Autochthonous Energy Sources in Streams
1. Autochthonous?
- Definition: generated from within --> in this case, instream
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
2. Riverine Ecosystems Energy Sources
- All energy from primary production (photosynthesis)
- Some autochthonous
- Some Allochthonous: from without or from terrestrial primary
production:
- Leaf and other plant detritus
- Microbes start the process detrital foodweb
---------->heterotrophs
3. Review of trophic roles
- Herbivory: plant feeders
- Carnivory: feed on other animals
- Detritivory: feed on detritus
- Omnivory: feed on more than one level
4. Figure 3.1. The sources of energy in streams:
autochthonous, allochthonous, DOM. Energy pathways: dashed =
autotrophic, solid = heterotrophic, dash-dot: chemotrophic.
Coagulation & precipitation convert DOM to POM. Decay
converts plant material to POM after death.
5.Autotrophs?
- Acquire energy from sunlight
- Acquire materials from non-living sources
- Taxonomy?
- Plantae - "macrophytes" : aquatic
vascular (&
non-vascular (mosses)
- Eubacteria: Cyanobacteria
- Protista
- Ochrophyta (mostly diatoms in streams)
- Chlorophyta (greens)
- Rhodophyta (reds, but only a few species)
6. Classification of algae: Margulis & Schwartz, 1998; Graham
& Wilcox, 2000.
Note: Classifications Change!!!!!
A. Kingdom Eubacteria (old Monera):
1. prokaryotic cell
structure with no membrane bound organelles, DNA in centralized
“nucleoids”
2. Photoautotrophs
a. Phylum: Cyanobacteria - use
light to split H2O for electrons and fix CO2 to biomolecules
b. Phylum: Chlorobia (anoxygenic green sulfur bacteria)
c. Phylum: Proteobacteria (purple bacteria)
1. Chromatium , the purple
sulfur phototroph, use light to split H2S for electrons.
2. Rhodospirillum use H2 for electrons
B. Kingdom Protista (Protoctista)
1. Description
a. nucleated microorganisms and
their descendants, exclusive of fungi, animals and plants
b. evolved by integration of
former microbial symbionts
1. mitochondria
2. plastids (chloroplasts, leucoplasts, chromoplasts).
1. members
a. diatoms
b. chrysophyceans
c. silicoflagellates
2. characteristics
a. size: micro to giant kelps
b. pigments: chla, chlc, fucoxanthin
c. food reserves: lipid, chrysolaminaran or laminaran
d. flagella: 2, heteromorphic
e. cell covering varied: silica, cellulose
8. Figure 3.3. Some common stream diatoms.
9. Focus on Rhodophyta (red algae)
1. member example:
Batrachospermum sp.
2. characteristics
a. size: micro to large
branched
b. pigments: chla, phycobilins, carotenoids
c. food reserves: granular floridean starch
d. no flagellated forms
e. cell covering: walls of cellulose + sulfated
polygalactans, some calcified
11. Chlorophyta (green algae)
Note: some have moved this to Plantae
1. member examples:
Mougeotia, Stigeoclonium
2. characteristics
a. size: micro to large
branched
b. pigments: chla, chlb,
b-carotene
c. food reserves: starch
d. cell covering: cellulose, some calcified
1. Description
a. haploid organisms
(gametophytes) of complementary sexes grow from spores produced
by meiosis (sporogenic meiosis) that takes place in the adult diploid
(sporophyte).
b. fertilization by sperm or pollen nucleus leads to diploid
embryo retained by the female haploid during early development.
- Benthic: grows on bottom, not floating
- thallus visible to the naked eye
- not all algae
- Microphytes
- only visible if in abundance
- Individuals not distinguishable to the naked eye
- What they grow upon
- Epilithic - stones
- Epipelic - soft sediments (mud, silt, sand)
- Epiphytic - plants
- How they attach to substrate: adpressed vs. erect
14. Graphic: Major growth forms of periphyton (variation in
shape, vertical layering). Vulnerability to grazers by………… line
15. Periphyton taxa = mostly diatoms
From Allan, 1995
|
|
All
habitats
|
|
|
|
|
Potomac
R
|
Savannah
R
|
White
Clay Cr
|
Epipelon
|
Epiphyton
|
Diatoms
|
81
|
80
|
59
|
321
|
176
|
Chlorophyta
|
12
|
12
|
7
|
32
|
27
|
Cyanobacteria
|
9
|
9
|
6
|
14
|
19
|
Euglenophyta
|
17
|
15
|
7
|
20
|
--
|
Chrysophyta
|
0
|
1
|
1
|
1
|
2
|
Rhodophyta
|
1
|
3
|
0
|
0
|
1
|
Total
|
120
|
120
|
80
|
388
|
225
|
16. Do similar portions of streams have similar groups of diatom
species?
Margalef, 1960 = 3 major associations
in European rivers
images from: rbg-web2.rbge.org.uk
- Upper, fast flowing => Hydrurus/Ceratoneis
- Middle reach => Diatoma/Meridion
- Downstream => Melosira
17. What causes microscale patchiness?
- Variation within a particular reach of a stream, even within
similar flows(riffle vs. riffle, pool vs. pool) is very high.
- Pringle (1990) - used artifical substrates with nutrient agar
-> patchiness patterns:
- Differences in type of substrate
- Availability of nutrients in water
- High variability within a particular type
18. Epipelion: Periphyton on sandy substrates - variation
by microhabitat
- 1. Bedload sandgrains
- 2. Upper story mat
- 3. Mucilaginous layers
- 4. Understory layer
19. What factors potentially influence periphyton?
- Light
- Temperature
- Current
- Substrate
- Scouring effects of floods
- Water chemistry
- Grazing
20. Graphic: Photosynthesis vs. Irradiance Curve:
light adapted and shade adapted community responses
21. Graphic: Seasonality in periphyton
22. Graphics: Changes in dominant diatom species in nutrient
addition experiments.
- Protocol: troughs built beside stream, add nutrients to
streamwater passing through troughs, measure periphyton accumulation
over time.
22. Graphic: Changes in relative abundance of the major
diatoms in response to nutrient manipulation.
- Note: decline in A. minutissima in PO4 only.
23. Graphic: diagram of continuous flow periphyton bioassay system
24. Abundance of diatoms colonizing nutrient-releasing substrates
in a nutrient poor stream.
25. Light, Nutrients . . . What else?
- Influence of Current
- How well attached
- Current influences substrate type
- Flow renews gases & nutrients => diffusion rates,
boundary layers
- Growth forms within a species responds to current:
Cladophora glomerata is plumose in slow water, long & rope-like in
faster flows (Whitton, 1975)
26. Flow Index: Shortreed & Stockner, 1983
flow index equation :sum (Fi/i) from i = 1 to d
Fi
= maximum daily flow i days prior to the sampling date
d = number of days in the
sampling interval
27. Graphic: Flow vs. periphyton accumulation
28. 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
- Presence of crevices = allows some taxa to persist in high flow
(Keithan & Lowe, 1985)
29. Graphic: Amount of stone surface covered by the moss
Hygrohypnum, as a function of stone size in a mountain stream.
30. Primary Production?
- Definition: the formation of new energy by photosynthesis.
- Who does it? Autotrophs
- How to do it?
- 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
31. Graphic: production of periphyton measured by 14C uptake
using substrate placed in recirculating chambers, New River, VA
32. Macrophytes
- Taxa: Anthophyta, Bryophyta, lichens, Charales (complex
green algae)
- Adaptations - Flowing water, current
- Tough, flexible stems and leaves
- Firm attachment by adventitious roots
- Rhizomes
- Vegetative reprodution
- Hydrophillous pollination
33. Macrophytes: Limitation to growth
- How much of the bottom of streams is covered with macrophytic
vegetation?
- Appalachian rivers = 27 - 42%
- Bavarian streams = 37% of the area had less than 10% cover
- What limits?
- Temperature
- temperate: dormancy via below sediment rhizomes during
winter
- Tropical: little seasonality
- Nutrients: limiting in oligotrophic areas, PO4 most often
limiting
- Hardness (calcium, alkalinity, pH) influences via free CO2
availability
- Light: most often limiting factor, along with current
34. Macrophyte productivity: Detrital
Macrophytes have high fiber content
Some have high tanin concentrations + other antiherbivore compounds
(phenolics)
Fiber + tanin = undigestable: animals have to have adaptations
for “harsh” diet
Most of the productivity is cycled through a detrital cycle
Herbivores
Some fish
Manatees
Some birds: ducks, geese
- Small autotrophs: algae, cyanobacteria
- Source: sloughing, import from lentic, or true plankton if
slow moving enough
- Dominated by centric diatoms
- Sometimes dense cyanobacterial blooms
- Limiters?
- Typical for any autotroph: light, nutrients, temperature
- Specific: discharge regime (flooding, current)
36. Graphic: Depth of mixing in Lakes vs. streams