Abstract
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 419:57-69 (2010) - DOI: https://doi.org/10.3354/meps08840 Effects of nutrients and turbulence on the production of transparent exopolymer particles: a mesocosm study M. L. Pedrotti1,*, F. Peters2, S. Beauvais1, M. Vidal3, J. Egge4, A. Jacobsen4, C. Marrasé2 1Marine Microbial Ecology Group, Laboratoire d’Océanographie de Villefranche, CNRS-UMR 7093, BP 28, 06234 Villefranche-sur-mer, France 2Institut de Ciències del Mar, CMIMA (CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalunya, Spain 3Departament d’Ecology, Universitat de Barcelona, Barcelona, Spain 4Department of Fisheries and Marine Biology, University of Bergen, HIB, 5020 Bergen, Norway *Email: pedrotti@obs-vlfr.fr ABSTRACT: The production of transparent exopolymer particles (TEP) in response to several environmental variables was studied in 2 mesocosm experiments. The first (Expt 1) examined a gradient of 4 nutrient levels; the second (Expt 2) examined different conditions of silicate availability and zooplankton presence. Tanks were separated in 2 series, one subjected to turbulence and the other not influenced by turbulence. In tanks with nutrient addition, TEP were rapidly formed, with net apparent production rates closely linked to chl a growth rates, suggesting that phytoplankton cells were actively exuding TEP precursors. High nutrient availability increased the absolute concentration of TEP; however, the relative quantity of TEP produced was found to be lower, as TEP concentration per unit of phytoplankton biomass was inversely related to the initial nitrate dose. In Expt 1, an increase in TEP volume (3 to 48 µm equivalent spherical diameter) with nutrient dose was observed; in Expt 2, both silicate addition and turbulence enhanced TEP production and favored aggregation to larger TEP (>48 µm). The presence of zooplankton lowered TEP concentration and changed the size distribution of TEP, presumably by grazing on TEP or phytoplankton. For lower nutrient concentrations, the ratio of particulate organic carbon (POC) to particulate organic nitrogen (PON) followed the Redfield ratio. At higher nutrient conditions, when nutrients were exhausted during the post-bloom, a decoupling of carbon and nitrogen dynamics occurred and was correlated to TEP formation, with a large flow of carbon channeled toward the TEP pool in turbulent tanks. TEP accounted for an increase in POC concentration of 50% in high-nutrient and turbulent conditions. The study of TEP dynamics is crucial to understanding the biogeochemical response of the aquatic system to forcing variables such as nutrient availability and turbulence intensity. KEY WORDS: Transparent exopolymer particles · TEP production · Phytoplankton · Particulate organic carbon · POC · Turbulence · Nutrients · Mesocosms Full text in pdf format PreviousNextCite this article as: Pedrotti ML, Peters F, Beauvais S, Vidal M, Egge J, Jacobsen A, Marrasé C (2010) Effects of nutrients and turbulence on the production of transparent exopolymer particles: a mesocosm study. Mar Ecol Prog Ser 419:57-69. https://doi.org/10.3354/meps08840 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 419. Online publication date: November 30, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.
Highlights
Transparent exopolymer particles (TEP) are nonliving organic particles formed abiotically from acid polysaccharides released as dissolved and colloidal matter from phytoplankton and bacteria (Zhou et al 1998, Passow 2000)
High nutrient availability increased the absolute concentration of transparent exopolymer particles (TEP); the relative quantity of TEP produced was found to be lower, as TEP concentration per unit of phytoplankton biomass was inversely related to the initial nitrate dose
The present study showed the effect of important bulk ecosystem properties on TEP production
Summary
Transparent exopolymer particles (TEP) are nonliving organic particles formed abiotically from acid polysaccharides released as dissolved and colloidal matter from phytoplankton and bacteria (Zhou et al 1998, Passow 2000). Turbulence is known to influence the structure of the pelagic trophic web and the dynamics of the particles suspended within, and exported from, the water column (Peters & Marrasé 2000, Peters et al 2002) This includes top-down processes such as shifts in contact rates between particles (MacKenzie & Kiørboe 1995) and bottom-up processes such as the increase in nutrient flux to cells (Savidge 1981, Kiørboe 1993, Moeseneder & Herndl 1995, KarpBoss et al 1996, Peters et al 2006). TEP formation is likely accelerated by turbulence (Schuster & Herndl 1995)
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