Spatial and seasonal distribution of the meiofauna in the seagrass posidonia oceanica

Abstract

Distribution and abundance of meiofauna in the seagrass Posidonia oceanica (L.) Delile in Ischia, Gulf of Naples, Italy, was studied during the annual growth cycle of the plant. Changes in habitat complexity are described by examination of macroepiphytic coverage of the leaves, and changes in trophic conditions for meiofauna by Scanning Electron Microscope investigation of bacterial and diatom distributions on the leaves of the plant. Meiofauna density in the leaf region is related to the annual growth rhythm of Posidonia, with maximum densities in September and minima in November, after the leaf fall of the plant. In the stem region numerical density of meiofauna remains high all the year, and fluctuates less drastically than in the leaf region. In the leaf region, harpacticoids and nauplii dominate all the year; an increase in relative abundance of foraminifers, nematodes and polychaetes occures during summer. In the stem region nematodes, harpacticoids and foraminifera constitute most of the meiofauna. © 1982.