ヤツマタモク群落内における葉上ワレカラ個体群の変動要因について (予報)
1988 年 1988 巻 32 号 p. 42-49
詳細
1988 年 1988 巻 32 号 p. 42-49
AOKI, Masakazu (Amakusa Marine Biological Laboratory, Kyushu University), 1988. Factors affecting population fluctuations of caprellid amphipods inhabiting a Sargassum patens bed (Preliminary report). Benthos Research (Bull. Jap. Assoc. Benthology), 32 : 42-49.
Factors affecting the population fluctuations of caprellid amphipods inhabiting Sargassum patens bed were analysed. S. patens began to grow in August and the height and volume reached maximums in April. Increase of caprellids correlated with the growth of the seaweed and the population size reached a maximum in March. The seaweed population began to decline in May and continued to be washed away until July, but caprellid populations showed a drastic decrease in March, ahead of the decline of the seaweed bed. Sudden increase of predation pressure by wrasses in March was considered to be an important factor responsible for drastic decrease of caprellids. Results of a cage experiment indicated the large effect of the predation pressure on caprellid populations. In summer, there was no substratum in the field for caprellids, and caprellid populations were limited to the shorter and shrub-like Sargassum bed on the rocky coast in Aka-iwa, about 400m north of the S. patens bed. Source populations are apparently maintained in such areas during summer and then drift into the S. patens bed in autumn.
