Seasonal Abundance of the Exotic Predatory Cladoceran, Bythotrephes Cederstroemi, in Western Lake Erie

摘要: The predaceous cladoceran, Bythotrephes cederstroemi, has recently invaded the Great Lakes and basic information on its seasonal abundance population demographics is lacking. Accordingly, we examined variation in abundance, length—weight relationships, fecundity, ontogeny of lateral spine production, sex ratio, incidence resting vs. subitaneous eggs. Seasonal these parameters was compared with water temperature presence a potential competitor, Leptodora kindti. Specimens for analyses were collected nocturnal surface tows western basin Lake Erie during summer fall, 1987. did not appear until 23 July, had maximum (111 individuals/m3) at night 9 October, persisted lower numbers samples through last sampling date, 14 December. correlation body weight tail length varies seasonally, individuals weighing less than fall. Neonates possess one pair spines add each first two molts, enabling determination instar distribution. Females produce to 12 eggs per brood, males occurring rarely. negatively correlated suggesting that or temperature, both, affect success Erie.