11:45 〜 12:00
[AOS13-11] Anthropogenic impact on the macrobenthic community in a mangrove forest in the Philippines
キーワード：マングローブ、マクロベントス、安定同位体
The macrobenthic community plays an important role in a mangrove forest as an ecosystem engineer and a component of the food web structure. The mangrove forest in tropical areas is a major habitat for the macrobenthic community. Previously, the mangrove forest had been threatened under anthropogenic impacts, and the restoration project had been implemented to recover the mangrove forest. This study aimed to evaluate the anthropogenic impacts on the macrobenthic community. We collected and identified macrobenthic species in the different four habitat types (under natural conditions: (1) natural mangrove forest, (2) natural tidal flat, and under anthropogenic conditions: (3) mono-species mangrove plantation, (4) abandoned aquaculture pond) during rainy and dry seasons in the Batan Bay Estuary in the Philippines, where is more than 90% of natural mangrove had converted into aquaculture pond since the 1980s. We also analyzed carbon and nitrogen stable isotope values to estimate macrobenthic food web structure at each site. The results showed that the anthropogenic sites had a high number of macrobenthic individuals but a low biodiversity index. While the macrobenthic communities in natural condition sites showed high biodiversity index and wide types of food sources. The stable isotope analysis showed simple food sources and simple food web structures in anthropogenic sites. These results implicated that simple environmental conditions which under the anthropogenic impacts (e.g. mono-specific plantation and aquaculture pond construction) simplify macrobenthic communities and their food sources. Our results could suggest that mono-species mangrove plantations may not restore macrobenthic communities to the natural condition. Moreover, the microbenthic community in abandoned aquaculture ponds was not recovered, it needs artificial treatments for restoration, such as raising the surface height.