The Survival Crisis Faced by Coastal Ecosystems In Tropical and Subtropical Areas

Abstract

In tropical and subtropical coastal areas, there are unique ecosystems in which the land hermit crab plays an important roll. Recent land developments have forced them into a survival crisis, particularly around the Okinawan islands in southern Japan.The islands of Okinawa used to be surrounded by cobalt color reef seas and abundant ecosystems, of which the land hermit crabs were at the heart. While still dominant, most of them are now being destroyed by the construction of artificial barriers such as sea walls for roads, and land development.Field surveys have revealed that coastal ecosystems in subtropical seas are facing a survival crisis. The main results can be summarized as follows:(1) The numbers of land hermit crabs that live on coasts with artificial eco-barriers are far less than the numbers living on natural coasts with no artificial eco-barriers.(2) On a coast that contains artificial barriers, the distribution of the land hermit crab population in different age groups does not follow the normal distribution pattern as seen in natural coasts. The natural coast shows a distribution that has the maximum number at breeding age and follows a pattern similar to the Gauss's distribution function.(3) One more important thing that this research has shown is that in developing countries, there are very few small coastal animals, such as land hermit crabs and beach crabs. This is almost certainly due to land development, as almost all of the resort island coasts are now taken up by resort hotels and affluent residences. Their ecosystems may also be facing a crisis similar to that in Okinawa.