NIPPONIA No. 42 September 15, 2007


Special Featuresp_star.gifOkinawa’s Beautiful Sea

Okinawa has more than 200 kinds of reef-building corals, and more than 1,000 species of fish. The sea around Okinawa is said to have the greatest concentration of different life forms in the world.

All Okinawan islands are lined with coral reefs, and those reefs are still growing. Some of the islands are little more than coral reefs that grew higher and higher until they reached the surface. Coral reefs define the scenery and the underwater topography of the entire island chain.

Corals grow, die, and then get broken down by the waves, becoming sediments that join in the everlasting reef-making process. They act as breakwaters, protecting the shoreline from the rough open seas. When the waves break over them, the water sprays into the air, dissolving large quantities of oxygen essential for marine creatures. The sheltered, shallow lagoons (called ino-o in the Okinawa dialect) offer ideal conditions for ecosystems that differ depending on the type of lagoon habitat.

Many of the islands have one side washed by the Kuroshio Current, the other side sheltered from it. This results in the development of different types of corals and coral reefs. And the varied underwater topography fosters a variety of subtropical life forms.

Bonito, tuna, manta rays and whale sharks swarm offshore in the Kuroshio Current, and humpback whales breed around the islands. Colorful tropical fish swim among the ever-growing coral colonies that form the boundary between the lagoons and the open sea. Okinawa, a treasure trove of subtropical creatures, has more than 200 species of reef-building corals and more than 1,000 species of fish, with new fish species discovered every year! Divers from other parts of Japan and other parts of the world come throughout the year, drawn by the great variety of marine life and the dramatic sea floor.

The ino-o (lagoons) lying quietly between the shore and the reefs feature seaweed such as grass wrack that creates an ideal habitat for young fish and other small creatures. If you are lucky you may even see a dugong, a herbivorous mammal belonging to the sirenian (“sea cow”) species, which feeds on seaweed.

The coastline has plenty to offer in addition to the coral reefs—a subtropical virgin forest lines the shores of Iriomote Island, mangrove swamps occupy river mouths, and tidal flats and muddy places also form their own local environments. Wetlands protected by the Ramsar Convention host many species in unique ecosystems.

Okinawa’s natural environment is amazing, and all Japanese should make sure that it continues to thrive for future generations to admire.