Widdig, A., and Schlichter D. (2001) Phytoplankton: a significant trophic source for soft corals? Helgol Mar Res 55: 198-211
That's another article worth reading, as it disputes the common belief that Dendronephthya are predominantly herbivores.
Abstract
Histological autoradiographs and biochemical
analyses show that 14C-labelled microalgae (diatoms,
chlorophytes and dinoflagellates) are used by the soft
coral Dendronephthya sp. Digestion of the algae took
place at the point of exit of the pharynx into the coelenteron.
Ingestion and assimilation of the labelled algae depended
on incubation time, cell density, and to a lesser
extent on species-specificity. 14C incorporation into
polysaccharides, proteins, lipids and compounds of low
molecular weight was analysed. The 14C-labelling patterns
of the four classes of substances varied depending
on incubation time and cell density. 14C incorporation
was highest into lipids and proteins. Dissolved labelled
algal metabolites, released during incubation into the
medium, contributed between 4% and 25% to the total
14C activity incorporated. The incorporated microalgae
contributed a maximum of 26% (average of the four species
studied) to the daily organic carbon demand, as calculated
from assimilation rates at natural eucaryotic phytoplankton
densities and a 1 h incubation period. The
calculated contribution to the daily organic carbon demand
decreased after prolonged incubation periods to
about 5% after 3 h and to 1–3% after 9 h. Thus the main
energetic demand of Dendronephthya sp. has to be complemented
by other components of the seston.
