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Freshwater Zones 1

Page history last edited by Rebecca Faust 10 years, 11 months ago

Benthic(freshwater): The Benthic zone is the region at the lower-most part of a lake, pond, or stream. Creatures that live in this part are called benthos. Many of these creatures are attatched to the bottom. Light does not penetrarte very deep in this zone so most of the organisms get their energy from organic matter higher up. 


Termocline: thin yet distinct layer on a body of water in which temperature changes more rapidly than the layers above or below. The Termocline may be thought of an invisable blanket that seperates the upper mixed layer from the calm deep water below in the ocean.


Littoral: This zone is the shallow, well lit water close to shore.  Since light is available, photosynthesis can take place. This is the warmest zone. There is a diverse population of algae, rooted aquatic plants, lichens, periwinkles, barnacles, corals, snails, clams, crustaceans, fish, and amphibians. Challenges can arise from coastal currents causing erosion.




Limnetic: It is an area of an open lake where sun shines. The water is too deep for light to penetrate to the bottom so no rooted under water plants can grow. Algae, plankton, crustaceans, and cyanobacteria live here. As well as the fish that inhabit the water system. Most photosynthesis occurs in this area. It is located above the profundal zone. Basically it is the area of the middle top layer of a lake.




Oligotrophic vs Eutrophic




Hypolimnion: This zone is one of three distinct layers of a freshwater lake characterized by different temperatures. The hypolimnion is a lower layer of colder, denser water with a lower concentration of dissolved oxygen because it is not exposed to the atmosphere. This layer does not receive many nutrients from the upper layers. The hypolimnion has several distinct characteristics. It is the coldest layer of a lake in the summer and the warmest layer during the winter. In addition, the hypolimnion layer receives insufficient amount of sunlight for photosynthesis to occur, thus it is unavailable as a habitat for most plants and animals.



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