Introduction

Abstract

The coral reef communities constitute one of the most important ecosystems on our Planet. The main feature of coral reef ecosystems is their extremely high productivity. The photo-synthetic production in reef communities attains 5–20 gm^-2 of organic carbon or 50–200g of wet biomass, it being actually independent of the nutrient concentration in surrounding waters. Primary production in coral reef ecosystems remains permanently high, while in other productive marine ecosystems — be it in pelagic communities of upwelling regions or in coastal shelf communities of the temperate zone — a high productivity (2–5 gCm^-2 day^-1) is attained only periodically. An extremely high autotrophic production of coral reefs, which is based on the three-dimensional structure of their bottom biotopes, supports the existence of unusually dense communities of zoobenthos and fish. Their biomass reaches on reefs hundreds of grams per 1 m^-2. The fish resources of reefs comprise a significant portion of their total stock in the World Ocean — about 9% — and fishery in reef areas is an important source of protein in the rations of the population in tropical coastal countries. The export of organic matter and combined nitrogen from coral reefs significantly enhances productivity of surrounding oceanic waters. Reefs are also the place of propagation and juvenile growth of many pelagic fish species important for fishery.