River Continuum ConceptRiver Continuum ConceptA Holistic ViewA Holistic View
Streams are gradients or continuaStreams are gradients or continua Downstream processes are linked to Downstream processes are linked to
upstream eventsupstream events Gradients and processes produce a Gradients and processes produce a
continuous and predictable change in the continuous and predictable change in the assemblages of organisms along the stream assemblages of organisms along the stream systemsystem
Functional Feeding GroupsFunctional Feeding Groups
Stream benthic macroinvertebratesStream benthic macroinvertebrates
FishesFishes
ProtozoaProtozoa
Functional Feeding GroupsFunctional Feeding Groups(Stream benthic macroinvertebrates)(Stream benthic macroinvertebrates)
Group Mechanisms FoodShredders Chewers of wood and CPOM Living/decomposing
plant tissue
Collectors Filtering/gathering FPOM (sewage)
and surface films
Scrapers Rasping, scrapingperiphyton
Predators Engulfing, piercing Whole animal, animal
tissue
Piercers Sucking Living hydrophytes
Parasites InvasionLiving animal and plant
tissue
Headwater stream, GSMNP
Upper ReachesUpper Reaches (headwater to 3rd order)(headwater to 3rd order)
- strong influence of riparian strong influence of riparian vegetationvegetation
- reduction of autotrophic - reduction of autotrophic production by shading (P/R <1)production by shading (P/R <1)
- most energy input via most energy input via allochthonous detritus (CPOM)allochthonous detritus (CPOM)
- microorganisms growing on microorganisms growing on surface of CPOM provide actual E. surface of CPOM provide actual E. to shredders (peanut butter on to shredders (peanut butter on crackers, Oreo cookie)crackers, Oreo cookie)
R. Grippo
Middle ReachesMiddle Reaches (order 4 to 6)(order 4 to 6)
- CPOM- CPOM FPOM via organic FPOM via organic transport from upstreamtransport from upstream
-Decrease in shading Decrease in shading increase in primary increase in primary production (P/R >1) production (P/R >1)
-Less dependent on external energy sources
Middle reach, Spring River, Centre Co., PA
Lower Reaches Lower Reaches (order > 6)(order > 6)
- still FPOM - still FPOM
- water more cloudy, deep - water more cloudy, deep decrease in decrease in primary productivity (P/R < 1 again) primary productivity (P/R < 1 again)
- increased importance of planktonic organisms
Note: streams are variable, much of Vannote is wrong for western streams
Headwater stream in Medicine Bow National Forest, Wyoming
R. Grippo
Impacts on StreamsImpacts on Streams
1.1. Physical – channel alteration, Physical – channel alteration, impoundment, sedimentationimpoundment, sedimentation
2.2. Chemical Chemical a.a. Point sources – toxic waste, sewagePoint sources – toxic waste, sewage
b.b. Nonpoint sources – urban, agricultural runoffNonpoint sources – urban, agricultural runoff
Major Water PollutantsMajor Water Pollutants
1. Oxygen-demanding wastes 1. Oxygen-demanding wastes (domestic sewage, animal (domestic sewage, animal manure, some industrial waste)manure, some industrial waste)
2.2. Disease-causing agentsDisease-causing agents (bacteria, parasites, and viruses) (bacteria, parasites, and viruses)
3. Inorganic wastes and minerals3. Inorganic wastes and minerals (acids, salts and toxic (acids, salts and toxic metals) metals)
4. Organic chemicals4. Organic chemicals (pesticides, plastics, detergents, (pesticides, plastics, detergents, industrial waste, oilindustrial waste, oil
5. Plant nutrients5. Plant nutrients (nitrates, and phosphates from fertilizers) (nitrates, and phosphates from fertilizers)
6. Sediments6. Sediments (soils, silt, and other solids from land erosion) (soils, silt, and other solids from land erosion)
7. Heat7. Heat (industrial and power plant cooling) (industrial and power plant cooling)
Anthropogenic EnrichmentAnthropogenic Enrichment
1.1. SewageSewage – alters normal E. source from – alters normal E. source from leaves/algae to disposable sewage (FPOM)leaves/algae to disposable sewage (FPOM)
Note: Fish hatcheries have a similar effectNote: Fish hatcheries have a similar effect2. Logging2. Logging – takes off riparian cover – takes off riparian cover
a. Decreases leaves entering systema. Decreases leaves entering systemb. increases runoff/siltationb. increases runoff/siltation
3. Farming3. Farming – causes nonpoint source input – causes nonpoint source inputa. input of crop nutrients a. input of crop nutrients excess algae excess algae
b. siltation – change in embeddedness b. siltation – change in embeddedness shift to shift to organisms that live on siltorganisms that live on silt
4. Other toxicants4. Other toxicants – reduce diversity by removing – reduce diversity by removing organisms according to sensitivityorganisms according to sensitivity