Marisol Felip

University of Barcelona | UB · epartment of Evolutionary Biology, Ecology and Environmental Sciences

Experimental nutrient additions are a fundamental approach to investigating plankton ecology. Possibilities range from whole-lake fertilization to flask assays encompassing a trade-off between closeness to the “real world” and feasibility and replication. Here we describe an enclosure type that minimizes the manipulation of planktonic communities d...

Due to global warming, shorter ice cover duration might drastically affect the ecology of lakes currently undergoing seasonal surface freezing. High-mountain lakes show snow-rich ice covers that determine contrasting conditions between ice-off and ice-on periods. We characterized the bacterioplankton seasonality in a deep high-mountain lake ice-cov...

1. Seasonal compositional changes in plankton communities are usually considered as species replacements. Given the enormous number of individuals integrating the communities and our limited capacity to count and determine most of them, we likely observe only alternative population peaks of some of the coexisting species. The contemporary coexisten...

La presencia inicial de los humanos en la alta montaña desde hace poco menos de 8000 años presenta más ele-mentos de domesticación de lo que inicialmente se había estimado. raciones arqueológicas es todavía limitada, hay evidencias de uso de ganado doméstico y, en algunos casos, una probable agricultura utilizando mezcla de cereales a cotas interme...

Planktonic communities are naturally subjected to episodic nutrient enrichments that may stress or redress the imbalances in limiting nutrients. Human-enhanced atmospheric nitrogen deposition has caused profound N:P imbalance in many remote oligotrophic lakes in which phosphorus has largely become limiting. These lakes offer an opportunity to inves...

The verification that many phytoflagellates ingest prokaryotes has changed the view of the microbial loop in aquatic ecosystems. Still, progress is limited because the phagotrophic activity is difficult to quantify in natural assemblages. Linking the food vacuole content in protist with the ingestion rate of prokaryotes would provide a crucial step...

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including...

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under-ice lake ecology, including...

Many phototrophic flagellates ingest prokaryotes. This mixotrophic trait becomes a critical aspect of the microbial loop in planktonic food webs because of the typical high abundance of these flagellates. Our knowledge of their selective feeding upon different groups of prokaryotes, particularly in field conditions, is still quite limited. In this...

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...

The ELF or fluorescence-labeled enzyme activity (FLEA) technique is a culture-independent single-cell tool for assessing plankton enzyme activity in close-to-in situ conditions. We demonstrate that single-cell FLEA quantifications based on two-dimensional (2D) image analysis were biased by up to one order of magnitude relative to deconvolved 3D. Th...

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

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...

Supplementary Figures S1-S6, Supplementary Tables S1-S13, Supplementary Methods and Supplementary References

Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems....

We compared different fluorescence-labelled enzyme activity (FLEA) methods for assaying phosphatase activity in phytoplankton. Unfixed and liquid incubations are devised. We demonstrated that the presence of intracellular labelling was persistent, which could point out a source of bias in ectoenzymatic activities measurements based either on the FL...

The relationship between flow cytometry data and epifluorescence microscopy measurements was assessed in bacterioplankton samples from 80 lakes to estimate bacterial biovolume and cell size distribution. The total counts of 4′,6′-diamidino-2-phenylindole-stained cells estimated by both methods were significantly related, and the slope of their line...

High mountain lakes offer research opportunities beyond what could be expected from their quantitative relevance in the Earth system. In this article we present a brief summary of the research carried out in the lakes of the Pyrenees in the last twenty years by the group of limnology of the Centre for High Mountain Research (CRAM) of the University...

We describe a catalyzed reported deposition-fluorescence in situ hybridization (CARD-FISH) protocol particularly suited to assess the phagotrophy of mixotrophic protists on prokaryotes, since it maintains cell and plastid integrity, avoids cell loss and egestion of prey, and allows visualization of labeled prey against plastid autofluorescence. Thi...

Assessment of the contribution of distinct algal groups to phytoplankton biomass in oligotrophic takes by marker pigments is compared with assessment by cell-counting biovolume estimates. Seasonal samples from an oligotrophic alpine take (Redon, Pyrenees) mostly included species of chlysophytes, dinoflagellates, cryptophytes and chlorophytes. The c...

Active microbial communities formed by autotrophic and heterotrophic flagellates, ciliates and bacteria, inhabit slush layers of the ice and snow cover of high mountain lakes. Our study of the ice and snow cover of Gossenkollesee (Tyrolean Alps) during 2 complete winter periods, with special emphasis on the relationship between slush layers and the...

The ecosystem response of Lake Red (Central Pyrenees) to fluctuations in seasonal air temperature during the last two centuries was investigated by comparison of reconstructed air temperatures with the sediment record. Fine slicing allowed a resolution of 3–6 years according to the 210Pb dating, although it was still difficult to easily investigate...

The seasonal distributions of phytoplankton biovolume and chlorophyll a content were monitored for 14 months in a deep oligotrophic, high mountain lake (Redó, Pyrenees). An allometric relationship of chlorophyll with biovolume was found throughout the period studied, with a correlation coefficient of 0.66. However, the relationship changed with sea...

Microbial plankton composition and biomass were monitored for two ice-free periods in a deep oligotrophic high-mountain lake (Redó, Pyrenees). Phytoplankton dominated microbial biomass, while the relationship between total water-column-integrated auto-trophic and heterotrophic biomass ranged from 1.5 to 6.5 (an average of 4.4). Heterotrophic biomas...

The biological activity of the planktonic community of lake Redó, expressed in terms of carbon fluxes, was measured and com- pared to the changes in DIC, DOC and POC in the water column. Planktonic photosynthesis ranged between c. 0.01 - 0.3 µg C m -2 h-1. Release of EOC phytoplankton was highly variable, between 5 and 80% of total fixation. Bacter...

It has recently been shown that a rich community of microorganisms inhabits the slush layers of the winter cover of high mountain lakes. In this study, temporal changes in species assemblages and environmental conditions in the ice and snow cover of Lake Redo in the Pyrenees (Spain) are presented. The winter cover was a highly dynamic environment,...

We studied the impact of ambient levels of solar ultraviolet B (UVB) radiation on the planktonic microbial food web (viruses, heterotrophic bacteria, heterotrophic nanoflagellates and ciliates) of a high-mountain lake (2417 m above sea level) under in situ conditions for 16 days. Enclosures of 1 m3 receiving either the full sunlight spectrum or sun...

The observation that metabolic processes are reduced or completely inhibited at freezing temperatures has influenced microbial ecologists and limnologists, who have commonly concentrated on warm seasons and temperate habitats. High altitude and high latitude sites are not easily accessible and conducting research at low temperatures is not a trivia...

Direct counts of virus-like particles (VLP) by transmission electron microscopy revealed abundances of up to 3 x 107 ml-1 in the plankton of two remote high-mountain lakes in the Alps and the Pyrenees. Most VLP were icosahedric without a tail, and with diameters between 40 and 90 nm, but very large ones with diameters of up to 325 nm were also obse...

The effect of solar UVB radiation on the growth and species composition of phytoplankton from a high-mountain lake (2417 m a.s.l.) was studied in situ for 16 days in two enclosures of 1 m(3), receiving either full sunlight or sunlight without UVB. A total of 20 species were identified in both enclosures, consisting mainly of dinoflagellates, chryso...

We examined the potential limitation of bacterial growth by temperature and nutrients in a eutrophic lake. Dilution cultures from winter and summer were incubated at both high (>20°C) and low (4°C) temperatures and enriched with various combinations of organic carbon (C), inorganic nitrogen (N), and inorganic phosphorus (P). Bacterial abundance, (3...

An exploratory study carried out in Pyrenean and Alpine lakes shows that a rich, active microbial community lives in the slush layers of the winter cover of such lakes in spite of the low temperature and the seasonal occurrence of the habitat. Bacteria were very diverse in morphology, with filaments reaching up to 100 (mu)m long; flagellates, both...

Lakes in the Pyrenees show a broad variability in nitrogen content and in the distribution of its different oxidation forms, which has no direct relation with any single physiographical, chemical or trophic feature of the lakes. Concentration of bound nitrogen in rain is low compared with other European mountains, but the annual load lies in the mi...

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