The ecological effect of acid conditions and precipitation of hydrous metal oxides in a Rocky Mountain stream

Abstract

Periphyton and benthic invertebrate assemblages were studied at the confluence of two Rocky Mountain streams, Deer Creek and the Snake River near Montezuma, Colorado. Upstream from the confluence the Snake River is acidic and enriched in dissolved trace metals, while Deer Creek is a typical Rocky Mountain stream. In the Snake River, downstream from the confluence, the pH increases and hydrous metal oxides precipitate and cover the streambed. The algal and benthic invertebrate communities in the upstream reaches of the Snake River and in Deer Creek were very different. A liverwort, Scapania undulata var. undulata, was abundant in the Snake River, and although periphyton were very sparse, there were as many benthic invertebrates as in Deer Creek. Downstream from the confluence, the precipitation of hydrous metal oxides greatly decreased the abundance of periphyton and benthic invertebrates. This study shows that in streams metal precipitates covering the streambed may have a more deleterious effect on stream communities than high metal-ion activities.

Environmental impact propagated by cross-system subsidy: Chronic stream pollution controls riparian spider populations

“…This pollution impact provides an ideal, if unintentional, alteration of the aquatic-terrestrial subsidy because (1) abandoned coal mine discharges can reduce benthic production of aquatic insects over entire stream reaches (McKnight and Feder 1984) without altering habitat conditions (i.e., inundation dynamics and vegetation structure) in the riparian zone; (2) most mine discharges provide a continuous impact over long time periods (.10 years) and large spatial scales, i.e., several 100-1000 m of stream length; and (3) they occur in many different stream systems, often into otherwise relatively clean waters. The iron-rich discharges from abandoned coal mines result in the precipitation of iron compounds (ochre) in receiving streams, which negatively affects the abundance and productivity of aquatic insects, primarily by reducing primary productivity and benthic habitat quality, i.e., smothering of the stream bed with ochre (McKnight and Feder 1984).…”

Factors controlling streambed coverage of Didymosphenia geminata in two regulated streams in the Colorado Front Range

“…Periphyton were sampled from mylar strips used as artificial substrate (McKnight & Feder, 1984) and from rocks collected from the natural substrate at the site that were scraped clean prior to being deployed on July 20, July 27, and August 1, 2006 at all five sites. Strips of mylar film having dimensions 6.4 9 29.2 cm were placed in riffles at each site on numerous dates.…”

Work plan of the Neversink watershed study in the Catskill Mountains of southeastern New York

“…During oversaturation conditions, aluminum can readily sorb to gill tissue and result in suffocation an'l, under extreme conditions, precipitating aluminum has been shown to disrupt benthic macroinverteb^ate communities (McKnight and Feder, 1984). Although evidence from laboratory experiments indicates tHt aluminum solubility affects fish mortality, it has ncf been investigated under natural conditions.…”