Organic matter breakdown as a measure of stream health in New Zealand streams affected by acid mine drainage

• Published in: Ecological indicators 2013-01, Vol.24, p.510-517
• Main Authors: Niyogi, Dev K., Harding, Jon S., Simon, Kevin S.
• Format: Article
• Language: English
• Subjects: acid mine drainage; aluminum; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; coal; cotton; Decomposition; drainage; Ecosystem function; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; hydrochemistry; hydroxides; iron; leaves; Litter; macroinvertebrates; metal ions; Metals; Microbes; microorganisms; organic matter; streams; Synecology; wood; zinc
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2012.08.003

► Litter breakdown was most closely related to metal hydroxide deposition as opposed to acidity or dissolved metals. ► Microbial activity can remain high even in very acidic sites with pH less than 3. ► Functional measures such as litter breakdown provide a good measure of health for streams affected by mine drainage. Functional indicators of stream health have the potential to provide insights into stream condition that cannot be gained by traditional structural indices. We examined breakdown of leaves, wood, and cotton cloth strips at 18 sites along a gradient of effects of drainage from coal mines in New Zealand to determine the usefulness of these methods as functional indicators of stream health. The pH varied from 2.7 to neutral across the streams, and the more acidic streams typically had higher concentrations of aluminum, iron, zinc, and other metal ions. Precipitates of metal (mainly iron) hydroxides were present in most streams affected by mine drainage, especially in those with a pH of 4–5. Breakdown rates of all organic matter types were highest in several reference streams with neutral pH and lowest in sites with high rates of metal hydroxide deposition. Breakdown was relatively fast in the most acidic streams (pH