Importance of preserving coastal environment.

Currently more than half of the world's population lives within 100 km of the coast and it wil incraes in next 10 years. 80% of marine pollution comes from land-based sources, and in the developing world more than 90% of sewage and 70% of industrial wastes are dumped untreated into surface waters. Why we are not serious about saving the coastal environment? What should be done? What is the alternative for not dumping waste water and even solid waste in the ocean?