The role and decomposition process of Microcystis in benthic ecosystems

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K21616
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Ecology/Environment; Civil and environmental engineering
• Research Institution: Ibaraki Kasumigaura Environmental Science Center
• Principal Investigator: Yumi Nao (長濱祐美) 茨城県霞ケ浦環境科学センター(湖沼環境研究室、大気・化学物質研究室), 湖沼環境研究室, 技師 (00618506)
• Project Period (FY): 2017-02-07 – 2019-03-31
• Keywords: Microcystis / 藍藻類 / アオコ / 底泥 / 分解 / 食物網 / ベントス / 二枚貝

Outline of Final Research Achievements

Cyanobacterial blooms, especially Microcystis spp., cause problems such as deteriorating visual appearance or bad smells at Lake Kasumigaura. Moreover, previous research suggested that cyanobacteria blooms occur more frequently because water temperature and solar radiation rise with time due to climate change. In this study, we focused on decomposition process and role to benthic food webs of Microcystis cells in lake sediments. Our results suggested that Microcystis cells in the water settled with suspended solid and that Microcystis cells in sediments decomposed anaerobically 26 days after. Furthermore, we feeding experimented of benthos, Chironomidae, Sinanodonta spp. and Corbicula leana to clarify the role of organic matter of Microcystis. We will more analyzed these benthos sample and we more clarify to the role of organic matter of Microcystis as food of these benthos.

Free Research Field

水環境

Academic Significance and Societal Importance of the Research Achievements

本研究によって，湖水中で増殖したMicrocystisが底泥中に堆積していること，また速やかに生物的分解を受けるが，Microcystis由来有機物が底泥中へとどまることが明らかになった。気候変動に伴う藻類の異常増殖は全国の湖沼やダム湖で懸念されており，本研究結果はそれらの湖沼におけるアオコの発生が底泥中に影響を与えている可能性もまた示唆している。今後，一次消費者である二枚貝や堆積物食者であるユスリカに対するMicrocystis由来有機物の移行明らかにすることで， Microcystisの発生が魚類を中心とした湖沼生態系に与える影響を検討する際の有効な知見を提供できるだろう。