Caceres, C. E.. Illinois Natural History Survey,
Soluk, D. E.. Illinois Natural History Survey,

Experimental studies of dispersal and colonization by zooplankton are rare. To test for colonization rates and identify dispersal vectors other than waterfowl, we performed a field experiment in which we manipulated access to 150 L mesocosms. Treatments were: 1) closed (covered with plastic), 2) 500 um netting, 3) 2.5 cm netting, 4) 10 cm netting, and 5) open (no netting). The 25 enclosures were placed in a Latin Square design within our experimental pond facility that has numerous ponds and cattle tanks as potential sources of zooplankton. Each tank was rinsed with EtOH and filled with filtered (1 um) city water. Sampling was weekly May-August 1998 and biweekly thereafter. Bdelloid and monogonant (e.g., Cephalodella, Lecane, Brachionus) rotifers were the first non-insect colonists in all treatments (beginning in week 3). The cyclopoid copepod Eucyclops agilis colonized several of the enclosures beginning in week 5. The first cladoceran (Chydorus sphaericus) did not appear until week 7. By week 16, there was no significant difference in mean number of zooplankton taxa per treatment (range 3-4.8). The low average number of taxa in all the treatments, despite the close proximity (<15m) of potential sources for many other species suggests limited transport of many zooplankton taxa.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: SS51TH0648S