Rivers, Streams, and Lotic Ecosystems

Stream Classification 1 st order 1 st order Small non branching stream/creek Small non branching stream/creek 2 nd order 2 nd order Two 1 st order streams combine Two 1 st order streams combine 3 rd order 3 rd order Two 2 nd order streams combine Two 2 nd order streams combine A 1 plus a 2 doesn’t equal a 3 A 1 plus a 2 doesn’t equal a 3 True headwaters of Mississippi True headwaters of Mississippi River is named for the largest order. River is named for the largest order. True name of Mississippi? True name of Mississippi?

Watershed Watershed/Drainage Watershed/Drainage Area a river drains Area a river drains New stream New stream High grade High grade Large fall Large fall Fast flowing Fast flowing V channel V channel Straight Straight Old Stream Old Stream Meanders Meanders Oxbow Lakes Oxbow Lakes Back waters Back waters U shaped Valley/channel U shaped Valley/channel

River Structure Bottom structure Bottom structure Changes in rivers Changes in rivers Hard/soft Hard/soft Scouring Scouring Washing away of river bottom Washing away of river bottom Flooding Flooding When river overflows its banks When river overflows its banks Can scour Can scour Ice Dams (Red River) Ice Dams (Red River)

River Structures (continued) Run Run Straight main body of river Straight main body of river Riffle/Rapids Riffle/Rapids Fast flowing usually shallow Fast flowing usually shallow Caused by equal volume must go through less area Caused by equal volume must go through less area Pool Pool Deep slow flowing Deep slow flowing Waterfall Waterfall Hard rock over soft Hard rock over soft Erosion rates differ Erosion rates differ Back waters Back waters Flooded area usually not part of river Flooded area usually not part of river

Biota Adaptations Adaptations Must overcome constant current Must overcome constant current Fish Fish Trout and salmon but also walleye, bass and others Trout and salmon but also walleye, bass and others Behavior adaptations Behavior adaptations Hide behind rocks Hide behind rocks Wait for food don’t chase it Wait for food don’t chase it Breed in shallows (dig holes) Breed in shallows (dig holes) Lay eggs upstream why? Lay eggs upstream why? Anatomy Adaptations Anatomy Adaptations Very streamlined body Very streamlined body Great sense of smell Great sense of smell Feast on hatches Feast on hatches

Biota (continued) Micro and Macro Invertebrates Micro and Macro Invertebrates Base of food chain Base of food chain Nymphs: Mayflies, dragonflies, stoneflies Nymphs: Mayflies, dragonflies, stoneflies Mass hatchings Mass hatchings Why? Why? When? When? Where? Where? Roads and Cars Roads and Cars Indicator Species Indicator Species Tell health of ecosystem Tell health of ecosystem

Biota (continued) Adaptations: Adaptations: Stream lined body Stream lined body Suction cups Suction cups Hooks Hooks Filter Feeders Filter Feeders Predators Predators Net Makers Net Makers Shredders Shredders

The End