In the last decades the scientific community has assembled a comprehensive set of data on the fate of phytoplankton production from the euphotic layer to the deepest layers of the ocean, based on measurements with sediment traps. This data, however, underestimates the flow of organic matter, because it does not consider the fraction of dissolved organic carbon. In contrast, the estimates of microbial respiration, especially in the deeper layers of the ocean, have received little attention, but they are excellent indicators of the flow of organic matter in aquatic systems, because they estimate the remineralization of different sources of organic carbon (particulate and dissolved). This study focuses on abundance/biomass of prokaryotes and microbial respiration in the water column of the Tyrrhenian Sea, in order to gain a better understanding of the factors that modulate the carbon cycle in environments epi-, meso-and bathy-pelagic. The data was produced in the context of several multidisciplinary projects (MedGOOS, FIRB, CIESM, VECTOR, Vetimer 4) in the Tyrrhenian Sea in a fixed pelagic station from 2005 to 2010 (Lat.N=39°30'; Long.E=13°30'), where a interannual time series was gained. On an annual scale, the parameters examined varied greatly in relation to the trophic status of the epipelagic zone and the trends in the deeper layers basically mirrored the superficial pattern. From the data of microbial biomass, a clear seasonal cycle related to the spring bloom period and the signal of "Summer of St. Martin" appeared. Matching the instantaneous rate of oxygen consumption with the cumulative consumption of oxygen (AOU), two major metabolic pathways emerged by microbial oxidation: a) from POC to DOC in the deep waters, b) DOC to CO2 in the intermediate waters. The biogeochemical implications will be discussed in the light of signal propagation of the "transient" from the Eastern Mediterranean to the study area.
Temporal variability of microbial biomass and respiratory activity in the epi-, meso- and bathypelagic waters of the Tyrrhenian Sea (Mediterranean Sea).
Maurizio Azzaro;Rosabruna La Ferla;Giovanna Maimone;
2011
Abstract
In the last decades the scientific community has assembled a comprehensive set of data on the fate of phytoplankton production from the euphotic layer to the deepest layers of the ocean, based on measurements with sediment traps. This data, however, underestimates the flow of organic matter, because it does not consider the fraction of dissolved organic carbon. In contrast, the estimates of microbial respiration, especially in the deeper layers of the ocean, have received little attention, but they are excellent indicators of the flow of organic matter in aquatic systems, because they estimate the remineralization of different sources of organic carbon (particulate and dissolved). This study focuses on abundance/biomass of prokaryotes and microbial respiration in the water column of the Tyrrhenian Sea, in order to gain a better understanding of the factors that modulate the carbon cycle in environments epi-, meso-and bathy-pelagic. The data was produced in the context of several multidisciplinary projects (MedGOOS, FIRB, CIESM, VECTOR, Vetimer 4) in the Tyrrhenian Sea in a fixed pelagic station from 2005 to 2010 (Lat.N=39°30'; Long.E=13°30'), where a interannual time series was gained. On an annual scale, the parameters examined varied greatly in relation to the trophic status of the epipelagic zone and the trends in the deeper layers basically mirrored the superficial pattern. From the data of microbial biomass, a clear seasonal cycle related to the spring bloom period and the signal of "Summer of St. Martin" appeared. Matching the instantaneous rate of oxygen consumption with the cumulative consumption of oxygen (AOU), two major metabolic pathways emerged by microbial oxidation: a) from POC to DOC in the deep waters, b) DOC to CO2 in the intermediate waters. The biogeochemical implications will be discussed in the light of signal propagation of the "transient" from the Eastern Mediterranean to the study area.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
