Abstract
We investigated faunal transitions in living (rose Bengal-stained) benthic foraminifera in the Honjo area of Lake Nakaumi (southwestern Japan) through monthly biological monitoring at a fixed station (approx. 8-m depth) to study the dispersal potential of benthic foraminifera. We observed the following transitions in benthic foraminifera: (1) few and sporadic occurrences of benthic foraminifera before November 2007; (2) Ammonia “beccarii ” forma 1 dominant in 2008 and 2009 with occasional occurrences of Miliammina fusca ; and (3) Trochammina hadai dominant from 2010 on, with occasional occurrences of Elphidium somaense and M. fusca . Young individuals of A. “beccarii ” forma 1 likely settled in the Honjo area in winters of both 2007/2008 and 2008/2009 as a result of widening and deepening of the southwestern channel. The young individuals seemed to grow in spring and summer, but likely died out toward fall, probably because of oxygen deficiency. The channel constructions, opening dikes isolating the Honjo area, in 2007–2008 and May 2009 could explain the dramatic changes in benthic foraminiferal fauna, especially the change in the dominant species from A. “beccarii ” forma 1 to T. hadai through a shift in the provenance of the individuals supplied from Lake Nakaumi.
https://ror.org/01an57a31 
