THE RIVER CONTINUUM

CONCEPTVANNOTE ET AL. (1980)

A synthetic framework to

describe the biological

function of streams from the

headwaters to the mouth.

THE RIVER CONTINUUM

CONCEPTVANNOTE ET AL. (1980)

Physical changes along the

stream continuum…

Alter the nature of organic

matter inputs…

Which causes changes in

the trophic structure of

stream communities…

And consequently, river

ecosystems are

longitudinally linked; i.e.,

changes upstream have

measurable effects

downstream.

PHYSICAL

• Narrow & Shallow

• Riparian Vegetation•CPOM inputs

•Shading

•LWD

• Low Discharge

• Highly Retentive

• Close link to groundwater & DOC

Organic Matter Dynamics

• Low Primary Productivity

• High rates of microbial activity

• Strongly Heterotrophic•P/R << 1 (0.01 – 0.3)

•NDM << 0

• High CPOM : FPOM ratio

Biological Community

• Bacteria and Fungi

• High Shredder Composition

• Few Grazers

• Salamanders are dominant predators

Dominant Function in Watershed

• Retention of CPOM and conversion of CPOM to

FPOM and biomass.

• Export of FPOM and biomass downstream.

HEADWATER STREAMS

(1ST-3RD ORDER)

Heterotrophic Headwater Stream

Unnamed Trib of Crooked Run

of Elk River

Pocahontas County, WV

PHYSICAL

• Wider but still Shallow

• Reduced link to riparian vegetation

• Increased light (radiant energy and heat)

• Higher Discharge

• Low Retention

• Reduced link to groundwater & DOC

Organic Matter Dynamics

• Increased rates of Primary Productivity

• Autotrophic Pathway of Increased Importance•P/R > 1 (0.7-3)

•NDM > 0

• Low CPOM : FPOM ratio (FPOM import from US)

• Diverse Energy Sources (CPOM, FPOM, Light)

Biological Community

• Increased Diversity

• Reduced shredders

• Increased grazers and collector gatherers

• Fishes increasingly diverse (mostly invertivores)

Dominant Function in Watershed

• Primary production and conversion of periphyton

and FPOM to biomass.

• Export of FPOM and biomass downstream.

MID-ORDER STREAMS

(3RD – 6TH ORDER)

Autotrophic Mid-Order Stream

Upper Shavers Fork

Randolph County, WV

PHYSICAL

• Wide and Deep

• Almost no link to riparian vegetation

• High Light but High Turbidity

• High Discharge but Low Gradient

• High Retention

Organic Matter Dynamics

• Low Primary Productivity (turbidity)

• Heterotrophic Pathway Dominates•P/R < 1 (0.3-1)

•NDM < 0

• Low CPOM : FPOM ratio (FPOM import from US)

Biological Community

• Increased filterers and collector gatherers

• Increased pelagic community

• Fishes (warmwater, piscivores and omnivores)

Dominant Function in Watershed

• Convert organic matter that has been processed

upstream into biomass.

LARGE RIVERS

(6TH – 12TH ORDER)

Ohio River near Parkersburg, WV

Heterotrophic Large River

Upper Odey Run, Pocahontas County, WV

Autotrophic Headwater Stream