Nutrient-specific responses of a phytoplankton community: a case study of the North Atlantic Gyre, Azores

Ramos, Joana Barcelos e; Schulz, Kai G.; Voß, Maren; Narciso, Áurea; Müller, Marius; Reis, Francisco Vieira; Cachão, Mário; Azevedo, Eduardo Brito de

doi:10.1093/plankt/fbx025

Cited by 36 publications

(22 citation statements)

References 78 publications

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“…On the one hand, interaction coefficient α showed a switch from a competitive superiority of the dinoflagellates to the diatoms as nitrate concentration increased at the low nutrient regime ( Figure 3 ), indicating that the dinoflagellates favor low nutrient condition, but the diatoms favor high nutrients. Our results are consistent with the succession trends in phytoplankton communities in the world ocean where high concentrations of nitrate are encountered, mainly in highly eutrophic bays and river inlets ( Aubry et al, 2004 ; Gettings et al, 2014 ; Mutshinda et al, 2016 ; Barcelos e Ramos et al, 2017 ; Ratmaya et al, 2019 ). For example, the Bay of Brest received high-nitrate-loaded freshwater (>700 μmol L –1 ) in winter in 1990s, which supported a diatom-dominated spring bloom ( Del Amo et al, 1997 ).…”

Section: Discussionsupporting

confidence: 90%

Responses of Marine Diatom-Dinoflagellate Competition to Multiple Environmental Drivers: Abundance, Elemental, and Biochemical Aspects

Cao

Ismar-Rebitz

et al. 2021

Front. Microbiol.

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Ocean-related global change has strongly affected the competition between key marine phytoplankton groups, such as diatoms and dinoflagellates, especially with the deleterious consequency of the increasing occurrence of harmful algal blooms. The dominance of diatoms generally shifts toward that of dinoflagellates in response to increasing temperature and reduced nutrient availability; however, contradictory findings have also been observed in certain sea areas. A key challenge in ecology and biogeochemistry is to quantitatively determine the effects of multiple environmental factors on the diatom-dinoflagellate community and the related changes in elemental and biochemical composition. Here, we test the interplay between temperature, nutrient concentrations and their ratios on marine diatom-dinoflagellate competition and chemical composition using bi-algal competition experiments. The ubiquitous diatom Phaeodactylum tricornutum and dinoflagellate Prorocentrum minimum were cultivated semi-continuously, provided with different N and P concentrations (three different levels) and ratios (10:1, 24:1, and 63:1 molar ratios) under three temperatures (12, 18, and 24°C). The responses of diatom-dinoflagellate competition were analyzed by a Lotka-Volterra model and quantified by generalized linear mixed models (GLMMs) and generalized additive models (GAMs). The changes in nutrient concentrations significantly affected diatom-dinoflagellate competition, causing a competitive superiority of the diatoms at high nutrient concentrations, independent of temperature and N:P supply ratios. Interestingly, the effect amplitude of nutrient concentrations varied with different temperatures, showing a switch back toward a competitive superiority of the dinoflagellates at the highest temperature and at very high nutrient concentrations. The ratios of particulate organic nitrogen to phosphorus showed significant negative correlations with increasing diatoms/dinoflagellates ratios, while lipid biomarkers (fatty acids and sterols) correlated positively with increasing diatoms/dinoflagellates ratios over the entire ranges of temperature, N and P concentrations and N:P ratios. Our results indicate that the integration of phytoplankton community structure and chemical composition provides an important step forward to quantitatively understand and predict how phytoplankton community changes affect ecosystem functions and biogeochemical cycles in the ocean.

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Section: Discussionsupporting

confidence: 90%

Responses of Marine Diatom-Dinoflagellate Competition to Multiple Environmental Drivers: Abundance, Elemental, and Biochemical Aspects

Cao

Ismar-Rebitz

et al. 2021

Front. Microbiol.

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“…Net growth rates of UCYN-A1, Crocosphaera , and the gammaproteobacteria γ-24774A11 have been reported to be stimulated by P, Fe+P, and to a lesser extent carbon additions in the South Pacific Ocean ( Moisander et al, 2011 ). However, increases in diazotroph abundances (growth) or the transcription of the nifH gene (a proxy for N 2 -fixing activity) are not always observed upon addition of P ( Zehr et al, 2007 ; Turk-Kubo et al, 2012 ; Krupke et al, 2015 ; Barcelose Ramos et al, 2017 ). Turk-Kubo et al (2015) observed fluctuations in net growth in mesocosms sampled for 23 days, underscoring that this is a dynamic process in which the top-down controls such as grazing and viral lysis are likely to be important factors.…”

Section: Introductionmentioning

confidence: 99%

In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre

et al. 2018

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Major advances in understanding the diversity, distribution, and activity of marine N2-fixing microorganisms (diazotrophs) have been made in the past decades, however, large gaps in knowledge remain about the environmental controls on growth and mortality rates. In order to measure diazotroph net growth rates and microzooplankton grazing rates on diazotrophs, nutrient perturbation experiments and dilution grazing experiments were conducted using free-floating in situ incubation arrays in the vicinity of Station ALOHA in March 2016. Net growth rates for targeted diazotroph taxa as well as Prochlorococcus, Synechococcus and photosynthetic picoeukaryotes were determined under high (H) and low (L) nitrate:phosphate (NP) ratio conditions at four depths in the photic zone (25, 45, 75, and 100 m) using quantitative PCR and flow cytometry. Changes in the prokaryote community composition in response to HNP and LNP treatments were characterized using 16S rRNA variable region tag sequencing. Microzooplankton grazing rates on diazotrophs were measured using a modified dilution technique at two depths in the photic zone (15 and 125 m). Net growth rates for most of the targeted diazotrophs after 48 h were not stimulated as expected by LNP conditions, rather enhanced growth rates were often measured in HNP treatments. Interestingly, net growth rates of the uncultivated prymnesiophyte symbiont UCYN-A1 were stimulated in HNP treatments at 75 and 100 m, suggesting that N used for growth was acquired through continuing to fix N2 in the presence of nitrate. Net growth rates for UCYN-A1, UCYN-C, Crocosphaera sp. (UCYN-B) and the diatom symbiont Richelia (associated with Rhizosolenia) were uniformly high at 45 m (up to 1.6 ± 0.5 d-1), implying that all were growing optimally at the onset of the experiment at that depth. Differences in microzooplankton grazing rates on UCYN-A1 and UCYN-C in 15 m waters indicate that the grazer assemblage preyed preferentially on UCYN-A1. Deeper in the water column (125 m), both diazotrophs were grazed at substantial rates, suggesting grazing pressure may increase with depth in the photic zone. Constraining in situ diazotroph growth and mortality rates are important steps for improving parameterization for diazotrophs in global ecosystem models.

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“…Axenic phytoplankton cells were cultivated under highly controlled conditions. Phosphorus (P) limitation condition was chosen to simulate those frequently observed during HAB events in estuaries and coastal waters (44,45). Bacterial communities in nature are highly complex and diverse.…”

Section: Introductionmentioning

confidence: 99%

Species-specific exudates from marine phytoplankton drive microbial community composition

Briand

Lassudrie

Noël

et al. 2023

Preprint

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Phytoplankton-bacteria interactions are governed by the transformation of algal-derived organic matter, exchange of metabolites and infochemicals. However, the assembly of the bacterial community within the phycosphere is not well understood. In this study, we performed experiments to tease apart the role of species-specific exometabolites, bacterial/bacterial interactions and algal/bacterial interactions in shaping bacterial community within the phycophere. Twelve bacterial isolates, representative of the main members of the phycosphere microbiome were selected and exposed to phytoplankton extracellular fractions (PEF) from Alexandrium minutum, Prymnesium parvum and Tisochrysis lutea. While all bacterial isolates were able to grow individually on the different PEF, the bacterial community analysis indicated that some species were selected and others were not when grown in a synthetic community (SynCom). In addition, we compared the SynCom assembly in the absence or presence of the harmful algal cells. If PEF, irrespective of the producing alga, allowed the growth of copiotrophic strains, we found that exometabolites of the two different species led to distinct SynCom composition and that the presence of algal cells also influenced the bacterial assemblage. Overall, our results support the assertion that algal exudates and the presence of algae are the main factors driving the composition of the bacterial community.

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Nutrient-specific responses of a phytoplankton community: a case study of the North Atlantic Gyre, Azores

Cited by 36 publications

References 78 publications

Responses of Marine Diatom-Dinoflagellate Competition to Multiple Environmental Drivers: Abundance, Elemental, and Biochemical Aspects

Responses of Marine Diatom-Dinoflagellate Competition to Multiple Environmental Drivers: Abundance, Elemental, and Biochemical Aspects

In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre

Species-specific exudates from marine phytoplankton drive microbial community composition

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