Prokaryotic abundance and heterotrophic metabolism in the deep Mediterranean Sea

A synthesis of field data carried out in the Mediterranean Sea are presented, aimed at contributing to the knowledge of three prokaryotic-mediated processes and their implications on the Carbon cycle. The distribution of exoenzymatic activities, secondary production and respiration rates was studied together with the prokaryotic abundances. Particular attention was paid to the meso- and bathypelagic layers which play an important role in the Mediterranean carbon cycle. The study is noteworthy because of its large spatial scale spanning the entire Mediterranean Sea over 4 years. In addition, two Atlantic stations in front of the Gibraltar Strait were investigated. The longitudinal distribution of prokaryotic activities and abundance along the MED showed different trends along the depthlayers. In particular, higher exoenzymatic rates were detected in the Eastern basin compared to the Western one; carbon respiration rate showed patterns variable with the sampling periods in the epipelagic and bathypelagic layers, while a consistent Westwards decreasing trend at the mesopelagic layers occurred. Specific enzyme activities per cell showed high values in the deepest layers for leucine aminopeptidase. Comparison with Carbon respiration rate data collected before the 2000s showed changing patterns of microbial heterotrophic processes in the Mediterranean Sea.

Download Full-text

Biogeography of planktonic microbial communities across the whole Mediterranean Sea

Ocean Science Discussions ◽

10.5194/osd-10-291-2013 ◽

2013 ◽

Vol 10 (1) ◽

pp. 291-319 ◽

Cited By ~ 3

Author(s):

F. Mapelli ◽

M. M. Varela ◽

M. Barbato ◽

R. Alvariño ◽

M. Fusi ◽

...

Keyword(s):

Mediterranean Sea ◽

Water Column ◽

Bacterial Community Composition ◽

Western Mediterranean ◽

Intergenic Sequence ◽

Β Diversity ◽

Intermediate Layers ◽

Prokaryotic Abundance ◽

Vertical Profiling ◽

Seawater Samples

Abstract. The M84/3 cruise recently held onboard of R/V Meteor represented a great and rare opportunity for the scientific community to realize a multidisciplinary survey on the whole Mediterranean Sea. In this context, molecular microbiology investigation, realized by applying Automated Ribosomal Intergenic Sequence Analysis (ARISA) and microscope evaluation of prokaryotic abundance, were performed on seawater samples aiming to identify the environmental factors driving planktonic bacterial community composition across both vertical and longitudinal transects. Prokaryotic abundance decreased along with depth in all the stations and presented similar values in sub-surface, meso- and bathypelagic layers across the whole Mediterranean basin. On the contrary, peculiar bacterial assemblages were selected along a longitudinal transect in the surface layers of the eastern and western sub-basins. Sharp vertical profiling of the bacterial communities was observed only considering the boundary of the water column, while the study of bacterial β-diversity at finer scale across the water column displayed higher variability at the intermediate layers. Nonetheless, different physico-chemical factors were significantly related to microbial zonation both according to geographic position and across the water column in the whole Mediterranean Sea. These results demonstrated that bacterial diversity is putatively correlated to different water masses across the water column of the complex hydrographical systems of the eastern and western Mediterranean sub-basins.

Download Full-text

Biogeography of planktonic bacterial communities across the whole Mediterranean Sea

Ocean Science ◽

10.5194/os-9-585-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 585-595 ◽

Cited By ~ 18

Author(s):

F. Mapelli ◽

M. M. Varela ◽

M. Barbato ◽

R. Alvariño ◽

M. Fusi ◽

...

Keyword(s):

Mediterranean Sea ◽

Water Column ◽

Bacterial Communities ◽

Population Distribution ◽

Western Mediterranean ◽

Intergenic Sequence ◽

Phylogenetic Groups ◽

Bacterial Populations ◽

Prokaryotic Abundance ◽

Bacterial Assemblages

Abstract. Bacterial population distribution in the Mediterranean Sea has been mainly studied by considering small geographical areas or specific phylogenetic groups. The present study is a molecular microbiology investigation aimed to identify the environmental factors driving total bacterioplankton community composition of seawater samples collected along a transect covering the whole Mediterranean Sea. We performed automated ribosomal intergenic sequence analysis (ARISA) and microscope evaluation of prokaryotic abundance of seawater sampled across both vertical profiles and longitudinal transects in the whole basin. Prokaryotic abundance decreased with depth at all the stations and presented similar values in epi-, meso- and bathypelagic layers across the whole Mediterranean Sea. However, peculiar bacterial assemblages were selected along a longitudinal transect in the epipelagic layers of the eastern and western sub-basins. Vertical differences of the bacterial communities were observed only when considering the epi- and bathypelagic waters, while the study of the structure of bacterial communities at a finer scale across the water column displayed higher variability at the intermediate layers. Nonetheless, different physico-chemical factors were significantly related to the distribution of bacterial populations, both according to geographic position and down the water column in the whole Mediterranean Sea. These results demonstrated that bacterial assemblages are putatively correlated to different water masses of the complex hydrographical systems of the eastern and western Mediterranean sub-basins.

Download Full-text

Patterns in planktonic metabolism in the Mediterranean Sea

Biogeosciences Discussions ◽

10.5194/bgd-6-8569-2009 ◽

2009 ◽

Vol 6 (4) ◽

pp. 8569-8588

Author(s):

A. Regaudie-de-Gioux ◽

R. Vaquer-Sunyer ◽

C. M. Duarte

Keyword(s):

Mediterranean Sea ◽

Gross Primary Production ◽

Western Mediterranean ◽

Community Respiration ◽

Net Community Production ◽

R Ratio ◽

Heterotrophic Metabolism ◽

The Mediterranean ◽

Net Heterotrophy ◽

Community Production

Abstract. Planktonic gross community production (GPP), net community production (NCP) and community respiration (CR) across the Mediterranean Sea was examined in two cruises, THRESHOLDS 2006 and 2007, each crossing the Mediterranean from West to East to test for consistent variation along this longitudinal gradient. GPP averaged 2.4±0.4 mmol O2m−3 d−1, CR averaged 3.8±0.5 mmol O2m−3 d−1, and NCP averaged -0.8&plusmn0.6 mmol O2m−3 d−1across the studied sections, indicative of a tendency for a net heterotrophic metabolism, prevalent across studied sections of the Mediterranean Sea as reflected in 70% of negative NCP estimates. The median P/R ratio was 0.58, also indicating a strong prevalence of heterotrophic communities (P/R<1) along the studied sections of the Mediterranean Sea. The communities tended to be net heterotrophic (i.e. P/R<1) at GPP less than 3.5 mmol O2m−3 d−1. Although the Western Mediterranean supports a higher gross primary production than the Eastern basin does, it also supported a higher community respiration. The net heterotrophy nature of the studied sections of the Mediterranean Sea indicates that allochthonous carbon should be important to subsidise planktonic metabolism, and that the planktonic communities in the Mediterranean Sea acted as CO2 sources to the atmosphere during the study.

Download Full-text

Prokaryotic dynamics and heterotrophic metabolism in a deep convection site of Eastern Mediterranean Sea (the Southern Adriatic Pit)

Continental Shelf Research ◽

10.1016/j.csr.2011.07.011 ◽

2012 ◽

Vol 44 ◽

pp. 106-118 ◽

Cited By ~ 23

Author(s):

M. Azzaro ◽

R. La Ferla ◽

G. Maimone ◽

L.S. Monticelli ◽

R. Zaccone ◽

...

Keyword(s):

Mediterranean Sea ◽

Eastern Mediterranean ◽

Deep Convection ◽

Eastern Mediterranean Sea ◽

Heterotrophic Metabolism

Download Full-text

Mediterranean Sea

AccessScience ◽

10.1036/1097-8542.413200 ◽

2015 ◽

Keyword(s):

Mediterranean Sea

Download Full-text

Evidence of a predation event on a tagged Mediterranean spearfish (Tetrapturus belone; Pisces, Istiophoridae), inferred from pop-up satellite tagging data

Aquatic Living Resources ◽

10.1051/alr/2020024 ◽

2020 ◽

Vol 33 ◽

pp. 23

Author(s):

Danilo Malara ◽

Pietro Battaglia ◽

Pierpaolo Consoli ◽

Erika Arcadi ◽

Simonepietro Canese ◽

...

Keyword(s):

Mediterranean Sea ◽

Research Group ◽

Marine Mammals ◽

Biodiversity Hotspot ◽

Pelagic Species ◽

Archival Tag ◽

Abiotic Parameters ◽

Predation Event ◽

Satellite Tagging ◽

First Time

The Strait of Messina is located at the centre of the Mediterranean Sea and is considered a biodiversity hotspot and an obligatory seasonal passage for different pelagic species such as sharks, marine mammals, and billfishes. For the first time, in the Strait of Messina, our research group tagged a Mediterranean spearfish (Tetrapturus belone) using a pop-up satellite archival tag (PSAT). The observation of abiotic parameters (depth, light, and temperature) recorded by the PSAT confirmed that the tagged specimen was predated after about nine hours. The tag was then regurgitated 14 days after the tag deployment date. The analysis of collected data seems to indicate that the predator may be an ectothermic shark, most likely the bluntnose sixgill shark (Hexanchus griseus).

Download Full-text