Intensive increase in oil production in Kazakhstan leads to pollution of air, surface and groundwater,
and through them – of soil and vegetation cover with oil and petroleum products. Pollutants enter the body of
hydrobionts, and then the body of vertebrates with polluted water through the food chain, causing diseases
and their death, thereby reducing the biodiversity of fauna in the oil-producing regions. Tadpoles of frogs are
a convenient object for assessing the state of ecosystems that are susceptible to anthropogenic impact. It is
known that a number of environmental pollutants, including oil hydrocarbons , can cause
morphophysiological disturbances in anuran amphibian larvae, resulting in their death. In this connection, a
study of the chronic effect of water-soluble fraction of oil (WSFO) on the tadpoles of the marsh frog (Rana ridibunda) was conducted.
The eggs of R. ridibunda artificially obtained using hormonal stimulation were incubated in aerated
dechlorinated water at 20±2°C. After reaching Gosner stage 26 tadpoles were divided into 4 groups: control,
0.05 mg/L, 0.5 mg/L, and 1.5 mg/L of WSFO. Each group consisted of 20 L aquaria containing 15 tadpoles.
The experiment continued 60 days. Water changes were made every two days, followed by the addition of
appropriate concentrations of WSFO. Morphometric parameters (weight, snout-vent length (SVL), full body
length), as well as frequency of morphological abnormalities occurrence were studied.
No differencies were observed between tadpoles exposed to 0.05 mg/L of WSFO and control group
for all endpoints of the study. The weight of the tadpoles exposed to 0.5 mg/L and 1.5 mg/L of WSFO was
decreased by 1.4- and 1.7-fold compared to control group, respectively. The SVL and the full body length of
the tadpoles of the experimental groups (0.5 mg/L and 1.5 mg/L) were redused 1.3- and 1.7-fold and 1.3- and
1.6-fold compared to control group, respectively. In addition, a dose-dependent increase in the frequency of
morphological abnormalities was observed. The most common were scoliosis, abnormal gut coiling, oedema
and diamond-shaped body.
Thus, it was shown that the chronic exposure to WSFO suppresses growth and causes morphological
abnormalities in R. ridibunda tadpoles.
Scientific adviser: Doctor of Biological Sciences, Professor Shalakhmetova Т.М.