Hugo Sarmento

• Professor
• Professor (Associate) at Federal University of São Carlos

Freshwater environments and coastal marine areas provide key ecosystem services to society and serve as habitats for biodiversity. However, they face major challenges from human activities and climate factors, leading to global degradation. The effect of these agents depends on geographic location and climate, among other factors. To comprehensivel...

The African Cladocera fauna is recognized by high endemism. Several studies have helped to understand the diversity and geographic distribution of some groups of Chydoridae on the continent. However, the literature indicates the presence of species whose natural distribution is presumed to be in other continents, suggesting that the diversity and e...

Mixotrophy, a physiological trait combining autotrophy and heterotrophy in one organism, significantly contributes to energy and matter transfer in aquatic ecosystems. However, understanding how environmental factors influence mixoplankton success across freshwater ecosystems has been uncertain. The grand écart hypothesis (GEH) posits that light an...

Background The backbone of the eukaryotic tree of life contains taxa only found in molecular surveys, of which we still have a limited understanding. Such is the case of Picozoa, an enigmatic lineage of heterotrophic picoeukaryotes within the supergroup Archaeplastida, which has emerged as a significant component of marine microbial planktonic comm...

The failure of breeding attempts is a major hindrance to bird reproduction, making nest site choice under strong selective pressure. Urbanization may offer lower risk of nest predation to certain bird species, but the impact of using anthropogenic structures as nesting sites on parental fitness is seldom studied. We studied the effect of anthropoge...

Food webs depict the tangled web of trophic interactions associated with the functioning of an ecosystem. Understanding the mechanisms providing stability to these food webs is therefore vital for conservation efforts and the management of natural systems. Here, we first characterised a tropical stream meta‐food web and five individual food webs us...

A number of species of Chydorus Leach, 1816 (Crustacea: Cladocera) need improvements in their taxonomy much more than any other genus within the family Chydoridae Dybowsky & Grochowski, 1894 emend. Frey, 1967, which makes the systematics of the genus still a puzzle that lacks several pieces. Here, we redescribe the African species Chydorus tilhoi R...

1- Describing food webs with precision and detail is critical for understanding the functioning of ecosystems. Streams in the Brazilian Atlantic Rainforest stand out as one of the most threatened ecosystems worldwide and yet, little is known about whether these systems house stable food webs and what are the trophic properties associated with that....

Tiny ocean plankton (picoplankton) are fundamental for the functioning of the biosphere, but the ecological mechanisms shaping their biogeography were partially understood. Comprehending whether these microorganisms are structured by niche versus neutral processes is relevant in the context of global change. We investigate the ecological processes...

In this review we highlight the relevance of biodiversity that inhabit coastal lagoons, emphasizing how species functions foster processes and services associated with this ecosystem. We identified 26 ecosystem services underpinned by ecological functions performed by bacteria and other microbial organisms, zooplankton, polychaetae worms, mollusks,...

Ocean currents are a key driver of plankton dispersal across the oceanic basins. However, species specific temperature constraints may limit the plankton dispersal. We propose a methodology to estimate the connectivity pathways and timescales for plankton species with given constraints on temperature tolerances, by combining Lagrangian modeling wit...

Tiny ocean plankton (picoplankton) are fundamental for the functioning of the biosphere, but the ecological mechanisms shaping their biogeography are partially understood. Comprehending whether these microorganisms are structured by niche vs. neutral processes is highly relevant in the context of global change. The ecological drivers structuring pi...

I present new perspectives and advances on the knowledge of free-living copepods in large tropical river basins. Currently, the greatest copepod diversity is known from the Palearctic region, with a surface about twice or thrice that of the Neotropical and Afrotropical areas, respectively. Interestingly, biological diversity estimators suggest a mu...

The Congo River Basin is the second largest in the world, and its plankton biota remains completely unknown. We studied the zooplankton diversity across 1700 km of the main channel (from the cities of Kisangani to Kinshasa) and subsequently in the mouths of the 25 largest tributaries during 2013 (N=39), and across 500 km of Kasai-Kwa River and trib...

The free-living copepods of the Congo River Basin in Africa, the second largest in the world just after the Amazonas River Basin, are still insufficiently known because of problematic accessibility and complex logistics related to sampling. We analyzed samples from 82 sites obtained during expeditions in 2010 and 2013. The Congo River main channel...

The biogeography of bacterial communities is a key topic in Microbial Ecology. Regarding continental water, most studies are carried out in the northern hemisphere, leaving a gap on microorganism’s diversity patterns on a global scale. South America harbours approximately one third of the world’s total freshwater resources, and is one of these unde...

Heterotrophic respiration of organic matter (OM) is thought to dominate over aquatic primary production (PP) in most freshwater lake ecosystems. This paradigm implies that lateral transport of OM from the terrestrial biosphere subsidize the major fraction of aquatic respiration and that many lakes are a net source of carbon dioxide (CO2) to atmosph...

The turnover of microbial communities across space is dictated by local and regional factors. Locally, selection shapes community assembly through biological interactions between organisms and the environment, while regional factors influence microbial dispersion patterns. Methods used to disentangle the effects of local and regional factors typica...

Soda lake environments are known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effects of different environmental conditions of six adjacent soda lakes in the Pantanal biome (Mato Grosso do Sul state, Brazil) on bacterial communities and their functioning using a metagenomic...

Mixotrophy is important to ecosystems functioning. Assuming that limiting resources induce phagotrophy in mixotrophs, we used a factorial experimental design to evaluate how nutrient and light affects phagotrophy in two mixotrophic phytoflagellates belonging to different lineages. We estimated cell-specific grazing rates (CSGR) by analyzing prey in...

Microbial lifestyles may reveal niche-specific signatures and can contribute to detecting the effects of abiotic fluctuations on biogeochemical cycles. Microorganisms make a tradeoff between optimizing nutrient uptake, improving biomass yield, and overcoming environmental changes according to environmental hostility. Soda lakes are natural environm...

The increasing amount of plastic particles introduced into continental aquatic environments has drawn the attention of researchers around the globe. These particles can be assimilated by a wide range of aquatic organisms, from microorganisms to fish, causing detrimental effects on trophic webs. Using an experimental approach, we investigated the ef...

Neophobia (i.e. the degree of avoidance to novel situations) is a personality trait that may predict the ability to exploit new resources, which potentially affects the success of settlement of urban animal populations. Despite the increasing amount of information on birds using artificial structures as nesting supports, the hypothesis that the pro...

Soda lakes environment is known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effect of different environmental conditions of six adjacent soda lakes on bacterial communities and their functioning using a metagenomic approach combined with flow cytometry and chemical analyses...

East-African Great Lakes are old and unique natural resources heavily utilized by their bordering countries. In those lakes, ecosystem functioning is dominated by pelagic processes, where microorganisms are key components, however protistan diversity is barely known. We investigated the community composition of small eukaryotes (< 10 µm) in surface...

Marine plankton form complex communities of interacting organisms at the base of the food web, which sustain oceanic biogeochemical cycles and help regulate climate. Although global surveys are starting to reveal ecological drivers underlying planktonic community structure and predicted climate change responses, it is unclear how community-scale sp...

Reports of programmed cell death (PCD) across the taxonomic spectrum of photosynthetic unicellular organisms raise questions concerning its ecological and evolutionary roles. However, prior to ecological studies or evolutionary interpretations, it is essential to document phenotypic changes associated with PCD at the single-cell level, since death-...

en Selection of safe nest sites is a first step toward improving the chances of breeding successfully. Reusing old nests can save time and energy for breeding birds, but nest reuse is rare among open-cup nesting songbirds and the factors contributing to this behavior and its consequences for reproductive output remain little known. We studied an ur...

Riverine ecosystems can be conceptualized as ‘bioreactors’ (the riverine bioreactor) which retain and decompose a wide range of organic substrates. The metabolic performance of the riverine bioreactor is linked to their community structure, the efficiency of energy transfer along food chains, and complex interactions among biotic and abiotic enviro...

Species prevalence across the landscape is related to their local abundance, which is a result of deterministic and stochastic processes that select organisms capable of recolonizing sites where they were once extinct, a process known as the rescue effect. The occupancy-frequency distribution (OFD) describes these patterns and has been extensively...

In order to increase the knowledge about pesticides considering the soil-water interaction, ecosystem models (mesoscosms) were used to analyze the of leachate on the immobility and feeding rate of the cladocerans, Ceriodaphnia silvestrii and D. similis and algae Raphidocelis subcapitata, at two different temperatures. Mesocosm were filled with natu...

Marine plankton form complex communities of interacting organisms at the base of the food web, which sustain oceanic biogeochemical cycles, and help regulate climate. Though global surveys are starting to reveal ecological drivers underlying planktonic community structure, and predicted climate change responses, it is unclear how community-scale sp...

Background The Amazon River is one of the largest in the world and receives huge amounts of terrestrial organic matter (TeOM) from the surrounding rainforest. Despite this TeOM is typically recalcitrant (i.e. resistant to degradation), only a small fraction of it reaches the ocean, pointing to a substantial TeOM degradation by the river microbiome....

Tropical floodplains secure the protein supply of millions of people, but only sound management can ensure the long‐term continuity of such ecosystem services. Overfishing is a widespread threat to multitrophic systems, but how it affects ecosystem functioning is poorly understood, particularly in tropical freshwater food webs. Models based on temp...

Background: The Amazon River is one of the largest in the world and receives huge amounts of terrestrial organic matter (TeOM) from the surrounding rainforest. Despite this TeOM is typically recalcitrant (i.e. resistant to degradation), only a small fraction of it reaches the ocean, pointing to a substantial TeOM degradation by the river microbiome...

How diversity is structured has been a central goal of microbial ecology. In freshwater ecosystems, selection has been found to be the main driver shaping bacterial communities. However, its relative importance compared with other processes (dispersal, drift, diversification) may depend on spatial heterogeneity and the dispersal rates within a meta...

Incubation is an energetically costly parental task of breeding birds. Incubating parents respond to environmental variation and nest site features to adjust the balance between the time spent incubating (i.e., nest attentiveness) and foraging to supply their own needs. Non‐natural nesting substrates such as human buildings impose new environmental...

Copper oxide nanoparticles (CuO NP) have been produced on a large scale due to their economically interesting thermophysical properties. This heightens the concern about risks they may pose on their release into the environment, possibly affecting non-target organisms. Microalga are important organisms in ecotoxicological studies as they are at the...

Background The Amazon River is one of the largest in the world and receives huge amounts of terrestrial organic matter (TeOM) from the surrounding rainforest. Despite this TeOM is typically recalcitrant (i.e. resistant to degradation), only a small fraction of it reaches the ocean, pointing to a substantial TeOM degradation by the river microbiome....

(LINK - FREE ACESS: https://rdcu.be/b0Mlg) Invasive species may affect the equilibrium of natural communities, competing for resources and occupying niches of the native biota. Dendrocephalus brasiliensis (DEN) has potential to aquaculture, although its use is concerning, since DEN is allochthone in some regions of Brazil. Here, we aimed to study t...

The description of life-history traits is a prerequisite to understand the complex patterns of bird biodiversity. However, most of the highly diverse Neotropical avifauna still lack basic information on their reproductive behavior. Here, we describe the breeding biology of the Creamy-bellied Thrush (Turdus amaurochalinus) in a periurban area of sou...

[This corrects the article DOI: 10.1371/journal.pone.0220695.].

Determining which processes take place in the spatial distribution of bacterioplankton metacommunities has been a central goal of microbial ecology. In freshwater ecosystems, selection has been spotted as the main driver shaping bacterial community. However, its relative importance compared with others processes (dispersal, drift, diversification)...

Nanoparticles (NPs) production is increasing worldwide. These products are likely to end up in aquatic environments. However, few studies evaluated the chronic toxicity of iron-based NPs (Fe-NPs) to cladocerans and their potential ecotoxicological hazards. In this study we aimed to investigate the effects of iron oxide nanoparticles (Fe3O4-NPs) to...

Background: The Amazon River is one of the largest in the world and receives huge amounts of terrestrial organic matter (TeOM) from the surrounding rainforest. Despite this TeOM is typically recalcitrant (i.e. resistant to degradation), only a small fraction of it reaches the ocean, pointing to a substantial TeOM degradation by the river microbiome...

Species prevalence across the landscape is related to their local abundance, which is a result of deterministic and stochastic processes that select organisms capable of recolonizing sites where they were once extinct; a process known as the rescue effect. The occupancy-frequency distribution (OFD) describes these patterns and has been extensively...

Bacterioplankton comprises a highly diverse group of microorganisms, which are dominant in aquatic ecosystems, and play a central role in ecosystem functioning and biogeochemical cycles. Due to their high turnover and dispersal rates, as well as high adaptability and plasticity, microbes are likely to respond quickly to environmental changes and pe...

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted...

Phytoplankton time‐series enable the observation of recurrent seasonal patterns on community composition, but drastic shifts in community structure are rarely observed, unless linked to anthropogenic impacts (e.g. changes in nutrient inputs). Here, we report a unique case of non‐seasonal, multiannual regime shift of phytoplankton community structur...

Amazonian floodplains form complex hydrological networks that play relevant roles in global biogeochemical cycles, and bacterial degradation of the organic matter in these systems is key for regional carbon budget. The Amazon undergoes extreme seasonal variations in water level, which produces changes in landscape and diversifies sources of organic...

Dissolved organic matter (DOM) is the main substrate for aquatic prokaryotes, fuelling their metabolism and controlling community composition. Amazonian rivers transport and process large fluxes of terrestrial DOM, but little is known about the link between DOM composition and heterotrophic bacteria in the Amazon basin. The aims of this study were...

Background Flow cytometry (FCM) is one of the most commonly used technologies for analysis of numerous biological systems at the cellular level, from cancer cells to microbial communities. Its high potential and wide applicability led to the development of various analytical protocols, which are often not interchangeable between fields of expertise...

The role of tropical lakes and reservoirs in the global carbon cycle has received increasing attention in the past decade, but our understanding of its variability is still limited. The metabolism of tropical systems may differ profoundly from temperate systems due to the higher temperatures and wider variations in precipitation. Here, we investiga...

The materials used for nesting have important structural and nonstructural functions in bird nests. A number of bird species incorporate anthropogenic debris in their nests, but there are few systematic studies about such use by terrestrial birds. Here, we test whether the prevalence and amount of plastic twine differs among nests of Neotropical bi...

In recent years, the rapid advances of culture-independent methods and new molecular tools have revolutionized our understanding of microbial biodiversity and ecological functions. DNA extraction from microbial communities is a critical step in this process and several methods have been proposed and used, but the influence of the extraction method...

The Amazon River receives, from the surrounding rainforest, huge amounts of terrestrial organic matter (TeOM), which is typically resistant to microbial degradation. However, only a small fraction of the TeOM ends up in the ocean, indicating that most of it is degraded in the river. So far, the nature of the genes involved in TeOM degradation and t...

Climate change is affecting the global hydrological cycle and is causing drastic changes in the freshwater hydrological regime. Water level (WL) reduction caused by drought tends to increase the concentration of nutrients favoring the dominance of cyanobacteria. We hypothesized that the WL reduction favors the dominance of cyanobacteria at regular...

Microalgae have been widely used in ecotoxicological studies in order to evaluate the impacts of heavy metals in aquatic ecosystems. However, there are few studies that analyze the effects of metals in an integrative way on photosynthetic apparatus of freshwater microalgae in the generation of reactive oxygen species (ROS) and biochemical compositi...

The simple view of the classical phytoplankton–zooplankton–fish food chain (CFC) has been replaced by a more complex framework, integrating microbial compartments (microbial food web, MFW). Few studies considered all components of the pelagic MFW in freshwaters and mostly are from temperate regions. We investigated carbon partitioning in the CFC an...

The 18th workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP), the first ‘‘tropical’’ IAP ever, the third one outside Europe, and the first one in South America, was held in Natal, Brazil, from August 27 to September 3, 2017, and its main ecological theme was the Phytoplankton and its biotic interactions. The taxon...

The materials used for nesting have important structural and nonstructural functions in bird nests. A number of bird species incorporate anthropogenic debris in their nests, but there are few systematic studies about such use by terrestrial birds. Here, we test whether the prevalence and amount of plastic twine differs among nests of Neotropical bi...

• Understanding spatial and temporal dynamics of microbial communities is a central challenge in microbial ecology since microorganisms play a key role in ecosystem functioning and biogeochemical cycles. Amazonian aquatic systems comprise a dynamic mosaic of heterogeneous habits but are understudied and there is limited information about the mechan...

Flow cytometry (FCM) is a powerful analytical tool that is widely used worldwide, as it allows the depiction of the innate complexity of a vast range of biological systems in few seconds. It is a technique based on the spectroscopic properties of suspended particles that allows data to be graphically summarized by biplots, known as cytograms. Such...

Flow cytometry (FCM) is a powerful analytical tool that is widely used worldwide, as it allows the depiction of the innate complexity of a vast range of biological systems in few seconds. It is a technique based on the spectroscopic properties of suspended particles that allows data to be graphically summarized by biplots, known as cytograms. Such...

Tropical reservoirs are main carbon sources to the atmosphere, and bacterial metabolism is a key process in these emissions. Here, we explored the drivers of bacterial metabolism in four tropical cascading reservoirs forming a trophic state gradient, and compared them with those found in the literature (mainly from temperate regions). Bacterial pro...

Zooplankton communities in tropical inland waters are generally characterized by small bodied individuals and the absence of large daphnids. However, the effects of this peculiar food web configuration on microbial compartments have not been tested experimentally. To establish which predator could be responsible for most bacterial loss in a tropica...

Element cycling in aquatic systems is driven chiefly by planktonic processes, and the structure of the planktonic food web determines the efficiency of carbon transfer through trophic levels. However, few studies have comprehensively evaluated all planktonic food-web components in tropical regions. The aim of this study was to unravel the top-down...

The Amazon region has the largest hydrographic basin on the planet and is well known for its huge biodiversity of plants and animals. However, there is a lack of studies on aquatic microbial biodiversity in the Solimões River, one of its main water courses. To investigate the microbial biodiversity of this region, we performed 16S rRNA gene clo...

Aerobic anoxygenic phototrophs (AAPs) have been shown to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and limited to local investigations. Here, we explore the occurrence, diversity and distribut...

Interspecific parental care (IPC) in birds, when one individual helps to rear the offspring of another species, is rare outside the context of brood parasitism. Reports of IPC addressed to non‐brood‐parasitic bird species are mostly anecdotal, and in some cases have been explained as a non‐adaptive response to the begging calls of interspecific nes...

Some prokaryotes are known to be specialized in the use of phytoplankton-derived dissolved organic carbon (DOCp) originated by exudation or cell lysis; however, direct quantification measurements are extremely rare. Several studies have described bacterial selectivity based on DOCp quality, but very few have focused on the quantity of DOCp, and the...

Recent studies reported comparatively lower heterotrophic bacteria (HB) abundances in tropical regions, indicating that factors involved in bacterial losses could be more relevant in the tropics. Heterotrophic nanoflagellates (HNF) are considered the main predators of HB in aquatic ecosystems, and one should expect higher abundances in the tropics...

We investigated the effects of an increase in dissolved CO2 on the microbial communities of the Mediterranean Sea during two mesocosm experiments in two contrasting seasons: winter, at the peak of the annual phytoplankton bloom, and summer, under lownutrient conditions. The experiments included treatments with acidification and nutrient addition, a...

The transformation of leucine incorporation into prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawat...

Microbes are dominant drivers of biogeochemical processes, yet drawing a global picture of functional diversity, microbial community structure, and their ecological determinants remains a grand challenge. We analyzed 7.2 terabases of metagenomic data from 243 Tara Oceans samples from 68 locations in epipelagic and mesopelagic waters across the glob...

Sharp boundaries in the physical environment are usually associated with abrupt shifts in organism abundance, activity, and diversity. Aquatic surface microlayers (SML) form a steep gradient between two contrasted environments, the atmosphere and surface waters, where they regulate the gas exchange between both environments. They usually harbor an...