N-2 

 NEUSTON 



Organisms associated with, or dependent 

 upon, the surface film (air-water interface) 

 of bodies of water. 



NEUTRAL ESTUARY 



Type of estuary in which neither the freshwater 

 inflow nor the evaporation predominates; 

 freshwater inflow + precipitation - evaporation. 

 (See Positive Estuary , Inverse Estuary) 



NICHE 



(See Ecological Niche. Habitat Niche) 



NOCTURNAL 



Pertaining to those organisms that are active 

 at night. (See Diurnal) 



NUISANCE ORGANISMS 

 (Pests) 



Those organisms capable of interfering with 

 the use or treatment of water. 



NUTRIENTS 



Elements, or compounds, essential as raw 

 materials for organism growth and development; 

 e.g., carbon, oxygen, nitrogen, phosphorus, 

 etc. 



NYMPH 



An immature developmental form characteristic 

 of the pre-adult stage in insects that do not 

 have a pupal stage; e.g., mayflies and 

 stoneflies. (See Larva) 



