The effect of short-term ammonia starvation on Nitrosospira briensis was investigated. The ammonia-oxidizing activity was determined in a concentrated cell suspension with a NOx biosensor. The apparent half-saturation constant [Km(app)] value of the NH3 oxidation of N. briensis was 3 microM NH3 for cultures grown both in continuous and batch cultures as determined by a NOx biosensor. Cells grow...

Nutrient uptake length is an important parameter for quantifying nutrient cycling in streams. Although nutrient tracer additions are the preferred method for measuring uptake length under ambient nutrient concentrations, short-term nutrient addition experiments have more frequently been used to estimate uptake length in streams. Theoretical analysis of the relationship between uptake length det...

phytoplankton communities play a significant role in the oceanic biological pump by forming the base of the trophic structure. increase in nutrients loading affects spatial and temporal distribution of phytoplankton. this study examined the phytoplankton community structure and ecological indices in relation to nutrients dynamics in both estuarine and oceanic areas of ramisi-vanga systems alon...

Atmospheric deposition of nitrogen (AD-N) is a significant source of nitrogen enrichment to nitrogen (N)limited estuarine and coastal waters downwind of anthropogenic emissions. Along the eastern U.S. coast and eastern Gulf of Mexico, AD-N currently accounts for 10% to over 40% of new N loading to estuaries. Extension of the regional acid deposition model (RADM) to coastal shelf waters indicate...

Each year, millions of hatchery-raised fish are stocked into streams and rivers worldwide, yet the effects of hatchery-raised fish on stream nutrient cycles have seldom been examined. We quantified the influence of supplemental nonnative fish stocking, a widespread recreational fishery management practice, on in-stream nutrient storage and cycling. We predicted that supplemental, hatchery-raise...

Some biochars produced by pyrolysis of biomass have the potential to sequester C and enhance nutrient supplies in agricultural soils. A 28-day lab incubation was used assess effects derived from pine chips (PC) or poultry litter (PL) applied at five application rates (0, 22.5, 45.0, 67.5, 90 Mg ha−1 equivalent). Biochars were two acidic Ultisols, a Cecil sandy loam Tifton loamy sand, found Geor...

Enhanced nitrogen (N) availability is one of the main drivers of biodiversity loss and degradation of ecosystem functions. However, in very nutrient-poor ecosystems, enhanced N input can, in the short-term, promote diversity. Mediterranean Basin ecosystems are nutrient-limited biodiversity hotspots, but no information is available on their medium- or long-term responses to enhanced N input. Sin...

1. A N-NH4 tracer release study was conducted in a macrophyte-rich stream, the River Lilleaa in Denmark. The objectives of the study were to compare uptake rates per unit area of NH4 by primary producers and consumers in macrophyte and non-macrophyte habitats, estimate wholestream uptake rates of NH4 and compare this to other stream types, and identify the pathways and estimate the rate at whic...

We examined the effects of riparian vegetation removal on algal dynamics and stream nutrient retention efficiency by comparing NH4-N and PO4-P uptake lengths from a logged and an unlogged reach in Riera Major, a forested Mediterranean stream in northeastern Spain. From June to September 1995, we executed 6 short-term additions of N (as NH4Cl) and P (as Na2HPO4) in a 200m section to measure nutr...