t content in the water is low; and although nitrogen is abundant, phosphorus is highly limited Low production of organic mater, particularly phytoplankton Oxygen concentration remains high
DYSTOTROPHIC SYSTEMS Lakes that receive large amounts of organic matter from surrounding lands particularly in the form of humic materials that stain the water brown Low only in planktonic vegetation but have generally high productive littoral zones Littoral vegetation dominates the metabolism of the lake, providing a source of both dissolved and particulate organic matter.
LAKE ORGANISMS THOSE THAT GO WHERE THEY CHOOSEFISH AMPHIBIANS LARGER TURTLES ZOOPLANKTON INSECTS THOSE THAT GO WHERE THE WATER TAKES THEMLIVING THINGS = PLANKTON DEAD MATERIAL = DETRITUS animals - zooplankton internal - produced within lake algae - phytoplankton external - washed in from watershed bacteria - bacterioplankton THOSE THAT LIVE ON THE LAKE BOTTOMBENTHOS = ANIMALS PLANTS BACTERIA & FUNGI aquatic insects higher plants - sewage sludge molluscs - clams, snails macrophytes aufwuchs - mixture other invertebrates - attached algae - of algae, fungi worms, crayfish periphyton and bacteria
PLANT ADAPTATIONS Zonation of emergent, floating, and submerged vegetation at the edge of a lake or a pond as a response of water depth
SHALLOW WATERSpike rushes and small sedgesADAPTATION: Roots are anchored in the bottom bud.
DEEPER WATERBulrushes, reeds, and cattailsADAPTATION:Narrow, tubular, linear leaves and have broad leaves
FLOATING PLANTS Pond lily (Nuphar spp.) and Pond weed (Potamegaton)ADAPTATION: Poorly developed root system but highly developed aerating system
SUBMERGED PLANTSCertain pond weed species (Chara muskgrass)ADAPTATION: Lacks cuticles. These plants absorb nutrients and gases directly from the water through thin and finely dissected or ribbon like leaves,
ANIMAL ADAPTATIONFishes lack strong lateral muscles characteristics of fish living in swift water such as sunfish.ADAPTATION: Have compressed bodies that permit them to move with ease through the masses of acquatic plants.
ANIMAL ADAPTATIONS Diving insects such as water boatman and Diving beetlesADAPTATION: Carry a bubble of air with them when they go under water in search of prey.
HUMAN IMPACT The shore line is parceled into lots, residences spring up, nutrient seep in the septic tanks and pesticides find their way into the lake. Before long the structure of the lake changes.
Motorboats discharge an oily mixture that can lower oxygen levels and adversely affect the growth and longetivity of fish. Wake created by motor boating disturbs littoral vegetation.
HUMAN IMPACT Overfishing, pollution and introduction of exotic species accidentally or on purpose Human activities like road construction, logging, mining, agriculture add another heavy loads of silts and nutrients, especially nitrogen, phosphorus and organic matter.