The Importance of Primary Inhabitants in Soft-Bottom Community Organization

Abstract

A biological community is organized by interspecific interactions among many species. The interactions form the structure of community through two main organizing systems, i.e., trophic and habitation systems. Habitation system consists of colonizers' classes graded by intensity of influences on environments. The primary inhabitant includes two types having opposit-directing influence to environments. As an example for destabilizer, one of them, thalassinid shrimps have been known. A removal experiment of the shrimps was conducted during over 2 years in Yamada Bay tidal flat, Japan. The results with obscure influences of the shrimps suggested the importance of combined effects with physical stresses. Another type of primary inhabitants was stabilizer like seagrasses. In a pure stand of Syringodium isoetifolium in Fiji, it was indicated that a huge biomass of filter-feeders was supported by the existence of a seagrass canopy. Through these considerations, mechanisms of community organization combined among functional groups, filter-feeders, deposit-feeders, symbionts, etc., were discussed.