Allelopathy Journal

Harmful algal bloom (HAB), caused by intense eutrophication, are threatening the biodiversity and ecological function of marine ecosystems. We studied the potential allelopathy of Salicornia bigelovii, a euhalophyte, to inhibit the growth of Skeletonema costatum, a marine bloom forming diatom. Experiments were done in 3 culture systems (alga +euhalophyte co-culture, monoculture of marine alga, monoculture of euhalophyte) to determine the allelopathic effect of S. bigelovii against S. costatum. Lower nutrient removal rate by S. bigelovii was observed in co-culture system compared to monoculture system. The chlorophyll a and cell density of S. costatum in co-culture system were much lower than in alga monoculture system. Moreover, the aqueous extract from S. bigelovii roots showed dose-dependent inhibition against the algal growth and the half maximal inhibitory concentration (IC50) of root extract was 10.37 g FW L⁻¹. Therefore, rather than nutrient competition, allelopathy was accounted for the growth inhibition of S. costatum by S. bigelovii. Our finding implies that S. bigelovii, as a euhalophyte, may play an active role in HAB prevention.