有明海沿岸域のクリークにおける淡水魚類の生息の有無・生息密度とクリークの護岸形状との関係

Abstract

The presence and populations of freshwater fishes and the revetment conditions in creeks were investigated at 48 sampling sites around the Sea of Ariake in northwestern Kyushu, Japan. Each creek studied in this survey was classified into one of the three following types in terms of revetment conditions: Type-1, the creeks have earthen revetments except when crossing roads; Type-2, although there are concrete revetments in the creeks, these revetments are short, and agricultural water flows over the revetments and reaches bank vegetations or earthen banks except during the agricultural off-season; Type-3, there are high concrete revetments around the creeks, and agricultural water does not flow over the revetments during any season. The amount of Hemigrammocypris rasborella present was affected by the revetment conditions, and the amount present in Type-3 was significantly lower than those in Type-1 and Type-2. The populations of H. rasborella, Rhodeus ocellatus kurumeus, and Pseudorasbora parva were affected by the revetment conditions. For H. rasborella and R. ocellatus kurumeus, the populations in Type-3 were significantly lower than those in Type-1 and Type-2. For P. parva, the population in Type-3 was significantly lower than that in Type-1.