Vertical distribution of epiphytic diatoms in relation to the eelgrass Zostera noltii canopy biomass and height

Abstract

Diatoms make an important contribution to the total primary production in Zostera beds. The study of the vertical distribution of diatoms in the canopy of Zostera noltii Hornemann 1832 and its relationship with the biomass and height of the host species was the goal of this paper.The Z. noltii canopy with a height of 39.2 ± 0.91 cm was divided into eight horizontal layers with a step of 5 cm. The mean biomass of the eelgrass canopy leaves per bottom area was 0.240 ± 0.091 kg dry weight (d.w.) m−2. On the leaves, stems, and rhizomes of Z. noltii, 34 diatom species belonging to 24 genera were found. In terms of relative cell density (43 ± 15.6%) and biomass (57.5 ± 15.2%), Cocconeis scutellum var. scutellum was the dominant species. In different layers of the canopy, the total abundance of diatoms and their biomass on Zostera per unit of its phytomass varied widely from 0.88·105 to 2.95·105 cells g−1 and from 0.24 to 2.10 mg g−1, respectively. The total abundance of diatoms and their biomass on Zostera leaves per bottom area covered by the canopy reached, on average, (54.879 ± 20.675)·106 cells m−2 and 0.332 ± 0.126 g m−2, respectively. The total mass of diatoms averaged 0.046 ± 0.0006% per wet weight of the aboveground part of Zostera. It is suggested that two factors play an important role in the distribution of diatoms in the horizontal layers of the Z. noltii canopy: the amount of the surface area available for settlement and its morphological characteristics.