No.150 研究課題 / Project
南浅川流域のヒガシカワトンボ生活史にみられる気候温暖化の影響Influence of climate mild ?ization that is observed in Mnais pruinosa costalis(Odonata Calopterygidae) life history at the Minami-Asakawa| 一般研究 General Research |
No.150 |
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| 代表研究者 Principal Investigator |
田口 正男 Masao Taguchi |
| 所属（採択当時） Affiliation |
神奈川県立弥栄東高等学校 教諭 Teacher, Kanagawa Prefectural Tukui High School |
| 研究内容要約 Research Summary |
ヒガシカワトンボの年一化性と2年一化性との境界域と思われる神奈川県北部に接する東京都南浅川地域において、気候温暖化が幼虫の生活史に及ぼす影響について調べた。保存されていた十数年前のヒガシカワトンボ幼虫の採取サンプルから、当時の南浅川流域での本種の化性は2年一化性と確認できた。南浅川と隣接する河川について水温、ヤゴ体サイズの年変化を、そして南浅川の上流から下流にかけてはさらに温度較差、成虫の体サイズを調べた。南浅川の下流域でのヤゴの体サイズの年変化は、現時点で年一化性であることを示した。また、発育ゼロ点を下回ると思われる冬季を除いて、上流から下流にかけて水温が高くなる温度勾配が見られた。発生の初期、及びピーク期では、成虫の体サイズは上流から下流にかけて、むしろ小さくなったが、発生後期では上流部において大きな個体の他に小さな個体の出現が見られた。有効積算温度の関係から、より低い温度域で育った上流部の大きな個体が、より暖かい下流域で育った年一化性の個体と同じ化性とは考えられず、上流部では以前のような2年一化性の生活史と、発生期の後半に出てくる小さな個体となる年一化性の生活史を過ごす2つの個体群が混在しているものと考えられた。 ここ十年の気候温暖化は、化性の境界域である南浅川のヒガシカワトンボの生活史に影響を与え、下流側から上流域へ遡って一年一化性の領域を広げさせたと言える。 We checked about the influence that climate mild ?ization exerts in the life history at the Minam Asakawa area which touches to the Kanagawa Pref. north that is thought as the boundary area between the 1 year univoltinism and 2 year univoltinism of Mnais pruinosa costalis. From the picking sample of the Mnais pruinosa costalis larva of 10 several years before that was preserved 1 year univoltinism of this seed in the south Asakawa valley in that time was able to confirm as 2 year univoltinism. The year change of water temperature, larvae body size, I checked the body size of the temperature range, adult furthermore from the upstream through the lower stream of south Asakawa furthermore about the river which adjoins with south Asakawa. Under south Asakawa, the year change of the body size of larvae in the downstream area showed that is 1 year univoltinism in the resent. Also, the temperature slope that the water temperature becomes high from upstream through the lower steam, except for the winter when is thought that at the developmental zero is fallen below was seen. The appearance of the small individual was seen other than a big individual in upstream department in an the occurrence latter period upstream through the lower stream from, rather, although the body size of the adult became small in the early period and also peak period of occurrence. As for the same univoltinism as the individual of the 1 year univoltinism that the big individual of the upstream department, that grew up in a lower temperature area from the relation of effective product arithmetic temperature, grew up in a warmer under valley 2 individual groups that spend the life history of the 1 year univoltinism when becomes the small individual that appears in the second half in life history and, occurrence period of 2 year 1 of univoltinism like previous in upstream department were considered to be coexisting, without being conceivable. Climate mild 0ization in here 10 is said that exert an/the influence on the life history of Mnais pruinosa costalis of south Asakawa when is the boundary area of the voltinism and trace back from at the lower stream side to top valley and the range of 1 year univoltinism is caused expanded. |
| 共同研究者 Collaborators |
谷 浩樹（秋田大学大学院生）・根本弘志（根本フィレンツェ工務店）・神奈川県立弥栄東・西高校 環境生態部・神奈川県立上溝高等学校 科学同好 |
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