MEPS 543:1-19 (2016)  -  DOI: https://doi.org/10.3354/meps11558

ABSTRACT: We investigated the influence of ocean mixing and nutrient supply dynamics on picoplankton community composition in the context of Margalef’s Mandala (Margalef 1978). Simultaneous measurements of microturbulence, nutrient concentration, and autotrophic and heterotrophic picoplankton properties, were collected during 3 cruises carried out in the northwestern Mediterranean Sea in March (F1), April/May (F2) and September (F3) 2009. The 3 cruises sampled different oceanographic conditions, starting with early stages of the late winter-early spring bloom, followed by the late stage of the bloom, and finally summer stratification. As a result of the variability in vertical diffusivity and the nitrate gradient across the nitracline, nitrate vertical fluxes were higher during F1 (23 ± 35 mmol m^-2 d^-1), compared to F2 (0.4 ± 0.2 mmol m^-2 d^-1) and F3 (0.09 ± 0.09 mmol m^-2 d^-1). Prochlorococcus abundance was low when nitrate supply was high, Synechococcus exhibited the highest abundances at intermediate levels of nitrate supply and highest irradiance during F2, and large and small picoeukaryotic groups increased their abundance under high nutrient supply in F1. No significant relationships between the abundance of high and low nucleic acid heterotrophic bacteria and nitrate supply were found. In agreement with Margalef’s model, our results show different responses of picophytoplankton groups to nitrate supply (probably reflecting differences in nutrient uptake abilities), and that the ratio of prokaryotic to picoeukaryotic photoautotrophic biomass decreases with increasing nitrate supply.

KEY WORDS: Turbulence · Nutrient supply · Margalef’s Mandala · Picoplankton · Mediterranean Sea

Full text in pdf format Information about this Feature Article

Cite this article as: Mouriño-Carballido B, Hojas E, Cermeño P, Chouciño P and others (2016) Nutrient supply controls picoplankton community structure during three contrasting seasons in the northwestern Mediterranean Sea. Mar Ecol Prog Ser 543:1-19. https://doi.org/10.3354/meps11558 Export citation Share:    Facebook - - linkedIn