Effect of manganese and nickel on growth of selected algae in pH buffered medium

Algal species distribution has frequently been correlated with pH and metal concentrations in streams contaminated by acid mine drainage. To determine if pH or metal is more influential in algal distribution, laboratory experiments were performed using two species of a filamentous green alga (Ulothrix) common in streams receiving acid mine drainage. Algae were exposed in acute toxicity tests to buffered growth media at various controlled pH levels and combinations of Mn and Ni concentrations. The growth of both species was affected by Mn and unaffected by pH levels typical of those in contaminated streams. Our results support the concept that metal concentration may be more influential than pH in determining algal distribution in streams receiving acid mine drainage. Also, we have identified a buffer that may be useful for algal toxicity tests since the buffer was resistant to daily pH drift, allowed formulation of a wide pH range and enabled vigorous growth of the algal species tested.