Composition, distribution and biomass of meiobenthos in the Oosterschelde estuary (SW Netherlands)

Abstract

Meiofauna composition, abundance, biomass, distribution and diversity were investigated for 31 stations in summer. The sampling covered the whole Oosterschelde and comparisons between the subtidalintertidal and between the western-central -eastern compartment were made .Meiofauna had a community density ranging between 200 and 17500 ind 10 cm -2, corresponding to a dry weight of 0 .2 and 8 .4 gm-2 . Abundance ranged between 130 and 17 200 ind 10 CM-2 for nematodes and between 10 and 1600 ind 10 cm -2 for copepods . Dry weight biomass of these taxa was between 0 .5-7 .0 gm-2 and 0 .008-0 .3 gm -2 for nematodes and copepods respectively .The meiofauna was strongly dominated by the nematodes (36-99%), who's abundance, biomass and diversity were significantly higher intertidally than subtidally and significantly higher in the eastern part than in the western part . High numbers were positively correlated with the percentage silt and negatively with the median grain size of the sand fraction . The abundance and diversity of the copepods were highest in the subtidal, but their biomass showed an inverse trend being highest on the tidal flats .The taxa diversity of the meiofauna community and species diversity of both the nematodes and the copepods were higher in subtidal stations than on tidal flats . In the subtidal, the meiofauna and copepod diversity decreased from west to east, whereas nematode diversity increased .The vertical profile clearly reflected the sediment characteristics and could be explained by local hydrodynamic conditions . Seasonal variation was pronounced for the different taxa with peak abundance in spring, summer or autumn and minimun abundance in winter .Changes in tidal amplitude and current velocity enhanced by the storm-surge barrier will alter the meiofauna community structure . As a result meiofauna will become more important in terms of density and biomass, mainly due to increasing numbers of nematodes, increasing bioturbation, nutrient mineralisation and sustaining bacterial growth . A general decrease in meiofauna diversity is predicted . The number of copepods is expected to decrease and interstitial species will be replaced by epibenthic species, the latter being more important in terms of biomass and as food for the epibenthic macrofauna and fishes .

Spatial distribution of subtidal Nematoda communities along the salinity gradient in southern European estuaries

“…Nematode density values were similar to those found in communities living in subtidal sediments of northern European estuaries, but the number of genera was relatively lower (Smol et al, 1994;Soetaert et al, 1994). On the other hand, nematode density was lower than in intertidal sediments which are often more diverse (Soetaert et al, 1994(Soetaert et al, , 1995Steyaert et al, 2003).…”

“…Warwick and Gee, 1984;Heip et al, 1985;Li and Vincx, 1993;Smol et al, 1994;Steyaert et al, 2003;RzeznikOrignac et al, 2003). There is a notorious imbalance between the northern European systems, relatively well studied, and the southern ones, which are insufficiently described (Soetaert et al, 1995;Adã o, 2004).…”

The relationship between sandy beach nematodes and environmental characteristics in two Brazilian sandy beaches (Guanabara Bay, Rio de Janeiro)

“…For some Sabatieria species such as S. punctata and S. celtica, the contribution of fine sediments seems to be much more important (Vanreusel 1991), but surprisingly this genus was not found in the LTL of Bananal Beach where a high percentage of fine sediments was found. Smol et al (1994) also reported this genus from sites with less than 5% silt. Perhaps its presence is related to the degree of pollution of the bay.…”

Trophic structure of free-living nematodes in the Saigon River, Vietnam

“…Most specifically, from 168.7 to 1602.6 inds/10 cm² in harbor stations in Italy [18]; 454.0±289.9 -3137.7±337.1 inds/10 cm² in the Mekong estuaries [5]; and 67-1666 inds/10 cm 2 in the Westerschelde [19]; 317-1002 inds/10 cm² in Shin River, Kasuga River, and Tsumeta River in Takamatsu, Japan [20]. However, nematode densities in the Saigon River were lower than that in the Oosterschelde [21] with values of 100-7100 inds/10 cm² or five European estuaries [22] with values from 130-14500 inds/10 cm².…”