Franco, M.; Soetaert, K.; Costa, M.; Vincx, M.; Vanaverbeke, J. (2008). Uptake of phytodetritus by meiobenthos using 13C labelled diatoms and Phaeocystis in two contrasting sediments from the North Sea. Journal of Experimental Marine Biology and Ecology. 362(1): 1-8.
Meiobenthic uptake of 13C labelled diatom Skeletonema costatum and Prymnesiophyte Phaeocystis was
investigated in permeable and fine grained depositional sediments from the Southern Bight of the North Sea
at different sediment horizons. Both the diatom and Phaeocystis–derived organic matter (OM) cascaded into
meiobenthic biomass in low but similar percentages and label uptake was highest at the upper cm in both
stations. Phaeocystis–derived OM might be as important as diatoms as a food source for the meiobenthos.
Meiobenthic biomass in the coarse sediment was lower than in the fine sediment; however label uptake per
unit of organism carbon was higher. This was explained as an adaptation to an environment where only low
amounts of labile OM are present. In this station, the so-called “stout nematodes” (length to width ratiob15,
[Vanaverbeke, J., Soetaert, K., Vincx, M. 2004a. Changes in morphometric characteristics of nematode
communities during a spring phytoplankton bloom deposition. Mar. Ecol. Prog. Ser. 273, 139–146]) showed
lower uptake compared to the slender nematodes. Therefore their previously reported opportunistic
response to a pulsed food supply must rely then on their life-history characteristics.
In finer sediments Sabatieria showed the highest uptake at the 1–3 cm layer, reflecting migration to the
sediment-water interface to feed on freshly deposited labile OM. Richtersia 13C uptake was fairly low,
indicating the exploitation of another carbon source than the one derived from Skeletonema costatum or
Phaeocystis. Enoploides presented the highest uptake, indicating that these predacious nematodes have
another food source besides meiobenthic preys.
Generally total uptake was low and not nearly sufficient to meet nematode carbon requirements.
