apes lakes

ogliotrophic

low productivity, low nutrients

mesotrophic

moderate productivity, moderate nutrients

eutrophic

high productivity, high nutrient

littoral zone

shallow, near shore, sunlight reaches bottom, plants grow

limnetic zone

open surface water away from shore, plenty of light, supports plankton

profundal zone

deep water, no light penetration, colder, low oxygen

benthic zone

bottom of lake, includes sediments and decomposers

stratification

layering of water in summer due to temperature differences

epilimnion

warm, top layer, well mixed sunlight reaches

hypolimnion

cold, dense, bottom layer, low oxygen

metalimnion

middle layer between warm and cold water, rapid temperature change

thermocline

the actual boundary in the metalimnion where temperature drops quickly

turnover

mixing of lake water in spring and fall, redistributes oxygen and nutrients