Field Experiment to Evaluate Impacts of pH Decrease on Marine Microbial Assemblage
We investigated the role of pH reduction, due to natural CO2 release, on the abundance, distribut... more We investigated the role of pH reduction, due to natural CO2 release, on the abundance, distribution and diversity of planktonic prokaryotes in seawater. A field experiment has been carried out during May 2008 on the seafloor east of Panarea Island in the Southern Thyrrenian Sea (Mediterranean Sea). Approaching the vent field pH values decreased from 8.1 to 6.3. Microbial assemblages are under analysis.
We report here the first findings of testate amoebae at high southern latitudes (54° S) from four... more We report here the first findings of testate amoebae at high southern latitudes (54° S) from four gravity cores recovered in the Lago Fagnano (Tierra del Fuego, Argentina), where twelve taxa have been recognized. Among them, Centropyxis constricta "constricta", Centropyxis elongata, Difflugia globulus, Difflugia oblonga "oblonga", and Difflugia protaeiformis "amphoralis" are always present, while other taxa are randomly distributed. According to the sand/silt ratio in the different cores, the Total Organic Carbon content and the Carbon/Nitrogen ratio, as well as the presence/disappearance and abundance of testate amoebae from cluster analysis, we infer a correlation between major textural/granulometrical changes found in the cores and environmental changes. A seismic event occurred on 1949, which substantially modified the morphology of the eastern Lago Fagnano shoreline and the supply pattern from two main eastern tributaries of the lake, is recorded in the studied cores. This event has in part modified the distribution of testate amoebae taxa within the studied cores. Present results show that testate amoebae represent important indicators to detect changes occurring in the environment in which they live.
, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CT... more , a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
We studied the influence of anomalous meteorological and hydrological conditions that occurred in... more We studied the influence of anomalous meteorological and hydrological conditions that occurred in the Gulf of Trieste from March 2006 to February 2007 on phytoplankton structure and function. We computed monthly mean (or median) air temperature, total precipitation, wind speed, river discharge, seawater temperature, salinity, photosynthetic available radiation (PAR), cyanobacteria, nano-and microphytoplankton abundances during the study year and compared them to climatological (1999-2014 for PAR; 1999-2007 for nanophytoplankton; 1998-2015 for the other variables) mean/median data. We then related the cyanobacteria (0.2-2 μm), nano-(2-20 μm) and microphytoplankton (20-200 μm) of the study year to inorganic nutrient concentrations. Median river inputs in October and November were 9-and 15-fold lower, respectively, than the time series medians, with consequent high salinity from May to November (up to +1.26 compared to the climatological data). Monthly mean seawater temperatures were lower than the climatological values (−2.95°C at the surface) from March to August 2006 and higher (+2.15°C at the surface) from September to February 2007. Reductions in freshwater input and nutrient depletion were likely responsible for a decrease in microphytoplankton (median annual abundance over 60% lower than the climatologic median) and cyanobacteria (up to 47% lower than the climatology). Significant seasonal differences in cyanobacteria and microphytoplankton abundances (R ANOSIM = 0.52; p b 0.05), as well as in seawater temperature and salinity (R ANOSIM = 0.73; p b 0.05) between the study period and the climatology were highlighted. The late spring diatom bloom was not reflected in high photosynthetic rates whereas an unusually high primary production was estimated in November (7.11 ± 1.01 μgC L −1 h −1), when a mucilage event occurred due to very stable atmospheric
A 2 years surveys showed that the variations of pH and of the carbonates system in a coastal area... more A 2 years surveys showed that the variations of pH and of the carbonates system in a coastal area of the northern Adriatic sea resulted mainly affected by the seasonal thermal cycle, by the inputs of carbonates from riverine waters of karstic origin and from degradation processes taking place below the main pycnocline in the warm season. The CO air – sea exchanges showed that the gulf was a sink during cold months and a source during the warm period.
In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observin... more In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observin... more In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
VariaZIONI DEll’ACIDITà, DEL SISTEMA CARBONATICO E DELL’ATTIVITA’BATTERICA IN AcqUE COSTIERE nord adriAtiche Variations in the acidity, carbonate SYSTEM AND Bacterial ACTIVITY IN tHE NoRTH ADRIATIC COASTAL WATERS
ABSTRACT The monthly distributions of prokaryotes, pH, and of the carbonate species were investig... more ABSTRACT The monthly distributions of prokaryotes, pH, and of the carbonate species were investigated in the coastal waters of North Adriatic Sea. Strong decrease of pH occurred particularly during the stratification period in late summer when also an increase in prokaryotic abundances and their production took place.
Field Experiment to Evaluate Impacts of pH Decrease on Marine Microbial Assemblage
We investigated the role of pH reduction, due to natural CO2 release, on the abundance, distribut... more We investigated the role of pH reduction, due to natural CO2 release, on the abundance, distribution and diversity of planktonic prokaryotes in seawater. A field experiment has been carried out during May 2008 on the seafloor east of Panarea Island in the Southern Thyrrenian Sea (Mediterranean Sea). Approaching the vent field pH values decreased from 8.1 to 6.3. Microbial assemblages are under analysis.
We report here the first findings of testate amoebae at high southern latitudes (54° S) from four... more We report here the first findings of testate amoebae at high southern latitudes (54° S) from four gravity cores recovered in the Lago Fagnano (Tierra del Fuego, Argentina), where twelve taxa have been recognized. Among them, Centropyxis constricta "constricta", Centropyxis elongata, Difflugia globulus, Difflugia oblonga "oblonga", and Difflugia protaeiformis "amphoralis" are always present, while other taxa are randomly distributed. According to the sand/silt ratio in the different cores, the Total Organic Carbon content and the Carbon/Nitrogen ratio, as well as the presence/disappearance and abundance of testate amoebae from cluster analysis, we infer a correlation between major textural/granulometrical changes found in the cores and environmental changes. A seismic event occurred on 1949, which substantially modified the morphology of the eastern Lago Fagnano shoreline and the supply pattern from two main eastern tributaries of the lake, is recorded in the studied cores. This event has in part modified the distribution of testate amoebae taxa within the studied cores. Present results show that testate amoebae represent important indicators to detect changes occurring in the environment in which they live.
, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CT... more , a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
We studied the influence of anomalous meteorological and hydrological conditions that occurred in... more We studied the influence of anomalous meteorological and hydrological conditions that occurred in the Gulf of Trieste from March 2006 to February 2007 on phytoplankton structure and function. We computed monthly mean (or median) air temperature, total precipitation, wind speed, river discharge, seawater temperature, salinity, photosynthetic available radiation (PAR), cyanobacteria, nano-and microphytoplankton abundances during the study year and compared them to climatological (1999-2014 for PAR; 1999-2007 for nanophytoplankton; 1998-2015 for the other variables) mean/median data. We then related the cyanobacteria (0.2-2 μm), nano-(2-20 μm) and microphytoplankton (20-200 μm) of the study year to inorganic nutrient concentrations. Median river inputs in October and November were 9-and 15-fold lower, respectively, than the time series medians, with consequent high salinity from May to November (up to +1.26 compared to the climatological data). Monthly mean seawater temperatures were lower than the climatological values (−2.95°C at the surface) from March to August 2006 and higher (+2.15°C at the surface) from September to February 2007. Reductions in freshwater input and nutrient depletion were likely responsible for a decrease in microphytoplankton (median annual abundance over 60% lower than the climatologic median) and cyanobacteria (up to 47% lower than the climatology). Significant seasonal differences in cyanobacteria and microphytoplankton abundances (R ANOSIM = 0.52; p b 0.05), as well as in seawater temperature and salinity (R ANOSIM = 0.73; p b 0.05) between the study period and the climatology were highlighted. The late spring diatom bloom was not reflected in high photosynthetic rates whereas an unusually high primary production was estimated in November (7.11 ± 1.01 μgC L −1 h −1), when a mucilage event occurred due to very stable atmospheric
A 2 years surveys showed that the variations of pH and of the carbonates system in a coastal area... more A 2 years surveys showed that the variations of pH and of the carbonates system in a coastal area of the northern Adriatic sea resulted mainly affected by the seasonal thermal cycle, by the inputs of carbonates from riverine waters of karstic origin and from degradation processes taking place below the main pycnocline in the warm season. The CO air – sea exchanges showed that the gulf was a sink during cold months and a source during the warm period.
In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observin... more In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observin... more In the framework of the ADRICOSM project, from October 2002 to September 2003, a coastal observing system network was set up in the Gulf of Trieste. During this period, 36 CTD cruises were performed over a grid of 19 stations. An accurate data acquisition and quality check protocol was implemented for data decimation and smoothing. However, data analysis showed that conductivity/ salinity spikes were recorded at the depth of the very sharp thermocline observed in summer 2003. The exceptionally high salinity waters and the marked thermocline observed in the Gulf of Trieste in spring and summer 2003 directed us to compare the distributions of the temperature and salinity fields observed during ADRICOSM cruises with the available climatological values of the Gulf of Trieste, in order to assess whether the data collected during this research deviated significantly from the climatology.
VariaZIONI DEll’ACIDITà, DEL SISTEMA CARBONATICO E DELL’ATTIVITA’BATTERICA IN AcqUE COSTIERE nord adriAtiche Variations in the acidity, carbonate SYSTEM AND Bacterial ACTIVITY IN tHE NoRTH ADRIATIC COASTAL WATERS
ABSTRACT The monthly distributions of prokaryotes, pH, and of the carbonate species were investig... more ABSTRACT The monthly distributions of prokaryotes, pH, and of the carbonate species were investigated in the coastal waters of North Adriatic Sea. Strong decrease of pH occurred particularly during the stratification period in late summer when also an increase in prokaryotic abundances and their production took place.
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