeno.
2 citations
TL;DR: In this paper , the authors analyzed the status of Mediterranean trout inhabiting 8 C&R areas of the Nera River Basin and compared the results with those from 11 exploited areas and 15 no-fishing areas.
2 citations
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