We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
In situ determinations of bacterial selectivity and filtration rates by five cladoceran zooplankters in a hypertrophic subtropical reservoir.
- Authors
Hart, R.C.; Jarvis, A.C.
- Abstract
Cladoceran feeding rates on natural bacteria labelled with [methyl-H] were studied in parallel with feeding rate determinations on C-labelled Chlorella in a hypertrophic subtropical reservoir (Lake Hartbeespoort) through spring and summer (1986/87). Community filtration rates (CFR5) on bacteria and algae were similar, but selection for (relative to natural bacteria) increased from midsummer in association with declining bacterial density and increasing dominance of ‘inedible’ components of the natural phytoplankton. Species-specific filtration rates (SSFRs) were determined for and during their respective seasonal occurrence in the study period. SSFRs on algae and bacteria increased with body length (, mm) in all species apart from . Species-specific differences in absolute feeding rate (FR, ml animal day), the slope of the FR- relationship and bacteria selectivity were evident. The feeding rate of all cladocerans on bacteria is described by the power equation FR 5.231 FR values on bacteria relative to FR values on algae averaged ∼60% overall for all size classes of , with ranges of 70–85, 58–79, 34–63 and 50–117% in various body length classes of and, respectively. Size dependency was evident in certain taxa. Selectivity coefficients (SCs) were ∼2 on average, indicating algal preferences in all taxa apart from , whose SC was ∼1 (unselective feeding). Food selectivity was independent of grazer size in and , but algal preference increased with body size in and particularly. Estimates indicate that bacteria contribute relatively little (≤3%) of the total dietary carbon intake of cladoceran zooplankters in Lake Hartbeespoort. thus challenging earlier views that bacteria are major dietary components of the summer grazer community in eutrophic waters. The findings are discussed in relation to other recent studies of freshwater zooplankton feeding ecology.
- Publication
Journal of Plankton Research, 1993, Vol 15, Issue 3, p295
- ISSN
0142-7873
- Publication type
Article