The distribution of seagrasses and the viability of seagrass transplanting in the broadwater, Gold coast, Queensland

Abstract

The species composition and distribution of seagrass in The Broadwater were mapped in January 1997 and compared with historical records. Three species of seagrass (Zostera capricorni, Halophila ovalis and Halophila spinulosa) were identified and were more widely distributed than in a previous study conducted ten years earlier (304 hectares compared with 180 hectares). In general, Z. capricorni was dominant to a depth of 0.7 m (below MLS) and H. ovalis or H. spinulosa dominated from 0.7 to 2 m. Mixed and pure plots of seagrass (Z. capricorni and H. ovalis) transplanted into an artificially disturbed habitat survived and grew over a 6 month study period but the overall survival of transplanted plots was less than fifty percent. Natural colonisation of the area was observed, with H. spinulosa (a species not even transplanted) found in high densities eight months after the area was disturbed. Seagrass transplantation in The Broadwater was not advised, due to its high costs, lack of effectiveness, damage to donor sites and the observed natural colonisation of suitable sites.