Richness, diversity and succession of late-glacial chironomid assemblages in New Brunswick, Canada

Chironomid analysis was performed on late-glacial sediment from four New Brunswick lakes in order to gain basic ecological information regarding 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 immediately following deglaciation and during the Younger Dryas, corresponding to the coldest times of the late-glacial period. Although cold-stenothermous taxa are characteristic of sediments deposited immediately following deglaciation, as well as during the Killarney Oscillation and Younger Dryas cooling events, the constituent taxa are different at each site. During the intervening warm periods, the larval assemblages at each site are also dissimilar, with the more southern sites containing a greater variety of temperate littoral taxa. This raises the possibility that a north-south temperature gradient existed during the warm intervals of the late-glacial period in New Brunswick.