[H-CG38_29PO1] 惑星と閉鎖生態系における生物のシステム―微生物からヒトまで

[HCG38-P01] ヤクシマカワゴロモに影響を与える付着藻類繁茂の原因解明

*北渕 浩之¹、永淵 修¹、中澤 暦¹、横田 久里子²、手塚 賢至³、鮎川 和康⁴、田辺 雅博⁵ (1.滋賀県立大学、2.豊橋技術科学大学、3.ヤクタネゴヨウ調査隊、4.環境システム株式会社、5.日科機バイオス株式会社)

キーワード：ヤクシマカワゴロモ, 付着藻類, 屋久島, 栄養塩

Hydrobryum puncticulatum (Yakushimakawagoromo), the national monument and endangered species are making their habitat only in Isso river of Yakushima. For the first time in our observation, the bloom of Melosira varians which is periphyton of diatom was observed to be covered over the H.puncticulatum from 2011. This impact for the H.puncticulatum is a serious concern .The purpose of this study is to clarify the cause of bloom of M.varians. We examined the annual variability of dissolved nutrient concentration which was most accessible to M.varians. As a result, there was no increase in concentration of NO₃-N, SiO₂-Si from 2009 to 2013. In addition, PO₄-P was much lower concentration(0.003±0.001 mg/ l). Therefore, we assumed that there was no relationship between the bloom of M.varians and dissolved nutrient concentration in Isso river. Meanwhile, the floating mud which was deposited in the bottom of the river has been continued during dry-spell. Tachibana et al (1986) reported that an algae can intake the suspended nutrient same as dissolved nutrient. It suggests that the M.varians and H.puncticulatum can take suspended nutrient.