Influence of nutrition on fecundity and survival in Tigriopus fulvus Fischer (Copepoda: Harpacticoida)

Abstract

In aquaculture, the availability of highly nutritive and inexpensive live food is a subject of major concern; from this point of view, some harpacticoid copepods (gen. Tigriopus) are suitable, owing to both the ease of finding in nature and their constant reproduction in culture. In order to optimize the production of nauplii in Tigriopus fulvus Fischer (a species cultured for several years in our laboratory and considered because of its high occurrence in rockpools along the Ligurian coast), the influence of diet composition on some reproductive and developmental parameters was analyzed under laboratory controlled conditions. Two series of cultured females born in culture and acclimatized in the laboratory for several weeks (> 10) were fed with algae ( Monochrisis lutheri) and yeast ( Saccharomyces cerevisiae), respectively; another series of females born in culture and acclimatized in the laboratory for only one week was fed with yeast. Results show that the diet affected survival and fecundity. Yeast-fed copepods showed better survival (median 71.5 and 75 days) than those fed algae (median 35 days) ( P < 0.01). A highly significant difference ( P < 0.01) was observed for the reproductive period with a high incidence of infertile females (28.15%) in the series fed M. lutheri. Lower production rate was recorded in yeast-fed (generally less than 4 nauplii per day) than in algae-fed (over 5 nauplii per day) specimens; nevertheless, yeast-fed copepods showed a more prolonged production of nauplii in time with a consequent higher nauplii per day global amount. No difference was observed between the differently acclimatized yeast-fed series. Overall, a short reproductive period along with fast production of nauplii was observed in algae-fed T. fulvus females; on the other hand, a slower production, although more durable and abundant, was recorded in yeast-fed copepods. Both results should be of interest in aquaculture in order to obtain live food for commercial fish and crustaceans culture.