MODENUTTI Beatriz Estela
Daphnia distribution in Andean Patagonian lakes: Effect of low food quality and fish predation.
E BALSEIRO,; BEATRIZ ESTELA MODENUTTI O BEATRIZ MODENUTTI O B. MODENUTTI; P QUEIMALINOS, CLAUDIA; MARIANA REISSIG,
Lugar: Holanda; Año: 2007 vol. 41 p. 599 - 599
Food quality in terms of carbon (C):phosphorus(P) ratio can constrain the success of highlydemanding P herbivores as Daphnia. North AndeanPatagonian lakes are ultraoligotrophic with lownutrient concentrations and well-developed euphoticzones. We investigated the distribution of the largeDaphnia commutata in relation with food quality(sestonic C:P ratio) and predation risk in these lakes.The predation risk was estimated based on the fishspecies present and their relative eye diameter andtransparency of the lake. The C:P ratios in the lakeswere high, varying from 350 to >1,200. The lakeswith D. commutata had significantly lower C:P ratiothan those without these daphnids. On the other hand,those lakes where Daphnia is present have the lowerpredation risk than those were Daphnia is absent. Inaddition, we carried out growth experiments withneonates and natural seston of three lakes withdifferent C:P ratio. The growth rates were inverselyrelated with C:P of the food. Food quality andpredation risk together determined the success orfailure of large Daphnia populations in these Andeanclear ultraoligotrophic lakes.