Monday, July 18, 2011

Feeding Frenzy

I could hear the faint clicking intensify as the school approached. Then the bottom of the river downstream of where I lay started to wriggle, and I realized that the school had arrived beneath me. The stonerollers were here. They moved across the bottom in a crazed grazing frenzy. Hundreds of them in the same school swam along the bottom scraping algae from rocks as they moved upstream. Their sides flashed silver with every twisting bite they gouged from the algae covering rocks and their jaws snapped, which explained the clicking sound. Stonerollers are some of my favorite fish partly because of the elaborate stone piling mating rituals the males use to attract females in the spring. But I also like them because they are really a non-descript fish for most of the year. However, careful observation reveals how well adapted they are for keeping algae in check in our rivers and streams, and the non-descript, even unnoticeable, become incredible. Their mouths slightly protrude downward, and hard bony plates on their upper jaw leave u shaped scrapes in rock coating algae. Dr. Mary Powers conducted an interesting exclusion experiment. Bass are stone roller predators, so she excluded stone rollers from sections of river by keeping bass there, and eliminated bass from other sections. The sections where the bass were kept became overgrown in algae. This demonstrates the importance of the stonerollers to the system, but it also illustrates the often unnoticed, and very hidden interrelationships between everything in nature. Everything matters and as John Muir said, “When we try to pick out anything by itself, we find it hitched to everything else in the universe.” Algae, bass, and marauding stonerollers.
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