Great Plains Natural Science Society

 

The Prairie Naturalist

Date of this Version

12-2013

Document Type

Article

Citation

The Prairie Naturalist 45: 68–76. December 2013

Comments

Published by the Great Plains Natural Science Society, 2013. Used by permission.

Abstract

Iron is an important micronutrient found in aquatic systems that can influence nutrient availability (e.g. phosphorus) and primary productivity. In streams, high iron concentrations often are associated with low pH as a result of acid mine drainage, which is known to affect fish and invertebrate communities. Streams in the Black Hills of South Dakota are generally circumneutral in pH, yet select streams exhibit high iron concentrations associated with natural iron deposits. In this study, we examined relationships among iron concentration, periphyton biomass, macroinvertebrate abundance, and fish assemblages in four Black Hills streams. The stream with the highest iron concentration (~5 mg Fe/L) had reduced periphyton biomass, invertebrate abundance, and fish biomass compared to the three streams with lower iron levels (0.1 to 0.6 mg Fe/L). Reduced stream productivity was attributed to indirect effects of ferric iron (Fe+++), owing to iron-hydroxide precipitation that influenced habitat quality (i.e. substrate and turbidity) and food availability (periphyton and invertebrates) for higher trophic levels (e.g. fish). Additionally, reduced primary and secondary production was associated with reduced standing stocks of salmonid fishes. Our findings suggested that naturally occurring iron deposits may constrain macroinvertebrate and fish production.

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