Functional
responses during the early larval stages of the charal fish Chirostoma
riojai (Pisces: Atherinidae) fed rotifers and cladocerans
J. Morales-Ventura, S. Nandini, S.S.S.
Sarma-2004
Journal of
Applied Ichthyology, 20(5):
417-421
Summary:
Survival during early fish larval stages
depends largely upon the availability of appropriate prey. Studied were the
functional responses from hatching to 6 weeks of age of whitefish
(Charal) (Chirostoma riojai) larvae that were offered selected
rotifers (Brachionus rotundiformis and B. rubens) and
cladocerans (Moina macrocopa and Ceriodaphnia dubia). The
experiments were conducted in a 50 ml medium at a salinity of 2 g L -1. Each treatment used four replicates. Rotifers were introduced at
densities of 0.5, 1, 2, 4, 8 and 16 individuals ml -1 and cladocerans at 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 4.8 and 6.4 individuals ml
-1. Two larvae, previously starved for 2 h, were introduced into
each test jar and allowed to feed for 45 min. The difference between
the initial and final zooplankton density represented prey consumption. C.
riojai larvae showed Type II functional response curves, i.e. they
consumed more zooplankton with increasing prey availability; above a certain
prey density (8-16 individuals ml
-1 in rotifers and 3.2-6.4 individuals ml
-1 in cladocerans) the consumption rate tended to stabilize in most
trials. Results are discussed in relation to aquaculture.
(División de Investigación y Posgrado,
Universidad Nacional Autónoma de México, Campus Iztacala, AP 314, CP
54090, Tlalnepantla, Edo. de México, México, e-mail of S. Nandini:
nandini@servidor.unam.mx)