The effects of flooding on shore aquatic invertebrates of pools at the Kamitashiro in the Ozegahara mire II : summer survey

尾瀬ヶ原上田代において池溏の岸辺水生無脊椎動物の調査を2018年夏季（7月）に23池溏で行い，洪水が与える影響の可能性を検討した．トンボ目を中心に高地・寒冷地に生息するとされる分類群が多数出現した．一定の降水量を設定して洪水影響大と小に分けた池溏群について，岸辺水生無脊椎動物の相対密度を比較したところ，総個体数（ササラダニ類を除く），サラダニ類，ミズダニ類，トンボ目，ハエ目，ハエ目の中のヌカカ科，ユスリカ科の相対密度は洪水影響大の池溏において低下し，洪水によって個体数が減少する可能性を見出した．この原因として直接的な流出と岸辺環境の攪乱が推定された．これらの結果は，先に報告した秋季の調査結果とほぼ一致し，洪水が岸辺水生無脊椎動物に与える影響の可能性が明確に示された．岸辺水生無脊椎動物の生活史特性を洪水影響との関係で論じた．Surveys of the shore aquatic invertebrates were conducted at 23 pools of the Kamitashiro at the Ozegahara mire (altitude; about 1,400 m, length; 6 km, width; 2 km, area; 7.6 km2) in summer (July, 2018) to estimate the possibility of influences of floods on them． Characteristic taxa habituating at high latitude and cool condition area were found in this mire. Possibility of the lowering the relative densities of total animals (except Cryptostigmata)，Cryptostigmata, Hydrachnellae，Odonata and Diptera, Chironomidae and Ceratopogonidae in Diptra were suggested after heavy flooding over the mire. Direct flowing out of animals from pools and disturbance of shores may result in lowering of densities of these animals. Relationships between the life cycle strategies of the animals and the effect of flooding were discussed