Biel Obrador

• PhD
• Professor (Associate) at University of Barcelona

Most lakes and reservoirs have surface CO2 concentrations that are supersaturated relative to the atmosphere1. The resulting CO2 emissions from lakes represent a substantial contribution to the continental carbon balance2, 3, 4. Thus, the drivers of CO2 supersaturation in lakes need to be understood to constrain the sensitivity of the land carbon c...

Many lakes exhibit seasonal stratification, during which they develop strong thermal and chemical gradients. An expansion of depth-integrated monitoring programs has provided insight into the importance of organic carbon processing that occurs below the upper mixed layer. However, the chemical and physical drivers of metabolism and metabolic coupli...

Despite the increasing understanding of the magnitude and drivers of carbon gas emissions from inland waters, the relevance of water fluctuation and associated drying on their dynamics is rarely addressed. Here, we quantified CO 2 and CH 4 fluxes from a set of temporary ponds across seasons. The ponds were in all occasion net CO 2 emitters irrespec...

Mining of biological and geochemical data pinpoints a key trait of freshwater plants

Several findings suggest that CO2 emissions in lakes are not always directly linked to changes in metabolism but can be associated with interactions with the dissolved inorganic carbon equilibrium. Alkalinity has been described as a determining factor in regulating the relative contributions of biological and inorganic processes to carbon dynamics...

Estimations of ecosystem metabolism have rarely been used to quantify productivity in structural reductionist approaches for the description of phytoplankton composition. However, estimations of ecosystem metabolism could contribute to a better understanding of the relationship between phytoplankton composition and ecosystem functioning. To examine...

Global assessments evaluating greenhouse gas emissions and climate benefits of hydropower rely on life cycle assessments (LCAs). However, small hydropower plants (i.e., installations with less than 10 MW; SHPs), are largely underrepresented in such schemes, despite their widespread proliferation and well known ecological concerns. Here we quantifie...

Wetlands are valuable ecosystems providing many ecosystem services. Among others, they provide a high potential for carbon storage, as anaerobic conditions reduce the decomposition of organic matter, resulting in high carbon stocks. Wetlands worldwide are expected to store 20-30% of the estimated global soil carbon while only covering 5-8% of the w...

Dam decommissioning (DD) is used to solve economic and social problems posed by old dams. However, we ignore the effect of DD on the content and reactivity of large stocks of organic matter (OM) buried in reservoir sediments. We explored temporal changes in the content and reactivity of sediment OM during the first 580 days after the drawdown phase...

In ice‐covered lakes, near‐bottom oxygen concentration decreases for most of the wintertime, sometimes down to the point that bottom waters become hypoxic. Studies insofar have reached divergent conclusions on whether climate change limits or reinforces the extent and duration of hypoxia under ice, raising the need for a comprehensive understanding...

Water availability is a fundamental driver of biogeochemical processing in highly dynamic ecosystems such as intermittent rivers and ephemeral streams (IRES), which are recognized as the most common fluvial ecosystem globally. Because of their global extent, IRES have a remarkable contribution to organic matter processing, which is expected to inte...

Dam decommissioning (DD) is a viable management option for thousands of ageing dams. Reservoirs are large carbon sinks, and reservoir drawdown results in important carbon dioxide (CO2) and methane (CH4) emissions. We studied the effects of DD on CO2 and CH4 fluxes from impounded water, exposed sediment, and lotic water before, during, and 3–10 mont...

Global change is modifying meteorological and hydrological factors that influence the thermal regime of water bodies. These modifications can lead to longer stratification periods with enlarged hypolimnetic anoxic periods, which can promote heterotrophic anaerobic processes and alter reservoir carbon cycling. Here, we quantified aerobic and anaerob...

Water availability is a fundamental driver of biogeochemical processing in highly dynamic freshwater ecosystems. Recent evidence demonstrates that flow disruption influences biogeochemical cycles globally, given the wide distribution of watercourses exposed to episodic drying. The complexity of the drying process can give rise to different annual a...

Sediment beds from drawdown areas of reservoirs constitute a relevant hotspot for carbon dioxide (CO2) emission to the atmosphere. This CO2 source is especially relevant in the case of Mediterranean reservoirs, where hydrological variability favors the exposure of large sediment areas to air. In spite of this, the role of dry sediments as CO2 emitt...

Despite substantial advances in quantifying greenhouse gas (GHG) emissions from dry inland waters, existing estimates mainly consist of carbon dioxide (CO2) emissions. However, methane (CH4) may also be relevant due to its higher Global Warming Potential (GWP). We report CH4 emissions from dry inland water sediments to i) provide a cross-continenta...

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and tot...

Zooplankton assemblages in the confined coastal lagoons of La Pletera salt marshes (Baix Ter wetlands, Girona, Spain) are dominated by two species: one calanoid copepod ( Eurytemora velox ) and the other rotifer ( Brachionus gr. plicatilis ). They alternate as the dominant species (more than 80% of total zooplankton biomass), with the former being...

Reservoir drawdown areas—where sediment is exposed to the atmosphere due to water-level fluctuations—are hotspots for carbon dioxide (CO2) emissions. However, the global extent of drawdown areas is unknown, precluding an accurate assessment of the carbon budget of reservoirs. Here we show, on the basis of satellite observations of 6,794 reservoirs...

Pelagic calcification shapes the carbon budget of lakes and the sensitivity of dissolved inorganic carbon (DIC) responses to lake metabolism. This process, being tightly linked to primary production, needs to be understood within the context of summer eutrophication which is increasing due to human stressors and global change. Most lake carbon budg...

Aquatic metabolism is an important descriptor of ecosystem functioning. The metabolism of ponds and confined coastal lagoons has been poorly studied in comparison to other aquatic systems, in which the metabolic dynamics are better understood. In this study, we described the ecosystem metabolism of two confined Mediterranean coastal lagoons located...

The origin and reactivity of dissolved organic matter (DOM) have received attention for decades due to the key role DOM plays in global carbon cycling and the ecology of aquatic systems. However, DOM dynamics in river networks remain unresolved, hampered by the lack of data integrating the spatial and temporal dimensions inherent to riverine ecosys...

Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO 2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global surve...

Hydrology is the main driver of dissolved organic matter (DOM) dynamics in intermittent rivers and ephemeral streams. However, it is still unclear how the timing and the spatial variation in flow connectivity affect the dynamics of DOM and inorganic solutes. This study focuses on the impact of flow cessation on the temporal and spatial heterogeneit...

Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of...

Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and...

Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and peri...

Intermittent rivers and ephemeral streams (IRES) encompass fluvial ecosystems that eventually stop flowing and run dry at some point in space and time. During the dry phase, channels of IRES consist mainly of dry riverbeds (DRBs), prevalent yet widely unexplored ecotones between dry and wet phases that can strongly influence the biogeochemistry of...

Coastal lagoons are a dynamic habitat, with varying marine and freshwater inputs determining the presence and extent of stratification, and the physical and chemical environment of the epi- and hypolimnion. As a result, the biotic assemblages that thrive in such environments are a diverse mix of species, with wide ranges of tolerances. While annual...

A large part of the world's inland waters, including streams, rivers, ponds, lakes and reservoirs is subject to occasional, recurrent or even permanent drying. Moreover, the occurrence and intensity of drying events are increasing in many areas of the world because of climate change, water abstraction, and land use alteration. Yet, information on t...

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent probl...

The impoundment of running waters through the construction of large dams is recognised as one of the most important factors determining the transport, transformation, and outgassing of carbon (C) in fluvial networks. However, the effects of small and very small water retention structures (SWRS) on the magnitude and spatiotemporal patterns of C emis...

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to thei...

Insight into how environmental change determines the production and distribution ofcyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus onhepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g.,anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their p...

Global change is dramatically altering flow regimes worldwide. Among the most important consequences are the transition of many permanent waterways to temporary waterways, the increase in duration and frequency of non‐flow periods of temporary streams, and the increase in the severity (i.e. irradiance, temperature and humidity) of the non‐flow peri...

Under-ice dissolved oxygen (DO) metabolism and DO depletion are poorly understood, limiting our ability to predict how changing winter conditions will affect lake ecosystems. We analyzed under-ice DO dynamics based on high frequency (HF) data at two depths (5 and 25 m) for three winters (January to March 2014, 2015, and 2016) in oligotrophic Lake T...

The potential for rivers to alter the flux of dissolved organic matter (DOM) from land to ocean is widely accepted. Yet anticipating when and where rivers behave as active reactors vs. passive pipes of DOM stands as a major knowledge gap in river biogeochemistry, resulting in uncertainties for global carbon models. Here, we investigate the controls...

Controls on the degradation of dissolved organic matter (DOM) are complex but key to understand the role of freshwaters in the carbon cycle. Both the origin and previous degradation history have been suggested to determine DOM reactivity, but it is still a major challenge to understand the links between DOM composition and biodegradation kinetics....

Inland waters are significant sources of carbon dioxide (CO2) to the atmosphere. CO2 supersaturation and subsequent CO2 emissions from inland waters can be driven by internal metabolism, external inputs of dissolved inorganic carbon (DIC) derived from the catchment and other processes (e.g., internal geochemical reactions of calcite precipitation o...

With the advent and proliferation of high frequency in situ data collection from lakes has come the need to process unprecedented quantities of data in a useful and effective manner. This need has driven the development, or adoption, of a variety of techniques, programs and methodologies for working with high frequency lake data. It was, therefore,...

The hydrological continuum in rivers can be altered by the presence of small dams that modify the water residence time (WRT) and prevailing habitat, turning lotic river sections into lentic ones and influencing downstream reaches. The structure and activity of the microbial community occurring in the benthic and planktonic compartments can be modif...

Recent technological developments have increased the number of variables being monitored in lakes and reservoirs using automatic high frequency monitoring (AHFM). However, design of AHFM systems and posterior data handling and interpretation are currently being developed on a site-by-site and issue-by-issue basis with minimal standardization of pro...

Most fluvial networks worldwide include watercourses that recurrently cease to flow and run dry. The spatial and temporal extent of the dry phase of these temporary watercourses is increasing as a result of global change. Yet, current estimates of carbon emissions from fluvial networks do not consider temporary watercourses when they are dry. We ch...

The composition of dissolved organic matter (DOM) in rivers results from the different sources and in-stream transformations along the land to ocean aquatic continuum. Riverine DOM sources are highly dependent on the hydrological connection between the river channel and the surrounding terrestrial ecosystems, but how the lack of this connectivity (...

Aquatic metabolism is a fundamental descriptor of ecosystem functioning in lakes. At an ecosystem scale, the metabolism represents the overall rates of production and consumption of organic matter, and is thus informative of the lake carbon balance. Rates of primary production and respiration in lakes are increasingly estimated from diel variations...

Freshwater reservoirs are significant components of the global carbon cycle. However, relatively few studies address the balance between the atmospheric carbon flux and sedimentation in these ecosystems. We performed a simultaneous analysis of the sedimentation fluxes of particulate organic carbon (SPOC) and atmospheric CO2 fluxes (FCO2) in the epi...

Environmental variables along the period studied in Guadalcacín 2009 (a) and Bornos 2010 (b). Air temperature (Tair, thicker black line), PAR radiation (Rad, grey line), and water inflow and outflow rates (Qin and Qout, dashed and dotted black line respectively). Supplementary material 1

During summer drought, Mediterranean fluvial networks are transformed into highly heterogeneous landscapes characterized by different environments (i.e., running and impounded waters, isolated river pools and dry beds). This hydrological setting defines novel biogeochemically active areas that could potentially increase the rates of carbon emission...

This paper reviews the current knowledge on the diversity, distribution and ecology of the genus Ruppia Linnaeus in the Mediterranean region. The genus Ruppia, a cosmopolitan aquatic plant complex, is generally restricted to shallow waters such as coastal lagoons and brackish habitats characterized by fine sediments and high salinity fluctuations....

ISSN:0211-4550

Carbon dioxide efflux during the flooding phase of temporary ponds Small water bodies, such as temporary ponds, have a high carbon processing potential. Nevertheless, despite the global occurrence of these systems, the carbon effluxes from such water bodies have been largely overlooked. In this study, we examined the intra-and intersystem variabili...

Temporary watercourses that naturally cease to flow and run dry comprise a notable fraction of the world’s river networks, yet estimates of global carbon dioxide (CO2) emissions from watercourses do not consider emissions from these systems when they are dry. Using data from a sampling campaign in a Mediterranean river during the summer drought per...

Recent advances in open-water measurements suggest significant temporal and spatial variability of gross primary production (GPP), net ecosystem production (NEP), and respiration (R) with implications for understanding carbon cycling in lakes. This study applied high-frequency depth profiles in three stratified lakes of different trophic status to...

Research on limnology in southern Europe had achieved a notable presence in the international arena before the onset of the current dramatic cuts in public investment in science. We assessed the limnological research published in peer-reviewed journals by Spanish and Portuguese (i.e., Iberian) researchers during the decade prior to the economic rec...

The complexity and variability of processes determining dissolved organic matter (DOM) quality is likely to increase in highly dynamic systems such as Mediterranean water bodies. We studied the dynamics of DOM in a Mediterranean lagoon dominated by seasonal submerged vegetation and receiving torrential freshwater inputs. In order to trace changes i...

Dietary patterns can substantially vary the resource consumption and environmental impact of a given population. Dietary changes such as the increased consumption of vegetables and reduced consumption of animal products reduce the environmental footprint and thus the use of natural resources. The adherence of a given population to the Mediterranean...

Excitation–emission matrix fluorescence spectra for the two DOC sources (AutoDOC and AlloDOC) prior to incubation (Initial) and after the 28 days of biodegradation (BD) and photo- plus biodegradation (UV + BD) treatments. Please note the different scale used for each DOC source

Carbon and oxygen metabolism in a densely vegetated lagoon: implications of spatial heterogeneity Ecosystem metabolism is an integrated descriptor of lake functioning. In systems dominated by submerged vegetation, as in many coastal environments, estimates of whole-system metabolism that are calculated through free-water diel techniques can be comp...

Dissolved organic carbon (DOC) reactivity in aquatic systems is essentially dependent on DOC precursor material and on the processes regulating its bioavailability, especially photodegradation and microbial activity. We investigated temporal changes (from hours to weeks) in the reactivity of allochthonous and autochthonous DOC sources in a macrophy...

In this article, we studied the fluxes of organic and inorganic (DIC) carbon in a coastal lagoon dominated by highly productive macrophyte meadows (Albufera des Grau, Balearic Islands). Seasonal and annual carbon budgets were performed from estimates of whole-system fluxes, and the fate of organic matter production was evaluated through a stable is...

Dissolved Organic Matter (DOM) is a fundamental component of the aquatic carbon cycle and a key driver of the biogeochemical interactions between terrestrial and aquatic ecosystems. The origin, properties and role of DOM are increasingly characterised in lakes, rivers and streams, but little is known about DOM characteristics in ephemeral washes, w...

In this work we discuss the historical record of metals as derived from a sediment core from the Port of Maó (Minorca, Spain), the second natural largest harbour in Europe. The sedimentation rate derived from radionuclide profiles increased by a factor of five since the 1960s due to the urbanisation of the town waterfront. Metal concentrations show...

The seasonal and interannual dynamics of the biomass and spatial distribution of a macrophyte meadow were explored in a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) from 2002 to 2007. The dynamics in the main physicochemical variables were also analysed to assess the factors involved in the spatiotemporal variability of the su...

In this study, a dynamic model for a Mediterranean coastal lagoon (Albufera des Grau, Menorca, Western Mediterranean) is presented. A simple model with limited data requirements was constructed to simulate the daily variations in water level (WL) and water salinity (S) in the lagoon. Both parameters constitute the main descriptors of the lagoon hyd...

The underwater light regime of a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) was studied during four years in order to characterise the spatial and temporal variations in the light attenuation coefficient (K) and to assess the relative contribution of the different water components to total light attenuation.During the studie...

This work aims to characterize the current autotrophic compartment of the Albufera des Grau coastal lagoon (Menorca, Balearic Islands) and to assess the relationship between the submerged macrophytes and the limnological parameters of the lagoon. During the studied period the submerged vegetation was dominated by the macrophyte Ruppia cirrhosa, whi...

The purpose of this paper is to review some of the methods that several epidemiological studies use to evaluate the adherence of a population to the Mediterranean diet pattern. Among these methods, diet indexes attempt to make a global evaluation of the quality of the diet based on a traditional Mediterranean reference pattern, described as a prior...