Allelopathic effects of euhalophyte Salicornia bigelovii on marine alga Skeletonema costatum
Abstract
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.
Keywords
Allelopathy, eutrophication, growth inhibition, harmful algal bloom, Salicornia bigelovii, Skeletonema costatum