[Morphological aspect and chemical composition of Skeletonema costatum (Bacillariophyceae) growing in natural nutritive media with the aid of a culture system of dialysing fibers].

The growth of Skeletonema costatum, under natural nutriment conditions, was studied using a bulk culture fiber dialyzing apparatus. The diatom displayed normal development of chain length (average cell number per chain) which coincided with the culture growth stages; that is, the cell number per colony increased during the active division period and decreased thereafter with the beginning of the prestationary phase. This morphological behaviour showed that the alga cells were not affected by such physical shocks as collision or tension occurring during repeated cell transfers from growth chambers to the dialyzing apparatus or at the time of their passage through the fiber fascicles.

Chemosensory grazing by marine calanoid copepods (arthropoda: crustacea).

In laboratory experiments, mixed populations of two marine copepods (Acartia clausi and Eurytemora herdmani) when fed artificial food particles consisting of microcapsules that were either enriched with an encapsulated homogenate of naturally occurring phytoplankton or nonenriched preferentially ingested the enriched capsules. Beads or nonenriched capsules were either seldom ingested or not ingested at all. The observations demonstrate that filter-feeding in these species is a behavioral process, under sensory control, and that the copepods are able to discriminate between enriched and nonenriched food particles.