New evidence of the copepod maternal food effects on reproduction

Failure of female reproductive capacity in the copepod Calanus helgolandicu s was related to number and combination of the phytoplankton species in the diets. The maternal food effects were detectable at different levels: fecu ndity, oogenesis and hatching. Fecundity and hatching were normal with two single (ca. Isochrysis galbana and Proracentrum minimum) and one mixed (Pha eodactylum tricornutum + Dunaliella tertiolecta + Pavlova lutherii + I. gal bana + P. minimum) diets. With the single P. lutherii diet, fecundity decre ased, but hatching remained optimal. The daily egg production and hatching rates decreased significantly in females fed the other single P. tricornutu m, D. tertiolecta and mixed (P. tricornutum + D. tertiolecta + P. lutherii + I. galbana) diets, or starved. The fecundity decrease coincided with gona d atresia, which was reversible when P. tricornutum and P. lutherii diets w ere replaced by P. minimum diet. It was irreversible when D. tertiolecta wa s replaced by P. minimum, leading to female sterilization expressed by the deterioration of OS3 and OS2 oocytes, as a function of the feeding duration . We assume that atresia of female gonads was caused by the limitation of e ssential nutrients in food, such as fatty acids, which induced catabolism a nd recycling of yolk reserves and thus, maintenance of gonad integrity and low spawning rates. With the D. tertiolecta diet, abnormally high increase of ornithine concentrations in eggs showed that the ornithine metabolism an d polyamine pathway were affected during oogenesis, leading atresia of oocy tes to be deeply disturbed and followed up by necrosis of the gonads. (C) 2 001 Elsevier Science B.V, All rights reserved.