摘要：The exotic cladoceran, Daphnia lumholtzi, was collected at various sites within the lower Atchafalaya River Basin throughout the summer of 1994. Stepwise regression revealed that seasonal abundance was related to late summer environmental conditions of high specific conductance, low river discharge, and high surface water temperature. Abundances of D. lumholtzi were greatest in sites with high percentages of dissolved oxygen saturation and low current velocity. Within this habitat type, D. lumholtzi exhibited a distinct nocturnal vertical migration, although this behavior was not evident in two other habitats.
