Potential causes for the unequal contribution of picophytoplankton to total biomass and productivity in oligotrophic waters

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 254:101-109 (2003) - doi:10.3354/meps254101 Potential causes for the unequal contribution of picophytoplankton to total biomass and productivity in oligotrophic waters Emilio Fernández1,*, Emilio Marañón1, Xosé Anxelu G. Morán2, Pablo Serret1 1Facultad de Ciencias, Departamento de Ecología y Biología Animal, Universidad de Vigo, Campus Lagoas-Marcosende, 36200 Vigo, Spain 2Instituto Español de Oceanografía, Centro Oceanográfico de Xixón, Camín de l¹Arbeyal s/n, 33212 Xixón, Spain *Email: esuarez@uvigo.es ABSTRACT: Size-fractionated chlorophyll a and primary production measurements during 7 latitudinal cruises (56 stations) in the Atlantic Ocean indicate that in subtropical and tropical regions the relative contribution of large (L) (>2 µm) phytoplankton to total (T) chlorophyll a biomass (B) is smaller (BL:BT ratio = 0.25 ± 0.01 SE) than their contribution to total primary production (P) (PL:PT ratio = 0.45 ± 0.02). This implies a lower assimilation number for picoplankton than for larger cells: 1.5 ± 0.2 and 3.7 ± 0.3 mg C mg chlorophyll a h-1, respectively (n = 90). During short-term time-course experiments in subtropical and tropical waters of the North Atlantic, a >50% reduction in the abundance of picoplankton, mainly Prochlorococcus spp., took place as early as the first 2 h of incubation. This suggests that long incubation times in bottle experiments can lead to underestimations of primary production rates, at least in oligotrophic waters. The phytoplankton size-structure remained fairly constant throughout the experiments, suggesting that the high PL:PT ratios in these environments cannot be due to enhanced loss rates of small-sized phytoplankton as a result of bottle enclosure. Our results indicate that the observed disagreement between BL:BT and PL:PT ratios is not necessarily an experimental artifact, but could be related to a higher light utilization efficiency of larger phytoplankton. KEY WORDS: Primary production · Size-fractionated chlorophyll · Picoplankton · Oligotrophic waters · Atlantic Ocean Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 254. Online publication date: June 04, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.