P-2 

 PHYTOPLANKTON 



The plants of the plankton . Unattached 

 microscopic plants subject to movement by 

 wave or current action. (See Zooplankton) 



PLANKTON 



Suspended microorganisms that have relatively 

 low powers of locomotion, or that drift in 

 the water subject to the action of waves and 

 currents. (See Benthos, Periphyton , Nekton) 



POND WEEDS 



(Higher Aquatic Plants) 



POOLS 



Areas of a stream, where the velocity of 

 current is reduced. The reduced velocity 

 provides a favorable habitat for plankton . 

 Silts and other loose materials that settle 

 to the bottom of pools are favorable for 

 burrowing forms of benthos . (See Riffle) 



POPULATION 



A group of interacting individuals of the 

 same species , area , or community . 



POSITIVE ESTUARY 



Coastal indentures in which there is a 

 measurable dilution of sea water by land 

 drainage; freshwater inflow + precipitation > 

 evaporation. (See Inverse Estuary, Neutral 

 Estuary) 



POTAMON ZONE 



Stream reach at lower elevations characterized 

 by reduced flow, higher temperature, and 

 lower dissolved oxygen levels . (See Rithron 

 Zone) 



