Population genetics information for the regional conservation of a tropical seagrass, Enhalus acoroides, around the Guimaras Strait, Philippines

Seagrasses are marine angiosperms and play an essential ecological role in coastal ecosystems; however, seagrass meadows are threatened locally by anthropogenic disturbances. Understanding the dispersal patterns of seagrasses is essential for appropriate ecosystem management and establishment of marine protected areas (MPAs) in coastal ecosystems. In the Guimaras Strait in the Philippines, Banate (BAN) has been established as an MPA. However, there is a lack of information on the genetic diversity of seagrasses in BAN and the surrounding areas. In the present study, population genetics analysis of Enhalus acoroides was performed by using polymorphic microsatellite markers, for the estimation of genetic diversity, differentiation, and migration patterns of seagrasses within the regional geographical scale (~200 km) around the Guimaras Strait. The results showed that the genetic diversity of BAN is extremely low, although the Guimaras Strait is located in the tropical central habitat. Guimaras Island geographically divides the populations of E. acoroides into south and north. However, the genetic structure did not show any relationship between the geographical location and distance. The floating, buoyant fruits of E. acoroides may play a role in their long-distance dispersal; however, such dispersal is not frequent. Almost all of the seeds and fruits are derived from self-recruitment in the natal meadow. This study suggests that E. acoroides populations possess a weak genetic connectivity, and that the persistence of the meadow is threatened due to the low genetic diversity and high degree of population isolation in BAN. To maintain and enhance the genetic diversity of seagrasses within the MPA, the seagrass meadows in the surrounding areas should also be conserved.