H— Continued 



homoiosmotic— Referring to an organism 

 which steadily maintains a total internal 

 concentration of body fluids independ- 

 ent of that of the environment. 



hydrophyte— A water- or moisture-loving 

 plant. As opposed to xerophyte. 



hydroseres,— A wet sere. See also sere. 



hypertonic— Osmotic concentration higher 

 than the surrounding medium. 



hypotonic— Osmotic concentration lower 

 than the surrounding medium. 



hypolimnion— That part of a lake below the 

 thermocline. 



__I_ 



increasers— A species which increases in 

 abundance under continuous grazing. 

 Opposite of decreasers. 



interstitial— A term referring to the spaces 

 between particles, (e.g., the spaces 

 between the sand grains). See also 

 meiofauna. 



instar— A term referring to the period in an 

 arthropod's life between each ecdysis or 

 molt. 



intrinsic factors— When referring to coloni- 

 zation by an organism, those attributes 

 or genotypes of that organism which 

 permit it to invade and survive in a new 

 area (e.g., locomotor ability, structure, 

 physiological and behavioral properties). 



lake, dimictic— See dimictic lake. 



lake, dystrophic— See dystrophic lake. 



lake, eutrophic— See eutrophic lake. 



lake, meromictic— See meromictic lake. 



lake, monomictic— See monomictic lake. 



lake, oligomictic— See oligomictic lake. 



lake, oligotrophic— See oligotrophic lake. 



lake, polymictic— See polyinictic lake. 



larva— A sexually immature form of any 

 animal unlike its adult form and requir- 

 ing changes before reaching the basic 

 adult form. 



lentic— Standing waters, lakes and ponds, as 

 opposed to lotic, running waters. 



light compensation level — The depth at 

 which production by photosynthesis just 

 balances respiration. 



light- dark-bottle technique— A method for 

 measuring primary productivity. Two 

 representative water samples are taken 

 and one is covered so no light can 

 penetrate. The bottles are "incubated" 

 at the original depths and location, then 

 oxygen content is measured. The differ- 

 ence can be related to productivity. 



limnetic zone — In freshwater, the water 

 zone from the surface to the light 

 compensation level. 



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