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ISSN Druckformat: 0018-8166
ISSN Online: 1943-5991
Indexed in
Influence of the Daylight Duration and Water Temperature on Numbers and Demographic Composition of Population of Polyphemus pediculus (Crustacea: Cladocera)
ABSTRAKT
Numbers, demographic composition and ratio of sexes in P. pediculus population are affected by absolute value and vector variation of the daylight duration. Different types of specimens display their maximal numbers under different environmental conditions. Photoperiodic reaction of crustaceans belongs to a long-day type. Maximum population development and parthenogenetic females predomination are observed in a limited daylight duration range, from 15.5 to 17.5 hours per day. The daylight duration of 14 hours per day is a threshold, the beginning of mass transition into the dormant state. Period with the daylight duration 12 hours per day and less is unfavorable for the population.