| Popis: |
Periphyton communities are influenced by the surrounding physical, chemical, and biological components of freshwater streams, and these factors can affect the growth, productivity, and composition of the biofilm. A field experiment was performed to analyze the interactive effects of acid mine drainage (AMD) and grazing on a periphyton biofilm community. Tiles with a mature biofilm, with and without grazers, were placed in enclosures along a stream being actively treated with a doser, which adds the alkaline material calcium oxide, for AMD remediation. Gross primary productivity (GPP) was calculated from dissolved oxygen measurements and chlorophyll-a, ash-free dry mass, and diatom community composition were analyzed. In general, the GPP of the periphyton community was strongly affected by the AMD water quality gradient, which was evident in both the non-grazed and grazed treatments. The GPP was lowest at the site closest to the doser and increased downstream, with the highest GPP at the reference site. For all five sites, biomass tended to be lower in the grazed treatments compared to the nongrazed treatments, but an effect of grazing was only statistically detected in three sites. The site closest to the doser did not show an effect of grazing and it is hypothesized that the grazers were affected by water quality, but another site that did not show the effect of grazing had much higher water quality and no explanation is evident. In this study, the effects of water quality on the periphyton were evident, but the effects of grazing were more difficult to detect and interpret. |
