Dynamics of microbial biomass and respiratory activity during late summer in a site of Arctic Kongsfjorden

• Published in: Frontiers in Marine Science
• Main Authors: Rosabruna La Ferla, Carmela Caroppo, Leonardo Langone, Stefano Aliani
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2014
• Subjects: Svalbard; Microbial biogeochemistry; microbial biomass; sediment trap; respiratory activity; mooring; Kongsfyorden; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Arctic; glacier; Kongsfjord*; Kongsfjorden; Phytoplankton
• Online Access: https://doi.org/10.3389/conf.fmars.2014.02.00132; https://doaj.org/article/ee552300db4d49ecabb63c3ab68181d4

Prokaryotic and phytoplankton interaction plays a key role in relevant processes such as carbon fluxes and nutrient regeneration (Zaccone et al ., 2004). Sinking biogenic particles drive respiration in the ocean and related studies are important to determine the flow of organic matter along the water column (Martin et al ., 1987; Karl et al ., 1987). However, organic matter collected by sediment traps (Langone et al ., 2000) or the studies of the disequilibrium 234Th/238U (Aliani et al ., 2004) does not take into account the entire pool of oxidable organic matter, which includes the dissolved organic matter present in the seawater. The study of microbial respiration rates instead fills this gap, since respiration includes oxidation of both dissolved and particulate organic mater, providing an integrated estimate of the carbon utilization in the sea (Azzaro et al ., 2006). In this context, a study on an Arctic fjord (Kongsfyorden, Svalbard) was done in late summer 2013, with the purpose of knowing the variability of prokaryotic and phytoplanktonic biomass and of microbial remineralization rates over short time scales in a coastal station (water depth ~105 m), where a mooring (Mooring Dirigibile Italia, MDI: 78° 54 .859'N; 12° 15. 411' E) is positioned. The Kongsfjorden was affected by inflow of Atlantic water as well as glacier melt water runoff (Cottier et al ., 2005). The experiment comprised 5 samplings performed during a 7 day period in MDI station. For each sampling, photosynthetically active radiation (PAR), temperature and conductivity (salinity) were recorded along the water column with a PNF-300 profiler and a SeaBird Electronics SBE-911 plus profiler, respectively . Water samples were taken at five different depths (surface, 5, 25, 50 and 100 m) to determine nutrients, particulate organic carbon, prokaryotes and phytoplankton biomass, and community respiration. In addition, prokaryotes sunk with the particulate matter were studied into the sediment trap positioned in the MDI during the period between ...