Size and Distribution of Resting Eggs in a Natural Population of the Rotifer Brachionus plicatilis

Abstract

Resting eggs of the rotifer Brachionus plicatilis were collected from the sediments of a brackish-water pond near Tampa, Florida. These core samples were examined for resting egg density and size. Resting egg density decreased exponentially from the surface down to 7 cm in the sediments at all stations, with depth in the sediments accounting for 42.3% of the total variance. The maximum resting egg density recorded was 194 RE/cm3 with no significant differences in density among stations. Resting eggs were found to be significantly larger in the top 2 cm of sediment than resting eggs from deeper in the sediments. These data are discussed with regard to other work on resting egg densities in natural populations. Hypotheses are offered to explain the observed decrease in resting egg size with depth in sediments.