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C. Depth and Width. D. Current Velocity and volume of the water’s flow Brings food to most aquatic organisms Exerts a force on organisms some resist some move with or against the current . E. Substrate – material making up stream bed
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D. Current Velocity and volume of the water’s flow Brings food to most aquatic organisms Exerts a force on organisms some resist some move with or against the current
E. Substrate – material making up stream bed Made up of organic (algae and other food sources) and inorganic (pebbles, mud, silt) Most invertebrates (sm animals with no backbone) and some fish live in substrate
F. Sunlight – ultimate source of energy ↑ in sunlight = ↑ biodiversity of organisms Plants (autotrophs) need sunlight; they are at the base of the food chain and needed for all else to survive.
G. Turbidity – the amount of suspended material in the water; water clarity material: silt, clay, small organisms Sources: soil erosion urban runoff heavy rains warm temps (↑ plankton....drifting animals... which ↑ turbidity) Effects: ↓ photosynthesis
H. Color and Odor – from substances such as chemical discharges or rotting leaves. may indicate other problems. Ex: green color may mean high levels of algae Ex: rotten egg smell may mean sulfur compounds present
II. Chemical Parameters • Measurement of dissolved and suspended substances in water • Concentrations vary throughout the year or even the day
A. Dissolved Solids Material: dissolved load Sources: runoffs industrial wastes most from groundwater & can be essential to organisms Ex: calcium (fish bones) phosphorus (plants) silicon (diatoms –shells)
Excess phosphorus stimulate algae growth and deplete oxygen levels (algal blooms); causes death of many organisms
B. Dissolved Gases 1. Oxygen – Dissolved Oxygen (DO) vital to aquatic life Sources that ↑ DO atmosphere or aeration from riffles (water over rocks) Photosynthesis (peaks during afternoon)
Temperature affects DO: ↑ temp means ↓ DO ↓ temp means ↑ DO (decomposition of organic matter wastes with ↑ temps) Other DO effects include pollutants such as acid mine drainage, sewage or agricultural runoff