Effects of food limitation and temperature on cladocerans from a tropical Brazilian lake |
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Authors: | Taís Cristina Bunioto Marlene Sofia Arcifa |
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Institution: | 1.Faculdade de Filosofia, Ciências e Letras de Ribeir?o Preto, Departamento de Biologia,Universidade de S?o Paulo,Ribeirao Preto,Brazil |
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Abstract: | Food limitation was tested in the laboratory by individual growth and reproduction of two cladoceran species, Ceriodaphnia richardi and Daphnia gessneri, from the shallow tropical Brazilian Lake Monte Alegre. The cladocerans were fed cultivated green alga Scenedesmus spinosus in concentrations of 0.20, 0.10, 0.05, and 0.025 mg C l−1. Higher biomass and growth rates occurred in the two highest-food concentrations; the two lowest ones negatively affected
clutch size and first reproduction. The threshold food concentration is lower than 0.025 mg C l−1 and the incipient limiting level is a value between 0.10 and 0.20 mg C l−1. The largest species, D. gessneri, was more sensitive to low food concentrations. The effects of low and high temperatures (19 and 27°C) were evaluated by
life table experiments with three cladocerans from the lake—Daphnia ambigua, D. gessneri, and Moina micrura—with no food limitation (1 mg C l−1 of S. spinosus). Higher population growth rates for the three species were found at 27°C; better performance in most life table parameters
was observed for the former two species at the highest temperature, D. gessneri being the most sensitive to the lowest temperature. There are indications that temperature is an important abiotic factor
that constrains populations of cladocerans for a short period in winter in the lake, when temperature decreases to 18–19°C.
However, its influence cannot be separated from a biotic factor such as food, whose effect is stronger in the cool season,
when concentrations are lower and contribution of inedible algae is relatively higher. |
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Keywords: | Biomass Life table Ceriodaphnia richardi Daphnia ambigua D gessneri Moina micrura |
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