This research was conducted to study the biodiversity status of marine macroalgae (seaweeds) in Blue Lagoon, Port
Dickson and assess the changes in species composition in the area. The sampling site is located in the west coast of
Peninsular Malaysia, which has been regarded as one of the Malaysia’s popular beach resort destinations. This tourist
spot has seen major physical changes over the last few decades. Despite habitat disturbance, our study recorded 44 species
of macroalgae with Sargassum asperifolium noted as a new record for this area. Brown seaweeds (Phaeophyta) and
green seaweeds (Chlorophyta) dominated the sampling areas with each division recorded 19 and 16 species, respectively.
Change to species composition was evident for the common genus Sargassum (Sargassaceae, Fucales). Chlorophyta
was mostly found in the upper intertidal to subtidal zones while Phaeophyta proliferated in the mid-tidal areas. The red
seaweeds (Rhodophyta) were distributed and grew better in lower light intensity in the subtidal zone. This study will
contribute to the seaweed database of Malaysia for future reference and this may help in the conservation of seaweeds.