The mangrove, seagrass and coral reef ecosystems are of paramount ecological importance but have already undergone great degradation, which is advancing at an alarming rate. If present trends continue, the natural resource basis of the economy and ecology of tropical coastal regions will soon be ruined. This was the unanimous conclusion of the 110 scientists from 23 countries who gathered in Mombasa, Kenya, for a Symposium on the ecology of these ecosystems.
Mangrove forest systems yield large amounts of fish, crabs, prawns and oysters. They are also valuable sources of fuelwood, timber, tannin and other natural products. Their non-marketable value is of equal importance: stabilization of the coastline, an indispensable nursery ground for numerous marine species with commercial value, a natural filter maintaining the clarity of nearshore water, a home for resident and migratory birds and other wildlife. Many of the true mangrove flora and fauna are now endangered by the clearing of the mangroves. It has been shown that in many countries between 25 and 100% of the mangrove forest has been destroyed alraedy in the last twenty years.
The international scientific assembly concluded that much can be done to stop the degradation of these damaged ecosystems and to rehabilitate them. But new techniques must be found to use them on a sustainable basis for long-term economic return and for the well-being of coastal human settlements and a healthy environment.

Zusammenfassung
Proceedings of the International Symposium held at Mombasa, Kenya, September 24-30, 1990

Inhalt
Status, Primary Productivity and Taxonomy of Mangroves, Seagrasses and Algae.- Developing management plans for the mangrove forest reserves of mainland Tanzania.- Structure and species distribution in Coringa mangrove forest, Godavari Delta, Andhra Pradesh, India.- Structural properties of two types of mangrove stands on the northwestern coast of Sri Lanka.- The current status of mangroves along the Kenyan coast: a case study of Mida Creek mangroves based on remote sensing.- Net primary productivity of two mangrove forest stands on the northwestern coast of Sri Lanka.- The effect of coastline changes on mangrove community structure, Portuguese Island, Mozambique.- The seagrass and associated macroalgal vegetation of Gazi Bay (Kenya).- Microphytoplankton of the Pitchavaram mangals, southeast coast of India: species composition and population density.- Users of the Mangals.- The ecology of Belizean mangrove-root fouling communities: patterns of epibiont distribution and abundance, and effects on root growth.- The meiobenthos of five mangrove vegetation types in Gazi Bay, Kenya.- Ecomorpholy of Crassostrea cucullata (Born, 1778) (Ostreidae) in a mangrove creek (Gazi, Kenya).- A note on the zooplankton distribution and diversity in a tropical mangrove creek system, Gazi, Kenya.- Coral Reef Ecosystems.- Phase shifts in coral reef communities and their ecological significance.- The incidence of hurricanes on the north coast ofJamaica since 1870: are the classic reef descriptions atypical?.- Importance of the Lac-lagoon (Bonaire, Netherlands Antilles) for a selected number of reef fish species.- Chemical and Physical Processes.- Hydrodynamics of mangrove swamps and their coastal waters.- Intratidal fluctuations in stratification within a mangrove estuary.- Physical processes in the Rufiji delta and their possible implications on the mangrove ecosystem.- Diurnal variation in physical-chemical properties and primary production in the interconnected marine, mangrove and freshwater biotopes of Kakinada coast, Andhra Pradesh, India.- Methanogenic bacteria in mangrove sediments.- Fishery Biology and Mariculture.- Mangroves as a habitat for fish and prawns.- Mariculture development in Kenya: alternatives to siting ponds in the mangrove ecosystem.- The effect of oocytic atresia on fecundity estimates of the rabbit fish Siganus sutor (Pisces: Siganidae) of Kenyan marine inshore waters.- Differences in biomass production and carrageenan yields among four strains of farmed carrageenophytes in Northern Bohol, Philippines.- Exploitation, Conservation and Management Aspects.- Status and exploitation on the mangrove and associated fishery resources in Zanzibar.- The management of Insular Caribbean mangroves in relation to site location and community type.- Regeneration strategy of mangroves along the Kenyan coast: a first approach.- Impact of past management practices on the present status of the Muthupet mangrove ecosystem.