1. Autochthonous Energy Sources in Streams
Aulacoseira sp.

2. What is an Autotroph?

3. Autotrophs? Acquire energy from sunlight
Acquire materials from non-living sources

4. Taxonomy? Ochrophyta (mostly diatoms in streams) Chlorophyta (greens)
Plantae
"macrophytes" : aquatic vascular & non-vascular
Eubacteria:
Cyanobacteria
Protista
Ochrophyta (mostly diatoms in streams)
Chlorophyta (greens)
Rhodophyta (reds, but only a few species)

5. Primary Production?
Definition: the capture of energy by photosynthesis.
NPP –vs- PP ??
Who does it? Autotrophs

6. How Might You Measure NPP??

7. How Do You Measure NPP? Biomass accrual over time
preferred for macrophytes
Problems getting accurate values for microphytes
Turnover rates may be too fast
Measurement of open stream gas exchange
Entire stream as a unit
Difficult in low productivity/high turbulence streams
Assumptions about diel productivity flawed . . Who respires?
Light/Dark Bottle method modified for stream beds
uses 14C uptake
Difficult: requires radioactive materials, community often very diverse

8. Hill and Webster, 1982
Primary production of periphyton measured by 14C uptake using substrate placed in recirculating chambers, New River, VA

9. Riverine Ecosystems Energy Sources
Autochthonous – instream
Allochthonous – out of stream
/streamwatch/ swm10.html
manual/6doing.htm
veg/brfredmaple.html
Autochthonous organic matter – produced within the stream
- diatoms; algae; submerged, floating, and emergent macrophytes
Allochthonous organic matter – produced outside of the stream and imported into the channel.
- includes, but is not limited to leaves, woody debris, dissolved organic compounds, dead organisms

10. Autochthonous? Definition: generated from within
In this case, in-stream energy sources
Source of energy: sun
Who captures the energy? - Photoautotrophs - use the sun plus inorganic matter
Includes organisms in the following kingdoms: Eubacteria, Protista, Plantae

11. The sources of energy in streams: autochthonous, allochthonous, DOM

12. What are the Autotrophs in a Stream?
Where might they live?

13. Benthic autotrophs
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community.
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community. Habitat specialization allows for classification of benthic autotrophs into groups; 1) species that grow on stones (epilithon), 2) species that grow on soft sediments (epipelon), and 3) species that grow on other plants (epiphyton).
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems. It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.

14. Biofilm
Slippery film on rocks
Periphyton
Aufwuchs

15. Periphyton
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems.
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community. Habitat specialization allows for classification of benthic autotrophs into groups; 1) species that grow on stones (epilithon), 2) species that grow on soft sediments (epipelon), and 3) species that grow on other plants (epiphyton).
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems. It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.

16. Organic microlayer-microbial community on submerged objects in streams

17. Periphyton
It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community. Habitat specialization allows for classification of benthic autotrophs into groups; 1) species that grow on stones (epilithon), 2) species that grow on soft sediments (epipelon), and 3) species that grow on other plants (epiphyton).
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems. It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.

18. Habitat Specialization
Allows for classification of benthic autotrophs into groups;
Species that grow on stones (epilithon)
Species that grow on soft sediments (epipelon)
Species that grow on other plants (epiphyton)
Benthic autotrophs grow on virtually all surfaces receiving light in flowing waters and are collectively referred to as the periphyton community. Habitat specialization allows for classification of benthic autotrophs into groups; 1) species that grow on stones (epilithon), 2) species that grow on soft sediments (epipelon), and 3) species that grow on other plants (epiphyton).
Periphyton is a complex matrix of algae and heterotrophic microbes attached to submerged substrata in almost all aquatic ecosystems. It serves as an important food source for invertebrates and some fish, and it can be an important sorber of contaminants.

19. Epipelion: Periphyton on sandy substrates
1. Bedload sandgrains
2. Upper story mat
3. Mucilaginous layers
4. Understory layer
From: Pringle, 1990

20. Periphyton taxa = mostly diatoms

21. What causes microscale patchiness?
Periphyton variation within a reach is very high.

22. What factors potentially influence periphyton?
Light
Temperature
Current
Substrate
Scouring effects of floods
Water chemistry
Grazing

23. Light Levels Green algae associated with high levels
Diatoms & cyanobacteria in lower light
Motile algae can pick their spot

24. Light adapted
Shade adapted
Photosynthesis vs. Irradiance Curve: light adapted and shade adapted community responses

25. Shading and other factors
Not all studies show direct correlation with light
Lack of nutrients can prevent response
Grazing can keep increased light from increasing biomass

26. Seasonality in periphyton
Peaks prior
To leaf-out
PAR
Chl a
Seasonality in periphyton

27. Seasonal succession in periphyton communities
Diatoms dominate during the winter, spring, and early summer
Green algae and cyanobacteria populations increase during the summer
Benthic autotrophs tends to decrease during the summer as a result of increased shading, increasing again in fall
Diatoms make up the majority of the species within periphyton communities, while green algae and cyanobacteria are common, and under some conditions may dominate the community. Species composition of periphyton communities varies seasonally in fairly regular patterns in temperate streams. Typically, diatoms dominate during the winter, spring, and early summer. Species composition within the diatom assemblage varies through this period and total abundance is generally the greatest during the spring prior while light levels are high prior to the emergence of leaves in riparian vegetation. Green algae and cyanobacteria populations increase during the summer, but the overall biomass of benthic autotrophs tends to decrease during the summer as a result of increased shading. Benthic autotroph biomass briefly increases again in autumn as a result of decreased shading (Moore, 1972

28. Nutrients
P, N, most important
But “micronutrients” matter Si Fe
CO2

29. Continuous flow periphyton bioassay system
Nutrient addition
Glass slides
Continuous flow periphyton bioassay system

30. Changes in dominant diatom species in nutrient addition experiments.
# of diatoms X 1011 m-2

31. Nutrient Response P seems most important N alone has little affect
But, in specific cases N can be limiting

32. Changes in relative abundance of the major diatoms in response to nutrient manipulation. Note: decline in A. minutissima in PO4 only.

33. Nutrient Response 2 N/P ratio can matter
Individual species respond differently

34. Diatom abundance on nutrient-releasing substrates in a nutrient poor stream.

35. Substrate effects? Chemical composition of rocks (Parker, et al, 1973)
Monostroma quaternarium confined to iron-rich rocks
Hydrurus occurred mainly on lime and sandstone
Batrachospermum showed no specificity

36. Current Matters
Why?

37. Influence of Current How well attached
Current influences substrate type
Flow renews gases & nutrients
diffusion rates, boundary layers

38. Growth Forms Respond to Current
Cladophora glomerata
plumose in slow water,
long & rope-like in faster flows (Whitton, 1975)

39. Cladophora glomerata

40. Impact of Floods & Spates
What difference should this make?

41. Flow vs. periphyton accumulation
has inverse relationship
To flood events.
Flow vs. periphyton accumulation

42. Stone surface coverage by the moss Hygrohypnum, as a function of stone size in a mountain stream.

43. Macrophytes Taxa: Flowering Plants Bryophyta Lichens Charales
(complex green algae)

44. Macrophyte growth forms
Emergents: banks and shoals
Floating-leaved: stream margins
Free-floating: slow (tropical) rivers
Submerged: midstream (limited by light penetration, current speed, and substrate type)
Emergent
cce.cornell.edu/onondaga/watersheds/images/milfoil.jpg
Floating-leaved
Free-floating
Submerged
Emergents: banks and shoals (
Floating-leaved: stream margins (
Free-floating: slow (tropical) rivers (
Submerged: midstream (limited by light penetration, current speed, and substrate type)(

45. What adaptations might help in streams?

46. Adaptations - Flowing water, current
Firm attachment by adventitious roots
Tough, flexible stems and leaves
Rhizomes
Vegetative reprodution
Hydrophillous pollination
aquat1.ifas.ufl.edu/zizaqu2.jpg
Stems and leaves
Adventitious roots

47. High flow species Almost all Bryophytes
Two families of flowering plant
Require free CO2
Most macrophytes do better in backwaters

48. Patchy distribution of macrophytes
Macrophyte distribution and abundance changes seasonally (temporally)
Ultimately, even within areas favorable to a specific macrophyte, heterogenous and changing environmental conditions can make their distribution and abundance patchy and highly variable. The consequence of this shown by vegetation mapped over several years is that stream vegetation exists as a constantly shifting mosaic.

49. Coverage varies within a system
How much of the bottom of streams is covered with macrophytic vegetation?
Variable
Appalachian rivers = %
Bavarian streams = 37% of the area had less than 10% cover

50. What might limit growth and distribution?

51. Macrophytes: Limitation to growth
What limits?
Temperature
temperate: dormancy via below sediment rhizomes during winter
Tropical: little seasonality
Nutrients: in oligotrophic areas, PO4 most often limiting
Being rooted can reduce the affect
Free CO2 availability
Light: most often limiting factor, along with current

52. Macrophyte Energy Flow
Even in streams with high macrophyte NPP, a small fraction of the streams energy comes from macrophytes.
Why?
Even in streams that show high macrophyte productivity, a relatively small fraction of the streams total energy results from macrophyte production. The fate of this primary production includes herbivory, secretion of dissolved organic matter, and decomposition. Herbivory is carried out in large part by vertebrates, including waterfowl, manatee, grass carp, muskrat (Westlake, 1975b), and moose.

53. Most productivity enters a detrital cycleOR
Secretion of dissolved organic matter
Works Like Allocthanous input

54. Macrophyte productivity: Detrital
Macrophytes have high fiber content
Some have high tanin concentrations
Fiber + tannin = indigestible
animals must adapt to “harsh” diet
Some produce anti-herbivore compounds
Phenolics

55. So Who Eats the Stuff? Mainly vertebrates And some invertebrates
Waterfowl
Manatee
Grass carp
Muskrat
Moose.
And some invertebrates
Rusty Crayfish
Invasive
Even in streams that show high macrophyte productivity, a relatively small fraction of the streams total energy results from macrophyte production. The fate of this primary production includes herbivory, secretion of dissolved organic matter, and decomposition. Herbivory is carried out in large part by vertebrates, including waterfowl, manatee, grass carp, muskrat (Westlake, 1975b), and moose.

56. Phytoplankton Lotic phytoplankton include:
Algae
Protozoans
Cyanobacteria
These are small enough to remain suspended in the water column and be transported by currents.
But what is the big problem for plankton in lotic systems?
phytoflagellates
(euglenophyta)
Biodidac
Hoffman Image Gallery
Hoffman Image Gallery
Lotic phytoplankton include algae, protozoans, and cyanobacteria that are small enough to remain suspended in the water column and be transported by currents. These planktonic organisms are drawn from the same pool of species found in standing water. Factors that limit the growth and abundance of phytoplankton include light, temperature, nutrients, and discharge. Adjacent standing or stagnant waters are viewed as critical in the establishment of lotic phytoplankton populations. Yellow-brown algae (chrysophyta) and red algae (rhodophyta) occur, but are less common.
University of Wisconsin Botanical Images Collection

57. Lotic Specific Phytoplankton Limiter
Discharge regime

58. Discharge Inverse relationship to plankton
Population Doubles once or twice per day
Reproductive rate must exceed loss rate
Requires slower flow
Where might this be possible in a stream?

59. Sources for phytoplanktonic input?

60. Phytoplankton Sources?
Sloughing
Import from lentic systems
Flood may connect to standing water
Source of plankton

61. What Limits Phytoplankton Productivity?
Typical for any autotroph:
Light
Nutrients
Temperature

62. Light, Turbidity, Turbulence and Depth
In Hudson River Algae 18-22h below 1% light level
But, source could be shallower water
Source-Sink & Plankton

63. Depth of mixing in Lakes vs. streams
Thermocline
River
Lake

64. Nutrients Rarely Limiting
Abundance several times lower than expected based upon nutrients

65. Grazing Zooplankton not a major factor Reproduce too slowly
Mollusks matter!
Asiatic Clam 40-60% reduction in Potomac
Zebra Mussels Can filter entire volume of the Hudson in 1-4 days!
85% drop in phytoplankton biomass
Changes energy flow
Increases clarity

66. Algal primary productivity
Photosynthesis
Light - Temperature
Nutrient - Chronic toxicity
Velocity
Respiration/Excretion
Grazing
Mortality
Acute toxicity
High temperature
Sinking
- Velocity
Stress
Algal biomass
Washout
Available substrate
Loading
Turbulent diffusion
Westlake (1975a) identifies current and light to be among the most important factors limiting macrophytes. Shading of streams reduces surface irradiance by 35-95%, and may completely exclude angiosperms. Turbidity, shading, and species specific light requirements can combine to inhibit the establishment of macrophytes in deep sections of rivers.

67. Water on the Web
This presentation includes material from Water on the Web (WoW)
WOW Water on the Web - Monitoring Minnesota Lakes on the Internet and Training Water Science Technicians for the Future - A National On-line Curriculum using Advanced Technologies and Real-Time Data.
University of Minnesota-Duluth, Duluth, MN
Authors: Munson, BH, Axler, R, Hagley C, Host G, Merrick G, Richards C.
I would also like to thank Dr. Jewett-Smith for her contributions to this presentation