Effect of pH, iron and aluminum on survival of early life history stages of the endangered freshwater pearl mussel, Margaritifera margaritifera

Glochidium larvae and juveniles of the endangered freshwater pearl mussel Margaritifera margaritifera may be sensitive to low pH and metal exposure, but to our knowledge, no tolerance tests have been performed. Therefore, we exposed glochidia, fish-attached glochidia, and juveniles of the pearl mussel to low pH and increased iron (Fe) and aluminum (Al) by using realistic pH (6.0–4.5), Fe (0.5–2.0 mg L−1), and Al (0.25–1.0 mg L−1) levels periodically observed in this study site. Survival of glochidia decreased with decreasing pH, increasing Fe, and increasing Al, as well as with increasing Fe + Al concentration in a 72 h exposure. All glochidia died within 24 h in pH 4.5 and Fe 2.0 mg L−1. W…