Streams and RiversArcilla, William AllanFernandez, Emma Louise
Streams• A body of water with a current, and is smaller than a river• When joined, they form a bigger body of water either flowing or nonflowing water ecosystem. ▫ Lakes – Rivers ▫ Ponds ▫ Inland wetlands
Rivers• A body of water with a current and is larger than streams• The volume of water it carries is larger than the volume of water streams carry.
Upper Course• Where the river begins• Many smaller streams join up to form larger streams• Several streams join up to form a river• Narrow and v-shaped river channel• Steep gradient
Middle Course• River starts to meander • Wider river channel• More tributaries than upper course joining the river • Gentler gradient as compared to upper course
Lower Course• Meanders are common• Distributaries distribute water away from the river to the sea• Wider river channel than middle course• High volume of water• Gentle gradient
Three main types of rivers• Youthful River - A youthful river has a steep gradient and very few tributaries. A youthful river is bound to flow quickly and swiftly. Mature River - A mature river is less steep and flows slowly compared to the youthful river. There are many tributaries that feed a mature river. The sediment deposit is also less. Old River - An old river has a low gradient and is depended on flood plains is known as old river.
Three main types of streams:• Ephemeral streams ▫ regularly exist for short periods of time, usually during a rainy period.• Intermittent streams ▫ flow at different times of the year, or seasonally, when there is enough water from either rainfall, springs, or other surface sources.• Perennial streams ▫ streams that flow year-round.
The tributaries (streams) are identified bytheir stream order, denoted by its position in the system. Stream Order Characteristics First Order not connected to any other tributaries connected to one other Second Order stream/tributary Third Order joining of two second order streams
ABIOTIC FACTORS• Precipitation ▫ Important in formation of streams and rivers. ▫ Amount of precipitation in an area determines which type of stream should be present at that area.• Current ▫ It will determine the substrate at the bottom of the stream or river.
ABIOTIC FACTORS• Landscape ▫ The direction of stream flow is dependent upon the slope and obstructions of the landscape.• Temperature ▫ Affects the organisms living in streams and rivers. ▫ Affects growth and development of organisms. ▫ Reproduction Different organisms reproduce at different temperatures
ABIOTIC FACTORS • Trout will not reproduce below 3 degrees and ideally between 5 and 16 degrees.
ABIOTIC FACTORS • Carp reproduce best above 20 degrees.
Plant adaptations• Air Spaces ▫ decrease density and increase buoyancy
• Broad leaves ▫ spread their weight more evenly across the water surface allowing them to float
• Waxy cuticle ▫ allow water to run off the surface preventing the weight of the water from dragging the leaves under the surface
• Strong holdfast ▫ Used by water mosses (Fontinalis) and heavily branched filamentous algae to cling on to rocks
• Cushion like colonies or closely appressed sheets that are covered with a slippery gelatinous coating
Animal adaptations • Streamlined form ▫ Offers less resistance to water current Brook trout Pearl dace
• Extremely flattened and broad bodies, flat limbs ▫ Allow the current to flow over the bodies of some larval forms Blackfly larvae
• Snails and planarians ▫ Attached themselves to sticky undersurfaces allowing them to cling tightly and move about on stones and rubble in the current.
• Smallmouth bass ▫ Strong lateral muscles (needed in the fast current for compressed bodies)that enable them to move through beds of aquatic vegetation
Four major groups of inhabitants(according to feeding habits)• Shredders ▫ Feed on coarse particulate organic matter (CPOM) CPOM – mostly leaves that fall into the stream and are softened by water and colonized by bacteria and fungi. Casemaker caddisfly
• Filtering and gathering collectors ▫ Feed on the fine particulate organic matter (FPOM) FPOM – leaves that are broken down by the shredders, partially decomposed by microbes, and invertebrate feces that drift downstream and settle on the stream bottom. Freshwater mussels
• Grazers ▫ Another group that feed on the algal coating of stones and rubble Water penny
• Gougers ▫ Invertebrates that burrow into water-logged limbs and trunks of fallen trees
Human impact• Draining of rivers and streams The now dry Colorado River delta branches into the Baja/Sonoran desert just five miles north of the Sea of Cortez, Mexico. Photo by Peter McBride
• Water diversion and regulation of flows due to dams. ▫ Principal reasons why dams are built: Flood protection Recreation Industrial purposes Electricity Water supply Political reason
Impacts of dams on streams• traps the suspended and dissolved load, starving the area downstream of sediment and nutrients• a barrier to any aquatic life going up or down stream, which can prevent aquatic life from mating and reduce the diversity of wildlife upstream
• Flood Control: ▫ Channelization: Straightening out the meanders of a stream to for a straight line, or smoothing out the natural levee by replacing it with concrete flood walls. ▫ Artificial Levees: Artificially raising the height of a natural levee. Channelization Artificial leevee
• Urbanization ▫ When houses or businesses are built in a floodplain, they get flooded. ▫ Increases runoff into streams, which further increases the chances of flooding