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Predation by Damselfly Naiads on Cladoceran Populations: Fluctuating Intensity
Author(s) -
Johnson Dan M.
Publication year - 1973
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934335
Subject(s) - damselfly , predation , odonata , biology , predator , ecology , population , functional response , population density , cladocera , zooplankton , demography , sociology
Ishnura verticalis naiads (Odonata: Zygoptera) were reared among simulated aquatic plants in eight large pools. Simocephalus serrulatus (Crustacea: Cladocera) was the principle prey. The intensity of damselfly predation on Simocephalus was estimated using two independent procedures: (1) a mathematical model predicating the potential density of prey at the end of successive 4—day intervals, and (2) exclosure nets which permit random samples of the prey population to grow, free from predation, during each 4—day interval. Potential densities minus observed density yield estimates of Simocephalus mortality during each interval. These estimates fluctuate dramatically, suggesting an intermittent influence of the predators. Peaks in prey mortality tend to follow periods during which large number of naiads molted. It is hypothesized that changes in feeding behavior associated with developmental phenomena are responsible for fluctuations in the intensity of predation by damselfly naiads.