Life history and feeding habits of the marine nematode, Chromadora macrolaimoides steiner.

Chromadora macrolaimoides Steiner, a free-living nematode present in the aufwuchs assemblages of several marine macrophytes located in North Sea Harbor, Southampton, New York, was isolated from Enteromorpha intestinalis and established in laboratory culture, where its life history and feeding habits were studied. Under the experimental conditions (25 C and 26‰ S) the worm has an average generation time (22 days) and average life span (45 days) similar to other chromadorids which have been studied in the laboratory.Tracer-feeding experiment with P-labelled bacteria, diatoms and chlorophytes indicate selectivity by the worm in both the ingestion and apparent digestion of potential food organisms, with the diatoms and chlorophytes being the preferred foods. Out of a total of 20 species of algae and 14 species of bacteria, two species of diatoms (Nitzschia acicularis and Cylindrotheca closterium) were found which are capable of sustaining indefinite growth. Bacteria-free culture has not been established, however, due to the extreme sensitivity of the worm to antibioties.A comparison of the feeding habits of C. macrolaimoides with Rhabditis marina, another marine nematode fed the same potential food organisms is made, and the influence of selective feeding on the spatial and temporal distribution of marine nematodes is discussed.