Protist Community Grazing on Prokaryotic Prey in Deep Ocean Water Masses

• Published in: PloS one 2015-04, Vol.10 (4), p.e0124505-e0124505
• Main Authors: Rocke, Emma, Pachiadaki, Maria G, Cobban, Alec, Kujawinski, Elizabeth B, Edgcomb, Virginia P
• Format: Article
• Language: English
• Subjects: Amino acids; Antarctic Regions; Bacteria; Carbon; Chlorophyll; Chlorophyll - chemistry; Deep water; Eukaryota - metabolism; Eukaryotes; Experiments; Fluorescent Dyes - chemistry; Food Chain; Geography; Geology; Geophysics; Grazing; In Situ Hybridization, Fluorescence; Intermediate water; Light; Microorganisms; Microscopy, Fluorescence; Motility; Oceans and Seas; Organic carbon; Oxygen - chemistry; Pelagic zone; Phenothiazines; Prey; Prokaryotes; Prokaryotic Cells; Respiration; Seawater; Stations; Temperature; Water circulation; Water column
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0124505

Oceanic protist grazing at mesopelagic and bathypelagic depths, and their subsequent effects on trophic links between eukaryotes and prokaryotes, are not well constrained. Recent studies show evidence of higher than expected grazing activity by protists down to mesopelagic depths. This study provides the first exploration of protist grazing in the bathypelagic North Atlantic Deep Water (NADW). Grazing was measured throughout the water column at three stations in the South Atlantic using fluorescently-labeled prey analogues. Grazing in the deep Antarctic Intermediate water (AAIW) and NADW at all three stations removed 3.79% ± 1.72% to 31.14% ± 8.24% of the standing prokaryote stock. These results imply that protist grazing may be a significant source of labile organic carbon at certain meso- and bathypelagic depths.