1,720,963 research outputs found
Monitoraggio bionomico, rilevamento dati biometrici pescato e marcatura crostacei decapodi nei compendi ittici Sardegna centro occidentale (Oristano – Putzuidu)
No full textMonitoraggio delle attività di predazione del cormorano sulle specie ittiche di interesse produttivo. Provincia di Oristano.
No full textMonitoraggio delle attività di predazione del cormorano sulle specie ittiche di interesse produttivo. Provincia del Sulcis.
No full textIMPACT OF Phalacrocorax carbo sinensis (AVES, PHALACROCORACIDE) ON TRANSITIONAL ENVIRONMENTS IN CENTRAL-WESTERN SARDINIA
No full textIMPACT OF Phalacrocorax carbo sinensis (AVES, PHALACROCORACIDE) ON TRANSITIONAL ENVIRONMENTS IN CENTRAL-WESTERN SARDINIA
1BUTTU S., 1MULAS A., 1PALMAS F.
1Dipartimento di Scienze della Vita e dell’Ambiente – Università degli Studi di Cagliari,
Via T.Fiorelli, 1 – 09126, Cagliari
[email protected]
Sardinia, for its peculiar environmental characteristics, the relative abundance and the quality of its lagoons and ponds, hosts the biggest wintering population of the Cormorant (Phalacrocorax carbo sinensis) on the Italian territory. Since the early ‘80s this species has began to rise considerably, probably due to conservation programs held in North Europe colonies. This fast population growth is cause of major concern among fishermen, afraid for the loss of the fish stocks.
In this work we analyse, through the mucous mixtures method (flock or bolus), the diet composition of the cormorants from the colony located in Cabras lagoon dormitory (ZPS ITB034008), to evaluate which species were more preyed and their impact on fisheries. The study of the diet was conducted during the wintering season 2010/2011, between October and March. A total of 438 pellets were collected. Through morphological analysis of hard body parts, such as otoliths found in the flock, it was possible to evaluate biomass and prey species composition as well as the average daily consumption.
The trophic spectrum was dominated almost exclusively by euryhaline fish species. The most important preys, by frequency of occurrence, belonged to Mugilidae (86%), Moronidae (7%), Atherinidae (4%) and Sparidae (3%) families. Regarding the qualitative composition of the diet, Mugilidae (mainly Liza spp. and Mugil spp. ) showed the highest index of relative importance (%IRI = 97,656). Moronidae (%IRI = 2,185) represented the second most important prey taxon, while Sparidae were the less (%IRI = 0,001). The values of percentage prey biomass of the entire wintering season amounted to 87% for Mugilidae and 10% for Moronidae, while the remaining 3% is represented by other prey taxa. Based on the data collected, it was estimated an average daily consumption (Daily Food Intake) of 478.4 g / day for example.
The Cabras lagoon represents the main Cormorants feeding area in Sardinia, with the highest concentration of specimens of the entire island. This fragile system seems to have reached, for some years, the carrying capacity in terms of presence of ichthyophagous birds, and it appears to have established a situation of balance between the various components of the ecosystem, which still requires constant monitoring
Impact of Phalacrocorax carbo sinensis (Aves, Palacrocoracide) on transitional environments in Central-Western Sardinia
No full textIMPACT OF Phalacrocorax carbo sinensis (AVES, PHALACROCORACIDE) ON TRANSITIONAL ENVIRONMENTS IN CENTRAL-WESTERN SARDINIA
1BUTTU S., 1MULAS A., 1PALMAS F.
1Dipartimento di Scienze della Vita e dell’Ambiente – Università degli Studi di Cagliari,
Via T.Fiorelli, 1 – 09126, Cagliari
[email protected]
Sardinia, for its peculiar environmental characteristics, the relative abundance and the quality of its lagoons and ponds, hosts the biggest wintering population of the Cormorant (Phalacrocorax carbo sinensis) on the Italian territory. Since the early ‘80s this species has began to rise considerably, probably due to conservation programs held in North Europe colonies. This fast population growth is cause of major concern among fishermen, afraid for the loss of the fish stocks.
In this work we analyse, through the mucous mixtures method (flock or bolus), the diet composition of the cormorants from the colony located in Cabras lagoon dormitory (ZPS ITB034008), to evaluate which species were more preyed and their impact on fisheries. The study of the diet was conducted during the wintering season 2010/2011, between October and March. A total of 438 pellets were collected. Through morphological analysis of hard body parts, such as otoliths found in the flock, it was possible to evaluate biomass and prey species composition as well as the average daily consumption.
The trophic spectrum was dominated almost exclusively by euryhaline fish species. The most important preys, by frequency of occurrence, belonged to Mugilidae (86%), Moronidae (7%), Atherinidae (4%) and Sparidae (3%) families. Regarding the qualitative composition of the diet, Mugilidae (mainly Liza spp. and Mugil spp. ) showed the highest index of relative importance (%IRI = 97,656). Moronidae (%IRI = 2,185) represented the second most important prey taxon, while Sparidae were the less (%IRI = 0,001). The values of percentage prey biomass of the entire wintering season amounted to 87% for Mugilidae and 10% for Moronidae, while the remaining 3% is represented by other prey taxa. Based on the data collected, it was estimated an average daily consumption (Daily Food Intake) of 478.4 g / day for example.
The Cabras lagoon represents the main Cormorants feeding area in Sardinia, with the highest concentration of specimens of the entire island. This fragile system seems to have reached, for some years, the carrying capacity in terms of presence of ichthyophagous birds, and it appears to have established a situation of balance between the various components of the ecosystem, which still requires constant monitoring
Differences in a diet of breeding Cormorants Phalacrocorax carbo sinensis in inland colony: an effect of seasons, breeding stages and colony parts
No full textA study of the diet of the Great Cormorant Phalacrocorax carbo sinensis (fish species and size) in (1) different seasons (years), (2) breeding stages (incubation and chick rearing), and (3) breeding areas (center and edge) in the colony in the Dzierno-Due Reservoir (southern Poland) was carried out. Overall, 147 pellets of the Great Cormorant were analysed. The low values of the indexes of Levin (Bi) and Shannon (H') showed a limited trophic spectrum in the diet of the Great Cormorant. Roach (Rutilus rutilus) with a percentage index of relative importance (%IRI) of 62.89, perch (Perca fluviatilis) (%IRI = 22.63) and carp (Cyprinus carpio) (%IRI = 10.43), were the most common prey. Evident changes in the diet between 2003 and 2014, with less roach and more perch and ruffe in 2014 were found. They could be probably related to changes in the fish community. Differences in the food of cormorants between breeding stages reflected dietary requirements of the chicks. During the breeding season younger chicks require feeding with smaller fish than older chicks. The proportion of fish species found in the cormorant diet differed between the edge and the centre of the colony. We concluded that the impact of Great Cormorants on native fish assemblages may be dependent on the location within the colony, development state of the chicks and season, not just fish availability
Estimated impact of the horizontal net opening in the calculation of biomass index in the trawl survey
No full textDistribution of nursery areas of Aristaemorpha foliacea (Risso, 1827) in the Sardinia seas
No full textImpact of Phalacrocorax carbo sinensis (Aves, Phalacrocoracidae) on the fishery resources of a Sardinian lagoon
No full textThe negative impact of ichthyophagous birds on fish stocks are now matter of great concern. The aim of this study is to assess the wintering diet of the Great Cormorant (Phalacrocorax carbo sinensis) in the S. Antioco lagoon (south-western Sardinia). Through the morphological analysis of undigested hard body parts, such as otoliths, it was possible to trace to the preyed species, their size, biomass and, then, to the average daily consumption of cormorants
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