PATTERNS OF PERIPHYTON CHLOROPHYLL α IN AN AGRICULTURAL NONPOINT SOURCE IMPACTED STREAM¹

Abstract

An agricultural nonpoint source polluted stream in northern Idaho was examined to determine seasonal and longitudinal patterns of periphyton chlorophyll α. Chlorophyll a was measured at eight sites along Lapwai Creek, a fifth order stream impacted by agricultural runoff containing nutrients and eroded soils. Seasonally, periphyton chlorophyll α was lowest in the spring (cumulative x̄= 60.4 mg m−2) and highest in the summer (cumulative x̄= 222 mg m−2). Winter concentrations were higher than expected (cumulative x̄= 168.6 mg m−2). The headwaters, flowing through an open grassy meadow, had the lowest concentrations of the study (two‐year x̄= 49.7 mg m−2). Immediately below a small, eutrophic reservoir, periphyton chlorophyll α increased markedly (two‐year x̄= 155.8 mg m−2) and remained high through a deep canyon (two year x̄= 135.5 mg m−2) and down to the mouth of the stream (two‐year x̄= 172.3 mg−2). Periphyton chlorophyll α in Lapwai Creek was at least two times greater than values reported in the literature for comparable, undisturbed Idaho streams. We suggest that increased nutrient concentrations via agricultural nonpoint source pollution and increased light penetration from the removal of large, woody riparian vegetation have resulted in high periphyton chlorophyll α along the continuum of Lapwai Creek.

Periphyton metabolism along a nutrient gradient in a desert river (Truckee River, Nevada, USA)

“…Uehlinger and J.T. Brock Periphyton metabolism in a desert river perature conditions has been observed elsewhere (Delong and Brusven, 1992;Shamsudin and Sleigh, 1994;Uehlinger et al, 1996). Seasonally changing responses of periphyton biomass to nutrient amendments was found in 12 New Zealand gravel bed streams, where stimulation of periphyton accrual was maximum in summer, minimum in winter, and intermediate in autumn and spring (Francoeur et al, 1999).…”

Effects of inorganic sedimentation and riparian clearing on benthic community metabolism in an agriculturally-disturbed stream

“…The stresses associated with agricultural practices in a watershed are examples of this. Streams flowing through an agricultural landscape are often subjected to riparian clearing, channelization, and both nonpoint and point source nutrient enrichment (Delong & Brusven, 1992;Lenat, 1984;Swales, 1982). Theseperturbations can drastically alter the physical conditions of a system.…”

“…Species composition in these areas consisted mainly of filter-feeding insects and algal grazers. Working with periphyton, Delong & Brusven (1992) found unusually high chlorophyll concentrations in an agriculturally disturbed watershed in Northern Idaho. They attributed these findings to non-point source nutrient enrichment.…”

“…Several studies have demonstrated pronounced effects of chemical and physical alterations, due to agricultural practices, on invertebrate composition and algal biomass (Lenat, 1984;'lkchman & Ring, 1993;Delong & Brusven, 1992). However, very little has been done to examine the effects of specific physical stresses on the ability of benthic communities to produce and utilize organic carbon either in the form of autochthonous production or allochthonous inputs.…”

Periphyton response to simulated nonpoint source pollution: local over regional control

“…In benthic habitats, periphyton communities are especially responsive to NPS pollution (DeLong and Brusven 1992;Dodds et al 2002) and, as a consequence, can be used to help establish nutrient criteria (Dodds and Welch 2000;Royer et al 2008). Periphyton also serves as a critical base of the food web, so its abundance and structure have implications for higher trophic levels (Lamberti 1996;Steinman 1996).…”