To assist the municipal government of Binmaley, Pangasinan in gathering baseline data on their proposed sanctuary in Buenlag-Sabangan River, the status of mangroves and associated flora were assessed as to species composition, frequency of occurrence, density, dominance, and diversity using combination of transect and quadrat method. Five stations were also established in the upstream, midstream and downstream portion of the river specifically for fishes and crustaceans sampling and water quality monitoring. Problems/issues associated with the utilization, management and conservation of the river ecosystem were also determined through ocular observation during transect walk in the mangrove area and through interview to key informants and their severity were measured using hedonic scale.
Results of the study revealed three types of macroflora present in the study area: True mangroves, associated mangroves, and beach forest species. True mangroves species consists of three species from Family Rhizophoraceae: Rhizophora apiculata, Rhizophora mucronata, Bruguiera cylindrica; two species from Family Avicenniaceae: Avicennia officinales and Avicennia marina: One species each from Family Euphorbiaceae (Excoecaria agallocha), Combretaceae (Lumnitzera racemosa), Myrsinaceae (Aegiceras corniculatum), Sonneratiaceae (Sonneratia alba), Palmae (Nipa fruticans), Pteridaceae (Acrostichum aureum), Acanthaceae (Acanthus elicifolius). Associated species include two species from Family Fabaceae (Derris trifoliate, Acacia farnisiana) and one species from each of the following Families: Combretaceae (Terminalia cattapa), Malvaceae (Hibiscus tiliaceus) Clusiaceae (Calophylum inophyllum), Moraceae (Artocarpus ovatus), Aizoaceae (Sesuvium portuculastrum), Pandanaceae (Pandanus tectorious), and Mimosaceae (Leuceana leucocephalia). Among the beach forest type, only coconut (Cocus nucifera) and Lambayong (Ipomea pescaprae) can be found in the study area.
Most frequently occurring true mangrove species are the Rhizophora apiculata, Excoecaria agalocha, Rhizophora mucronata and Brugueira cylindrica. The wildlings outnumbered the saplings and the matured true mangroves with Rhizophora mucronata on the top rank considering all stages. For the associated mangrove species, matured outnumbered the wildlings and the saplings. Most frequently occurring associated species is the Derris trifoliate and Actocapus ovatus which is a shrub.
Among the true mangrove species Rhizophora apiculata has the highest density (1.01 stand/m2) and Transect 22 has denser (4.54/m2) vegetation. Highest Dominance Index, as computed using the Simpson Index of Dominance of 1 was computed from Transect 19. Mean species diversity of the area is 0.90 with Transect 21 having the highest (H = 2.1923).
Macrofaunal species in the study area is composed of fishes, crustaceans and mollusks. Fifteen species of fish (Mugil cephalus, Apogon sp., Tetraodon fluviatilis, Oreochromis mossambicus, Glossogobius sp., Stolephorus heterolobus, Rhynchorhamphus georgii, Suggrundus macracanthus, Bunaka pinguis, Gerres erythrourus, Leognathus equulus, Anadontostoma chacunda, Sillago sp., Anguilla sp., Pseudotriancanthus strigilifer) constitute 48.39% of the total macrofaunal species.
Crustaceans constitute 32.26%, 40% of which are crabs and 60% are shrimps. Crab species include two species of the family Portunidae (Portunus pelagicus, Scylla serrata, and two species of the Family Grapsidae (Metapograpsus messor and Varuna litterata). The shrimps are composed of three species of the family Penaiedae (Penaeus sp. Penaeus indicus, Penaeus monodon and Metapenaeus ensis) and two species of the family Palaemonidae (Macrobrachium sp. and one unidentified species (Tampal bae). Six species of mollusks (Telescopium telescopium, Terebralia sp, Perna sp., Crassostrea sp., Isognomon ephippium, Nerita communis) were found in the study area.
The frequency per species of fish and crustaceans is low. The size of most of the species is also small. Computed catch per unit effort (CPUE) is also very low. This indicates overfishing in the river.