Feeding rate inhibition in crowded Daphnia pulex

Abstract

Feeding rates of Daphniapulex fed a range of levels of the alga Chlamydomonas reinhardi af 15 "C are strongly density-dependent. At lower densities, Daphnia (30 1-l) fed at higher rates than crowded (270 1-l) Daphnia which manifest a relatively depressed saturation feeding response. At 30 individuals/liter, Daphnia consumed 8.5 -15.7 x 104 cells d-'h-l (on a volume basis, 12.1 -22.2 x lo6 pm3), at 270 L-r 3.7 -3.9 x lo4 (5.2 -5.5 = lo6 pm3 cells d-'h-l when feeding on algae at 80000 cells ml-' (11.3 x lo6 pm3 ml-'). The feeding rate data best fit an Ivlev feeding function. An "autoallelopath" might be causing the repression. Water preconditioned with crowded Daphnia comnletely repressed feeding in uncrowded Daphnia after six hours.

Impact of algae and their concentrations on the reproduction and longevity of cladocerans

“…However, the reproductive values they recorded were 2.6 times lower than the ones we recorded. One consideration is that they tested eight specimens in 50 mL water, and density of specimens is a major variable because D. pulex shows high algae ingestion when cultivated at low densities and the opposite when cultivated at high densities (Helgen 1987). Since high ingestion can produce better growth and fecundity rates (Sanders et al 1996), differences in results between both reports may have resulted from differences in the density of specimens per container, as shown by Cox et al (1992) and Guisande (1993) using the related D. magna species.…”

Functional response and potential impact of invertebrate predators on benthic fish eggs: analysis of the Calliopius laeviusculus-capeWn (Mallotus villosus) predator-prey system

“…Contact water from the copepod Epischura navadensis inhibited the feeding rate of the copepod, Diaptomus tyrelli (Folt & Goldman 1981); Folt (1986) found reduced feeding rates in high density Diaptomus; Daphnia hyalina cultured in water from high density D. hyalina or D. cucullata produced fewer eggs (suggesting lower feeding rates) compared with egg production by D. hyalina in lake water only (Seitz 1984). Helgen (1987) speculated that either prey mortality, or a substance released by invertebrates directly, could trigger the reduction in feeding rate observed in these studies. Since, in our experimental system, water exchange was allowed between low and high egg density containers, a reduction in feeding rate due either to high egg mortality, or to satiation in amphipods exposed to high egg densities, could have inhibited amphipod feeding in low egg density containers.…”

“…However, we found no evidence that amphipods continued to feed for more than 8 h at these lower egg densities. There is growing interest in, and evidence of, allelopathic interactions in zooplankton (Helgen 1987). Contact water from the copepod Epischura navadensis inhibited the feeding rate of the copepod, Diaptomus tyrelli (Folt & Goldman 1981); Folt (1986) found reduced feeding rates in high density Diaptomus; Daphnia hyalina cultured in water from high density D. hyalina or D. cucullata produced fewer eggs (suggesting lower feeding rates) compared with egg production by D. hyalina in lake water only (Seitz 1984).…”

Specificity of crowding response that induces sexuality in the rotifer Brachionus

“…Crowding in laboratory populations of cladocerans and rotifers can affect feeding, growth, age at first reproduction, and fecundity. In many of these cases, the positive or negative effects of crowding are attributable to unidentified chemicals produced by the population (Seitz 1984;Helgen 1987;Matveev 1993;Goser and Ratte 1994;Burns 1995Burns , 2000Kirk 1998;Yoshinaga et al 1999;Mitchell and Carvalho 2002). In addition, crowding provides a stimulus for the initiation of bisexual reproduction in both Daphnia (Stross and Hill 1965) and Brachionus (Gilbert 1963a(Gilbert , 2002Hino and Hirano 1976;Snell and Boyer 1988).…”