RICHNESS, DIVERSITY AND SUCCESSION OF LATE-GLACIAL CHIRONOMID ASSEMBLAGES IN NEW-BRUNSWICK, CANADA

Chironomid analysis was performed on late-glacial sediment from four N ew Brunswick lakes in order to gain basic ecological information regar ding the richness and diversity of late-glacial chironomid assemblages , and to compare the pattern of succession at each site. At all sites, the richness and diversity of the larval assemblages were lowest imme diately following deglaciation and during the Younger Dryas, correspon ding to the coldest times of the late-glacial period. Although cold-st enothermous taxa are characteristic of sediments deposited immediately following deglaciation, as well as during the Killarney Oscillation a nd Younger Dryas cooling events, the constituent taxa are different at each site. During the intervening warm periods, the larval assemblage s at each site are also dissimilar, with the more southern sites conta ining a greater variety of temperate littoral taxa. This raises the po ssibility that a north-south temperature gradient existed during the w arm intervals of the late-glacial period in New Brunswick.