Seagrass is a general term for marine submerged monocotyledonous flowering plants, which have roots, stems, leaves, flowers, fruits, and seeds. Sea grass can use vascular bundles t o transport gases and nutrients, while conducting sexual reproduction. Thus, sea grasses differ from seaweeds.     According to the categorization framework of Tomlinson (1982), seagrass can be divided into 4 families: the Hydrocharitaceae, Posidoniaceae, Cymodoceaceae, and Zosteraceae, with a total of 13 genera and 66 species.     In Taiwan ’s marine territory, Taiwan Island, the Pratas Island, and neighboring islands (Penghu, Xiaoliuqiu, Green Island, and Kinmen) all have seagrass distribution. Currently, Taiwan has 12 types of seagrass recorded, which accounts for 1/5  of the world ’s total (Ko, 2004; Lin et al., 2005). Seagrass types recorded in Taiwan include: Halophila beccarii, Halophila depcipiens, Halophila ovalis, Thalassia hemprichii, Cymodocea rotund ata, Cymodocea serrulate, Syringodium isoetifolium, Thalassiodendron ciliatum, Halodule pinifolia, Halodule uninervis, Zostera japonica,  Halophila major. Currently, many samples are being identified, waiting to be published.       Seagrass beds are important coastal ecosystems in shallow tropical and temperate marine areas across the globe. They have high productivity and biodiversity because they can prov ide food (Lanyon et al., 1989; Lee et al., 2001), habitats, sanctuary (Fong et al., 2000; Hindell et al., 2000), and incubation places (Bell & Pollard, 1989) for many fish and shrimps, large vertebrates (such as sea turtles and sharks), and benthic invertebrates. Seagrass beds can also protect the coast by settling silt , stabilizing the seabed, preventing coastal erosion, purifying water quality, and improving the visibility of the water. Because seagrass beds can resist waves and tides, they are great natural barriers for protecting the coast, while serving an important ecological function and having economic value.    

      Mangroves are small trees that grow in the muddy areas of tropical or subtropical coastal regions. These plants have developed unique morphological and physiological features to adapt to their habitat environment. Mangroves belong to the family Rhizophoraceae, feature mostly red trunks, are rich in tannic acids, and can be used to make red dye.      Taiwan possesses mangrove forests totaling approximately 938.8 Ha. The forests can be found from the Keelung Bay to the Dapeng Bay and contain 3 families, 6 genera, and 6 species of mangroves: Bruguiera gymnorrhiza (L.) Lamk., Ceriops tagal C.B. Rob., Kandelia obovata Sheue, Liu & Young, Rhizophora stylosa, Avicennia marina and Lumnitzera racemosa Willd.       Mangroves grow in tropical or subtropical regions and are important coastal ecosystems serving important ecological functions. Together with seagrass beds and coral reefs, they a re listed as the three typical marine coastal ecosystems. In addition, mangroves are a critical part of wetland ecosystems, providing the environment needed by marine organisms to grow and develop. Moreover, their leaves are crucial sources of energy. Furthermore, mangroves provide a place for birds to rest and stay during migrations. To humans, mangroves of fer many ecosystem-related functions, such as stabilizing coasts, preventing erosion, purifying water, providing shelter from wind, and reducing the impact of storms and waves. Man groves are the coasts ’ natural protectors, offer important ecological functions, and possess economic value.

Algal reefs are biological and algae-formed reefs. They are formed when coralline algae accumulate calcium carbonate and attract other organisms, after which they slowly evolve int o a unique terrain structure. Coralline algae grow remarkably slowly, increasing approximately 1 cm in thickness every ten years. Coralline algae resemble coral reefs, are highly “productive ” with high biodiversity, and possess a 3D space and porous environment that enable organisms to grow, hide, and forage.      Large-scale algal reefs are distributed across the coasts of Taoyuan City and are mainly found in the intertidal zone between south of the Xiahai River (in Dayuan District) and th e Yongan Fishing Harbor (in Xinwu District). In this intertidal zone, an algae area measuring approximately 7 km long and containing baiyu algal reefs, datan algal reefs, and guanx in algal reefs can be found. Said area is a relatively healthy algal reef area rich in crustose coralline algae (aka. hermatypic coral red algae). Other areas containing crustose c oralline algae (albeit considerably less in number) include Shimen and Sanzhi Districts in New Taipei City, Kenting in Pingtung County, and Sanxiantai and Shanyuan in Taitung Count y.      Animals found around algal reefs include various small fish, crustaceans, shellfish, and polychaeta. Algal reefs also provide shelter for birds and are a place for them to forage and breed. For migratory birds such as anatidae, Chinese egrets, and terns, algal reefs are their main food supply stations and resting places. Most importantly, because living cru stose coralline algae attach themselves to aging calcified algal reefs, they ultimately protect the algae reefs from wave-led erosion, serving the role of protectors in marine ecos ystems.  

    Corals are marine invertebrates classified under the phylum Cnidaria. Their bodies consist of mesoglea sandwiched between two layers of epithelium (i.e., an ectoderm and endoderm ). The ectoderm is where cnidocytes are found. Polyps are the living parts of corals and are the contributors of colonial corals in most corals (e.g., Acropora austere); said colon ial corals are formed by polyps undergoing asexual reproduction. However, solitary corals (e.g., mushroom corals) also exist. When polyps grow, they accumulate calcium carbonate, f orming calcareous bones that in turn become coral reefs.       Corals are found in all parts of Taiwan, including the Northeast Corner, Kenting, Green Island, Orchid Island, Hsiao Liouciou Island, Penghu Islands, Pratas Islands, and Taiping Island. Coral reefs in Taiwan can be divided into two types: non-reefal coral communities and tropical coral reefs. The distribution of corals is determined by climate and ocean cu rrents. Because non-reefal coral communities are exposed to water temperatures lower than those required for reef-building corals to grow, they grow on hard matrix and do not form coral reefs. Non-reefal coral communities are primarily found on rocky shores in Northern Taiwan, the inner seas of Penghu Islands, and the northern seas of Penghu Islands. In cont rast, tropical coral reefs are mainly found in Southern Taiwan, Green Island, Orchid Island, Hsiao Liouciou Island, Penghu Islands, Pratas Islands, and Taiping Island, where temper atures are suitable for corals to grow.       Coral reef ecosystems are the most “productive ” and biologically rich ecosystems in the oceans. Their complex structure and environment provide not only marine life with habitat and food sources, but also coastal residents wit h means of livelihood and for developing marine tourism. Coral reef ecosystems support people ’s livelihood, prevent coastal erosion, reduce the magnitude of severe weather-led waves, and ensure coastal stability.