Allelopathic Effects of Three Intertidal Marine Macrophytes on the Growth of Nanochlorum sp.
Benthic marine macrophytes produce secondary metabolites which whenreleased to the environment could potentially influence the immediate surroundings to the detriment of their competitors (i.e., other species of algae or phytoplankton). The response of the phytoplankton, Nanochlorum sp. to crude extracts (1% and 4% concentration) of the intertidal macrophytes Gracilaria salicornia, Chaetomorpha linum and Sargassum polycystum was investigated. On the average, there was a significant decrease (40-61% decrease at 4% conc. and 11-40% decrease at 1% conc.) in cell densities three days after the addition of the extracts relative to the control. Crude extracts of some common intertidal macrophytes may contain allelochemicals that could inhibit the growth of phytoplankton. The potential applications of these allelopathic effects in controlling phytoplankton blooms in small ponds and tanks have been suggested and needs further investigation.