Introduction

Organic material produced by primary processes in wetlands, or imported, has various fates: part may be grazed by animals, part may be mechanically destroyed and then decomposed, part may be released into the environment during the life or after the death of primary producers, part may undergo autolysis, part may enter the detritus food chain, part may be sedimented and part may be exported out of the ecosystem. The proportion of organic matter entering these pathways may be very different in various types of wetlands.

The organic matter supports the many different kinds of organisms which feed on it, forming the base of a developed trophic pyramid. In general, it seems to be true that wetlands are typical detritus food chain ecosystems (Odum, 1971). Only relatively few animals consume the plant matter directly. On the other hand, numerous organisms feed on materials pretreated by micro-organisms, on decomposition products, and on micro-organisms carrying out the decomposition. However, qualitative and quantitative data on wetlands about the occurrence of various biota, the trophic pyramids and/or food webs related to the detritus and grazing food chains are still rather scanty. This lack of knowledge is confounded by the extreme diversity and complexity of forms and functions in wetlands.