Microbial metabolic rates in the Ross Sea: the ABIOCLEAR Project

The Ross Sea is one of the most productive areas of the Southern Ocean and includes several functionally different marine ecosystems. With the aim of identifying signs and patterns of microbial response to current climate change, seawater microbial populations were sampled at different depths, from...

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Bibliographic Details
Published in:Nature Conservation
Main Authors: Azzaro, Maurizio, Packard, Theodore T., Monticelli, Luis Salvador, Maimone, Giovanna, Rappazzo, Alessandro Ciro, Azzaro, Filippo, Grilli, Federica, Crisafi, Ermanno, La Ferla, Rosabruna
Format: Article in Journal/Newspaper
Language:English
Published: 2019
Subjects:
251001 Oceanografía biológica
Bacterial-Growth Efficiency
Electron-Transport Activity
Leucine Incorporation
Biomass Production
Mediterranean Sea
Protein-Synthesis
Organic-Matter
Water-Column
Carbon Flux
Deep-Water
Microbial respiration
Heterotrophic production
Heterotrophic energy production
Ross Sea
Antarctica
LTER
Antarctic
Southern Ocean
Victoria Land
Antarc*
Online Access:http://hdl.handle.net/10553/60010
https://doi.org/10.3897/natureconservation.34.30631
Description
Summary:The Ross Sea is one of the most productive areas of the Southern Ocean and includes several functionally different marine ecosystems. With the aim of identifying signs and patterns of microbial response to current climate change, seawater microbial populations were sampled at different depths, from surface to the bottom, at two Ross Sea mooring areas southeast of Victoria Land in Antarctica. This oceanographic experiment, the XX Italian Antarctic Expedition, 2004-05, was carried out in the framework of the ABIOCLEAR project as part of LTER-Italy. Here, microbial biogeochemical rates of respiration, carbon dioxide production, total community heterotrophic energy production, prokaryotic heterotrophic activity, production (by H-3-Ieucine uptake) and prokaryotic biomass (by image analysis) were determined throughout the water column. As ancillary parameters, chlorophyll a, adenosine-triphosphate concentrations, temperature and salinity were measured and reported. Microbial metabolism was highly variable amongst stations and depths. In epi- and mesopelagic zones, respiratory rates varied between 52.4-437.0 and 6.3-271.5 nanol O-2 l(-1)h(-1); prokaryotic heterotrophic production varied between 0.46-29.5 and 0.3-6.11 nanog C l(-1) h(-1) and prokaryotic biomass varied between 0.8-24.5 and 1.1-9.0 mu g C l(-1), respectively. The average heterotrophic energy production ranged between 570 and 103 mJ l(-1)h(-1)in upper and deeper layers, respectively. In the epipelagic layer, the Prokaryotic Carbon Demand and Prokaryotic Growth Efficiency averaged 9 times higher and 2 times lower, respectively, than in the mesopelagic one. The distribution of plankton metabolism and organic matter degradation was mainly related to the different hydrological and trophic conditions. In comparison with previous research, the Ross Sea results, here, evidenced a relatively impoverished oligotrophic microbial community, throughout the water column.

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