The Turtle Islands, Tawi-tawi

Typical of low-island flora, the Turtle Islands marine macrobenthic flora (large, bottom-dwelling plants) is characterized by low species diversity. The populations are sparsely distributed on the fringing reef and do not form apparent or distinct communities. According to a 1998 report by Filipino seaweed expert Dr. Gavino Trono, algae (seaweeds) grow among the piles of dead coral branches, on dead portions of coral heads and mixed with seagrasses, which form very thin stands on sandy bottoms near the shore. Of the 62 species found in the area, 27 are members of the Chlorophyta (green algae), 22 are Rhodophyta (red algae) and six Phaeophyta (brown algae). The Turtle Islands' flora represents only a little more than one-third of that found at Santiago Island in Bolinao, Pangasinan, which supports 170 species. The seagrass community at the Turtle Islands is represented mainly by the pioneering species such as the Halophila ovalis, Cymodocea rotundata, Halodule pinifolia, H. uninervis and Syringodium isoetifolium. These species colonize small sandy patches near the shore. Intermixed with the seagrasses are some seaweed populations such asHalimeda macroloba, Udotea geppii and Caulerpa serrulata.

Turtle Island in Tawi-tawi

Turtle Island in Tawi-tawi

The seaweed and seagrass populations of the islands appear to be at their seral stages of development. This is shown by the presence of pioneer and ephemeral or opportunistic species. Almost all species have some known economic value. Only those food species, when developed, are likely to be of immediate economic benefit to the local populations, however. These include Caulerpa racemosa, C. lentillifera, and the Kappaphycus alvarezii. G. acerosais a known agar source, while K. alvarezii is a carrageenan source. These last two species are important raw materials for making gel-like desserts. G. acerosa, in particular, appears to have some commercial applications, but it does not seem to occur in the area abundantly enough for commercial harvest and utilization.

Typical of most disturbed low-lying small island ecosystems, the terrestrial flora of the Turtle Island groups namely Boan, Lihiman, Great Bakkungan, Taganak and Baguan is a mosaic of remnants of sea coast or strand vegetation and ornamental and weed species attendant to agricultural and human settlement areas.

                                                  Turtle Islands' vegetation

The vegetation of the islands is typically of limited growth, development and complexity, which is mainly a function of relatively recent geologic age and, more importantly, anthropogenic influence. Typical beach vegetation forms a narrow strip of woodland along the sandy and gravelly shores of the seacoast, gradually giving way to other types of forest formation depending on topography, size of the island and other factors. The principal woody species that occur in the Philippines in general and the Turtle Islands group in particular are Terminalia catappa, Desmodium umbellatum, Pandanus tectorius, Premna serratifolia, P. obtusifolia, Erythrina variegata, Barringtonia asiatica, Thespesia populnea, Hibiscus tiliaceus, Sterculia ceramica, Callphyllum inophyllum, Guettarda speciosa, Xylocarpus moluccensis, Pongamia pinnata and Scaevola frutescens.

Succession may be in more advanced stages in areas that are less influenced by human activity, such as slopes, enclosed area and the sanctuary, as well as in islands with larger areas. This is shown by the presence of pioneering tree species like Macaranga tanarius.

Agricultural crops, ornamental plants and associated weeds in human settlements comprise 60% of the plant species identified in all the islands. It is common practice for residents to propagate plants introduced from outside the Turtle Islands.Most species are widely distributed and no local endemic species have been observed