Sergio M. Vallina

Sergio M. Vallina
Instituto Español de Oceanografia | IEO · Centro Oceanográfico de Gijón

PhD Marine Sciences
https://oceanglobe.org

About

40
Publications
21,657
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Introduction
https://oceanglobe.org -- # His lines of research are numerical ecology, marine ecosystem modelling, and global biogeochemical cycles. The questions he is trying to answer are: i) what are the mechanisms that allow the coexistence of plankton communities that are competing for the same resources (Plankton Paradox); ii) what is the effect of plankton biodiversity on marine ecosystem functioning (productivity, stability); iii) what is the role of ecological evolution (eco-evo) of phytoplankton functional traits (e.g. optimal values of temperature, light, and nutrients) on ecosystem dynamics. The temporal scales of interest range between seasonal to inter-decadal. Higher impact journals: Sience (1), Nature Communications (1), PNAS (2), Scientific Reports (1)
Additional affiliations
October 2012 - March 2017
Spanish National Research Council
Position
  • Researcher
October 2009 - September 2012
Massachusetts Institute of Technology
Position
  • Research Associate
March 2007 - September 2009
University of East Anglia
Position
  • Research Associate
Education
October 2002 - September 2003
Universitat Politècnica de Catalunya
Field of study
  • Applied Physics
October 2002 - December 2006
Spanish National Research Council
Field of study
  • Marine Sciences
October 2001 - July 2002
Sorbonne Université
Field of study
  • Oceanography

Publications

Publications (40)
Article
Full-text available
The shape of the productivity-diversity relationship (PDR) for marine phytoplankton has been suggested to be unimodal, that is, diversity peaking at intermediate levels of productivity. However, there are few observations and there has been little attempt to understand the mechanisms that would lead to such a shape for planktonic organisms. Here we...
Article
Full-text available
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 functio...
Chapter
Full-text available
Microbial modelling is today a central aspect of ecological theory applied to microorganisms. Ecological theory and numerical modelling are essential for developing a deeper understanding of the mechanisms that shape the assembly and evolution of microbial communities. Microbes have complex interactions among them and with their local environment,...
Article
Full-text available
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 recen...
Article
Full-text available
Background Ecological interactions among microorganisms are fundamental for ecosystem function, yet they are mostly unknown or poorly understood. High-throughput-omics can indicate microbial interactions through associations across time and space, which can be represented as association networks. Associations could result from either ecological int...
Preprint
Full-text available
The fossil record of marine invertebrates has long fueled the debate on whether or not there are limits to global diversity in the sea1–4⁠. Ecological theory states that as diversity grows and ecological niches are filled, the strengthening of biological interactions imposes limits on diversity5–7⁠. However, the extent to which biological interacti...
Preprint
Full-text available
Background Ecological interactions among microorganisms are fundamental for ecosystem function, yet they are mostly unknown or poorly understood. High-throughput-omics can indicate microbial interactions through associations across time and space, which can be represented as association networks. Associations could result from either ecological int...
Presentation
Full-text available
SPEAD 1.0 is an eco-evolutionary phytoplankton model where phytoplankton are characterized by two traits: the half-saturation constant for a nutrient, and the optimal temperature for growth. Contemporary evolution is allowed through a recently developed method called trait diffusion. After explaining how its equations are derived, this presentation...
Preprint
Full-text available
Diversity plays a key role in the adaptive capacities of marine ecosystems to environmental changes. However, modeling phytoplankton trait diversity remains challenging due to the strength of the competitive exclusion of sub-optimal phenotypes. Trait diffusion (TD) is a recently developed approach to sustain diversity in plankton models by allowing...
Presentation
Full-text available
Our recent size-based studies of phytoplankton communities and plankton ecosystems reveal an apparent inconsistency between laboratory-based results and oceanic observations. Uni-modal distributions of maximum phytoplankton growth rate over cell size have been reported from laboratory experiments using single-species cultures. Our models, formulate...
Article
Full-text available
With global climate change altering marine ecosystems, research on plankton ecology is likely to navigate uncharted seas. Yet, a staggering wealth of new plankton observations, integrated with recent advances in marine ecosystem modeling, may shed light on marine ecosystem structure and functioning. A EuroMarine foresight workshop on the " Impact o...
Article
Full-text available
Biodiversity is known to be an important determinant of ecosystem-level functions and processes. Although theories have been proposed to explain the generally positive relationship between, for example, biodiversity and productivity, it remains unclear which mechanisms underlie the observed variations in Biodiversity-Ecosystem Function (BEF) relati...
Article
Full-text available
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 pr...
Article
Full-text available
Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem...
Presentation
Full-text available
We examine Biodiversity and Ecosystem Function (BEF) in a model phytoplankton community, using two recently developed mechanisms for sustaining diversity. The Trait Diffusion (TD) formulation represents the maintenance of diversity via endogenous mechanisms, such as inter-generational trait plasticity and rapid evolution. The ’Kill-the-Winner’ (KTW...
Article
Full-text available
Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid rela- tive to other sili...
Article
Microorganisms attain high population densities, which has led microplankton ecologists to assume that samples of a few tens of millilitres suffice to characterize the assemblage of species. However, the observation that microbial plankton communities contain a large pool of species with low population densities casts doubt on the validity of estim...
Article
Aerosols have a large potential to influence climate through their effects on the microphysics an optical properties of clouds and, hence, on the Earth’s radiation budget. Aerosol–cloud interactions have been intensively studied in polluted air, but the possibility that the marine biosphere plays an important role in regulating cloud brightness in t...
Article
During the last decade the number of seawater dimethylsulfide (DMS) concentration mea-surements has increased substantially. The importance this gas, emitted from the ocean to the atmosphere, may have in the cloud microphysics and hence in the Earth albedo and radiation budget, makes it necessary to accurately reproduce the global distribution. Rec...
Article
Full-text available
The potentially significant role of the biogenic trace gas dimethylsulfide (DMS) in determining the Earth's radiation budget makes it necessary to accurately reproduce seawater DMS distribution and quantify its global flux across the sea/air interface. Following a threefold increase of data (from 15,000 to over 47,000) in the global surface ocean D...
Article
Full-text available
Ocean dimethylsulfide (DMS) produced by marine biota is the largest natural source of atmospheric sulfur, playing a major role in the formation and evolution of aerosols, and consequently affecting climate. Several dynamic process-based DMS models have been developed over the last decade, and work is progressing integrating them into climate models...
Article
Full-text available
The emission of dimethyl-sulphide (DMS) gas by phytoplankton and the subsequent formation of aerosol has long been suggested as an important climate regulation mechanism. The key aerosol quantity is the number concentration of cloud condensation nuclei (CCN), but until recently global models did not include the necessary aerosol physics to quantify...
Article
We study the dynamics of dimethylsulphide (DMS) and dimethylsulphoniopropionate (DMSP) using the global ocean biogeochemistry model PlankTOM5, which includes three phytoplankton and two zooplankton functional types (PFTs). We present a fully prognostic DMS module describing intracellular particulate DMSP (DMSPp) production, concentrations of dissol...
Article
Full-text available
Here we present and analyse the behaviour of four different parameterizations of the preferential uptake of NH4 over NO3. The first three (Wroblewski–Fasham, Spitz, Hurtt and Armstrong) are commonly used in current marine ecosystem models. However, they show either formulational inconsistencies (e.g. Wroblewski–Fasham), unrealistic features (e.g. Sp...
Article
Full-text available
In the work of Vallina et al. [2007] we showed that the seasonality of the solar radiation dose received in the upper mixed layer (or SRD) was highly positively correlated with dimethylsulfide (DMS) concentration seasonality over most of the global ocean. The underlying mechanism wassuggested to be an increase in phytoplankton (direct) DMS producti...
Article
Full-text available
A new one-dimensional model of DMSP/DMS dynamics (DMOS) is developed and applied to the Sargasso Sea in order to explain what drives the observed dimethylsulfide (DMS) summer paradox: a summer DMS concentration maximum concurrent with a minimum in the biomass of phytoplankton, the producers of the DMS precursor dimethylsulfoniopropionate (DMSP). Se...
Article
Full-text available
The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds...
Article
Full-text available
The CLAW postulate states that an increase in solar irradiance or in the heat flux to the ocean can trigger a biogeochemical response to counteract the associated increase in temperature and available sunlight. This natural (negative) feedback mechanism would be based on a multistep response: first, an increase in seawater dimethylsulfide concentra...
Article
Marine biogenic dimethylsulfide (DMS) is the main natural source of tropospheric sulfur, which may play a key role in cloud formation and albedo over the remote ocean. Through a global data analysis, we found that DMS concentrations are highly positively correlated with the solar radiation dose in the upper mixed layer of the open ocean, irrespecti...
Article
Environmental context. Over the last twenty years, large and continued research efforts have been invested in deci-phering whether oceanic plankton contribute to the regulation of climate by the production and release of cloud-seeding atmospheric sulfur. Our recent research using globally spread observations and satellite-derived data suggest that...
Article
Full-text available
A 3-year time series set (from January 2002 to December 2004) of monthly means of satellite-derived chlorophyll (CHL) and cloud condensation nuclei (CCN), as well as model outputs of hydroxyl radical (OH), rainfall amount (RAIN), and wind speed (WIND) for the Southern Ocean (SO, 40°S–60°S) is analyzed in order to explain CCN seasonality. Chlorophyl...

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Projects

Projects (5)
Project
www.prodigio-project.eu The renewable energy technologies that will form the backbone of the energy system by 2030 and 2050 are still at an early stage of development today. Bringing these new technologies faster to commercialization is challenging. The European project PRODIGIO aims to contribute to this challenge by establishing a base of knowledge for the development of a system failure prediction technology that will boost the sustainable production of biogas from microalgal biomass.
Project
Global ocean ecosystem models should include the ecology & evolution (eco-evo) of microbial plankton to accurately simulate the expected changes in the patterns of diversity, community assembly and ecosystem functioning (i.e. productivity, stability) under future global warming conditions. The GOMMA'21 project goals are: 1) to include eco-evo dynamics in a model of microbial plankton at the global ocean scale; 2) to simulate several evolving populations with the eco-evo model, each of them with adaptive capacity along a three-dimensional fitness landscape (nutrients, temperature, irradiance); 3) to simulate the eco-evolutionary trajectories of microbial plankton to the future (2000 - 2100) using IPCC scenarios of climate change. Ecological indicators of ecosystem functioning such as primary production, biological carbon pump, community trait diversity, and food web structure, will be computed, analysed and compared to simulations using the same model without eco-evo dynamics. The overarching goal is to evaluate the potential of adaptive evolution to impact the response of marine ecosystems to current and future environmental changes.
Project
«Simulating Plankton Evolution with Adaptive Dynamics (SPEAD)» The project SPEAD is based on the notion of dynamic fitness landscapes (DFL), which gives the relationship between genotype and survival fitness for non-constant environmental conditions, to simulate the ecological evolution (eco-evo) of planktonic organisms for the global ocean. The aims of this project are: i) to develop a marine ecosystem model that includes the adaptive evolution of planktonic organisms along several environmental gradients (nutrients, temperature, irradiance) in order ii) to better predict the response of marine ecosystems to future climate change scenarios. To achieve this goal we propose to combine within the same modelling framework two approaches that are so far being developed independently of each other. The classical approach to simulate the dynamics of plankton communities relies on solving phytoplankton populations as discrete entities with fixed environmental optima (Nopt, Topt, Iopt) that do not change over time. A newer alternative approach includes adaptive dynamics using trait diffusion (TD) to solve the temporal evolution of these physiological traits for a single population. The SPEAD project seeks to combine both approaches in order to build a unified model that is able to resolve the adaptive evolution of species-traits for many populations of phytoplankton simultaneously.