F-/ 



FALCULTATIVE 



Refers to the capability of an organism to 

 live under varying conditions; e.g., a 

 f alcultative anaerobe is an organism that 

 although usually living in the presence of 

 free oxygen can live in the absence of free 

 oxygen. (See Obligate) 



FALL OVERTURN 



A physical phenomenon that may take place in 

 a body of water during early autumn. The 

 sequence of events leading to fall overturn 

 include: (1) cooling of surface waters, 



(2) density change in surface waters producing 

 convection currents from top to bottom, 



(3) circulation of the total water volume by 

 wind action, and (4) vertical temperature 

 equality. The overturn results in a uniformity 

 of the physical and chemical properties of the 

 entire water mass. (See Spring Overturn) 



FATHOM 



A unit of measurement equal to 6 feet (1.83 

 meters) . 



FAUNA 



Animal life . 



FIRTH 



A narrow arm of the sea; also the opening of 

 a river into the sea. (See Estuary) 



FJORD 

 (Fiord) 



A narrow arm of the sea between highlands . 

 (See Firth . Estuary) 



