Inventory of Benthic Macroalgae in Pristine and Clear Waters of the Island Towns of Northern Samar, Philippines

Abstract

This study conducted a comprehensive investigation to examine the species composition, abundance, classification, anthropogenic threats, economic uses, and ethnobotanical practices associated with benthic macroalgae in the pristine and clear waters of the island towns in Northern Samar. A thorough reconnaissance survey was conducted in the study areas during the summer months of April to June over a five-year period from 2015 to 2019. Data on macroalgae growth, abundance, and usage were gathered through a range of techniques, such as quadrat sampling, transect walks, the line intercept method, ocular inspection, interviews, focus group discussions, and snorkeling. A total of 112 macroalgae species were identified, representing three classes, 17 orders, 28 families, and 53 genera. Among these species, Sargassum oligocystum Montagne, a brown alga, was the most abundant and widely distributed. The study revealed the presence of 11 species of Sargassum, 8 species of Caulerpa, 7 species of Halimeda, 6 species of Gracilaria, and 4 species of Ulva. The family Sargassaceae exhibited the highest abundance among the seaweed families assessed. The macroalgae were found to serve various purposes including food, medicine, income generation, soil fertilizer, fish bait, animal feed, insect repellent, packaging material, and protection of fish and marine products during transportation to the market. Additionally, the study documented important ethnobotanical practices related to macroalgae usage. It was observed that pregnant women were advised against consuming algae, red algae were not suitable for domestic animal consumption, fresh macroalgae were preferred for consumption, selected species were recommended for children, sick individuals, and older people, and the collection of algae after a typhoon was prohibited. This research provides valuable insights into the diversity and ecological significance of benthic macroalgae in the study areas, highlighting the socio-economic importance and cultural practices associated with their utilization. The findings underscore the need for sustainable management and conservation strategies to safeguard these valuable resources and protect them from the identified anthropogenic threats.