Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Tuesday, February 13, 2001, Time: 2:45:00 PM

Location: Aztec

Chiavelli, D, A, Dartmouth College, Hanover, NH, USA, deborah.a.chiavelli@dartmouth.edu

AGGREGATION AND MOVEMENT PATTERNS OF DAPHNIA PULEX POPULATIONS AFFECT THE POPULATION SIZE OF THEIR EPIBIONT COLACIUM VESICULOSUM

I compared population size of the epibiotic algae Colacium vesiculosum on populations of Daphnia pulex using a crossed three-factor experiment with two distribution patterns, movement patterns, and mean densities of Daphnia. Uniform and aggregated Daphnia 'populations' had the same mean density, with all local densities the same for the uniform distribution. The aggregated distribution had one high local density (swarm), resulting in remaining local densities below the mean. In preliminary experiments, epibiont colonization increased then leveled with increasing Daphnia density. Local densities used in the low density treatment were within the increasing region of the colonization function, while for the high density treatment, the mean density and swarm density were above, and the low density was below the leveling point. Daphnia were either moved three times to new locations or did not move. Epibiont populations were higher on the high density Daphnia populations. Epibionts were greater on the aggregated distribution for the low mean density, but greater on the uniform distribution for the high mean density. Daphnia movement resulted in decreased epibiont populations on the aggregated populations. Mechanisms leading to these results and their implications for hosts (i.e. zooplankton) with ephemeral distribution patterns will be discussed.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

Quicklinks