Background and aims – Studies on the diversity of the seaweed flora of the Philippines have waned in the past decades, and detailed data on the distribution of these economically important resources is missing. We attempt to bridge this gap by providing information on the diversity, distribution, and some aspects of the ecology of the seaweed flora of a marine biodiversity corridor in the western Philippines, the Balabac Marine Biodiversity Conservation Corridor (BMBCC). Methods – In seventeen stations of the BMBCC, seaweed floras were assessed. All seaweeds encountered were identified in situ, down to species level, when possible. All unidentified specimens were collected and identified in the laboratory. Cluster analysis based on Jaccard index was used to infer similarities among the seaweed floristic components of each station. A comprehensive checklist was made using data from this study and other available literature. Key results – There were 176 seaweed species in the area (Chlorophyceae: 70 spp., Rhodophyceae: 75 spp., and Phaeophyceae: 31 spp.). Cluster analysis showed a separation between the seaweed flora of areas within the Sulu Sea and those of the West Philippine Sea. Similarities among the floristic components of these areas may be attributed to the resemblances in the prevailing ecological conditions (i.e. substrate, wave exposure, and water movement, among others). Conclusions – BMBCC harbours a relatively diverse seaweed flora, considering its small area. In addition, habitat characteristics, particularly the substrate type, appear to influence floristic compositions and similarities among the different surveyed areas. This report is the first to consolidate floristic information in a marine biodiversity conservation corridor in the country.

BALABAC; CHECKLIST; DIVERSITY; FLORISTICS; MACROALGAE; PALAWAN; PHILIPPINES; SEAWEEDS