AUTOTROPHS

1. AUTOTROPHS • Periphyton (Aufwuchs) • Phytoplankton • Macrophytes • Vascular plants (aquatic angiosperms) • Non-vascular plants • Large periphyton • Green algae • Chara

2. Periphyton Virtually all surfaces receiving light in rivers & streams can sustain a periphyton community • Epilithon (rocks) • Epidendron (wood) • Epipelon (fine sediments) • Epipsammon (sand) • Epiphyton (other plants) • Epizoon (aquatic animals)

3. Dominant Periphyton Taxa

4. After 1 month in the dark Cleaned stone at start After 2 months in the light After 3 months in the dark

5. Cladophora (Chlorophyta) Cladophora crispita Courtesy: Protist Information Server

6. Cladophora filaments may reach one meter in length and thick mats may form on benthic surfaces http://www.owwrc.com/AA.htm

7. Seasonal Progression of Periphyton Species

8. Diatoms (Bacillariophyta) • Silica shell (frustule) composed of two lid-like valves • Golden brown color that colors stream rocks • Very old (400 million years) • >7,500 N.A. species • Primarily vegetative reproduction until cells reach a minimum critical size • Species are specific to the habitats in which they grow

9. Diatom Structure Pennate (bilateral symmetry) Striae arranged linearly Valve view Girdle View Centric (radial symmetry) Striae arranged radially

10. Factors Affecting Distribution of Periphyton • Temperature • Hard to separate from effects of light, which is also low in winter • Occurrence: cold water hot springs • Diatoms are more abundant in cold water • Light • Can be a limiting factor in small streams with dense canopy cover

11. headwater tributaries, Deschutes River, WA From: Bilby and Bisson (1991)

12. Primary production as a function of light intensity (after McIntire and Phinney, 1965) Shade-adapted community (- - -) developed at 2500 lux; the light- adapted community ( ) at 6000 lux.

13. Rate of O2 production by algal communities In lab streams at different temp. & light

14. Factors (continued) Current - Affects: Particle distribution – attachment sites Nutrient availability – ‘physiological richness’ Force on organisms - Can select for certain species - Can select for attachment strategies within the same species (e.g., erect vs. prostrate position)

15. Mean monthly chlorophyll declines with discharge in a New Zealand stream Chl a R2 = 0.711 P < 0.001 Flood frequency • [Chl a] lowest at sites with frequent floods (>15 per year) • Chlorophyll variation = F(frequency of floods, % catchment • in intense agriculture, % alkaline rocks in catchment From: Biggs (1995)

16. Force exerted by the Current d Flow Index = ∑ Fi i = 1 i where: Fi= max. daily Q i days prior to sampling d = # days in sampling interval example: 100cfs/1 day ago vs. 100cfs/20 days ago

17. Flow Index and periphyton accumulation rate Carnation Creek, Vancouver Island

18. Effect of Current on Algal Growth in Lab ++ = good growth; + = growth; o = no growth or death

19. Current effects may also lead to vertical zonation

20. Factors (continued) Grazing Gastropods, insect larvae (water pennies & riffle beetles), crustaceans & herbivorous fish Can be locally important Elimination of grazers can result in rapid increase in periphyton biomass

21. Invertebrate grazers affect periphyton biomass Mean algal biomass in the grazing experiment. 0 = initial stone samples; -1N = non-insecticide-treated stones; +1N = insecticide-treated stones. In lowland Danish streams From: Kjeldsen (1996)

22. Factors (continued) Nutrient Availability R2 = 0.561 P<0.05 R2 = 0.948 P<0.001 Cellular N Cellular N % catchment in hard rock % catchment in agriculture In 16 New Zealand stream sites From: Biggs (1995)

23. Autotrophy/Heterotrophy • Headwaters: • turbulent • shaded • cool • Orders 4-6: • wider stream • less turbulence • periphyton become more important Heterotrophic Respiration P/R = 1 Autotrophic Photosynthesis

24. Autotrophic Index (AI) Means for determining the trophic state of the periphyton community AI = Biomass (AFDM) (mg/m2) chlorophyll a (mg/m2) Normal values: 50-200; >200 heterotrophic conditions or poor water quality

25. Study of Periphyton Units = # individuals/area or biomass/area Glass slides placed in stream Some species don’t grow well Ceramic tiles Sampling directly from stones Artificial substrates

26. Bryophytes Have no lignin usually Are small, low-lying, (generally) moisture-loving plants Have no roots, only filamentous rhizoids Occurrence can be particularly dense in spring regions rich in CO2 Favor turbulent flow

27. Macrophytes Characteristics of lotic macrophytes compared to lentic macrophytes Smaller leaves Shorter petioles Shorter internodes Rarely produce floating leaves Often produce no (or few) flowers w/o seed production, reproduction is largely vegetative

28. Chara and Nitella Macro-algae Very dense mats on slow moving water Chara has garlic odor when crushed

29. Lotic macrophyte functions(angiosperms + Chara/Nitella) Provide habitat Supply labile organic matter Trap organic matter washed from upstream Remove NO3 from the water (0.56 – 1.14 g N/m2-day)

30. South Saskatchewan River (Carr & Chambers, 1998) • biomass > downstream of • WWTF (no P removal) • enrichment • experiments suggest • P-limitation • used Potamogeton • pectinatus in troughs • installed on stream • bottom

31. Habitat partitioning occurs in stream macrophytes (French & Chambers, 1996)

32. Rooted plants create their own instability

33. Phytoplankton Not very important in low order streams Are washed out of the reach quickly Inverse relationship between Q and phytoplankton Lower river reaches have more phytoplankton; however, even in large rivers phytoplankton productivity is several times lower than that in a lake.

34. Autotrophic Production Rates