A review of issues in seagrass seed dormancy and germination: implicationsfor conservation and restoration

Seagrasses have received considerable attention over the past 2 decades bec ause of the multiple ecological roles they play in estuarine and coastal ec osystems and concerns over worldwide losses of seagrass habitat due to dire ct and indirect human impacts. Restoration and conservation efforts are und erway in some areas of the world, but progress may be limited by the paucit y of information on the role of seeds in bed dynamics. Although flowering o ccurs in most of the 58 seagrass species, seed germination data exist for o nly 19 of the 42 species that have some period of dormancy, with only 93 pu blished references to field and/or laboratory studies. This review addresse s critical issues in conservation and restoration of seagrasses involving s eed dormancy (e.g. environmental vs physiological), existence and type of s eed bank (transient or persistent), and factors influencing seed germinatio n (e.g, salinity, temperature, light). Results of many earlier published st udies relating seed germination to various environmental factors may need r e-examination given more recent published data which show a confounding inf luence of oxygen level on the germination process. We highlight the importa nce of conducting ecologically meaningful germination studies, including ge rmination experiments conducted in sediments. We also identify questions fo r future research that may figure prominently in landscape level questions regarding protected marine or estuarine reserves, habitat fragmentation, an d restoration.