Transcript Stream Communities and The Continuum Theory

Stream Communities and
River Continuum Concept
Stream Energy Inputs and Foodwebs
Biofilms and Periphyton
Organic Matter Transformations
Macroinvertebrate Functional Feeding Groups
Seasonality of Stream Communities
River Continuum Concept
Stream Energy Inputs
Dissolved organic matter (DOM) is
being taken up by bacteria and fungi as
part of the formation of fine particulate
organic matter (FPOM), which is eaten
directly by some filter feeding
(collector) consumers.
Nutrients Spiral
• Net unidirectional flow moves nutrient inputs downstream.
• The chemical form will change between those in particles and those dissolved in
the flowing water.
• We largely view the benthic habitat as where most dissolved forms are taken up
into particulate forms; however, this does happen in the water too, particularly for
larger order streams (>7; aka rivers).
• Spiral length (S) is the sum of particle (Sp) plus dissolved (Sw) transport lengths.
Biofilms:
Substrate may be rock, woody
debris, macrophytes, CPOM, or
even certain animals.
Periphyton Community Controls
Periphyton Morphology
Velocity will influence the species and morphology; think boundary layers.
Organic Matter Transformations
Immediate leaching to DOM, which is used by bacteria or aggregates to FPOM.
Fungal colonization is critical as they possess cellulase enzymes.
Abrasion and shredder macroinverts release FPOM
Cold-Water Stream Foodweb with
Functional Feeding Groups
Soil DOM
and
FPOM!
Functional
Feeding Groups
Shredders: Tear and eat
CPOM for nutrition of
microbial colonizers.
Scrapers: “Grazers” of
biofilms and benthic algae.
Piercers: Suck juices from
macrophytes.
Collectors: FPOM specialists.
Predators: Eat other inverts.
All produce FPOM in the
form of feces!
Seasonal community
succession in small
cold-water streams…
• Why the drop-off in light
at the stream surface?
• Can you detect a spring
scour event?
• What happens to the
leaves in the stream from
spring to summer – by
whom?
• Notice there is about a
constant insect larvae
biomass throughout the
year. How can this
happen?
River
Continuum
Concept
Study and
understand
the contents
of Table 22.2!