Community structure and grazing of the nano-microzooplankton on the continental shelf of the Bay of Biscay

Abstract

International audienceIn order to investigate the parameters controlling the heterotrophic protists (nano-microzooplankton) on the continental shelf of the southern Bay of Biscay, plankton communities and their physico-chemical environment were studied 4 times in February, April, June and SeptembereOctober 2004 at three stations in the euphotic zone in the Bay of Biscay. The abundance and carbon biomass of heterotrophic protists (ciliates, heterotrophic dinoflagellates and nanoflagellates) as well as all the others groups of plankton (picoplankton, nanophytoplankton, diatoms, autotrophic dinoflagellates, metazoan micro-zooplankton and mesozooplankton), the environmental parameters and the primary and bacteria production were evaluated at each sampling period. Microzooplankton grazing experiments were undertaken at the same time. Ciliates and heterotrophic dinoflagellates accounted for the main major component of nano-and microzooplankton communities in term of biomass. The total carbon biomass of heterotrophic protists was highest in spring and lowest at the end of summer. The development of heterotrophic protists started after a winter microphytoplankton bloom (principally large diatoms), the biomass was lower in June and was low in September (through inappropriate prey). The carbon requirement of microzooplankton ranged from 50 to more than 100% of daily primary, bacterial and nanoflagellate production. The heterotrophic protist community was predominantly constrained by bottom-up control in spring and at the end of summer via food availability and quality

Major changes in sardine growth and body condition in the Bay of Biscay between 2003 and 2016: Temporal trends and drivers

“…Otherwise, sardine nursery grounds in the Bay of Biscay are mainly distributed over coastal areas, where both the hydrological structure and primary production have been shown to be highly influenced by the plumes of the Gironde and Loire rivers (Dupuy et al, 2011;Pasquaud et al, 2012;Planque et al, 2004). Moreover, river discharges are known to potentially impact fish body condition (Brosset et al, 2017).…”

In situ video and fluorescence analysis (VFA) of marine particles: applications to phytoplankton ecological studies.

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Phytoplankton growth inhibited by the toxic and bacterivorous ciliate Uronema marinum (Protozoa, Ciliophora)

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