Effect of spring water on distribution pattern of submerged macrophytes
Takahashi, Kazuya; Asaeda, Takashi
Spring water is recognized as an important component of regional ecosystems, affecting the growth and distribution of aquatic plants such as submerged macrophytes. However, there have been few studies on how spring water affects submerged macrophyte habitats. In order to understand this relationship, we conducted observations in Kurohashi River flowing into Lake Biwa, Shiga prefecture, Japan. Plant observation and sediment, and water samplings were carried out from May to October 2010. Three submerged macrophyte species (Egeria densa, Elodea nuttallii, and Sparganium japonicum) were found at the study site. The distribution pattern of these species showed that S. japonicum dominates the reaches most affected by spring water. The PO4-P concentration in the waters where S. japonicum stands dominated was significantly lower compared to those sites where E. nuttallii dominated (S. japonicum; 0.012 ± 0.00 mg/L, E. nuttallii; 0.016 ± 0.04 mg/L, p < 0.05). This paper discusses the possibility of spring water being a PO4-P dilution factor in the channel, providing S. japonicum with better competitive ability as compared to the other submerged macrophytes.