Tropical Limnology Research Project, Edificio UIICSE, de Investigación y Posgrado, Universidad Nacional Autónoma de México, Campus Iztacala, AP 314, CP 54090, Tlalnepantla, Edo. de México, México, E-mail: rosarios@servidor.unam.mx.
*Correspondence author
1Lab. de Zoolog&ieacute;a Acuática, Edificio UMF, División de Investigación y Posgrado, Universidad Nacional Autónoma de México, Campus Iztacala, AP 314, CP 54090, Tlalnepantla, Edo. de México, México.
Planktonic ciliates and rotifers feed on algae of similar size, hence compete for limited resources in nature. However, ciliates influences the rotifers through their metabolic products (allelochemicals) into the medium. We quantified the changes in population growth of two brachionid rotifers (Brachionus calyciflorus and Plationus patulus (= Brachionus patulus), when exposed to allelochemicals from the culture filtrates of common planktonic ciliate Paramecium caudatum. In control, the population density of B. calyciflorus increased during the first week and later stabilized. On the other hand, when grown in the presence of allelochemicals from P. caudatum, the population density and the growth rates were decreased. In P. patulus also, there was a steady decline in population when grown in ciliate-conditioned medium compared to controls. The culture in medium containing allelochemicals from ciliates, decreased the population of both B. calyciflorus and P. patulus, over the controls. Regardless of treatment, the r varied from −0.20 to −0.24 for P. patulus and 0.31 to +0.03 for B. calyciflorus. Results are discussed in relation to allelopathic interactions between the ciliates and rotifers.
Allelochemicals, Brachionus calyciflorus, Chlorella vulgaris, ciliate, plankton, population growth, Paramecium caudatum, Plationus patulus, rotife
