title: Relevance of the dinoflagellate Gonyaulax fragilis in mucilage formations of the Adriatic Sea.
abstract: Oceanographic cruises were carried out monthly from June 1999 to July 2002 to follow the mucilage formation process in the Northern Adriatic Sea. Results show that in correspondence with these events the dinoflagellate Gonyaulax fragilis (Schütt) Kofoid was observed both in the water column and within mucilage aggregates. In the water column, increasing abundances were observed from May until July, with values never exceeding 8500 cells l(-1). Much higher densities were observed within superficial gelatinous aggregates (22800-3400000 cells l(-1)). In mucilage samples, a large number of decomposing cells were present, together with abundant alive cells, enveloped in exudates. G. fragilis isolated from mucilage samples was cultured in three different culture media; it was characterized by a low growth rate but it produced a high amount of polysaccharides. The highest yield both in terms of cell number and carbohydrate production was observed in the medium having the highest nitrogen and phosphorus content and the lowest N/P ratio. The monomeric composition of G. fragilis carbohydrates, compared with that of mucilage samples, showed that in both natural and cultured samples galactose was the most abundant sugar; in addition, an overall good correlation, especially between the monomeric carbohydrate composition of G. fragilis grown in f/2 medium and that of a mucilage sample in which this species was present in high density, was observed.
authors.affiliation: Centro Interdipartimentale di Ricerca per le Scienze Ambientali, Università di Bologna, Via Sant'Alberto 163, 48100 Ravenna, Italy. rossella.pistocchi@unibo.it
authors.forename: Rossella
authors.initials: R
authors.lastname: Pistocchi
authors.forename: Monica
authors.initials: M
authors.lastname: Cangini
authors.forename: Cecilia
authors.initials: C
authors.lastname: Totti
authors.forename: Ranieri
authors.initials: R
authors.lastname: Urbani
authors.forename: Franca
authors.initials: F
authors.lastname: Guerrini
authors.forename: Tiziana
authors.initials: T
authors.lastname: Romagnoli
authors.forename: Paola
authors.initials: P
authors.lastname: Sist
authors.forename: Simona
authors.initials: S
authors.lastname: Palamidesi
authors.forename: Laurita
authors.initials: L
authors.lastname: Boni
authors.forename: Marinella
authors.initials: M
authors.lastname: Pompei
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000737:chemistry / Q000254:growth & development*; D017753:Ecosystem; D008386:Marine Biology / Q000706:statistics & numerical data*; D008522:Mediterranean Sea; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D011134:Polysaccharides / Q000032:analysis; D011157:Population Dynamics; D012623:Seawater / Q000469:parasitology*; D015048:Zooplankton / Q000737:chemistry / Q000254:growth & development*
chemical_list: D011134:Polysaccharides; D010758:Phosphorus; D009584:Nitrogen