1. Biotic - living components; each fill their own niche 2. Abiotic – non living components; important in determining which organism can live where Physical Chemical
A. Stream Order smallest streams are the headwaters and called 1st order streams 1st order → 2nd order → 3rd order→ 4th order etc… (think small to big) 80% of PA streams are either 1st or 2nd order streams
1st order and 2nd order have ↑ macroinvertebres (insects) ↓ fish ↓ plants 3rd order and 4th order have ↑ fish ↑ plants ↑ biodiversity
B. Water Temperature Factors that affect water temp include: velocity – more velocity less temp differences depth – deeper is lower temps vegetation – more at water edge shades water and ↓ temps seasonal changes – ex: melting snow water source – esp 1st and 2nd streams in mountains are cooler temps
Water Temp effects: plants tend to like warmer temps algae, protists and trout have smaller temp range. carp and catfish have wider temp range
Stream temperatures do not vary as much as air temperatures. WHY? Specific Heat!!
C. 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
D. 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
E. 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.
F. 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
G. 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 many mean sulfur compounds