|
Oyster reef restoration refers to the process of rebuilding or restoring of oyster reefs all over the globe. Over time, oysters have been negatively affected by environmental change, such as harmful fishing techniques, over harvesting, water pollution, and other factors. The results of these factors have been disease and ultimately, a large decline in the global population of oysters and the prevalence and sustainability of oyster reefs. Apart from the ecological importance of oyster reefs, oyster farming is an important industry, particularly in coastal areas. Both artificial materials and natural components have been used to rebuild the reefs in an attempt to regenerate the oyster population thus fostering the reformation of reefs. == Ecosystem and history == The first stage in an oyster’s life cycle is the free-swimming larval stage. After about three weeks, the larva attaches to a hard substrate—surface area to attach to—such as prop roots, dock pilings, natural rock, and other oysters becoming an oyster spat—oysters that have just settled to the bottom.〔(【引用サイトリンク】title=Oyster Reef Restoration Project )〕 A large number of oysters often join together, thus forming an oyster reef (also referred to as oyster bed, oyster mat).〔(【引用サイトリンク】title=Eastern Oyster (Crassostrea virginica) )〕 Once attached to a surface, oysters will stay there for the remainder of their lives. Oyster beds provide a number of ecological, economical and recreational benefits to the environment. On the Atlantic coast of the United States, the Eastern Oyster acts as a keystone species by filtering estuaries and maintaining healthy coastal ecosystems. In addition to being a keystone species, oysters also serve as an indicator species—they are used to gather information on the overall health of the ecosystem.〔 Since the early Americas, oyster beds have been beneficial for the North American Indians, who harvested oysters for subsistence purposes, and for the European colonists in the region.〔 Since the 19th century oyster beds have been vital for commercial harvests and have generated substantial income.〔(【引用サイトリンク】title=Oyster_reef )〕 However, the majority of oyster populations have greatly declined within the last century due to over-harvesting, dredging, increased sedimentation, invasive species, pollution and disease.〔(【引用サイトリンク】title=NOAA Habitat Conservation | Restoration Center | Restoration Techniques and Monitoring | Oyster Restoration )〕 It is estimated that more than 85% of oyster reefs are gone, making it the most threatened marine habitat in the world.〔()〕 As a result, this has spawned a need for oyster restoration projects in order to revitalize the depleted natural resource of the oyster population.〔 In response to this decline, many oyster restoration projects have been put into place throughout the southeastern United States. The projects develop a long-term strategy of sustained productivity for oyster reefs and restore the ecological role they provide to nearby reef habitats.〔http://main2.carteret.edu/~kemps/files/Oyster%20Gardening%20Manual%20print.pdf〕〔http://www.southalabama.edu/marinesciences/oysterproposal.doc〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oyster reef restoration」の詳細全文を読む スポンサード リンク
|