Nitrogen Fixation in Canadian Precambrian Shield Lakes

Epilimnetic rotifer community responses to Bythotrephes longimanus invasion in Canadian Shield lakes

We studied whether the effects of Bythotrephes longimanus, a new predatory cladoceran zooplankton species to North America, can extend beyond the macrozooplankton to the rotifer community, which is known to be an important controller of the microbial loop. During summer 2003, 14 Canadian Shield lakes were sampled biweekly to evaluate the effect of Bythotrephes on epilimnetic rotifers. Rotifer d...

Spatial variation of nitrogen fixation in lakes of the northern Great Plains

Cyanobacterial ; blooms are a regular feature of lakes in central North America, but little is known of their importance to the nitrogen (N) cycle and nutrition of aquatic food webs. We hypothesized that N2-fixing cyanobacteria constitute a significant source of N to prairie lakes, that fixed N is effectively transferred to primary and secondary consumers, and that the importance of fixed N is ...

Nitrogen Fixation

Plant growth is directly dependent upon an adequate supply of fixed nitrogen. Water and fixed nitrogen are the most common limiting factors for plant growth.There is an abundance of nitrogen in the atmosphere, but it is in the form of the relatively inert gas, N2, and this must be converted chemically or biologically into a more active form before plants can utilize it. Chemical fixation most c...

Nitrogen fixation in ruminants.

The amount of nitrogen gas (N2) available for microbial protein synthesis via nitrogen fixation in the rumen was estimated. Measurements were made of nitrogen fixation by ruminal ingesta from goats fed low protein rations for a prolonged period of time, and by ingesta from sheep fed high protein rations. Nitrogen fixation by rumen microorganisms incubated for 30 or 180 min in vitro was measured...

Canadian Precambrian Iron-formations: Ages and Trace Element Compositions