The importance of organic carbon and inorganic nutrients in controlling bacterial production was investigated in two tropical lowland rivers draining undisturbed forested catchments. Glucose (C), ammonium (N), phosphate (P), leaf leachate, and algal leachate were added alone or combined to water collected from one clear-water (Cataniapo) and one black-water (Autana) river of the Middle Orinoco ...

Bacterial respiration (BR) of organic matter is an important flux in the carbon budgets of large rivers, yet the regulation of BR and the relationship of this respiration to various organic matter sources is poorly understood. Using detailed spatial transects, we evaluated transport and consumption of dissolved organic matter in the Hudson River estuary, and compared both with BR. Dissolved org...

High-latitude rivers supply the Arctic Ocean with a disproportionately large share of global riverine discharge and terrigenous dissolved organic matter (DOM). We used the abundance of lignin, a macromolecule unique to vascular plants, and stable carbon isotope ratios (d13C) to trace the high molecular weight fraction of terrigenous DOM in major water masses of the Arctic Ocean. Lignin oxidatio...

An evaluation of several potential factors limiting carbon dioxide excretion by rainbow trout (Oncorhynchus mykiss) red blood cells was performed in vitro using a recently developed radioisotopic assay. Red blood cell (RBC) CO2 excretion was reduced by pretreatment (30min) of blood with the carbonic anhydrase inhibitor acetazolamide (final nominal concentration 1024 mol l21) or the Cl/HCO3 exch...

We quantified within-species variation in the tolerance of the large, lake-dwelling daphnid, Daphnia pulicaria, to toxic cyanobacteria in the diet. Juvenile growth rates on diets consisting of 100% Ankistrodesmus falcatus (a nutritious green alga) or 100% Microcystis aeruginosa (toxic) were compared for D. pulicaria clones isolated from lakes expected to have low and high levels of bloom-formin...

During a springtime study of pelagic microbial activities in the coastal Alaskan Arctic (Chukchi Sea, June 1998), a selective serial dilution technique was used to estimate the relative abundance of cold-loving (psychrophilic) and cold-tolerant (psychrotolerant or psychrotrophic) pelagic bacteria at four stations representing different stages of an algal bloom. Psychrophiles were numerically do...

We examined the ability of dimethylsulfoniopropionate (DMSP), its cleavage products dimethyl sulfide (DMS) and acrylic acid (AA), and the oxidized form of DMS dimethylsulfoxide (DMSO), to inhibit infection of Emiliania huxleyi virus 86 (EhV-86). Infectivity was assessed by plaque assay of viral stock that had been exposed to these compounds. The initial concentrations of the compounds tested we...

In the present study, effect of ??-phase dispersed particles on both L21(B2)-10M/14M-L10 martensitic transformations and elastocaloric in aged Ni54Fe19Ga27 single crystals oriented along [001]-direction was investigated. It experimentally shown that aging strongly affects properties these crystals. The precipitation semi-coherent up to 500 nm size at 773 K for 1 h leads a 1.4 times increase ope...