The use of high protein microalgae obtained by increasing the content of nitrate in the culture medium is recommended to improve the performance of broodstock, larvae and juveniles in bivalve hatchery. However, the effect of these concentrations of nitrate on the composition of fatty acids in microalgae is not known and it is relevant to assess possible changes in its nutritional properties for filtering bivalves. The results of nitrate increase in Isochrysis aff. galbana (clone T-Iso) showed that in the high nitrate medium, T-Iso is high in protein and carbohydrate and low in ash, and also exhibits higher values of polyunsaturated fatty acids (PUFA), especially n-3PUFA. The best culture medium for Tetraselmis suecica would also be the one high in nitrate because of it is high in protein and lipid and low in ash, although the best values PUFA were observed in the standard nitrate medium. T-Iso was characterized by its tendency to increase the level of n-3 PUFA with the increase of nitrate, while T.suecica was characterized by no effect of nitrate on the contents of n-3 PUFA of the cells nor a PUFA pattern related to the increase or decrease of nitrate.

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Histology and mucous histochemistry of the integument and body wall of a marine polychaete worm,Ophryotrochan. sp. (Annelida: Dorvilleidae) associated with Steelhead trout cage sites on the south coast of Newfoundland. A new species of polychaete (Ophryotrochan. sp. (Annelida: Dorvilleidae)) was identified from sediment below Steelhead trout cages on the south coast of Newfoundland, Canada. The organisms were observed to produce a network of mucus in which groups of individuals would reside. Questions regarding the nature and cellular source of the mucus were addressed in this study. Samples of worms were taken from below cages and transported to the laboratory where individuals were fixed for histological study of the cuticle and associated mucus histochemistry. The body wall was organized into segments with an outer cuticle that stained strongly for acid mucopolysaccharides. The epidermis was thin and supported by loose fibrous connective tissue layers. Channels separating individual segments were lined with cells staining positive for Alcian blue. Mucoid cellular secretions appeared thick and viscous, strongly staining with Alcian blue and Periodic Acid Schiff Reagent. It was noted that lateral channels were connected via a second channel running through the anterior/posterior axis. The role of mucus secretion is discussed.