7 páginas, 3 figuras, 2 tablas ; If the size dependence of species richness varies across ecosystems, it should be reflected in the size distribution of total abundance. Using a database of phytoplankton abundance, species composition and cell size from coastal, shelf and open-ocean environments, we show that the biogeographical patterns of phytoplankton size distribution in the ocean are a result of systematic changes in the relationship between species richness and cell size. Our results indicate that, regardless of the environmental conditions, population abundance decreases consistently to the –3/4 power of cell size. By contrast, marine phytoplankton diversity peaks at small sizes in oligotrophic waters but is either a log-normal function or independent of cell size in eutrophic systems. It is argued that, operating on evolutionary time scales, size-dependent biophysical constraints for resource acquisition are reflected in the size distribution of species richness and consequently in the size structure of phytoplankton communities in the ocean. These findings indicate that the way in which biological diversity changes with body size is crucial to a better understanding of the structure and functioning of microbial plankton communities and how energy flows through pelagic ecosystems ; AMT data collection was supported by the UK Natural Environmental Research Council through the Atlantic Meridional Transect consortium (NER/O/S/2001/00680). P.C. was supported by a Fulbright Postdoctoral Research Fellowship from the Spanish Ministry of Education and Science and a Marie Curie Outgoing International Fellowship from the European Union ; Peer reviewed
9 pages, 3 figures, supplementary material https://doi.org/10.1038/s41598-017-16257-w ; The marine invertebrate fossil record provides the most comprehensive history of how the diversity of animal life has evolved through time. One of the main features of this record is a modest rise in diversity over nearly a half-billion years. The long-standing view is that ecological interactions such as resource competition and predation set upper limits to global diversity, which, in the absence of external perturbations, is maintained indefinitely at equilibrium. However, the effect of mechanisms associated with the history of the seafloor, and their influence on the creation and destruction of marine benthic habitats, has not been explored. Here we use statistical methods for causal inference to investigate the drivers of marine invertebrate diversity dynamics through the Phanerozoic. We find that diversity dynamics responded to secular variations in marine food supply, substantiating the idea that global species richness is regulated by resource availability. Once diversity was corrected for changes in food resource availability, its dynamics were causally linked to the age of the subducting oceanic crust. We suggest that the time elapsed between the formation (at mid-ocean ridges) and destruction (at subduction zones) of ocean basins influences the diversity dynamics of marine invertebrates and may have contributed to constrain their diversification ; P.C. was supported by a Ramón y Cajal contract from the Spanish Government. This research was funded by the Spanish Government through research grant CTM2014-54926-R. ; Peer Reviewed
37 pages, 10 figures, 3 tables, 2 appendices, supplement https://doi.org/10.5194/gmd-14-1949-2021-supplement ; Diversity plays a key role in the adaptive capacity of marine ecosystems to environmental changes. However, modelling the adaptive dynamics of phytoplankton traits remains challenging due to the competitive exclusion of sub-optimal phenotypes and the complexity of evolutionary processes leading to optimal phenotypes. Trait diffusion (TD) is a recently developed approach to sustain diversity in plankton models by introducing mutations, therefore allowing the adaptive evolution of functional traits to occur at ecological timescales. In this study, we present a model called Simulating Plankton Evolution with Adaptive Dynamics (SPEAD) that resolves the eco-evolutionary processes of a multi-trait plankton community. The SPEAD model can be used to evaluate plankton adaptation to environmental changes at different timescales or address ecological issues affected by adaptive evolution. Phytoplankton phenotypes in SPEAD are characterized by two traits, the nitrogen half-saturation constant and optimal temperature, which can mutate at each generation using the TD mechanism. SPEAD does not resolve the different phenotypes as discrete entities, instead computing six aggregate properties: total phytoplankton biomass, the mean value of each trait, trait variances, and the inter-trait covariance of a single population in a continuous trait space. Therefore, SPEAD resolves the dynamics of the population's continuous trait distribution by solving its statistical moments, wherein the variances of trait values represent the diversity of ecotypes. The ecological model is coupled to a vertically resolved (1D) physical environment, and therefore the adaptive dynamics of the simulated phytoplankton population are driven by seasonal variations in vertical mixing, nutrient concentration, water temperature, and solar irradiance. The simulated bulk properties are validated by observations from Bermuda Atlantic Time-series Studies (BATS) in the Sargasso Sea. We find that moderate mutation rates sustain trait diversity at decadal timescales and soften the almost total inter-trait correlation induced by the environment alone, without reducing the annual primary production or promoting permanently maladapted phenotypes, as occur with high mutation rates. As a way to evaluate the performance of the continuous trait approximation, we also compare the solutions of SPEAD to the solutions of a classical discrete entities approach, with both approaches including TD as a mechanism to sustain trait variance. We only find minor discrepancies between the continuous model SPEAD and the discrete model, with the computational cost of SPEAD being lower by 2 orders of magnitude. Therefore, SPEAD should be an ideal eco-evolutionary plankton model to be coupled to a general circulation model (GCM) of the global ocean ; This work was funded by national research grant CTM2017-87227-P (SPEAD) from the Spanish government. We acknowledge support for the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). The Institute of Marine Sciences (ICM – CSIC) is supported by a "Severo Ochoa" Centre of Excellence grant (CEX2019-000928-S) from the Spanish government ; Peer reviewed
17 pages, 9 figures, 2 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2021.683354/full#supplementary-material.-- Data Availability Statement: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation ; Particulate organic matter (POM) lability is one of the key factors determining the residence time of organic carbon (OC) in the marine system. Phytoplankton community composition can influence the rate at which heterotrophic microorganisms decompose phytoplankton detrital particles and thus, it controls the fraction of OC that reaches the ocean depths, where it can be sequestered for climate-relevant spans of time. Here, we compared the degradation dynamics of POM from phytoplankton assemblages of contrasting diatom dominance in the presence of mesopelagic prokaryotic communities during a 19-day degradation experiment. We found that diatom-derived POM exhibited an exponential decay rate approximately three times lower than that derived from a community dominated by flagellated phytoplankton (mainly coccolithophores and nanoflagellates). Additionally, dissolved organic matter (DOM) released during the degradation of diatom particles accumulated over the experiment, whereas only residual increases in DOM were detected during the degradation of non-diatom materials. These results suggest that diatom-dominance enhances the efficiencies of the biological carbon pump and microbial carbon pump through the relatively reduced labilities of diatom particles and of the dissolved materials that arise from their microbial processing ; This research was funded by projects SUAVE (CTM2014-54926-R), ANIMA (CTM2015-65720-R), and BIOGAPS (CTM2016-81008-R) and the institutional support of the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S) from the Spanish government. MC-B was supported by a FPU pre-doctoral contract (FPU16/01925) from the Spanish government. We acknowledge support for the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI) ; Peer reviewed
13 pages, 7 figures, 3 tables, 2 appendices, supplementary data https://doi.org/10.1016/j.ecolmodel.2017.06.020 ; The effect of biodiversity on ecosystem functioning is one of the major questions of ecology. However, the role of phytoplankton functional diversity in ecosystem productivity and stability under fluctuating (i.e. non-equilibrium) environments remains largely unknown. Here we use a marine ecosystem model to study the effect of phytoplankton functional diversity on both ecosystem productivity and its stability for seasonally variable nutrient supply and temperature. Functional diversity ranges from low to high along these two environmental axes independently. Changes in diversity are obtained by varying the range of uptake strategies and thermal preferences of the species present in the community. Species can range from resource gleaners to opportunists, and from cold to warm thermal preferences. The phytoplankton communities self-assemble as a result of species selection by resource competition (nutrients) and environmental filtering (temperature). Both processes lead to species asynchrony but their effect on productivity and stability differ. We find that the diversity of temperature niches has a strong and direct positive effect on productivity and stability due to species complementarity, while the diversity of uptake strategies has a weak and indirect positive effect due to sampling probability. These results show that more functionally diverse phytoplankton communities lead to higher and more stable ecosystem productivity but the positive effect of biodiversity on ecosystem functioning depends critically on the type of environmental gradient ; This work was funded by national research grants CGL2013-41256-P (MARES) and CTM2014-54926-R (SUAVE) from the Spanish government. S.M.V. and P.C. are supported by «Ramon y Cajal» (RyC) contracts from the Spanish government. S.D. was supported by NSF (grant 1434007) from the United States government. M.L. and J.M.M. are supported by the French Laboratory of Excellence project «TULIP» (ANR-10-LABX-41; ANR-11-IDEX-0002-02). M.L. was also supported by the BIOSTASES Advanced Grant, funded by the European Research Council under the European Union's Horizon 2020 research and innovation programme (grant agreement No 666971) and J.M.M. by the Region Midi- Pyrenees project (CNRS 121090) ; Peer Reviewed
10 páginas, 6 figuras, 1 tabla.-- Pedro Cermeño . et al.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms ; The number of species of autotrophic communities can increase ecosystem productivity through species complementarity or through a selection effect which occurs when the biomass of the community approaches the monoculture biomass of the most productive species. Here we explore the effect of resource supply on marine primary productivity under the premise that the high local species richness of phytoplankton communities increases resource use through transient selection of productive species. Using concurrent measurements of phytoplankton community structure, nitrate fluxes into the euphotic zone, and productivity from a temperate coastal ecosystem, we find that observed productivities are best described by a population growth model in which the dominant species of the community approach their maximum growth rates. We interpret these results as evidence of species selection in communities containing a vast taxonomic repertory. The prevalence of selection effect was supported by open ocean data that show an increase in species dominance across a gradient of nutrient availability. These results highlight the way marine phytoplankton optimize resources and sustain world food stocks. We suggest that the maintenance of phytoplankton species richness is essential to sustain marine primary productivity since it guarantees the occurrence of highly productive species ; This research was supported by grants CTM2011-25035, CTM2012-30680, and CGL2013-41256-P from the Spanish Government (SG). PC and SV are supported by Ramon y Cajal contracts from the SG ; Peer reviewed
19 pages, 9 figures, 3 tables ; 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 d), compared to F2 (0.4 ± 0.2 mmol m d) and F3 (0.09 ± 0.09 mmol m d). 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 ; This work was funded by the Spanish projects TRYNITROP (CTM2004-05174-C02), FAMOSO (CTM2008-06261-C03), TURBIMOC (CTM2009-06712-E/MAR), and CHAOS (CTM 2012-30680). P.C. was supported by a Ramon y Cajal fellow-ship. B.F.-C. thanks the Spanish Government for support through a FPU fellowship (AP2010-5594) ; Peer Reviewed
The effect of inorganic nutrients on planktonic assemblages has traditionally relied on concentrations rather than estimates of nutrient supply. We combined a novel dataset of hydrographic properties, turbulent mixing, nutrient concentration, and picoplankton community composition with the aims of (i) quantifying the role of temperature, light, and nitrate fluxes as factors controlling the distribution of autotrophic and heterotrophic picoplankton subgroups, as determined by flow cytometry, and (ii) describing the ecological niches of the various components of the picoplankton community. Data were collected at 97 stations in the Atlantic Ocean, including tropical and subtropical open-ocean waters, the northwestern Mediterranean Sea, and the Galician coastal upwelling system of the northwest Iberian Peninsula. A generalized additive model (GAM) approach was used to predict depth-integrated biomass of each picoplankton subgroup based on three niche predictors: sea surface temperature, averaged daily surface irradiance, and the transport of nitrate into the euphotic zone, through both diffusion and advection. In addition, niche overlap among different picoplankton subgroups was computed using nonparametric kernel density functions. Temperature and nitrate supply were more relevant than light in predicting the biomass of most picoplankton subgroups, except for Prochlorococcus and low-nucleic-acid (LNA) prokaryotes, for which irradiance also played a significant role. Nitrate supply was the only factor that allowed the distinction among the ecological niches of all autotrophic and heterotrophic picoplankton subgroups. Prochlorococcus and LNA prokaryotes were more abundant in warmer waters (> 20°C) where the nitrate fluxes were low, whereas Synechococcus and high-nucleic-acid (HNA) prokaryotes prevailed mainly in cooler environments characterized by intermediate or high levels of nitrate supply. Finally, the niche of picoeukaryotes was defined by low temperatures and high nitrate supply. These results support the key role of nitrate supply, as it not only promotes the growth of large phytoplankton, but it also controls the structure of marine picoplankton communities. ; We thank the officers and crew of the research vessels Hespérides, Sarmiento de Gamboa, Mytilus, Ramon Margalef and Lura for their help during the cruises. We are also very grateful to Fátima Eiroa for the flow cytometry analysis in the NICANOR, HERCULES1, HERCULES2, HERCULES3, and ASIMUTH cruises. Finally, we would like to thank Julia Uitz and the two anonymous reviewers for their valuable comments on the paper. This research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through projects CTM2012-30680 to Beatriz Mouriño, CTM2008-0626I-C03-01 to Mikel Latasa, REN2003-09532-C03-01 to Ramiro Varela Benvenuto, CTM2004-05174-C02 to Emilio Marañón, and CTM2011-25035 to Pedro Cermeño; by the Galician government through grants 09MMA027604PR to Manuel Ruiz Villareal and EM2013/021 to Beatriz Mouriño; by the Instituto Español de Oceanografia (IEO) through the time series project RADIALES coordinated by Antonio Bode and by the 7th Framework Programme of the European Commission through grant FP7 SPACE.2010.1.1-01 261860 to Manuel Ruiz Villareal. Jose Luis Otero Ferrer acknowledges the receipt of a FPI contract from MINECO (CTM2012-30680) and Bieito Fernádez Castro a Juan de La Cierva Formación fellowship (FJCI-641 2015-25712, Ministerio de Economía y Competitividad, Spanish government).
22 pages, 4 tables, 5 figures ; The effect of inorganic nutrients on planktonic assemblages has traditionally relied on concentrations rather than estimates of nutrient supply. We combined a novel dataset of hydrographic properties, turbulent mixing, nutrient concentration, and picoplankton community composition with the aims of (i) quantifying the role of temperature, light, and nitrate fluxes as factors controlling the distribution of autotrophic and heterotrophic picoplankton subgroups, as determined by flow cytometry, and (ii) describing the ecological niches of the various components of the picoplankton community. Data were collected at 97 stations in the Atlantic Ocean, including tropical and subtropical open-ocean waters, the northwestern Mediterranean Sea, and the Galician coastal upwelling system of the northwest Iberian Peninsula. A generalized additive model (GAM) approach was used to predict depth-integrated biomass of each picoplankton subgroup based on three niche predictors: sea surface temperature, averaged daily surface irradiance, and the transport of nitrate into the euphotic zone, through both diffusion and advection. In addition, niche overlap among different picoplankton subgroups was computed using nonparametric kernel density functions. Temperature and nitrate supply were more relevant than light in predicting the biomass of most picoplankton subgroups, except for Prochlorococcus and lownucleic- acid (LNA) prokaryotes, for which irradiance also played a significant role. Nitrate supply was the only factor that allowed the distinction among the ecological niches of all autotrophic and heterotrophic picoplankton subgroups. Prochlorococcus and LNA prokaryotes were more abundant in warmer waters ( > 20 C) where the nitrate fluxes were low, whereas Synechococcus and high-nucleic-acid (HNA) prokaryotes prevailed mainly in cooler environments characterized by intermediate or high levels of nitrate supply. Finally, the niche of picoeukaryotes was defined by low temperatures and high nitrate supply. These results support the key role of nitrate supply, as it not only promotes the growth of large phytoplankton, but it also controls the structure of marine picoplankton communities ; This research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through projects CTM2012-30680 to Beatriz Mouriño, CTM2008-0626I-C03-01 to Mikel Latasa, REN2003-09532-C03-01 to Ramiro Varela Benvenuto, CTM2004-05174-C02 to Emilio Marañón, and CTM2011- 25035 to Pedro Cermeño; by the Galician government through grants 09MMA027604PR to Manuel Ruiz Villareal and EM2013/021 to Beatriz Mouriño; by the Instituto Español de Oceanografia (IEO) through the time series project RADIALES coordinated by Antonio Bode and by the 7th Framework Programme of the European Commission through grant FP7 SPACE.2010.1.1- 01 261860 to Manuel Ruiz Villareal. Jose Luis Otero Ferrer acknowledges the receipt of a FPI contract from MINECO (CTM2012-30680) and Bieito Fernádez Castro a Juan de La Cierva Formación fellowship (FJCI-641 2015-25712, Ministerio de Economía y Competitividad, Spanish government) ; Peer reviewed
