Fil: Cochero, Joaquin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Limnologia Dr. Raul A. Ringuelet. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnologia; Argentina

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 69:1-16 (2013) - DOI: https://doi.org/10.3354/ame01619 FEATURE ARTICLE Interlake variation and environmental controls of denitrification across different geographical scales Antti Juhani Rissanen1,2,*, Marja Tiirola1, Susanna Hietanen3, Anne Ojala4 1Department of Biological and Environmental Science, University of Jyväskylä, Survontie 9, 40500 Jyväskylä, Finland 2Lammi Biological Station, University of Helsinki, Pääjärventie 320, 16900 Lammi, Finland 3Department of Environmental Sciences, University of Helsinki, PO Box 65 (Viikinkaari 1), 00014 University of Helsinki, Finland 4Department of Environmental Sciences, University of Helsinki, Niemenkatu 73, 15140 Lahti, Finland *Email: antti.j.rissanen@jyu.fi ABSTRACT: Denitrification in lakes significantly reduces the nitrogen (N) load from land to oceans, but the factors controlling it remain poorly understood. Therefore, interlake variation of denitrification in sediments of small to medium-sized lakes (from 0.03 to 17.8 km2) was studied across different geographical scales. At the local scale, the denitrification rates and sediment microbial communities were studied in 4 boreal lakes in close proximity (within 20 km) using the isotope pairing technique (IPT) and molecular methods. These local scale data were combined with previously published data on denitrification rates from 10 other European lakes to extend the analysis to the regional (boreal area) and continental (boreal and temperate areas) scales. Denitrification varied considerably among lakes, ranging from ~50 to ~600, ~0 to ~600 and ~0 to ~12900 μmol N m-2 d-1 at the local, regional and continental scales, respectively. This variation was primarily due to nitrate availability. The structure of the denitrifier community studied at the local scale was independent of the denitrification rates but varied among lakes correlating with nitrate availability and sediment organic content. Removal of nitrate and total N load by denitrification was less efficient in boreal than in temperate lakes. In addition, a meta-analysis of published N mass balance data indicates that the total N retention (denitrification + N sedimentation) is less efficient in boreal than in temperate lakes. Anaerobic ammonium oxidation (anammox) was studied at the local scale but was not detected, although (based on molecular markers) several anammox genera were present in the sediments. KEY WORDS: Denitrification · Lake · Sediment · nirK Full text in pdf format Information about this Feature Article NextCite this article as: Rissanen AJ, Tiirola M, Hietanen S, Ojala A (2013) Interlake variation and environmental controls of denitrification across different geographical scales. Aquat Microb Ecol 69:1-16. https://doi.org/10.3354/ame01619 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 69, No. 1. Online publication date: April 03, 2013 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2013 Inter-Research.

We analysed the diversity and abundance of ammonia-oxidizing Archaea (AOA) and Bacteria (AOB) in the shallow warm-water sponge Halisarca caerulea and the deep cold-water sponges Higginsia thielei and Nodastrella nodastrella. The abundance of AOA and AOB was analysed using catalyzed reporter deposition-fluorescence in situ hybridization and (real-time) quantitative PCR (Q-PCR) targeting archaeal and bacterial amoA genes. Archaeal abundance was similar between sponge species, while bacterial abundance was higher in H. caerulea than in N. nodastrella and H. thielei. Q-PCR showed that AOA outnumbered AOB by a factor of 2 to 35, suggesting a larger role of AOA than of AOB in ammonia oxidation in sponges. PCR-denaturing gradient gel electrophoresis was performed to analyse the taxonomic affiliation of the microbial community associated with these sponges. Archaeal and bacterial amoA genes were found in all 3 sponges. The structure of the phylogenetic trees in relation to temperature and sponge species was analysed using all published amoA sequences retrieved from sponges. Temperature was an important factor influencing the distribution of nitrifiers in sponges. Both archaeal and bacterial amoA sponge sequences tended to cluster with sequences retrieved from habitats of similar temperature. This is the first time that similarity in AOB diversity is described between distantly related species (H. thielei belonging to the class Demospongiae, and N. nodastrella to Hexactinellida). The results described here support the idea of a relatively uniform microbial community between distantly related sponges and suggest that temperature (rather than phylogenetic distance) is determining the diversity of AOA and AOB in sponges.

Recurring blooms of the photosynthetic ciliate Mesodinium rubrum (= Myrionecta rubra) are observed each summer in the Columbia River estuary. Although cultured isolates of M. rubrum have been shown to consume cryptophyte prey during growth, the feeding behavior of M. rubrum in the field is poorly known. In the present study, a 3 mo time series of observations from a locale of putative bloom formation (Ilwaco harbor in Baker Bay, WA) showed that cryptophytes were present at relatively high abundance prior to and during M. rubrum blooms and declined with M. rubrum abundance. During 3 years of observation (summers of 2009, 2010, and 2011), we observed M. rubrum cells bearing numerous cryptophytes attached to the cirri throughout the estuary, especially during the bloom initiation phase and particularly in the peripheral bays. We performed a laboratory investigation in 2011 in which cryptophyte prey were introduced to high-density red-water samples in aquarium tanks. Within 2 h, individual M. rubrum cells collected multiple cryptophytes on their cirri, likely as a precursor to ingestion. The cells ceased their jumping motion and instead exhibited an undulation of the cirri and drifted slowly. We hypothesize that the availability and type of cryptophyte prey is important for bloom formation and that the acquisition of several cryptophytes at once by M. rubrum may be indicative of its ability to 'gather' or concentrate cryptophytes from the environment.

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 69:223-229 (2013) - DOI: https://doi.org/10.3354/ame01645 Weak seasonality and synchrony among bacterial communities in small pools Örjan Östman1,*, Silke Langenheder2 1Department of Ecology and Genetics/Animal Ecology, and 2Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, Uppsala 752 36, Sweden *Email: orjan.ostman@ebc.uu.se ABSTRACT: Temporal dynamics of microbial communities show seasonal trends and synchronous dynamics between communities in different aquatic habitats, but previous studies have mainly focused on larger systems such as oceans, rivers, or lakes. However, a large part of aquatic water bodies consists of small pools, ponds, and streams, which tend to be environmentally heterogeneous over relatively small spatial scales. We studied a bacterial metacommunity of 16 rock pools at a spatial scale of 600 m2, which was sampled at approximately monthly intervals over the course of 1 yr. We show that temporal dynamics were not evidently synchronous between rock pools over time and that there was no clear seasonal pattern. The environmental variable that explained the most of the temporal dynamics in rock pools over time was water colour, which is often not the main variable explaining spatial differences in bacterial composition between pools. Our results suggest that temporal dynamics of bacterial communities both among and within small water bodies show markedly different patterns compared to larger previously investigated systems, presumably due to their larger heterogeneity and less synchronous environmental changes. KEY WORDS: Bacterioplankton · Seasonal dynamics · Spatial synchrony · Time series · t-RFLP Full text in pdf format PreviousNextCite this article as: Östman Ö, Langenheder S (2013) Weak seasonality and synchrony among bacterial communities in small pools. Aquat Microb Ecol 69:223-229. https://doi.org/10.3354/ame01645 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 69, No. 3. Online publication date: July 04, 2013 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2013 Inter-Research.

Research (IOLR), prominent member of the Aquatic Microbial Ecology community, and member of the editorial board of this journal.Tom died from a fall when hiking in the Galapagos Islands, one of his life-long dream trips.Tom was a paradigmatic member of our community, having published extensively on phytoplankton, protozoans and bacteria, in both freshwater and marine ecosystems.Tom's examples showed that microbial ecological principles are general to all aquatic systems.Tom was born on February 25, 1934 in Hronov, former Czechoslovakia.In June 1939, his parents put him on one of the special Kindertransport trains from Prague to London that saved 668 Czech children from certain death by the Nazis.Tom grew up in Scotland, but moved to the USA for his bachelor's degree at Rutgers University, followed by a PhD in Microbiology at MIT.Tom then moved to Kibbutz Amiad in Upper Galilee, Israel, and was responsible for setting up the Kinneret Lab.As its first director (1967)(1968)(1969)(1970)(1971), Tom participated in designing the basic approach that has been so successful, involving extensive and persistent lake monitoring and an integrated approach to limnological re search.He was again director between 1986 and his retirement in 1999, and initiated expansion of the Kinneret Lab to also deal with applied aspects of lake management.The great majority of Tom's research revolved around uncovering the role of phytoplankton and bacteria in organic matter and inorganic nutrient cycling.He thus contributed to the establishment of aquatic microbial ecology as a prospering discipline.Tom did not have a scientific pet model organism but he did have a pet model ecosystem: Lake Kinneret.To understand this ecosystem he early on delved into the nitrogen and phosphorus cycles.From the early 1970s, and throughout his scientific career, Tom explored the dynamics of phytoplankton

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 68:77-90 (2012) - DOI: https://doi.org/10.3354/ame01604 Bacterioplankton productivity in lakes of the Taylor Valley, Antarctica, during the polar night transition Trista J. Vick, John C. Priscu* Montana State University, Department of Land Resources and Environmental Science, 334 Leon Johnson Hall, Bozeman, Montana 59717, USA *Corresponding author. Email: jpriscu@montana.edu ABSTRACT: Research on the lakes of the McMurdo Dry Valleys, Antarctica, is typically conducted during the period of 24 h sunlight (October to January) when logistical support is readily available. As part of the International Polar Year initiative, we obtained logistical support to study microbial dynamics in the permanently ice-covered lakes of the Taylor Valley during the transition from 24 h of sunlight to the complete darkness of the polar night (mid-April). Our study focused on the perennially ice-covered lakes Fryxell (FRX), East Lobe Bonney (ELB), and West Lobe Bonney (WLB), all of which are chemically stratified and have food webs dominated by microorganisms. Depth-integrated bacterioplankton productivity (BP; leucine incorporation [Leu] and thymidine incorporation [TdR]) in the lakes ranged from 1.2 to 3.4 mg C m−2 d−1. Overall, summer was characterized by relatively high rates of BP and photoautotrophic primary productivity. Rapid decreases in photosynthetically active radiation marked a subsequent transition period, which was characterized by variable cell counts and decreasing Leu:TdR ratios (ratios >1 signify a physiological shift from growth to maintenance mode). Finally, cell counts decreased and Leu:TdR increased by as much as 280% during the fall, revealing a distinct change in the physiological state of the bacterioplankton as light-mediated primary productivity ceased. Our data reveal that the shift in physiological state may result from a switch from contemporary phytoplankton-excreted carbon to other sources of dissolved organic carbon, which can support the bacterioplankton populations through the winter. KEY WORDS: Leucine · Thymidine · Leu:TdR · Dissolved organic carbon · Winter · Loss rates · Survival · Sunlight Full text in pdf format PreviousCite this article as: Vick TJ, Priscu JC (2012) Bacterioplankton productivity in lakes of the Taylor Valley, Antarctica, during the polar night transition. Aquat Microb Ecol 68:77-90. https://doi.org/10.3354/ame01604 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 68, No. 1. Online publication date: December 18, 2012 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2012 Inter-Research.

Heterotrophic bacteria in aquatic environments are almost universally distributed into 2 distinct flow cytometric clusters based on their relative nucleic acid content: low (LNA) and high (HNA). The dynamics and possible regulation processes of both subgroups in southern Bay of Biscay coastal waters were examined by comparing weekly measurements over 2 yr at a shallow environment (L’Arbeyal beach) with monthly samples at 3 continental shelf stations off Xixon (Spain). Similar seasonal variations of temperature and chlorophyll a characterized inshore and offshore waters. Total bacterial abundances were also similar in shallow and shelf waters (from 0.22 to 3.72 × 106 cells ml−1), with the most remarkable difference being the higher abundance and larger size of HNA bacteria at L’Arbeyal, probably related to greater substrate availability. There, apparent net growth rates estimated from coherent periods (6 to 26 wk) of sustained increase or decrease (−0.02 to 0.04 d−1) were similar for LNA and HNA cells, although related to different factors. LNA bacteria net growth rates were strongly positively correlated with temperature (r = 0.95, p < 0.01, n = 6) and negatively with chlorophyll a (r = −0.90, p = 0.01, n = 6), supporting the hypothesis that they are independent from phytoplankton, which was recently suggested for this and other coastal sites using different approaches. We also show an opposite relationship between cell size and apparent net growth rates of LNA and HNA bacteria, providing further evidence of fundamentally different ecological roles.

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 66:117-131 (2012) - DOI: https://doi.org/10.3354/ame01562 Interactive climate change and runoff effects alter O2 fluxes and bacterial community composition of coastal biofilms from the Great Barrier Reef Verena Witt1,2,*, Christian Wild2, Sven Uthicke1 1Australian Institute of Marine Science (AIMS), PMB 3, Townsville MC, Queensland 4810, Australia 2Coral Reef Ecology (CORE), Leibniz Center for Tropical Marine Ecology (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany *Email: verena.witt@zmt-bremen.de ABSTRACT: Global (i.e. ocean warming) and local (i.e. land runoff) anthropogenic disturbances affect coastal coral reefs worldwide. Terrestrial runoff, leading to reduced light and increased nutrient availability, may have interactive effects with ocean warming in promoting shifts in benthic communities. Because microbial biofilms rapidly reflect environmental changes, we investigated the quantitative (C, N and chlorophyll a contents) and qualitative (microbial community composition) parameters and metabolic responses (O2 fluxes) of biofilms established on glass slides to combinations of manipulated water temperatures (26, 29 and 31°C), nitrate (0.5, 1.0 and 1.4 µM), and light availabilities (40 and 200 µmol photons m−2 s−1) in a 28 d flow-through aquarium experiment. The findings revealed that, independent of light availability, a temperature of 31°C significantly decreased the 24 h net O2 production and all of the quantitative parameters. Under high light, additive effects of 31°C and 1.4 µM nitrate reduced the 24 h net O2 production. Terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes showed light-independent temperature-induced microbial community shifts driven by increases in the relative abundance of Oceanospirillum (Gammaproteobacteria) and decreases of Cyanobacteria. The relative abundances of diatom plastids increased in response to elevated nitrate only in high-light-exposed biofilms. Overall, high temperatures altered microbial biofilm community composition, biomass and productivity. Under predicted near-future inner reef scenarios (low light and high nitrate availability), biofilms become light-limited through sedimentation, while outer (high light and low nitrate availability) inshore reef biofilms remain nitrate-limited. Understanding the interactive effects of environmental changes on microbial biofilm communities may contribute to bioindicator development and improved coastal management strategies for coral reefs. KEY WORDS: Light · Nitrate · Temperature · Water quality · Terrestrial runoff · Coral reef Full text in pdf format Supplementary material PreviousNextCite this article as: Witt V, Wild C, Uthicke S (2012) Interactive climate change and runoff effects alter O2 fluxes and bacterial community composition of coastal biofilms from the Great Barrier Reef. Aquat Microb Ecol 66:117-131. https://doi.org/10.3354/ame01562 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 66, No. 2. Online publication date: May 25, 2012 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2012 Inter-Research.

Glacial lakes cover large areas of northern Europe and North America. These freshwater systems represent important habitats accommodating diverse microbial communities. Here, 27 lakes in northern Germany, Poland and Finland were surveyed for the presence of aerobic anoxygenic phototrophic (AAP) bacteria during the summer seasons of 2008 and 2009. Using infrared epifluorescence microscopy, AAP bacteria were found to represent from 2 to 12% of total bacteria in surface layers of the studied lakes. The AAP abundance was correlated with total bacterial numbers, total phosphorus and chlorophyll concentration. The size fractionation analyses indicated that a significant portion of AAP cells was attached to particles. Our findings suggest that AAP bacteria represent a significant component of the microbial community in the studied lakes.