Variabilità spazio-temporale della struttura del fitoplancton nel Golfo dell'Asinara (Sardegna) = Spatial and temporal variability of phytoplankton structure in the Asinara Gulf (Sardinia)

The spatio-temporal variability of phytoplankton and some environmental parameters in the gulf of Asinara are examined (05/97-04/98). Along the whole coastal area, stations at 500 and 3000 mfrom coast across 6 transects are considered. Results point out some variations in phytoplankton composition and dynamics. Multidimensional Scaling ordinations and Bray-Curtis cluster analuses identified two major zones at 500 m from coast, one for the site of Lu Bagnu and one for the other five sites; at each stations, a great similarity was found in its respactive share. On the contrary, at 3000 m from coast, no cluster was identified

Il Genere <i>Oscillatoria</i> nel fitoplancton del Lago Mulargia (Sardegna centro-meridionale) nell'arco di sette anni (dal 1985 al 1991)

Il genere Oscillatoria, con le specie Oscillatoria rubescens DC. ed Oscillatoria tenuis Ag., negli ultimi sette anni (dal 1985 al 1991) è stato un elemento costitutivo fondamentale e caratterizante del fitoplancton del Lago Mulargia (Sardegna centro-meridionale). Dal febbraio 1985, subito dopo un'intensa fioritura di O. rubescens, la continua osservazione del fitoplancton del lago ha permesso di rilevare la costante presenza di questa specie, affiancata dal 1989 da O. tenuis

First Integrative Morphological and Genetic Characterization of Tremoctopus violaceussensu stricto in the Mediterranean Sea

An integrative approach based on morphological and genetic analyses was undertaken for the first time to confirm the species identification of Mediterranean samples belonging to the genus Tremoctopus. Sequences of two mtDNA genes (cytochrome c oxidase subunit (COI) and 16S) were generated for the first time from Mediterranean samples. Both the similarity-based identifications and tree-based methods indicated that three females can be identified as Tremoctopus violaceus sensu stricto in agreement with their morphological classifications. All Mediterranean sequences clustered with the sequences of Tremoctopus violaceus from the Gulf of Mexico and were clearly differentiated from the sequences attributed to T. gracilis and T. robsoni. The chromatic pattern of the web and some features of gill filaments, arms formula, stylets, radulae, beaks, and stomach contents were given for all the samples; 105,758, 20,140, and 11,237 oocytes were estimated in the mature, immature, and developing samples, respectively. The presence of four spermatangia inside the cavity of the maturing female suggested the ability of this species to mate before reaching full maturity with more partners. Age investigation using beaks, performed for the first time in T. violaceus and within the genus gave results consistent with the different sizes and maturity conditions of the samples