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Stream Ecology Roland Sigurdson Aquatic Education Specialist Minnesota DNR - Division of Fish and Wildlife MinnAqua Aquatic Education and Angling Program What is a stream? Body of water moving under the influence of gravity, to lower levels, in a welldefined natural channel. What is a stream – Take 2 Body of water moving under the influence of gravity, to lower levels, in a welldefined natural channel. Why study streams/rivers? Why does a river flow when there is no rain? Why do rivers look the way they do? What's in the water? Where does the energy come from to run the system? What kinds of organisms do you find in rivers? How are these organisms organized and distributed? How do humans affect rivers and their biota? And finally, how does it all fit together? Time…is on their side Water in a stream is continually in motion. It is the erosional forces of this moving water that has sculpted the landscape of much of the earth. The Watershed A watershed is the surrounding land area that drains into a lake, stream, river system. It includes natural and artificial drainage systems It’s all about scale Minnesota has nine major watersheds. Minnesota is a net exporter of water, no water enters the state other than by precipitation. Stream Order First Order Stream – small, stony & shaded Second Order – when two First Order streams combine Third Order – when two Second Order streams combine Etc (10th is about the maximum world-wide Succession in Streams Width and Depth Substrate Gradient Temperature Pool-Riffle Spacing Meanders Temporal – changes taking place over long periods at a single site Spacial – changes from headwater to mouth from a ‘snapshot’ in time Reset by disturbance River Continuum Concept The structure (numbers and kinds of species) of biological communities changes downstream (ie the numbers and species of plants, insects and fish The function (what they do) of organisms change downstream according to available food resources Stream food web Heterotrophy Allochthony – Materials from outside a system, such as leaves and insects that fall from terrestrial plants into a stream. Autotrophy Primary Productivity/Photosynthesis Primary producers in most stream systems – periphyton and macrophytes Functional Feeding Groups Feeding Strategy Food Category I. II. Shredders Collectors filter feeders miners browsers III. Scrapers IV. Piercers V. Predators dead leaves/live macrophytes fine organic particles (live/dead) particles in water column buried particles bottom surface deposits live benthic algae (diatoms) live filamentous algae other invertebrates + small fish Tough Bugs Hey!! Who you calling ‘fish food’ now frog face!!! Invertebrate Biodiversity Flatworms Leeches Aquatic earthworms Snails Mussels/Clams Water Mites Crustaceans True Bugs True Flies Water Beetles Dragonflies/Damselflies Stoneflies Mayflies Dobsonflies, Fishflies, Hellgrammites, Alderflies Caddisfliees Meet a few of them Fish Cold Water - Brook Trout - Brown Trout - Rainbow Trout - Sculpins - White Sucker - Dace Warm Water - Smallmouth Bass - Walleye/Sauger - Largemouth Bass - White Bass - Catfish - Suckers - Minnows Number of fish species by major drainage system Red River Rainy River Superior Drainage Upper Mississippi River St Croix River Minnesota River Missouri River Lower Mississippi River 82 73 83 75 106 95 42 127 Human impacts Let’s talk…shall we? Good, Bad, Ugly, Normal