Community structure and spatial variation of meiobenthic animal groups associated with artificial low-crested facility

Abstract

The community structure of meiobenthos were studied in the tidal-flat near the study site in Iwon and Hogokri tidal-flat were carried out in May and August, 2002. A total of 12 meiofaunal groups were found in the study area in Iwon. Nematodes were the most dominant among the meiofaunal groups as a whole. The total density of meiobenthos at each stations was 418 ~ 1,886 inds./10㎠ in the tidal flat of the study area in Iwon. As the sediment depth increase, the density of meiobenthos in each station decrease gradually. The change of meifaunal density in the study area were mainly occur in sediment surface (0~1cm). Generally, the density of nematodes was increased, and the density of another dominant meiofaunal group (benthic harpacticoids, nauplius of crustacean, benthic foraminiferans etc.) was decreased near the sediment trap against the control site of sediment trap during the period of spring to summer. Based on the results of cluster and MDS plots, meiofaunal community was changed by construction of artificial low-crested wood groin facility. In Hogok-ri tidal flat, a total of 14 major meiofaunal taxa, including Copepoda nauplius, were recorded. At all stations during the all sampling time, nematodes, sarcomastigophorans and harpacticoids were observed. Much higher densities of meiobenthic animals, for instance 11,318 inds./10㎠ in May and 9,710 inds./10㎠ in Apr 2000, were observed in intertidal habitats where reed forests were developed, while only 100~200 inds./10㎠ were observed in in adjacent sand dune habitats, which showed reed forests provided advantageous environments to the habitat of meiobenthos. Nematodes first immigrated into new artificial habitats at Hogok Ri. Benthic harpacticoids were second in occurrence to nematodes which already showed maturation and reproduction. After a certain period, the foraminiferans showed rapid increase in density, then became the most predominant group. Depth distributional extension according to density increase was