Species specific uptake of radio-labelled phytodetritus by benthic meiofauna from the Baltic Sea

Abstract

ABSTRACT:The diatom Skeletonema costatum is one of the dominant phytoplankton species during spring in the northern Baltic Sea. We followed the uptake of radio-labelled S costatum by all major meiofauna species in a laboratory experiment. The uptake of labelled diatom carbon varied greatly among major meiobenthic taxa and anlong species belonging to the same class or phylum. Both total uptake and uptake per unit biomass were by far highest in the ostracod Candona neglecta accounting for 4 6 % of the total meiofauna uptake. The total uptake of I4C was significantly different among all 3 common ostracod species, Candona neglecta taking 10 and 100 times more than Paracyprideis fennica and Heterocypndeis sorbyana respectively. Nematodes accounted for over 40% of the total uptake of 14C in the microcosms, of which 84 % was taken up by large nematode species such as Paracanthonchus spp. Nematodes with similar buccal cavities and of similar size showed surprisingly large differences in the uptake of the radio-labelled material. There seems to be quite strong selection both for and against the diatom among epistrate feeders as well as anlong so-called non-selective deposit feeders Only a small portion of the total meiofauna population was found below 1 cm in the sediment; this was composed almost solely of nematodes. These nematodes assimilated as much I4C per unit biomass as the surface ones did, which contradicts the hypothesis claiming that meiobenthic animals react in 2 ways to phytoplankton sedimentation, with surface feeders directly assimilating sedimented phytoplankton. while subsurface feeders experience a more stable food supply and rely only indirectly on sedirnented phytoplankton KEY WORDS: Pelagic-benthic coupling. Food-web . Meiofauna . 14C radio label

Resource availability and meiofauna in sediment of tropical seagrass beds: Local versus global trends

“…Our rationale for studying taxon rather than species diversity are: (1) the taxonomic limitations of different meiofaunal groups, especially in tropical ecosystems (e.g., about 70% of meiofaunal harpacticoid copepods in these regions are new to science, De Troch, 2001); (2) food preferences and strategies within a specific meiofauna group are far from known. Species-specific food preferences are only documented for a few nematode (e.g., Moens, Verbeeck, de Maeyer, Swings, & Vincx, 1999;Ó lafsson, Modig, & van de Bund, 1999) and copepod species (e.g., Buffan-Dubau & Carman, 2000;De Troch, Steinarsdó ttir, Chepurnov, & Ó lafsson, 2005;Pace & Carman, 1996) and may imply that certain levels of productivity will be used in different ways, i.e., less or more intensive so certain segments of the productivity range will be characterised by lower or higher species diversity. The use of higher taxa may skew the resolution of the diversity trends, however, it is hard to say whether this would consequently result in a hump-shaped relationship between productivity and diversity.…”

An insight into the feeding ecology of deep-sea canyon nematodes — Results from field observations and the first in-situ 13C feeding experiment in the Nazaré Canyon

“…Consequently, providing just diatom-based detritus may be responsible for the attenuated response of the nematode community. In addition, the size of diatom cells may limit the number of diatom-feeding nematodes that are large enough to consume the cells (Olafsson et al, 1999). However, with a small average cell radius of ca.…”

Temporal Variations of Shallow Subtidal Meiofauna in Los Cristianos Bay (Tenerife, Canary Islands, Ne Atlantic Ocean)

“…For example, in subtidal areas, no inequivocal influence of phytoplankton sedimentation on the density and biomass of meiofaunal nematodes was found (HEIP ET AL, 1985, ÓLAFSSON ET AL, 1999. However, SCHRATZBERGER ET AL (2007) showed that populations of the nematode Spilophorella paradoxa that feed on fresh organic material exhibited temporal patterns in their abundance and size distribution.…”