caa a22 4500 469095776 CHVBK 20180323133030.0 cr unu---uuuuu 170328e19921001xx s 000 0 eng 10.1007/BF00317261 doi (NATIONALLICENCE)springer-10.1007/BF00317261 Food quality effects on life history traits and fitness in the generalist herbivore Daphnia [Elektronische Daten] [Michael Vanni, Winfried Lampert] Summary: Life table experiments were conducted on the generalist suspension feeder Daphnia galeata, using as food the two green algae (Chlorophyta) Scenedesmus acutus and Oocystis lacustris. Oocystis was hypothesized to be a lower quality food because it is convered with a thick sheath, believed to reduce digestibility. Results showed that Oocystis is a lower quality food for Daphnia, but only at relatively low food concentrations (0.15 mg C/L) and not at higher concentrations (1.0 mg C/L). At 0.15 mg C/L, Daphnia intrinsic rate of increase (r) when grown on Oocystis was only half that when grown on Scenedesmus. Daphnia r was similar at 0.15 mg C/L Oocystis and 0.075 mg C/L Scenedesmus, indicating that Daphnia requires twice as much Oocystis as Scenedesmus to achieve the same fitness. Intrinsic rate of increase was lower on Oocystis mainly because age at first reproduction was greatly delayed compared to that on Scenedesmus (13.6 vs 7.3 d). In addition, juvenile growth and survivorship were reduced on Oocystis compared with Scenedesmus. Clutch sizes were similar on the two foods, indicating that once individuals reached adulthood, the two foods were similar in quality. In contrast, at high food concentrations (1.0 mg C/L), the two algae were similar in quality for both juveniles and adults, and r was not significantly different on the two foods. Ingestion and assimilation rate experiments whowed that Daphnia consumes the two algae at identical rates, and that adults assimilate the two algae at similar rates. However, juveniles assimilate Oocystis at much lower rates than Scenedesmus, possibly accounting for reduced juvenile growth and delay in age at maturity at low concentrations. Thus, Daphnia exhibits an ontogenetic shift in its ability to utilize Oocystis, and this can result in "juvenile bottlenecks” in which survival and growth of young age classes are of critical importance in determining population dynamics. Because food quality effects were manifested primarily in juveniles and at low concentrations, food quality effects in nature will depend on phytoplankton abundance and age-structure of Daphnia populations. Springer-Verlag, 1992 Food quality nationallicence Life history nationallicence Fitness nationallicence Daphnia nationallicence Oocystis nationallicence Vanni Michael Max-Planck-Institut für Limnologie, W-2320, Plön, Federal Republic of Germany aut Lampert Winfried Max-Planck-Institut für Limnologie, W-2320, Plön, Federal Republic of Germany aut Oecologia Springer-Verlag 92/1(1992-10-01), 48-57 0029-8549 92:1<48 1992 92 442 https://doi.org/10.1007/BF00317261 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317261 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vanni Michael Max-Planck-Institut für Limnologie, W-2320, Plön, Federal Republic of Germany aut NATIONALLICENCE 700 1- Lampert Winfried Max-Planck-Institut für Limnologie, W-2320, Plön, Federal Republic of Germany aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 92/1(1992-10-01), 48-57 0029-8549 92:1<48 1992 92 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer