||Preliminary observations on spatial variation in the biotic and abiotic properties of high mountain ponds in central Japan
186 , 2015-11-30 , 専修大学学会
This paper examined differences in biotic and abiotic properties among mountain ponds with different geomorphic origins. Water characteristics, the timing of snow disappearance, and the occurrence of a salamander species were measured in 29 ponds scattered throughout a mountainous area in central Japan. Of these, 23 ponds were formed in linear depressions on and around main ridges, while five were formed in depressions on cirque floors. Only one pond was formed in a volcanic crater. Water in the linear depression ponds was characterized by low electrical conductivity (EC) and a weakly acidic pH. The values of both EC and pH were similar to those of snow and rain in the region. The EC of cirque ponds was as low as that in linear depression ponds, whereas the pH was neutral-acidic. The neutral acidity may be caused by acid neutralization by soil and bedrock in the basins of the cirque ponds, which are larger than those of the linear depression ponds. The pond in the volcanic crater had high EC and a strongly acidic pH, probably due to the presence of sulfuric acid in the crater. Larvae of the salamander Hynobius nigrescens were common in the linear depression ponds, while no larva was observed in the volcanic and cirque ponds ; they may have been excluded by the adverse effects of acidity and by either or both the longer snow-covered period and lower water temperature in these ponds. Linear depression ponds < 100 m often lacked salamander larvae. This may be related to seasonal water-level lowering or desiccation.