I used to avoid the larger eddies, those areas of sluggish water behind rocks and shoreline aberrations. The slower moving water created by the upstream obstruction allows the finest silt particles to settle to the bottom and expanses of barren mud-covered flats extend downstream. I always thought of muddy eddies as lifeless, and I usually created chocolate milk water conditions by accidentally stirring the fine bottom before I could really see who was living in these areas.
I skimmed over one of these eddies on my way to what I thought was the more interesting habitat of a cobbly riffle when I came upon a line in the mud that led 5 feet or so to a Virginia river snail slowly but surely making its way upstream. In the moment I paused to admire the snail, other life became apparent. Tiny squiggles of new fish schooled in a small hazy cloud. Black smudges of other kinds of fry swam towards me to investigate. Comma mark toad poles squiggled along the bottom. The importance of this perceived lifeless barren became apparent: this is a nursery for the stream, and suddenly, this barren wasn’t so barren.
Sedimentation results in the loss of habitat and is one of the leading causes of stream degradation. The inputs of soil we send to our streams through ground disturbing activities like farming and construction, and scouring runoff that comes from hard surfaces like driveways and roads needs to be controlled. But small amounts of erosion and resulting sedimentation are natural processes, and the fine muds that form the bottom of these eddies are important in the continuum of stream habitats, from quiet muddy eddies, to violent bouldery rapids. Life has evolved and developed to nestle in a particular spot on the spectrum, and all habitats are essential. Even the muddy ones.
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