Egg viability in the copepod Temora stylifera

Abstract

Estimates of production rate and viability of eggs are reported for Temora stylifera collected in the Bay of Naples (Italy). Complementary observations on rates of fecal pellet and spermatophore production and female longevity were also conducted during the incubations. In situ egg viability was highly variable during the 2 yr of observation, with mean monthly values of <80% of total egg production. Under experimental food‐saturated conditions, the nature and hatching success of eggs were modified depending on type of food. With a dinoflagellate diet (Prorocentrum minimum), the responses of copepods were characterized by maximum production of viable eggs, high female longevity in the presence or absence of males, and low rates of fecal pellet production. The opposite was true with a diatom diet (Thalassiosira rotula), except fecal pellets were produced at a higher rate, showing indirectly that this algae was neither properly assimilated nor transformed into production. Total and mean daily egg production were more or less the same with the two diets, indicating that under poorer food conditions copepods can maximize total egg production but not viability.