Linda Wilhelm and colleagues report about patterns of microbial biodiversity in Alpine glaciers and their streams, vanishing ecosystems in Alpine landscapes due to global warming. Original publication (free download) and press release.

Diversity–productivity relationships are largely known from the primary producer level. Based on experiments in mesocosms Maren Striebel, Gabriel Singer, Herwig Stibor and Tom Andersen demonstrate effects of aquatic primary producer (phytoplankton) diversity on higher trophic levels (zooplankton). Phytoplankton diversity increased the means of both zooplankton growth rate and abundance while suppressing their variability, and sustained
higher zooplankton diversity. The results of their study can be found in a recent publication in Ecology.

Glaciers store organic matter, which is released to alpine streams by glacial melt. In the light of global warming and disappearing glaciers worldwide, a team from DeLi set out to explore the organic matter from 30 glaciers distributed throughout the Austrian Alps. In Nature Geoscience, Gabriel Singer, Christina Fasching and colleagues report about the unexpectedly high molecular diversity of organic matter stored in European glaciers and the contribution of this highly bioavailable organic carbon pool to microbial metabolism in downstream lotic ecosystems. Read more here and access the full story on Nature Geoscience.

Michael Schagerl´s team published two papers about the alkaline-saline ecosystems in the East African Rift Valley.

The first paper deals with flamingo migrations between alkaline-saline lakes. We hypothesised that changes in nutritional composition and quality of the pelagic phytoplankton community influence the occurrence of Lesser Flamingo populations. In Lake Nakuru, Lesser Flamingos had a significant positive relationship with lipids and Arthrospira biomass but a negative relationship with small cyanoprokaryotes. For Lake Bogoria, no significant differences were observed as the Arthrospira was available throughout the sampling period though the flamingo numbers still fluctuated. We concluded that the nutritional composition and quality of the phytoplankton community influence the temporal and spatial abundance of Lesser Flamingos although other factors such as the prevailing environmental conditions may take precedence.

DOI 10.1007/s10750-012-1105-1

In another study, we investigated the feeding behaviour of the dominant microzooplankton of saline lakes in the East African Rift Valley. A set of grazing experiments revealed high ingestion rates of the two euryhaline rotifers Brachionus dimidiatus and Brachionus plicatilis and of the large-sized omnivorous ciliates Frontonia sp. and Condylostoma magnum reflecting the unique nature of tropical saline systems. The size spectrum of ingested particles was broad and even included filamentous cyanobacteria such as the commonly dominating Arthrospira fusiformis. Feeding selectivity on cyanobacteria, however, was rather low showing higher values for cryptomonads and small ciliates. Bacterial biomass was favoured by the presence of grazers, as small bacterivorous predators were reduced at an average of 13.9%, showing the cascading effect of large zooplankton on the food web structure. Overall, based on this first-time study of the microzooplankton feeding behaviour in East African soda lakes, a strong structuring effect of rotifers and large ciliates on microbial plankton communities is assumed, especially in times of high consumer biomass. DOI 10.1007/s10750-012-1023-2

Ed Hall leaves us another legacy from his famous series of FUTURE experiments conducted during his time at DeLi. Together with Katharina Besemer and colleagues Ed reports about effects of resource chemistry on stream hyporheic biofilms. Targetting phosphorus, they found a surprise: It´s arsenic... no, manganese actually! Read more in their paper: Hall EK, Besemer K, Kohl L, Preiler C, Riedel K, Schneider T, Wanek W & TJ Battin (2012) Effects of resource chemistry on the composition and function of stream hyporheic biofilms. Frontiers in Microbiology 3: Article 35, doi: 10.3389/fmicb.2012.00035. Link to journal.

Andreas Weilhartner and coauthors report about nitrate and phosphate impacts of gravel pit lakes... and actually these man-made ecosystems reduce levels of these nutrients in the outflowing groundwater. Find details in the recent publication: Weilhartner A, Muellegger C, Kainz M, Mathieu F, Hofmann T & TJ Battin (2012) Gravel pit lake ecosystems reduce nitrate and phosphate concentrations in the outflowing groundwater. Science of the Total Environment 420: 222-228. Link to journal.

Peter Akoll has successfully defended his PhD at DeLi in March 2011. His findings about fish parasites in Nile tilapia and African catfish have now been published in a series of papers:

Akoll P, Konecny R, Mwanja MW, Nattabi KJ, Agoe C & F Schiemer (2011) Parasite fauna of farmed Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) in Uganda. Parasitology Research, doi: 10.1007/s00436-011-2491-4 Link to journal. 

Akoll P, Fioravanti ML, Konecny R & F Schiemer (2011) Infection dynamics of Cichlidogyrus tilapiae and C. sclerosus (Monogenea, Ancyrocephalinae) in Nile tilapia (Oreochromis niloticus L.) from Uganda. Journal of Helminthology, doi: 10.1017/S0022149X11000411 Link to journal. 

Akoll P, Konecny R, Mwanja WW & F Schiemer (2011) Infection patterns of Nile tilapia (Oreochromis niloticus L.) by two helminth species with contrasting life styles. Parasitology Research, doi: 10.1007/s00436-011-2649-0 Link to journal. 

Philipp Oberrisser and Johann Waringer report about mayfly drift induced by salamander presence in Freshwater Biology. Baetidae mayflies avoid predators and shift drift patterns towards the nighttime when salamanders are present, salamander kairomones may induce the behavioral change compared to a stream reach without predators. Abstract and full article here.

In his doctoral thesis in 1942 Jacques Monod described a phenomenon now widely distributed in microbiology textbooks and known as diauxic growth or - in a more modern phrasing - carbon catabolite repression. Using micro-autoradiography Gabriel Singer and colleagues show how this mechanism controls the spatial distribution of uptake of carbohydrate monomers in stream biofilms and leads to a micro-scale "metabolic stratification" within biofilms with potential consequences for stream ecosystem functioning.

Singer G, Besemer K, Hochedlinger G, Chlup A-K & Battin TJ. (2011). Monomeric carbohydrate uptake and structure-function coupling in stream biofilms. Aquatic Microbial Ecology 62: 71-83.

A new Mini-Review in the journal Ecosystems authored by Ed Hall and Tom Battin along with colleagues from The Dept. of Microbial Ecology, The Department of Chemical Ecology, IIASA, and The Institute for Mummies and the Ice Man integrates ecological theory with microbial ecology using a suite of novel single cell techniques. Hall and colleagues lay out a conceptual model that shows how microbial community stoichiometry can be deconstructed into constituent; populations, cells and macromolecules, in a hierarchical manner. They demonstrate how deciphering the underlying variance in microbial community stoichiometry may lead to a better understanding of whether the microbes will act as a source or sink of mineral nutrients in a wide variety of environments. A link to a preprint will be made available shortly.