In situ determinations of bacterial selectivity and filtration rates by five cladoceran zooplankters in a hypertrophic subtropical reservoir |
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Authors: | Hart, R.C. Jarvis, A.C. |
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Affiliation: | Department of Zoology and Entomology, University of Natal PO Box 375, Pietermaritzburg 3200 1Sastech PO Box 1, Sasolburg 9570, South Africa 2Authors listed alphabetically |
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Abstract: | Cladoceran in situ feeding rates on natural bacteria labelledwith [methyl-3H] were studied in parallel with feeding ratedeterminations on 14C-labelled Chlorella in a hypertrophic subtropicalreservoir (Lake Hartbeespoort) through spring and summer (1986/87).Community filtration rates (CFR5) on bacteria and algae weresimilar, but selection for Chlorella (relative to natural bacteria)increased from midsummer in association with declining bacterialdensity and increasing dominance of inedible componentsof the natural phytoplankton. Species-specific filtration rates(SSFRs) were determined for Daphnia pulexllongispina, Ceriodaphniareticulata, Diaphanosoma excisum, Bosmina longirostris and Moinamicrura during their respective seasonal occurrence in the studyperiod. SSFRs on algae and bacteria increased with body length(L, mm) in all species apart from Bosmina. Species-specificdifferences in absolute feeding rate (FR, ml animal1day1), the slope of the FR-L relationship and bacteriaselectivity were evident. The feeding rate of all cladoceranson bacteria is described by the power equation FR 5.231L1.42FR values on bacteria relative to FR values on algae averaged |
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