Spatial distribution of the biomass of submerged macrophytes in the southern Lake Biwa basin in September 2017

Hiroki HAGA, Yoichiro SAKAI, Kanako ISHIKAWA
2019 Japanese Journal of Limnology (Rikusuigaku Zasshi)  
The spatial distribution of submerged macrophytes, in terms of dry weight and species composition, was surveyed in the southern Lake Biwa basin in September 2017, using SCUBA. Submerged macrophytes were observed at 40 out of 52 sampling stations. The average total biomass of submerged macrophytes per site was 54 g dry wt. m -2 . During study period, the area covered by vegetation in the basin was estimated to be 39.7 km 2 and the total biomass was estmated to be 2761 t. Thirteen species of
more » ... een species of submerged macrophytes were observed in this study, and the average number of species per site and its standard deviation was 4.5±3.0. Hydrilla verticillata and Elodea nuttallii dominated the observed submerged macrophytes, with biomass of 777 t and 776 t, respectively. Potamogeton maackianus (556 t), Egeria densa (283 t), and Myriophyllum spicatum (257 t) followed. Biomasses of other species were each less than 100 t. We also observed that a substantial amount of filamentous algae existed in the south basin, and its biomass (1161 t) is equivalent to about 40% of the total biomass of submerged macrophytes in the basin. 琵琶湖南湖で 2017 年 9 月に沈水植物の現存量(乾燥重量)の平面分布を SCUBA サンプリングにより 調査した。沈水植物は 52 地点中 40 地点に出現した。南湖における全沈水植物の単位面積あたり平均現 存量は 54 g dry wt. m -2 だった。これらの結果から,沈水植物の分布範囲の面積と現存量はそれぞれ 39.7 km 2 ,2761 t と推定された。沈水植物は 13 種が出現した。1 地点あたりの平均出現種数と標準偏差は 4.5± 3.0 だった。優占したのはクロモ Hydrilla verticillata とコカナダモ Elodea nuttallii で,それぞれの現存量 1) 滋賀県立琵琶湖博物館 〒 525-0001 滋賀県草津市下物町 1091 番地 Lake Biwa Museum, Oroshimo-cho 1091, Kusatsu, Shiga 525-0001, Japan 2) 滋賀県琵琶湖環境科学研究センター 〒 520-0022 滋賀県大津市柳が崎 5-34 Lake
doi:10.3739/rikusui.80.13 fatcat:aawwbphbqfbp3bxemxilemnwkq