The influence of resource limitation on the allelopathic effect of Chlamydomonas reinhardtii on other unicellular freshwater planktonic organisms

Because we found previously that Chlamydomonas reinhardtii produces allelochemicals to which the rotifer Brachionus calyciflorus is sensitive, we explored its effects on other freshwater plankton. We used Chlamydomonas under light-, nitrogen- and phosphorus-limitation to test its allelopathic effect on Microcystis aeruginosa, Cryptomonas ozolinii, Ochromonas danica, Tetrahymena thermophila and Paramecium aurelia. Allelopathy depended strongly on the target organism. Only Cryptomonas suffered a marked negative effect. Among the resource limiting regimes, light limitation exerted the greatest effect.