1. Nutrient diffusing substrata were used to determine the effect of added inorganic nitrogen (N) and phosphorus (P) on the development of epilithic and epixylic biofilms in 10 North American streams. Four treatments of diffusing substrata were used: Control (agar only), N addition (0.5 M NaNO3), P addition (0.5 M KH2PO4), and N + P combined (0.5 M NaNO3 + 0.5 M KH2PO4). Agar surfaces were cove...

The diversity of aerobic anoxygenic phototrophic (AAP) bacteria in freshwater environments, particularly in rivers, has not been examined in as much detail as in ocean environments. In the present study, we investigated the phylogenetic and physiological diversities of AAP bacteria in biofilms that developed on submerged stones in a freshwater river using culture methods. The biofilms collected...

Lichens appear to be essential and effective colonisers of bare substrates including the extremely contaminated wastes of slag dumps. This study examines the metal accumulation capacity of epilithic lichens growing directly on the surface of artificial slag sinters. Four species representing different growth forms, i.e., crustose Candelariella aurella, Lecanora muralis, and Lecidea fuscoatra an...

Microbial biogeography studies expend much effort in determining whether environmental selection or stochastic processes related to dispersal are more important in shaping community composition. While both types of factors are possibly influential, it is tacitly assumed that protists, or microbial eukaryotes in general, behave biogeographically as prokaryotes because of their small physical siz...

Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecolog...

1. Epilithic biofilm biomass was measured for 14 months in two sites, located upand downstream of the city of Toulouse in the Garonne River (south-west France). Periodical sampling provided a biomass data set to compare with simulations from the model of Uehlinger, Bürher and Reichert (1996: Freshwater Biology, 36, 249–263.), in order to evaluate the impact of hydraulic disturbance. 2. Despite ...

The extent to which different grazers are functionally redundant has strong implications for the maintenance of community structure and function. Grazing by red urchins (Strongylocentrotus franciscanus) on temperate rocky reefs can initiate a switch from invertebrate or macroalgal dominance to an algal crust state, but can also cause increases in the density of molluscan mesograzers. In this st...

Microbial communities are major players in the biogeochemical processes and ecosystem functioning of river networks. Despite their importance ecosystem, biomonitoring tools relying on prokaryotes still lacking. Only a few studies have employed both metabarcoding quantitative techniques such as catalysed reported deposition fluorescence situ hybridization (CARD-FISH) to analyse prokaryotic epili...