Mesozooplankton grazing minimally impacts phytoplankton abundance during spring in the western North Atlantic

PeerJ

article

Francoise Morison¹  James Joseph Pierson²  Andreas Oikonomou¹  Susanne Menden-Deuer¹ 

[1] Graduate School of Oceanography, University of Rhode Island;Center for Environmental Science, University of Maryland;Institute of Balances of internal water, Hellenic Centre for Marine Research

关键词: Mesozooplankton;    Microzooplankton;    Grazing;    North Atlantic;    Phytoplankton;    Spring bloom;    Microbial food web;    Plankton;    Primary production;   

DOI  :  10.7717/peerj.9430

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

The impacts of grazing by meso- and microzooplankton on phytoplankton primary production (PP) was investigated in the surface layer of the western North Atlantic during spring. Shipboard experiments were performed on a latitudinal transect at three stations that differed in mixed layer depth, temperature, and mesozooplankton taxonomic composition. The mesozooplankton community was numerically dominated by Calanus finmarchicus at the northern and central station, with Calanus hyperboreus10 °C warmer than the other stations and had the most diverse mesozooplankton assemblage, dominated by small copepods including Paracalanus spp. Microzooplankton grazing was detected only at the northern station, where it removed 97% of PP. Estimated clearance rates by C. hyperboreus and C. finmarchicus 10 µm particles, altering the particle-size spectrum. At the southern station, grazing by the whole mesozooplankton assemblage resulted in a removal of 14% of PP, and its effect on net phytoplankton growth rate was similar irrespective of ambient light. In contrast, reduction in light availability had an approximately 3-fold greater impact on net phytoplankton growth rate than mesozooplankton grazing pressure. The low mesozooplankton grazing impact across stations suggests limited mesozooplankton-mediated vertical export of phytoplankton production. The constraints provided here on trophic transfer, as well as quantitative estimates of the relative contribution of light and grazer controls of PP and of grazer-induced shifts in particle size spectra, illuminate food web dynamics and aid in parameterizing modeling-frameworks assessing global elemental fluxes and carbon export.

【 授权许可】

CC BY