Seagrass cover and associated macrobenthic marine invertebrates in Southern Philippines

Abstract

In Southern Philippines where coastal research is scarce and hindered by safety and security concerns, the present study on seagrass assessment and its associated macroinvertebrates is imperative for resource conservation and management. The study was conducted in 19 seagrass sites across 18 coastal municipalities spanning the seagrass beds in the Southern Philippines. The results identified eight seagrasses with Thalassia hemprichii, Enhalus acoroides, and Cymodocea rotundata as the most frequent species. Seagrass cover ranged from 26.50 (fair) to 91.30% (very good conditions), highest in Sitangkai and lowest in Tubig Indangan, Simunul. In six sites, the seagrass was below good quality (fair). Forty-eight (48) macroinvertebrate species, represented by five phyla, were recorded in the seagrass sites. The highest total number of species is the Mollusks (26). The sea urchin Diadema setosum was the species with the highest density (0.1327 ind/m²), while the prevalence of commercial-important species was observed, like conch shells (Canarium, Strombus, Lambis). Thirteen sites are recorded with high macroinvertebrate diversity values (> 2). Tubig Indangan, Simunul had the highest dominance value, which is attributed to the high density of Trepneustes gratilla. The loss of seagrass habitat would equate to great economic losses through the risk of their different ecological and economic functions. This study provides novel baseline information about the status of the tropical seagrasses in Southern Philipines and the region of Mindanao, as well as the invertebrate communities they host, which is essential to establishing adequate management practices.