1,721,027 research outputs found
Musei scrigni di storia: l'isola che non cè ̈ più
No full textPer fenomeni vulcanici al largo della parte meridionale della Sicilia, nel Mar di Sciacca, emerse nel 1831 un'isolotto che ebbe breve vita. sprofondò di nuovo dopo soli 3 mesi. Molti paesi europei ne rivendicarono la nazionalità
Oligochetes in the Southern basin of the Venetian Lagoon: community composition, species abundance and biomass.
No full textThe oligochaete community of the Chioggia Lagoon (southern basin of the Venetian Lagoon) has been studied from May 1992 to May 1994, at ten fixed sampling stations, distributed across the lagoon. Numerous data regarding composition, abundance, biomass and the breeding periods of the species in the community have been obtained. Nine tubificid species, recently reported for the Mediterranean and Ponto-Caspian areas have been collected. Among them only three were abundant everywhere, except in the innermost part of the lagoon, and throughout the year: Tubificoides vestibulatus, T. swirencowi and Limnodriloides maslinicensis. Only one enchytraeid genus, Grania, has been found restricted to an area near the connection with the sea. The values for the Shannon Diversity Index for the community never exceeded 0.8 and were mainly between 0.4 and 0.7. The most interesting result was the decrease of abundance and biomass, proceeding from the sea mouth (about 6000 ind m–2) towards the innermost part of the lagoon (less than 100 ind. m–2). Correlations are suggested with the different grain size of the sediment
Il corallo:Minerale, Pianta, Animale?
No full textA lungo nei secoli scorsi la natura animale dei coralli rimase sconosciuta. Solo nell'800 si comincio ad identificare correttamente questi "prodotti del mare
Life cycle and Karyology of Branchiura sowerbyi Beddard (Oligochaeta, Tubificidae)
No full textData on the life-cycle of a population of Branchiura sowerbyi Beddard in a water-lily tank at the Botanical Garden in Padua are reported. The breeding period is from April to July, after which the reproductive system is partially resorbed (August–September) and reformed later in the autumn. The karyology of the species was also studied, and revealed 38 mitotic chromosomes in the gonia, and 19 bivalents in the primary spermatocytes and in the primary oocytes
Oligochaetes of the Karavasta Lagoon (Albania). Preliminary results.
No full textIn a study of the composition and structure of the benthic community of the Lagoon of Karavasta (Albania),carried out in June 1996, a peculiar distribution of oligochaetes was observed. Four species of tubificids were collected, together with 32 species of other benthic invertebrates (crustaceans, polychaetes, molluscs, nemerteans and chironomids). The oligochaete species found are well-known for the Adriatic coast. Their distribution in the lagoon was mostly restricted to a longitudinal zone near the sea and their densities decreased landwards, to be completely replaced by other faunal groups (particularly chironomids and molluscs). Zonation was distinct
according to a salinity gradient and variable hydrodynamic and sediment characteristics
Le "tegnue" del Golfo di Venezia: una sorprendente ricchezza di fauna rara da proteggere
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