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Nitrogen is a fundamental chemical component of amino acids, the molecular building blocks of protein. As such, nitrogen balance may be used as an index of protein metabolism. [1] When more nitrogen is gained than lost by an individual, they are considered to have a positive nitrogen balance and be in a state of overall protein anabolism.
The most significant advantage of fishless cycling is that it can reduce fish loss due to ammonia and nitrite spikes. Fish loss can be very discouraging for beginners of fish keeping, so indirectly, fishless cycling can also help beginners get a good start. Cycling aquariums using feeder fish is risky, because it infects the aquarium with any ...
Primary production fuelled by nitrate is, therefore, making use of a "fresh" nutrient source rather than a regenerated one. Production by nitrate is thus referred to as new production. [2] To sum up, production based on nitrate is using nutrient molecules newly arrived from outside the productive layer, it is termed new production.
Nitrogen enters the ocean through precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N 2 so it must undergo nitrogen fixation which is performed predominantly by cyanobacteria. [82] Without supplies of fixed nitrogen entering the marine cycle, the fixed nitrogen would be used up in about 2000 ...
Putrefying bacteria use amino acids or urea as an energy source to decompose dead organisms. In the process, they produce ammonium ions. Nitrifying bacteria then convert this ammonium into nitrate by oxidation, which can then be used by plants to create more proteins thus completing the nitrogen cycle. [6] This process is called nitrification.
The urea cycle and the citric acid cycle are independent cycles but are linked. One of the nitrogen atoms in the urea cycle is obtained from the transamination of oxaloacetate to aspartate. [11] The fumarate that is produced in step three is also an intermediate in the citric acid cycle and is returned to that cycle. [11]
Adding urea to the ocean can cause phytoplankton blooms that serve as a food source for zooplankton and in turn feed for fish. This may increase fish catches. [54] However, if cyanobacteria and dinoflagellates dominate phytoplankton assemblages that are considered poor quality food for fish then the increase in fish quantity may not be large. [55]
Relationship of phosphate to nitrate uptake for photosynthesis in various regions of the ocean. Note that nitrate is more often limiting than phosphate The Redfield ratio or Redfield stoichiometry is the consistent atomic ratio of carbon , nitrogen and phosphorus found in marine phytoplankton and throughout the deep oceans.