title: Effects of N and P availability on carbon allocation in the toxic dinoflagellate Ostreopsis cf. ovata.
abstract: Blooms of the toxic dinoflagellate Ostreopsis cf. ovata are usually associated with shallow and calm coastal waters, characterized by low nutrient concentrations. The algal cells typically cover the benthic substrates, such as the macroalgal and invertebrate communities and rocks, forming a mucilaginous film. Data reported on O. cf. ovata toxin production observed under both field and culture conditions show high variability in terms of toxic profile and cellular content; little is known about the environmental and physiological aspects which regulate the toxin dynamics. In this study, O. cf. ovata physiology was investigated using batch cultures supplied with nutrient concentrations similar to those found in the Adriatic Sea during the recurrent blooms and the observed cellular dynamics were compared with those found in a culture grown under optimal conditions, used as a reference. Data on the cellular C, N and P content during the growth highlighted a possible important role of the cellular nutritional status in regulating the toxin production that resulted to be promoted under specific intervals of the C:N and C:P ratios. The variable toxicity found for O. cf. ovata in various geographic areas could be related to the different in situ prevalent environmental conditions (e.g., nutrient concentrations) which affect the cellular elemental composition and carbon allocation. The obtained results strongly suggest that in the environment toxin production is steadily sustained by a low and constant nutrient supply, able to maintain appropriate cellular C:N (>12) or C:P (>170) ratios for a long period. These results explain to some extent the variability in toxicity and growth dynamics observed in blooms occurring in the different coastal areas.
authors.affiliation: Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via S'Alberto 163, 48123 Ravenna, Italy. Electronic address: laura.pezzolesi@unibo.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Pezzolesi
authors.affiliation: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, Viale Ferdinando d'Alcontres 31, 98166 S. Agata, Messina, Italy.
authors.forename: Silvana
authors.initials: S
authors.lastname: Vanucci
authors.affiliation: Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Dell'Aversano
authors.affiliation: Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy.
authors.forename: Emma
authors.initials: E
authors.lastname: Dello Iacovo
authors.affiliation: Department of Pharmacy, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy.
authors.forename: Luciana
authors.initials: L
authors.lastname: Tartaglione
authors.affiliation: Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via S'Alberto 163, 48123 Ravenna, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Pistocchi
mesh_terms: D002244:Carbon / Q000378:metabolism*; D004141:Dinoflagellida / Q000737:chemistry / Q000378:metabolism*; D057097:Harmful Algal Bloom; D008387:Marine Toxins / Q000737:chemistry; D008522:Mediterranean Sea; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry*; D013696:Temperature
chemical_list: D008387:Marine Toxins; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen
keywords: C:N; C:P; N:P; Nutrients; Ostreopsis; Ovatoxins