The aim of the study was to elucidate the microbial processes related to C and P biogeochemical cycles which occur at the surface layer (5-100 m) of the Ionian Sea during late autumn period. Two successive steps, concerning respectively the enzymatic hydrolysis of proteins, polysaccharides and organic phosphates and the incorporation of the released monomers into new microbial biomass were investigated, together with the abundance and biomass of total bacterioplankton and picophytoplankton and measurement of chlorophyll-a content as an index of phytoplankton biomass. Three main hydrological areas (Central Eastern -ICOr, Central- IC and Central-Western-Sicily Channel -ICOc-CS) with distinctive characteristics were identified by the analysis of 6 microbiological variables. ICOc-CS area was characterised by the highest values of microbial activity (production and decomposition) and consumption of inorganic phosphorus (Pi). IC area showed high potential mineralisation rates of organic phosphates and glycosides, while low total bacterioplankton and picophytoplankton abundances were found. In IC and ICOr areas, the high values of potentially mineralised Pi: consumed Pi ratio (59 and 250 respectively) provide the supply of Pi for further productive processes.
Lo studio ha avuto come obiettivo principale individuare i processi microbici legati ai cicli biogeochimici del carbonio e fosforo che avvengono simultaneamente nello strato superficiale (5-100 m) del Mar Ionio durante il periodo tardo autunnale. L'analisi simultanea di sei variabili microbiologiche ha permesso di individuare tre aree ben distinte fra loro (Centro Orientale -ICOr, Centro- IC e Centro Occidentale-Canale di Sicil - ICOc-CS) caratterizzate anche dalle loro proprietà idrologiche. I valori più elevati di attività (produzione batterica eterotrofica, attività proteolitica) e di consumo potenziale autotrofico ed eterotrofico di fosfati inorganici (Pi) sono stati riscontrati nell'area ICOc-CS; l'area IC è risultata invece caratterizzata da un elevato tasso di mineralizzazione potenziale dei fosfati organici e poli ßglucosidi e da bassi conteggi di cellule batteriche e di picofitoplancton. Nelle aree IC ed ICOr i valori del rapporto Pi potenzialmente mineralizzato: Pi potenzialmente consumato (59 e 250 rispettivamente) assicurano una elevata quantità di Pi disponibile per ulteriori processi produttivi.
Attività e biomasse microbiche nelle acque superficiali del mar Ionio.
Monticelli LS;Caruso G;Azzaro F;Azzaro M;La Ferla R;Leonardi M;Maimone G;Decembrini F
2008
Abstract
The aim of the study was to elucidate the microbial processes related to C and P biogeochemical cycles which occur at the surface layer (5-100 m) of the Ionian Sea during late autumn period. Two successive steps, concerning respectively the enzymatic hydrolysis of proteins, polysaccharides and organic phosphates and the incorporation of the released monomers into new microbial biomass were investigated, together with the abundance and biomass of total bacterioplankton and picophytoplankton and measurement of chlorophyll-a content as an index of phytoplankton biomass. Three main hydrological areas (Central Eastern -ICOr, Central- IC and Central-Western-Sicily Channel -ICOc-CS) with distinctive characteristics were identified by the analysis of 6 microbiological variables. ICOc-CS area was characterised by the highest values of microbial activity (production and decomposition) and consumption of inorganic phosphorus (Pi). IC area showed high potential mineralisation rates of organic phosphates and glycosides, while low total bacterioplankton and picophytoplankton abundances were found. In IC and ICOr areas, the high values of potentially mineralised Pi: consumed Pi ratio (59 and 250 respectively) provide the supply of Pi for further productive processes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
