#17 - Streams (and review for exam #2)

#17 - Streams (and review for exam #2) - Announcements Next...

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1 Announcements • Next week’s lab is a field trip . We will leave campus exactly at 1:30pm. Don’t be late or you will miss the bus. • Review sessions: – Wednesday 9:00-10:00am – Wednesday 1:30-2:00pm • Come armed with specific questions, not “I don’t get any of this stuff” questions. •Today’s lecture will NOT be on the exam! Aquatic habitats • Streams • Lakes, reservoirs, and ponds • Freshwater wetlands • Tidal wetlands • Shallow marine habitats • Open seas and ocean Streams What is a stream? • A stream is water and sediment moving downhill under the influence of gravity. The force of gravity acting on the water (which flows readily) produces power that can be used to do work. The “work” that a stream does is to transport sediment, moving it generally downstream, but also rearranging it within the stream. An estimated 2% - 4% of the potential energy of the water in streams is used to move sediment. Streams move billions of tons of sediment to the oceans annually.
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Sediment supply vs. water supply • In a natural river system, the amount of water and the amount of sediment are in balance – If one changes, the other must change – If either changes the stream character may change • Even though balanced, the stream system exists in a state of “dynamic” balance Stream systems • It is difficult to study just a single stream or stream section. .. • Individual streams are part of larger stream systems – headwaters – middle reaches – downstream reaches • Stream systems are hierarchical Stream systems • Streams flow downhill – Stream systems are highest in the headwaters and move progressively downward. Thus, streams at higher elevation feed streams at lower elevation. – Stream systems are also
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This note was uploaded on 04/24/2008 for the course BIOL 216 taught by Professor Baker during the Spring '08 term at Clark University.

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#17 - Streams (and review for exam #2) - Announcements Next...

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