ISSN 10674136, Russian Journal of Ecology, 2011, Vol. 42, No. 4, pp. 339–343. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.R. Koporikov, V.D. Bogdanov, 2011, published in Ekologiya, 2011, No. 4, pp. 309–313.
Burbot larvae passively migrate downstream from
spawning sites to shallow areas of the floodplain
(Evropeitseva, 1946; Meshkov, 1967; Volodin and
Ivanova, 1968; Sorokin, 1976; Pavlov et al., 1981;
Bogdanov, 1989; etc.), where they undergo the second
stage of development involving transition to active
feeding. Their size in this period varies from 3.9 to
9 mm (Pavlov et al., 1981; Sorokin, 1976). In the mid
dle and at the end of this stage, the larvae usually avoid
open waters and areas with strong current, keep near
the surface, and show positive phototaxis (Girsa, 1972;
Pavlov et al., 1981). Earlyjuvenile burbot choose
zones where the water is well warmed (Kjellman and
Miler and Fischer (2004), who studied the foraging
of burbot larvae in Lake Constance, attributed their dis
tribution by depth and along water temperature gradi
ents to movements of copepods and rotifers, which are
the main food objects of this larval stage. According to
Harzevili et al. (2003), burbot larvae kept at relatively
high water temperatures (above
) grow more rap
idly but have higher mortality, while at lower tempera
) their growth is retarded but survival
rate is the highest. These authors conclude that the opti
mum temperature for burbot larvae after transition to
active feeding is
. Burbot larvae are more toler
ant of fluctuations in water temperature, pH, and oxy
gen content than the larvae of other fish species
(Sorokin, 1976). However, strong water acidification
(to pH below 5.5) can result in their retarded develop
ment or even mass mortality (Kjellman and Hudd,
1996; Hudd and Kjellman, 2002).
The purpose of this study was to reveal the distribu
tion patterns of semianadromous burbot larvae at the
second stage of their development in the Lower Ob
floodplain, one of the world’s largest floodplain sys
tems (Fig. 1).
Field studies (2000–2006, 2008) were performed in
a 385km segment of the floodplain between the
Azovskaya Channel and Shchuch’ya River mouth.
Samples were taken at the same sites every year.
The ecological density (Odum, 1986) of burbot lar
vae in their foraging areas was estimated after the end
of their downstream migration from spawning tribu
taries. Samples were taken in the shallow nearbank
zone (with depths of no more than 0.6 m), using a trap
bag made of nylon bolting cloth no. 21 with a 60
cm aperture. The collected larvae were preserved in
4% formaldehyde solution.
The ecological density of the larvae at these sampling
) was calculated by the formula
is catch size, ind.;
is trap movement dis
tance, m; and
is trap width, m.
Sampling stations in larval foraging areas were
grouped with regard to their distance from spawning
tributaries (Fig. 1) and biotope type (Koporikov,
2004). This approach allowed us to single out the indi
vidual effects of the above two factors on the ecological
density of burbot larvae.
By the criterion of biotope type, we distinguished
three basic types of foraging areas characterized by
certain water depth, temperature, vegetation, and bot
tom substrate. They were conditionally named “flood
plain meadow” (FM), “sand–pebble beach,” and
“steep undercut riverbank” (SR). The type “sand–
pebble beach,” in turn, was divided into two subtypes,
with still or flowing water (SB and FB, respectively).
By the criterion of distance from the spawning trib
utary, the foraging areas were divided into four zones
(Fig. 2): (1) the floodplainlake system of a spawning
); (2) nearby floodplain areas lying less
than 30 km downstream of the mouth of the spawning
); (3) mediumdistance foraging areas (
within a 20 to 30km stretch downstream of
(4) distant foraging areas (
) downstream of
mouth of the next spawning tributary.
The indicated lengths of
approximate, because they can vary from year to year
and between different spawning tributaries depending
on specific hydrological conditions in different seg
Spatial and Biotopic Distribution Patterns of Semianadromous Burbot,
L. (Lotidae), Early Larvae in the Lower Ob Floodplain
A. R. Koporikov and V. D. Bogdanov
Institute of Plant and Animal Ecology, Ural Branch, Russian Academy of Sciences, ul. Vos’mogo Marta 202, Yekaterinburg,
620144 Russia; email: Koporikov@mail.ru; Bogdanov@ipae.uran.ru
Received March 4, 2010
: burbot, larvae, feeding, spatial distribution, biotopic distribution, floodplain, Lower Ob River.