PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 8 - Aquatic ecology
Exhibit Hall, Ballroom Level, Cook Convention Center

Aquatic submerged vegetation in suburban streams contributed to aquatic animal communities.

Otsuki, Maki^*,1, Koike, Fumito², ¹ Graduate School of Environment and Information Sciences Yokohama National University, Yokohama, Japan, Yokohama, Japan² Graduate School of Environment and Information Sciences Yokohama National University, Yokohama, Japan, Yokohama, Japan

ABSTRACT- Distribution of aquatic plants might be limited in suburban landscapes due to embankment and culvertization. Submerged aquatic plants might contribute to high biological diversity of aquatic animal communities in suburban landscapes. We investigated distribution of submerged aquatic plants in Kaname river running through a suburb of Tokyo, Japan, and analyzed the habitat suitability of these plants in suburban streams. Contribution of submerged aquatic plants to aquatic animal communities was evaluated using removal experiment of submerged vegetation. In the studied region, two aquatic plants(Potamogeton orientalis and exotic Egeria densa) existed sympatrically in streams of gentle slope, high electric conductivity, and high water temperature in summer. Reduction of submerged plants in eutrophicated streams was not detected, although the water quality (COD) was similar to eutrophicated lakes, and N and P concentrations were higher than them. It might be due to less competition with phyteplankton for light in shallow running waters. In the removal experiment, aquatic insects of Hydropsychidae, Chironomidae and Baetidae significantly decreased by the treatment, although a snail (Semisulcospira libertina) did not decreased. The total number of individuals in aquatic animal communities decreased to 22% by vegetation removal. The number of individuals decreased more significantly in communities on stones and plants than in substrates. Number of animal taxa decreased slightly. Grain size of substrate at stream bed became coarse by vegetation removal. In conclusion, submerged vegetation can grow in slightly eutrophicated streams and can contribute to high biological diversity in suburban landscapes.

Key words: Submerged aquatic plants, Distribution, Aquatic animal communities