87,792 research outputs found
IMPACT 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
Knowledge-based bioinformatics for the study of mammalian oocytes
No full textBioinformatics tools have been recently applied to study the differentiation of the mammalian oocyte during folliculogenesis. In this review, we will summarize our knowledge of 1) the use of biological databases for the extraction of relevant information, 2) bioinformatics methods for knowledge extraction and representation, 3) the application of these methods to the study of mammalian oocyte differentiation and 4) state-of the-art prediction approaches for the assessment and estimation of the cell differentiation status
Diet of Phalacrocorax carbo sinensis (Aves, Phalacrocoracidae)on transitional environments of the central-western Sardinia
No full text
Spectral theory of weighted hypergraphs via tensors
No full textOne way to study a hypergraph is to attach to it a tensor. Tensors are a generalization of matrices, and they are an efficient way to encode information in a compact form. In this paper, we study how properties of weighted hypergraphs are reflected on eigenvalues and eigenvectors of their associated tensors. We also show how to efficiently compute eigenvalues with some techniques from numerical algebraic geometry
Hydrogen absorption processes in Mg(2)Ni-based systems: Thermal and mechanochemical kinetics
No full textMg2Ni/Ni and LaMg2Ni alloy powders were exposed to hydrogen under isothermal and
mechanical treatment conditions. In the former case, the amount of hydrogen absorbed
tends with time to a final asymptotic value. Once such a value has been reached, further
hydrogen absorption can be obtained only by submitting the powders to mechanical processing
in the presence of hydrogen. Hydrogen absorption processes under isothermal and
mechanical treatment conditions exhibited different kinetics and their rates have been
compared on a phenomenological basis starting from kinetic evidences. It appeared that
mechanical treatment enhances the rate of hydrogen absorption by four orders of
magnitude as a consequence of a mix of surface area enlargement, temperature rise and local structural excitation processes
Effects of reduction of photosynthetic radiation on the vegetative and fruiting performance of the 'Nonpareil' almond cultivar
No full text- …
