12 



Usinger: Introduction 



Intro, fig. 14. Stream organisms on a submerged rock — diagrammatic. 1) Rhyacophil idae (Trich- 

 optera), larva in a case of sand grains; 2) Ancylus (Gastropoda); 3) Blepharoceratidae (Diptera), 

 a, pupae, b, larva; 4) Elmidae (Coleoptera), a, larva, b, adult; 5) Goeridae (Trichoptera), larva; 

 6) Simuliidae (Diptera), a, pupa, b, larva; 7) Baetidae (Ephemeroptera), nymph; 8) Heptageniidae 

 (Ephemeroptera), nymph; 9) Perlodidae (Plecoptera), nymph; 10) Rhyacophil idae (Trichoptera), 

 o, pupal case, b, larva; 11) Heptageniidae (Ephemeroptera), nymph; 12) Planaria (Turbellaria); 

 13) Philopotamidae (Trichoptera), larva in its catching net (Ruttner, 1953). 



c. Placid water habitats — pools and holes 



d. Marginal areas — on or under rocks, in soil 



2. Interrupted habitats, with native biota 



e. Deposits — on rocks, bottoms, or shores 



f. Splash areas — on rocks 



3. Temporary habitats — transient and transitional, 



with varied biota 



g. Marginal pools 

 h. Recession areas 



These apply to mountain streams. Obviously other 

 habitats should be mentioned including slow moving 

 rivers of considerable depth with steep banks and 

 mud bottoms. Also, springs are of various types (see 

 below) and offer a variety of special habitats includ- 

 ing basins, seepage areas, and the like. 



Stream classification. — Differentclassifications have 

 been proposed for the streams of the European conti- 

 nent (Steinmann, 1907; Thienemann, 1912; Huet, 1948), 

 the British Isles (Carpenter, 1928), Yellowstone 

 National Park (Muttkowski, 1929), Ontario (Ricker, 

 1934), and other areas. These have been variously 

 based on source of water, size, speed of current, 

 slope, elevation, temperature, substrate, permanence, 

 oxygen and carbon dioxide, pH, hardness of water, 

 productivity, or combinations of several of the above 

 factors. Actually, most of these are interdependent, 

 and it may very well be that no classification can be 

 devised that will reveal in a meaningful way all the 



complicated interrelations. Therefore, each factor 

 will be discussed separately and will be related, as 

 far as possible, to California conditions. 



Source. — The sources of surface waters are glaciers, 

 snow, springs, and surface run-off from rain. The 

 latter results in very temporary storm courses and, in 

 arid regions with little vegetation, in flash floods. 

 Temporary storm courses have no real significance 

 for stream ecology except in rare instances when 

 aquatic organisms may be transported long distances 

 and survive in new regions. Snow is also a temporary 

 source of water but the Sierran snow pack is so great 

 — 20 feet or more in many places — that long-flow 

 intermittent streams are numerous and support a 

 special biota of short-lived organisms with adaptations 

 for surviving the periodic dry periods. Glaciers are, 

 of course, a permanent source of water but are so 

 small and so few in number in California that they 

 are a minor factor. 



Springs, on the other hand, are of major importance 

 throughout the state and are the only source of peren- 

 nial streams below snow line and throughout most 

 of the southern part of the state. Muttkowski (1929) 

 said of the springs of Yellowstone Park that "every 

 conceivable type occurs," and this is equally true 

 of California. Muttkowski says further that "One 

 could employ a dozen different criteria for their 

 classification and still not exhaust them. One might 



