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 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!