Riverine Ecosystems Energy sources: allochthonous + autochthonous Interrelated Utilized by different functional groups of organisms How do the relationships change from headwaters to mouth?

X-section of a typical stream Photosynthesis Geology Temperature Nutrients Current Photosynthesis Detritus CPOM Plants Algae FPOM 1o Production Grazers Collectors Shredders Predators 2o Production

River continuum Concept (RCC) Vannote, R.L., G.W. Minshall, K.W. Cummings, J.R. Sedell, and C.E. Cushing. 1980. The River Continuum Concept. Can. J. Fish. Aquat. Sci. 37:130-137 General outline of how a river changes along its length Physical dimensions Changing energy inputs Changes in community of organisms

River Continuum Concept

Shaded headwater stream, Ohio www.epa.state.oh.us/dsw/wqs/headwaters/A-P6280010.jpg Shaded headwater stream, Ohio

Outlet to Crescent Lake, Pocono Watershed, Monroe Co., PA

What are some features of headwater streams?

Hypothetical headwater stream conditions Typical of Eastern deciduous forest Flows through heavily shaded forest riparian canopy Narrow Stream bottom rocky or sandy: depends upon geological characteristics of drainage

Where does the energy come from?

Hypothetical headwater stream conditions Low light + low nutrients: Low algal and macrophyte growth Mosses 1o primary producers CPOM from terrestrial environment enters strea Leaves (1o autumn), twigs & branches Respiration exceeds primary production: Heterotrophic stream reach Energy from terrestrial sources

Which Guilds Should We See?

Which Guilds do we see? Diversity of functional groups Shredders: 35 % Collectors: 45% Grazers: few to 5% Predators: 15% Diversity pattern? large CPOM supports shredders FPOM generated by shredders and mechanical breakdown supports collectors No plants = no grazers

Headwaters fishes Minnows Trout Sculpins Brown trout Minnows Trout Sculpins Other fishes tolerant of seasonal and daily cold temperature regimes Sculpin

Mid-reach streams: Salmon and Lemhi in Idaho www.lewisandclarkpictures.com/

How should conditions change in the mid reaches?

Mid-reach Conditions: Structure Stream wider, bottom well lit, temperatures and [nutrients] increased Stream bottom: rubble, rocks, pebbles with sand and silt in low current areas

Where does the energy come from?

Mid-reach Conditions: Energy Bottom algae proliferate (filamentous greens or diatoms) Where protected -> sediment accumulates and rooted aquatics grow Primary production > respiration = autotrophic reach

What FFGs do you expect to find?

Mid-reach functional groups Collectors = 50%: export of FPOM from headwaters + that generated in mid-reach Shredders = 5%: low input of CPOM Grazers 30%: more algae on stream bottom Predators = 15% Export of FPOM to lower reach

Mid-reach fishes Typically tolerate wider fluctuations in daily and seasonal temperature Overlap with some headwater species Examples Trout Suckers Minnows Blue suckerfish

Lower reach river: Confluence of Snake & Columbia River at Oregon/Washington Border

What physical features do you expect in lower reaches?

Lower Reach Conditions: Physical Slow-flowing, deeper, lake-like Increased turbidity & fine-grained, shifting bottom

Where does the energy come from in the lower reaches?

Lower Reach Conditions: Energy No sunlight on bottom = no algal growth Autochthonous production from phytoplankton + macrophytes along the margins Terrestrial input of CPOM small Water column has high FPOM from mid-reach Respiration > primary production -> heterotrophic reach

Which FFGs do you expect in lower reaches?

Lower Reach Functional Groups Collectors (filterers + gatherers) = 85% Sediment dwellers: mollusks or dipteran larvae Shredders and grazers absent: lack of CPOM and periphyton Predators = 15%

Lower Reach Fishes Adapted to environments where temperatures fluctuate widely Suckers Carp Chubs Exotic

Problems with RCC Different geomorphologies Shorter streams in New Zealand: CPOM flushed by floods, few shredders in many streams Western US streams in dry areas often less shaded, even in headwaters Anthropogenic changes to streams interrupt continuum: Logging or removal of riparian vegetation Damming: change in temperature depending whether water release is surface (warm) or bottom (cold)

Reset mechanisms Changes in a river below a confluence Makes receiving stream more like a stream higher in the continuum FFGs closer to that of tributary Will revert below the inlet of the tributary Removal of riparian buffer in headwater Change to pattern of mid-reach

Hyporheic community Organisms occurring in the interstitial spaces between rocks and stones on bottom Examples: insect larvae Stoneflies (Plecoptera) Midges (Chironomidae)

Water on the Web This presentation includes material from Water on the Web (WoW) WOW. 2004. Water on the Web - Monitoring Minnesota Lakes on the Internet and Training Water Science Technicians for the Future - A National On-line Curriculum using Advanced Technologies and Real-Time Data. http://WaterOntheWeb.org). University of Minnesota-Duluth, Duluth, MN 55812. Authors: Munson, BH, Axler, R, Hagley C, Host G, Merrick G, Richards C. I would also like to thank Dr. Jewett-Smith for her contributions to this presentation