Abstract
The southern- central Tyrrhenian Sea is a poorly studied area of the Mediterranean Sea, although its importance for the biological fluxes among the western and eastern basins is recognised. This note aimed at evaluating in the waters of the Southern Tyrrhenian Sea the efficiency of some steps of the organic matter processing (enzymatic hydrolysis, prokaryotic production and oxidation) and the role played by the prokaryotic community in this context. During the MEDBIO multidisciplinary cruise performed in July 2005, the distribution of prokaryotic abundance and activities (exo enzymatic activity, heterotrophic production and respiratory activity) was studied. The results showed the presence of high exo enzymatic activity rates (mostly leucine amino peptidase) in the deep sea, while heterotrophic production and respiratory activity rates were high at surface. Some speculations on the different behaviors of the Carbon fluxes occurring among the different epi, meso and bathypelagic layers are reported. At the epipelagic layer both the decomposition and biomass production processes were high. At the mesopelagic layer the organic matter was quickly mobilised but not efficiently incorporated into biomass, therefore the dissolved monomers remained available in the water column for export to other trophic levels or utilization in other chemical processes (lateral advection, oxidation). The bathypelagic layer was characterised by high levels of hydrolytic activity coupled with relatively high prokaryotic production; in this layer, exo enzymatic activity levels fall in an order of magnitude similar to that observed at the epipelagic one. This finding highlights the importance of microbially mediated processes in sustaining life in the marine depths.
Highlights
Prokaryotes are an important component of the planktonic community of aquatic ecosystems and a critical link in the microbial loop, playing a vital role in nutrient cycling and food-web structure within the marine environment [1,2,3]
The role played by the prokaryotic community at different depths of the Southern Tyrrhenian Sea is evaluated by estimating the efficiency of some steps in organic matter processing, so allowing to draw some considerations on the implications of prokaryotic metabolism on organic matter transformation
In the examined Tyrrhenian area the general decrease of activity rates and abundances with increasing depth suggests the predominant weight of export production in this basin
Summary
Prokaryotes (including Bacteria and Archaea) are an important component of the planktonic community of aquatic ecosystems and a critical link in the microbial loop, playing a vital role in nutrient cycling and food-web structure within the marine environment [1,2,3]. Heterotrophic microorganisms (bacteria, fungi) are the main consumers of Dissolved Organic Matter (DOM) and they are the major players in organic matter turnover within the “microbial loop” [4]. Thanks to their wide biodiversity and their large variety of metabolic activities, microorganisms contribute significantly to the regulation of the flux of organic matter and energy from the biotic to abiotic compartments, acting in both decomposition (by DOM hydrolysis and nutrient release) and production processes (new living biomass production). The determination of enzymatic hydrolysis rates allows to quantify the contribution of the microbial community to organic matter turnover [6,7,8,9,10]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
