Distribution and Biomass of Halophila ovalis (R. Brown) Hook. f. at Pulau Gazumbo, Penang, Straits of Malacca

Abstract

Pulau Gazumbo is a small man-made island (14.25 km2) located in the Straits of Malacca, however it has an extensive seagrass bed that mainly consist of Halophila ovalis surrounding the island and extend to the subtidal area. This paper aims to study the distribution and biomass of the dominant seagrass in the island after recolonization in 23-26 years. Three 50m transects parallel to the shore, i.e. nearshore, middle and offshore, were established at the flat intertidal area at the northeastern part of the island. For each transect, twelve 50 x 50cm quadrates and 0.0035 m2 core were observed and collected for seagrass distribution and biomass data. H. ovalis were widely distributed at the offshore transect (1.5 km2) where the mudflat patches can be found followed by the seagrass at the nearshore transect (1.2 km2). More patchy and limited distribution of H. ovalis were observed at the middle transect (0.6 km2). Leaf biomass of H. ovalis was 44 - 47% of the total biomass and the highest below-ground biomass occurred at the offshore transect. Although the main threat to the seagrass ecosystem in this island is the construction work and reclamation of the coastline nearby, H ovalis still can survive on the island.