TY - JOUR
T1 - Mesopelagic prokaryotic bulk and single-cell heterotrophic activity and community composition in the NW Africa-Canary Islands coastal-transition zone
AU - Gasol, Josep M.
AU - Alonso-Sáez, Laura
AU - Vaqué, Dolors
AU - Baltar, Federico
AU - Calleja, Maria Ll
AU - Duarte, Carlos M.
AU - Arístegui, Javier
PY - 2009/1
Y1 - 2009/1
N2 - Mesopelagic prokaryotic communities have often been assumed to be relatively inactive in comparison to those from epipelagic waters, and therefore unresponsive to the presence of nearby upwelled waters. We have studied the zonal (shelf-ocean), latitudinal, and depth (epipelagic-mesopelagic) variability of microbial assemblages in the NW Africa-Canary Islands coastal-transition zone (CTZ). Vertical profiles of bacterial bulk and single-cell activity through the epi- and mesopelagic waters were combined with point measurements of bacterial respiration, leucine-to-carbon conversion factors and leucine-to-thymidine incorporation ratios. The overall picture that emerges from our study is that prokaryotes in the mesopelagic zone of this area are less abundant than in the epipelagic but have comparable levels of activity. The relationship between prokaryotes and heterotrophic nanoflagellates, their main predators, remains constant throughout the water column, further contradicting the assumption that deep ocean bacterial communities are mostly inactive. Both bulk and single-cell activity showed clear differences between stations, with higher mesopelagic activities closer to the shelf or affected by upwelling features. We also tested whether differences in microbial function between stations could be related to differences in bacterial community structure, and conclude that bacterial communities are very similar at similar depths in the deep ocean, even if the stations present order-of-magnitude differences in bacterial function.
AB - Mesopelagic prokaryotic communities have often been assumed to be relatively inactive in comparison to those from epipelagic waters, and therefore unresponsive to the presence of nearby upwelled waters. We have studied the zonal (shelf-ocean), latitudinal, and depth (epipelagic-mesopelagic) variability of microbial assemblages in the NW Africa-Canary Islands coastal-transition zone (CTZ). Vertical profiles of bacterial bulk and single-cell activity through the epi- and mesopelagic waters were combined with point measurements of bacterial respiration, leucine-to-carbon conversion factors and leucine-to-thymidine incorporation ratios. The overall picture that emerges from our study is that prokaryotes in the mesopelagic zone of this area are less abundant than in the epipelagic but have comparable levels of activity. The relationship between prokaryotes and heterotrophic nanoflagellates, their main predators, remains constant throughout the water column, further contradicting the assumption that deep ocean bacterial communities are mostly inactive. Both bulk and single-cell activity showed clear differences between stations, with higher mesopelagic activities closer to the shelf or affected by upwelling features. We also tested whether differences in microbial function between stations could be related to differences in bacterial community structure, and conclude that bacterial communities are very similar at similar depths in the deep ocean, even if the stations present order-of-magnitude differences in bacterial function.
UR - http://www.scopus.com/inward/record.url?scp=71549131888&partnerID=8YFLogxK
U2 - 10.1016/j.pocean.2009.07.014
DO - 10.1016/j.pocean.2009.07.014
M3 - Article
AN - SCOPUS:71549131888
SN - 0079-6611
VL - 83
SP - 189
EP - 196
JO - Progress in Oceanography
JF - Progress in Oceanography
IS - 1-4
ER -