Bioremediation and fodder potentials of two Sargassum spp. in coastal waters of Shenzhen, South China

•Two Sargassum species were cultured in a fish farm.•Growth, chemical and nutritional compositions of the seaweeds were estimated.•The seaweeds grown in the fish farm achieved higher growth rates than those grown in the seaweed bed.•The S. hemiphyllum had higher nutrient bioremediation and fodder potentials.•The S. henslowianum can be used as biofilter and/or biomonitor for heavy metal contamination.

In this study, the bioremediation potentials of two seaweeds (Sargassum hemiphyllum and S. henslowianum) against pollution in a coastal mariculture area of Shenzhen, South China, were investigated by comparing the growth, nutrient bioaccumulation capacity of plants from the seaweed bed (control site) with plants from the fish farm. Results indicated that both species are potential candidates for bioremediation in the fish farm areas in terms of their high growth rates and high bioaccumulation capacities on inorganic nutrients. Both Sargassum spp. contain high levels of crude protein (11.7-14.0%) and crude fat (2.2-2.7%), suggesting high nutritional values. The S. hemiphyllum may serve as a good aquaculture fodder with high nutritional compositions and low heavy metal contents. However, heavy metals (Cr, Pb and Cd) of S. henslowianum exceed the maximum allowable concentrations as aquatic feed, which restricts its fodder application. In general, the results of this study may contribute to the marine pollution bioremediation in the coastal areas of South China, especially in mariculture zones.