Mechanisms Regulating the Feeding Rate of Daphnia Magna Straus

Abstract

feed in^ regulation h?' the plan ktunir rr11IiL+wri1li Pnpkri 1 7~nffrm war; srtrdied it1 incrrasing r -n r~r e n t~~t i o n s r l i tmcl Ior>ds: Chlnrrllfl r-rrlyoris arid Sort hnronz.vce.~ cermisine. Dirtxt ohr~rraiinn st~~rlies shrrw t h ;~~ Iticdi~le ratc i s propcrrtinr~;il ICI conrclltration of food only belnn. a 'crilic~l COIITI'III~:L t ion'. ;\bnrr this cririrnl val~ut further iricrencc in mnrc~~tr:xtio~~ ol Imrl II,~R little trr ncl rtttrt or1 f~eding rate. Dopknis m-as shosll to ycqulatc rnllr=r.ti(>n . i r~t l i~~~t -s~i o n or lrrnrl I>v dcrre.i<-in^ pun~pin!: n t e and r e j c c~i n~ excess Food from t h r Fnocl Ernow. The :irnol~~tt of food prrqelit in thc aninr:11s' ~L I t prior to an cxprrirnc~~ t alsn nilects feeding clip u i Dnphrrra in foorl susperl.;ions < l h o l~ the critical rr>nrrritratiotl, Krstllts shoii-that xnirl~alh, prefed at n very Iuw r:ite (1110 n~asimutn ratc) rlo, Inr n short time, Yeed nlnrt. rapidly illnr~ those prufrrl a t thc ~r~auinttlni rate. 'l'hcnr results arc colisirlc.terl ill relation to i hnsc oi R~t h e r ;l~u! kiylcr for free-s\\+i.irrlmi~lg Daphnin magna.

Effects of products released by Aphanizomenon flos‐aquae and purified saxitoxin on the movements of Daphnia carinata feeding appendages

“…Elevated rejections are not only a response to excessive food (McMahon and Rigler 1963) and filaments (Burns 1968) or, as previously assumed, the presence of toxic cells in the food groove (Lampert 198 1). Our findings suggest that chemicals in the water play an important role in feeding by Daphnia.…”

The dichotomous oxyregulatory behaviour of the planktonic crustaceanDaphnia magna

“…The decelerating effect of high food concentrations on fA has been known for quite some time (McMahon and Rigler, 1963;Burns, 1968;Porter et al, 1982). Above a critical food Ventilatory parameters…”

“…Several studies have shown that Daphnia spp. exhibits close to maximum appendage beating rates when there is little or no food available, whereas high food concentrations (≥10 4 unicellular algae·ml -1 ) effect a pronounced deceleration of appendage movement (McMahon and Rigler, 1963;Burns, 1968;Porter et al, 1982). Since the latter effect is inevitably associated with a reduction in ventilatory power, and since the oxygen demand increases as a consequence of the activation of digestive processes (Lampert, 1986;Bohrer and Lampert, 1988) despite lower energetic expenditures for appendage movement (Philippova and Postnov, 1988), it is possible that the oxyregulatory responses exhibited under these conditions deviate from those described so far (Paul et al, 1997;Pirow et al, 2001).…”

The importance of the time factor in the response of zooplankton to varying concentrations of naturally occurring particulate matter 1

“…1 are thus in contradiction to what might be expected from the saturation concept of copepod feeding. In fact when time is given to the animals to acclimate to an increase in food supply, they shift their apparent feeding rate up to a physiological maximum which very likely corresponds to the abnormally high saturation level found by McMahon and Rigler (1963) and Frost (1972) with previously starved copepods.…”

“…If food is continuously or regularly available to herbivorous zooplankton, it is unlikely that gut capacity is ever limiting under natural conditions. Such limitation might occur when a large amount of food is ingested rapidly in a short time, as in exposure to plentiful food after starvation, and probably explains the high maximum feeding rates found by McMahon and Rigler (1963Rigler ( , 1965 and Frost (1972).…”