A quantitative study of reproduction in some species of Ceriodaphnia (Crustacea: Cladocera)

Abstract

The world distribution of species of the genus Ceriodaphnia has been compiled from the literature and is summarised. The nomenclature of C. cornuta is discussed.The present study is based on collections of C. pulchella, C. reticulata, C. megalops and C. laticaudata from the Long Water and the Wick Pond of Hampton Court, Middlesex during the period April 1963 - July 1964. The seasonal variations in the size of parthenogenetic females and of their reproductive capacity were investigated and are recorded. The relationships of egg numbers and egg volumes to body lengths and to the temperature and chlorophyll content of the water are analysed and discussed.The occurrence of sterile eggs in Ceriodaphnia pulchella and C. reticulata during 1963 is recorded. A few details of body size, egg number and egg size of an unidentified species from Malta are given and compared with those of the British species. The results of these recordings and analyses are discussed in relation to the principle of the ecological niche and the idea that size difference is a prerequisiteof cohabitation of species of the same genus. The results are also discussed in the light of those of other authors' work on other cladoceran species.