B. Hansen et al., PARTICLE GRAZING EFFICIENCY AND SPECIFIC GROWTH EFFICIENCY OF THE ROTIFER BRACHIONUS-PLICATILIS (MULLER), Journal of experimental marine biology and ecology, 215(2), 1997, pp. 217-233
A complete particle retention spectrum for the grazing of Brachionus p
licatilis on phyto; plankton of different cell size revealed optimal g
razing on an algae (Tetraselmis suecica) with an equivalent spherical
diameter (ESD) of 8.3 mu m. Furthermore, although grazing sub-optimall
y, the rotifer grazed with an equal efficiency (60%) on two different
algae Rhodomonas baltica (R.b.) and Thalassiosira fluviatilis (T.f.) w
ith equivalent spherical diameters of 6.5 mu m and 12.9 mu m, respecti
vely, when they were offered one algae at a time. These two algal spec
ies were in size positioned symmetrically in the bell shaped curve aro
und the optimal prey size for the rotifers. In mixtures of these two a
lgal species the total grazing on the two algae remained equal regardl
ess of the ratio between the two species in the mixtures. The function
al responses to the two algal species offered separately resulted in s
imilar maximum ingestion (I-max) but different half saturation constan
ts (K-m). In order to describe the growth efficiency for the rotifer,
a 7 day growth experiment with the haptophyte Rhodomonas baltica was c
onducted at 15 degrees C with 7 different food concentrations. The spe
cific growth rate vs. food availability followed Monod kinetics with a
maximum specific growth rate (G(max)) = 0.49 day(-1) and a K-m = 2.25
ppm (R.b. 12 150 ml(-1)). The mean carbon content of the individual r
otifers vs. algal concentration also followed a Monod curve. Body leng
th could be related to carbon by C-(ngC) = 1.06 x 10(-4) L-(mu m)(2.74
). The carbon density of the rotifers were 0.11 pgC mu m(-3). The carb
on yield (specific growth rate vs. specific ingestion rate) was 0.29.
The maintenance food concentration was 1.02 ppm (R.b. 5000 ml(-1)). Th
e rotifer lost 0.22 day(-1) when starved. The high specific growth rat
e and the high saturation food concentrations as well as the high ener
gy requirement during starvation supports the idea that the rotifer fo
llows a life strategy with a fast growth response. (C) 1997 Elsevier S
cience B.V.