Leduc, D.; Probert, P. K. (2009). The effect of bacterivorous nematodes on detritus incorporation by macrofaunal detritivores: A study using stable isotope and fatty acid analyses. Journal of experimental marine biology and ecology. 371 (2), 130-139.
Leduc, D.; Probert, P. K.
The effect of bacterivorous nematodes on detritus incorporation by macrofaunal detritivores: A study using stable isotope and fatty acid analyses
Journal of experimental marine biology and ecology
Several studies have investigated the effect of nematodes on microbial
degradation of macrophyte detritus, but little is known about the
potential effect of bacterivorous nematodes on productivity of
macrofaunal detritivores. We investigated the influence of the
bacterivorous nematode Rhabditis (Pellioditis) mediterranea on the
incorporation rate of isotopically-labelled macroalgal detritus by the
amphipod Paramoera chevreuxi in a laboratory microcosm. The fatty acid
composition of amphipods, nematodes, and macroalgal detritus was
characterized to he;p determine the pathway of detritus incorporation
by amphipods. The potential importance of R. mediterranea as a source
of highly unsaturated fatty acids (HUFAs) to higher trophic levels was
We found no clear evidence for an effect of nematodes on the
incorporation rate of fresh macroalgal detritus by amphipods, although
there was some indication that the type of detritus (i.e. the green
Chaetomorpha sp. vs the red Polysiphonia sp.) is important in
determining the nature and extent of the relationship between nematodes
and macrofaunal detritivores. Fatty acid data indicated that nematodes
did not contribute significantly to the diet of amphipods when detritus
was present, and there was no evidence that nematodes affected the
pathway of detritus incorporation by amphipods. Amphipods incorporated
Chaetomorpha sp. detritus about 10 times faster than Polysiphonia sp.
detritus despite the higher C/N ratio and lower HUFA content of the
former. This suggests that other factors, such as the presence of
grazer deterrent compounds, are important in determining the
palatability of macroalgal detritus. Amphipods fed exclusively on
nematodes retained high HUFA levels but suffered high mortality. The
burrowing behaviour of nematodes is suggested as the most likely factor
limiting their availability to predators.
Results suggest a limited interaction between amphipods and
bacterivorous nematodes in detrital food webs. Further experiments are
needed to test the wider applicability of these findings to different
nematode and macrofaunal taxa, and for different types of detritus. (C)
2009 Elsevier B.V. All rights reserved.