EFFECTS OF TEMPERATURE ON NATIVE DAPHNIA AND THE EXOTIC DAPHNIA LUMHOLTZI FROM THE ALABAMA RIVER DELTA
Daphnia lumholtzi is a nonindigenous zooplankton that has demonstrated an exceptional ability to rapidly invade diverse habitats throughout the U.S. following its unintentional introduction to Texas reservoirs during exotic sport fish stocking. Recreational fishing activities facilitated inland range expansion to reservoirs throughout south-central states, where high thermal tolerance allowed D. lumholtzi to occupy a vacant niche that occurs during the seasonal decline of native Daphnia during summer. However, less is known about the factors that allowed D. lumholtzi to reach and colonize other environments. Here, we investigated the presence of D. lumholtzi in Alabama estuaries. Surveys of the zooplankton community structure showed that unlike the pattern observed in reservoirs, D. lumholtzi and native Daphnia occur together year-round, at temperatures ranging from 13°C-32°C. Assays using laboratory clones showed that 36-hour survival following acute exposure to 32°C was not significantly different, but varied at 37°C, with survival in order from lowest to highest being D. ambigua, D. laevis, D. lumholtzi and D. obtusa. Currently, we’re using DNA barcoding to confirm native species identity and haplotype analysis to determine the source of D. lumholtzi populations in the estuary.
Robert Fischer (Co-Presenter/Co-Author), Middle Tennessee State University, Bud.Fischer@mtsu.edu;
Melissa Pompilius (Primary Presenter/Author), Middle Tennessee State University, email@example.com;