Establishing healthy seedlings of Enhalus acoroides for the tropical seagrass restoration

Enhalus acoroides, the dominant species in tropical seagrass meadows, is experiencing declines worldwide for complicated reasons and the restoration of these meadows is extremely urgent. Nursery stock grown from the initial seedlings could be used to enhance success of E. acoroides meadow restoration. In this study, the effects of different cultivation methods on the seedling development and longer-term cultivation of E. acoroides were compared using various artificial culture substrates (culturing with sea mud substrate, agar substrate, without a matrix, and using a submerged foam substrate). Results suggested that none of the seedlings showed any sign of root gemination when cultured with sea mud substrate. Though the seedlings cultured with an agar substrate grew faster than those cultured with sea mud, those seedlings could not be cultured further as the agar substrate softened and became rotten after 3 weeks. The initial seedlings cultured in matrix-free seawater germinated with normal leaf growth but no roots developed. In contrast, the initial seedlings planted in holes of a submerged foam substrate grew successfully, developing into healthy seedlings with green leaves and long roots. These seedlings could be cultured for up to 23 weeks. Based on these results, a new, low-cost and labor-efficient method for E. acoroides seedling development was established, which might have a great application potential for efficient E. acoroides seagrass meadows restoration.