Coupling between upper ocean layer variability and size-fractionated phytoplankton in a non-nutrient-limited environment

Marine Ecology Progress Series

Sheila N. Estrada-Allis¹  Ángeles Marrero-Díaz¹  Santiago Hernández-León¹  Cristina García-Muñoz¹  Carlos M. García¹  Luis M. Lubián¹  Mónica Hernández-Arencibia¹  Cristian Henríquez-Pastene¹  Beatriz Mouriño-Carballido¹  Cristina Sobrino¹  Elsa Vázquez¹  Borja Aguiar-González¹  Ángel Rodríguez-Santana¹  Pablo Sangr๠

关键词: Physical-biological coupling;    Mesoscale;    Submesoscale;    Vertical mixing;    Phytoplankton composition;    Antarctica;   

DOI  :  10.3354/meps10668

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: We describe the coupling between upper ocean layer variability and size-fractionated phytoplankton distribution in the non-nutrient-limited Bransfield Strait region (BS) of Antarctica. For this purpose we use hydrographic and size-fractionated chlorophyll a data from a transect that crossed 2 fronts and an eddy, together with data from 3 stations located in a deeply mixed region, the Antarctic Sound (AS). In the BS transect, small phytoplankton (<20 µm equivalent spherical diameter [ESD]) accounted for 80% of total chl a and their distribution appeared to be linked to cross-frontal variability. On the deepening upper mixed layer (UML) sides of both fronts we observed a deep subducting column-like structure of small phytoplankton biomass. On the shoaling UML sides of both fronts, where there were signs of restratification, we observed a local shallow maximum of small phytoplankton biomass. We propose that this observed phytoplankton distribution may be a response to the development of frontal vertical circulation cells. In the deep, turbulent environment of the AS, larger phytoplankton (>20 µm ESD) accounted for 80% of total chl a. The proportion of large phytoplankton increases as the depth of the upper mixed layer (Z_UML), and the corresponding rate of vertical mixing, increases. We hypothesize that this change in phytoplankton composition with varying Z_UML is related to the competition for light, and results from modification of the light regime caused by vertical mixing.

【 授权许可】

Unknown