Acid Mine Drainage
Disrupted food webs in acid mine drainage streams
Acid mine drainage (AMD) generated from mining activities is a prominent and complex environmental issue worldwide. Mineral deposits (e.g., coal) often contain pryrite, which has elevated levels of sulphur and metals, such as iron and aluminium. These elements are exposed to air and water during coal extraction and generate acidic runoff. AMD causes significant changes in water chemistry by lowering pH and increasing the concentration of dissolved metals and can alter biological communities in different ways. Sensitive species of algae, benthic invertebrates, and fish are eliminated in streams receiving AMD inputs and the stream community structure usually shifts to one dominated by a few tolerant species.
Kristy Hogsden's PhD research is focusing on the structure and function of food webs in streams impacted by acid mine drainage (AMD). In particular, Kristy is interested in understanding if changes in food web structure and community composition affect how energy is processed and moves through the system. Her research will be based on the northern west coast of the South Island where current and historic AMD inputs from coal mining activities have impacted numerous waterways.
Kristy is currently conducting a survey of twenty streams to separate the effects of anthropogenic versus natural acidity and metals on stream food web structure. To do this, Kristy has been sampling bacteria, fungi, algae, invertebrates, and fish in streams with distinctly different water chemistries including: (1) AMD; (2) naturally acidic; (3) naturally high metals; and (4) circumneutral (Fig. 1).
 |
Figure 1. Streams used in the survey will have distinctively different water chemistries from AMD streams (1) with low pH and high metal concentrations to circumneutral streams (4) with higher pH and low metal concentrations. |
People involved in this project
University of Canterbury
Kristy Hogsden (PhD student)
Jon Harding