Abstract. Pototan BL, Capin NC, Delima AG, Novero AU. 2021. Assessment of mangrove species diversity in Banaybanay, Davao Oriental, Philippines. Biodiversitas 22: 144-153. This study determined mangrove species diversity and community structure in Banaybanay, Davao Oriental, Philippines. Ten 150m long transects plots were laid out perpendicular through the mangrove forests yielding 30 plots and total sampled area of 3, 000 m2. Individual trees within plots were counted, identified and measured for diameter at breast height (dbh) and tree height. For diversity analysis, Shannon-Weiner Index of Diversity (H’), Pielou’s Index of Evenness (J), Simpson’s Index of Dominance (C), and Effective Number of Species (ENS) were used. Results showed a total of 33 species belonging to 14 families, 31 of which are true mangroves and two associates. Two threatened species, the endangered Camptostemon philippinensis and vulnerable Avicennia rumphiana, and three near-threatened species were recorded. Diversity analysis showed a high diversity index (H’=3.145; ENS=23) and high species evenness (J=0.85) but low dominance (C=0.05). Sonneratia alba attained the greatest importance value (IV=59.79%) due to high relative density, relative frequency, and relative dominance. Also, Rhizophoraceae is the most represented among 14 families. Hence, Banaybanay being highly diverse with the presence of threatened and near-threatened mangrove species calls for immediate protection and conservation measures because of increasing anthropogenic activities and environmental problems observed in the area.

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Seagrasses are an important coastal resource that serves as homes and breeding grounds of fishes and other marine organisms and are useful indicators for the detection of changes in the coastal environment since they are vulnerable to bio-physical stressors. This study assessed the seagrass resources in terms of composition, percent cover, community similarity, and diversity in four municipalities (Banaybanay, Governor Generoso, Lupon, and San Isidro) situated in the southwest coast of Davao Oriental province facing Davao Gulf. Thirty-six (36) transects, each with ten quadrats arranged in an alternate manner, were laid perpendicular to shore yielding a total of 360 plots. A total of eight seagrass species were observed: Cymodocea rotundata, Enhalus acoroides, Halodule pinifolia, Halophila minor, Halophila ovalis, Halophila spinulosa, Syringodium isoetifolium, and Thalassia hemprichii. Governor Generoso (33.77%) and San Isidro (26.01%) were classified to have fair seagrass bed conditions while Banaybanay (24.31%) and Lupon with the lowest coverage (15.90%) had poor status. T. hemprichii dominated the seagrass community in Banaybanay and Governor Generoso while C. rotundata were dominant in Lupon and San Isidro. The two most abundant species, T. hemprichii (41%) and C. rotundata (34.48%), had fair coverage comprising 75% of the entire seagrass while the remaining 25% cover was shared by Enhalus acoroides (19%) and other five species with very poor cover (0.30–2.43%). Diversity analysis using percent cover data revealed low diversity with overall Shannon index, H’= 1.2955, evenness J = 0.6657, and Simpson’s index of diversity, D = 0.3577. Dice community of coefficient grouped Banaybanay, Governor Generoso, and San Isidro together, indicating high similarities while separating Lupon, which had the poorest seagrass condition in terms of coverage. The status of seagrass diversity on the southwest coast of Davao Oriental calls for immediate attention and effective strategies to alleviate poor conditions and protect the seagrass beds