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 well- defined natural channel. What is a stream – Take 2 Body of water moving under the influence of gravity, to lower levels, in a well- defined 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 Temporal – changes Substrate taking place over Gradient long periods at a single site Temperature Spacial – changes Pool-Riffle Spacing from headwater to Meanders mouth from a ‘snapshot’ in time Reset by disturbance River Continuum Concept The structure The function (what (numbers and kinds they do) of of species) of organisms change biological downstream communities changes according to downstream (ie the available food numbers and resources species of plants, insects and fish 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. Shredders dead leaves/live macrophytes II. Collectors fine organic particles (live/dead) filter feeders particles in water column miners buried particles browsers bottom surface deposits III. Scrapers live benthic algae (diatoms) IV. Piercers live filamentous algae V. Predators other invertebrates + small fish Tough Bugs Hey!! Who you calling ‘fish food’ now frog face!!! Invertebrate Biodiversity Flatworms Water Beetles Leeches Dragonflies/Damselflies Aquatic Stoneflies earthworms Mayflies Snails Mussels/Clams Dobsonflies, Fishflies, Hellgrammites, Alderflies Water Mites Crustaceans Caddisfliees True Bugs True Flies Meet a few of them Fish Cold Water Warm Water - Brook Trout - Smallmouth Bass - Brown Trout - Walleye/Sauger - Rainbow Trout - Largemouth Bass - Sculpins - White Bass - White Sucker - Catfish - Dace - Suckers - Minnows Number of fish species by major drainage system Red River 82 Rainy River 73 Superior Drainage 83 Upper Mississippi River 75 St Croix River 106 Minnesota River 95 Missouri River 42 Lower Mississippi River 127 Human impacts Let’s talk…shall we? Good, Bad, Ugly, Normal.