Streams offer a variety of habitats. Riffles are shallow areas where water flows fast. Many riffles have gravel bottoms of fist-size rocks that create a turbulence that mixes air into the water. Food is carried and distributed by the rushing water. If the water quality is good, riffles are home to mayfly larvae, crayfish and small fish such as darters. The riffle’s shallow, rocky bottom can also protect animals from larger predators.
Stream pools are deeper and darker than riffles, and have relatively quiet water. Good pool habitats provide cover–sometimes ledge rocks or a tree rootwad that offers a good hiding place. Bass and catfish prefer pool habitats.
A mid-water stream channel is also a distinct habitat. Gar have few enemies, and they lounge around here in the open sunlight with few worries except where their next meal will come from.
A stream provides homes for large or small inhabitants in nearly every part of its channel. Stable channels, good water quality and tree-lined banks contribute to good stream habitats.
Watershed Wordplay
Aquifers, loess, and necktonic… what do they mean? Here’s a shortlist of some watershed words to know.
- Necktonic: Organisms that live in the open water areas (mid and upper) of water bodies and streams.
- Aquifer: An underground layer of porous, water-bearing rock, gravel, or sand.
- Fragipans: A natural subsurface soil horizon seemingly cemented when dry, but when moist showing moderate to weak brittleness, usually low in organic matter, and very slow to permeate water
- Loess: Loamy soils deposited by wind, often quite erodible.
- Riparian corridor: The parcel of land that includes the channel and an adjoining strip of the floodplain, generally considered to be 100 feet on each side of the channel.
- Alluvial soil: Soil deposits resulting directly or indirectly from the sediment transport of streams, deposited in river beds, flood plains, and lakes.
Find more watershed terms with this guide from the MDC.
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