Algae as Bioindicators of Stream Function in Acid Mine Drainage Systems: Qualitative Analyses of Algal Communities in Santa Cruz Watershed

Authors: Hannah Moore, Jessica E. Gwinn, Peter N. Reinthal, Gray Floyd

Year: 2014 (xlvi)

Abstract

Acid Mine Drainage (AMD) alters stream characteristics usually via an input of acidic and metal-laden water from abandoned mines and tailings. In the Santa Cruz watershed, many geologic workings, tailings, and mine drainages periodically discharge metal-rich, acidic water and leachates into surrounding streams. These impacted aquatic systems are characterized by increased acidity and metal levels. Algae communities can be used as bio-indicators of stream function as indicated through decreased biodiversity and primary production. Here we examined algal communities in two sites in the Patagonia Mountains: Harshaw Creek, with neutral pH and low metal content and Alum Creek, with inputs from mine tailings and adits, which has relatively low pH and elevated metals content. We qualitatively analyzed the algae community structure during pre- and post- monsoon seasons, February 2011 and July 2011, respectively. Harshaw Creek had higher algae generic richness (14 total genera present with five of those being Chrysophyta, six Chlorophyta, and three Cyanophyta/ Dinoflagellates) than Alum Gulch (seven genera present with four being in Chrysophyta and three Chlorophyta) in both seasons. Based on these preliminary findings, we investigated algae diversity of both sites in 2013 and 2014 using quantitative and qualitative techniques. We used a Sedgwick rafter slide to determine the relative abundance of the algae, as indicated by average cell counts, present at each location. Fluorometric techniques were then used to examine the amount of chlorophyll A, a key biochemical component in photosynthesis, in each stream. Comparisons were then made between 2013 and 2014. Such information is crucial to understand the impacts of abandoned mines on aquatic resources and biotic communities in the Santa Cruz drainage.

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