Maria Montserrat Sala

Institut de Ciències del Mar · Biologia Marina i Oceanografia

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...

Biotic and abiotic particles shape the microspatial architecture that defines the microbial aquatic habitat, being particles highly variable in size and quality along oceanic horizontal and vertical gradients. We analyzed the prokaryotic (bacterial and archaeal) diversity and community composition present in 6 distinct particle size classes ranging...

The sinking of organic particles formed in the photic layer is a main vector of carbon export into the deep ocean. Although sinking particles are heavily colonized by microbes, so far it has not been explored whether this process plays a role in transferring prokaryotic diversity from surface to deep oceanic layers. Using Illumina sequencing of the...

Prokaryotes play a fundamental role in decomposing organic matter in the ocean, but little is known about how microbial metabolic capabilities vary at the global ocean scale and what are the drivers causing this variation. We aimed at obtaining the first global exploration of the functional capabilities of prokaryotes in the ocean, with emphasis on...

COVID-19 has led to global population lockdowns that have had indirect effects on terrestrial and marine fauna, yet little is known on their effects on marine planktonic communities. We analysed the effect of the spring 2020 lockdown in a marine coastal area in Blanes Bay, NW Mediterranean. We compared a set of 23 oceanographic, microbial and bioge...

Supplementary Tables and Figures from: Particulate and dissolved fluorescent organic matter fractionation and composition: abiotic and ecological controls in the Southern Ocean (2022)

Phytoplankton-derived organic matter sustains heterotrophic marine life in regions away from terrestrial inputs such as the Southern Ocean. Fluorescence spectroscopy has long been used to characterize the fluorescent organic matter (FOM) pool. However, most studies focus only in the dissolved FOM fraction (FDOM) disregarding the contribution of par...

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 de...

The bathypelagic ocean (1000-4000 m depth) is the largest aquatic biome on Earth but it is still largely unexplored. Due to its prevalent low dissolved organic carbon concentrations, most of the prokaryotic metabolic activity is assumed to be associated to particles. The role of free-living prokaryotes has thus been mostly ignored, except that of s...

Anthropogenic carbon emissions are causing changes in seawater carbonate chemistry including a decline in the pH of the oceans. While its aftermath for calcifying microbes has been widely studied, the effect of ocean acidification (OA) on marine viruses and their microbial hosts is controversial, and even more in combination with another anthropoge...

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and in...

Estimation of prokaryotic growth rates is critical to understand the ecological role and contribution of different microbes to marine biogeochemical cycles. However, there is a general lack of knowledge on what factors control the growth rates of different prokaryotic groups and how these vary between sites and along seasons at a given site. We car...

Different factors affect the way dissolved organic matter (DOM) is processed in the ocean water column, including environmental conditions and the functional capabilities of the communities. Recent studies have shown that bathypelagic prokaryotes are metabolically flexible, but whether this versatility translates into a higher ability to process DO...

We explored how changes of viral abundance and community composition among four contrasting regions in the Southern Ocean relied on physicochemical and microbiological traits. During January–February 2015, we visited areas north and south of the South Orkney Islands (NSO and SSO) characterized by low temperature and salinity and high inorganic nutr...

Seasonal dynamics of ocean prokaryotic communities in the free-living fraction have been widely described, but less is known about the seasonality of prokaryotes inhabiting marine particles. We describe the seasonality of bacterial communities in the particulate matter continuum by sampling monthly over two years in a temperate oligotrophic coastal...

Isoprene is a biogenic trace gas produced by terrestrial vegetation and marine phytoplankton. In the remote oceans, where secondary aerosols are mostly biogenic, marine isoprene emissions affect atmospheric chemistry and influence cloud formation and brightness. Here, we present the first compilation of new and published measurements of isoprene co...

Deep ocean microbial communities rely on the organic carbon produced in the sunlit ocean, yet it remains unknown whether surface processes determine the assembly and function of bathypelagic prokaryotes to a larger extent than deep‐sea physico‐chemical conditions. Here, we explored whether variations in surface phytoplankton assemblages across Atla...

Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) acids are ubiquitous in the oceans, including remote regions, and are toxic to fish and mammals. The impact to the lowest trophic levels of the food web, however, remains unknown. We challenged natural bacterial communities inhabiting Antarctic coastal waters (Deception Island) with PFOS...

Microbial extracellular enzymes are fundamental to the cycling of elements in aquatic systems. The regulation of these enzymatic reactions in oceans, lakes and streams is under complex multiple control by environmental factors and the metabolic capacities of different taxa and communities. While the environmental control of enzyme-mediated processe...

Experiments with bacteria in culture have shown that they often display ´feast and famine´ strategies that allow them to respond with fast growth upon pulses in resource availability, and enter a growth-arrest state when resources are limiting. Although feast responses have been observed in natural communities upon enrichment, it is unknown whether...

Organic pollutants are continuously being introduced in seawater with uncharacterized impacts on the engines of the marine biogeochemical cycles, the microorganisms. The effects on marine microbial communities were assessed for perfluoroalkyl substances, organophosphate esters flame retardants and plasticizers, polycyclic aromatic hydrocarbons, and...

Transparent exopolymer particles (TEPs) are a class of gel particles, produced mainly by microorganisms, which play important roles in biogeochemical processes such as carbon cycling and export. TEPs (a) are colonized by carbon-consuming microbes; (b) mediate aggregation and sinking of organic matter and organisms, thereby contributing to the biolo...

Microbial taxa range from being ubiquitous and abundant across space to extremely rare and endemic, depending on their ecophysiology and on different processes acting locally or regionally. However, little is known about how cosmopolitan or rare taxa combine to constitute communities and whether environmental variations promote changes in their rel...

Transparent Exopolymer Particles (TEPs) are a subclass of organic particles with high impact in biogeochemical and ecological processes, such as the biological carbon pump, air-sea interactions, or the microbial loop. However, the complexity in production and consumption makes TEP dynamics hardly predictable, calling for the need of descriptive stu...

Climate warming affects the development and distribution of sea ice, but at present the evidence of polar ecosystem feedbacks on climate through changes in the atmosphere is sparse. By means of synergistic atmospheric and oceanic measurements in the Southern Ocean near Antarctica, we present evidence that the microbiota of sea ice and sea ice-influ...

The bathypelagic ocean is one of the largest ecosystems on Earth, and sustains half of the ocean's microbial activity. This microbial activity strongly relies on surface-derived particles, but there is growing evidence that the carbon released through solubilisation of these particles may not be sufficient to meet the energy demands of deep ocean p...

In oligotrophic regions, such as the Mediterranean Sea, atmospheric deposition has the potential to stimulate heterotrophic prokaryote growth and production in surface waters, especially during the summer stratification period. Previous studies focused on the role of leaching nutrients from mineral particles of Saharan (S) origin, and were restrict...

Changes in the excitation (Ex)–emission (Em) matrixes of FDOM after the aerosol addition in the six experiments. The value of florescence before the addition in all the microcosm – expressed in quinine sulfate units (QSU) – is the same than in the C, whereas A and S matrixes show the values after the additions. The different peaks are indicated: Pe...

Aerosol-induced ratios (AIR) of the biogeochemical variables studied (abbreviations as in the main text). TREAT, TREATMENT (A = anthropogenic, S = Saharan); FILT, filtration (F = samples filtered by 0.8 μm; NF = not filtered); WI, winter; SP, spring; SU, summer; BCN, Barcelona; BLA, Blanes; OFF, offshore. A dash indicates that the ratio could not b...

During the Austral summer 2009 we studied three areas surrounding the Antarctic Peninsula: the Bellingshausen Sea, the Bransfield Strait and the Weddell Sea. We aimed to investigate, whether viruses or protists were the main agents inducing prokaryotic mortality rates, and the sensitivity to temperature of prokaryotic heterotrophic production and m...

Transparent Exopolymer Particles (TEP) are relevant in particle and carbon fluxes in the ocean, and have economic impact in the desalination industry affecting reverse osmosis membrane fouling. However, general models of their occurrence and dynamics are not yet possible because of the poorly known co-variations with other physical and biological v...

Bivariate plot between depth-averaged (upper mixed layer) temperature (abscises) and salinity (ordinates) in the 13 sampling stations along the diel cycle.

Variations of dissolved inorganic nitrogen (DIN, orange circles), dissolved inorganic phosphorus (DIP, green-yellow triangles), and estimated bacterial production with factor 1.55 kgC mol leucine (BP, purple triangles) in the coastal transects in May (A) and June (B).

Depending on their relationship with the pelagic particulate matter, planktonic prokaryotes have traditionally been classified into two types of communities: free-living (FL) or attached (ATT) to particles, and are generally separated using only one pore-size filter in a differential filtration. Nonetheless, particulate matter in the oceans appears...

Vibrios include several pathogenic bacteria that occur in aquatic environments. The presence of Vibrio has been assessed in many ecosystems by culture-based techniques. However, little is known on the contribution of vibrios in the sea, especially in areas subject to harmful algal blooms. A preliminary study in Sant Andreu de Llavaneres beach (NW M...

Summary: We carried out monthly photosynthesis-irradiance (P-E) experiments with the 14C-method for 12 years (2003–2014) to determine the photosynthetic parameters and primary production of surface phytoplankton in the Blanes Bay Microbial Observatory, a coastal sampling station in the NW Mediterranean Sea. Our goal was to obtain seasonal trends an...

Two mesocosms experiments were conducted in winter 2010 and summer 2011 to examine how increased pCO2 and/or nutrient concentrations potentially perturbate dissolved organic matter dynamics in natural microbial assemblages. The fluorescence signals of protein- and humic-like compounds were used as a proxy for labile and non-labile material, respect...

Volatile and semi-volatile gas-phase organic carbon (GOC) is a largely neglected component of the global carbon cycle, with poorly resolved pools and fluxes of natural and anthropogenic GOC in the biosphere. Substantial amounts of atmospheric GOC are exchanged with the surface ocean, and subsequent utilization of specific GOC compounds by surface o...

The refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also be generated by microbial activity. It has been recent...

Oral contribution to the ASLO conference 2015 in Granada, Spain

We present a comprehensive study of the composition of the bacterial communities attached to particles and their temporal variations. We performed a 2-year study in a NW Mediterranean Sea coastal site (the Blanes Bay Microbial Observatory, BBMO). Monthly, 10 L of surface water were filtered sequentially through 6 size fractions: 0.2, 0.8, 3, 5, 10...

Matter in the ocean has traditionally been divided into dissolved or particulate fractions and associated to these, the life-style of bacteria can be classified as free-living (FL) or particle-attached (PA). We followed the size structure of bacterioplankton from September 2010 to June 2013 in a NW Mediterranean Sea coastal site (Blanes Bay Microbi...

METABOLIC DIVERSITY OF BACTERIOPLANKTON IN THE OCEAN Bacterioplankton plays a key role in decomposing organic matter and recycling nutrients in the ocean, although still little is know on the metabolic abilities of bacterioplankton, and even less of bacteria living in the deep ocean. We tested the utilization of 95 carbon sources (belonging to the...

Due to logistic difficulties, biological processes along the Arctic winter remain poorly known. In particular, carbon sources used by bacterioplankton have not been identified. A previous study in Franklin Bay suggested that polymers were one of the main substrates used by bacteria. During the Circumpolar Flaw Lead System Study, we analyzed metabol...

We estimated the bacterial production and losses to predators along an open ocean trophic gradient from coastal upwelling waters to oligotrophic waters in the Subtropical Northern Atlantic Ocean. Two zonal sections (21 and 268N) extending from the NW African shelf to the Open Atlantic Ocean at 268W were sampled during September– October 2002 (autum...

Despite representing only a small fraction of the ocean’s dissolved organic matter pool, dissolved free amino acids (DFAA) have high turnover rates and are major nitrogen and carbon sources for bacterioplankton. Both phytoplankton and bacterioplankton assimilate and release DFAA, but their consumption and production are difficult to quantify in nat...

Asexual and sexual reproduction were studie