Analysis of environmental problems, assessment and prediction are closely related to the study of populations of widespread animal species, in our case, of mollusk Arianta arbustorum (Linnæus, 1758), mass invasion of which is known for the Leningrad region and in St. Petersburg since the second half of the 2000 years. The concentration of heavy metals (HM) in snail's hepatopancreas was measured on an atomic absorption spectrophotometer and an atomic emission spectrometer using inductively coupled plasma emission. In order to monitor accumulated anthropogenic pollution in the parks on the coast of the Neva bay the thermoresistance of snails from various coastal biotopes was studied. The rate of decrease in heart rate (HR) after switching off the heat exposure (lasting for 20 minutes) was compared in snails from the village of New Ropsha (reference location) and other locations: Alexandria Park, Oranienbaum Park, Dubki Park. According to the accumulation of HM in the snail's hepatopancreas, in Oranienbaum Park significant (p ≤ 0.05) excess for all studied HM (Cu, Mn, Zn, Ni, Cd, Pb) was found in comparison with the reference location in the village of New Ropsha and with other locations. The potential environmental risk determined according to Hakanson in Oranienbaum Park was rated as high. The thermoresistance of snails from this location contaminated with HM is characterized as low, which suggests a possible violation of the protective system of heat shock proteins. This may reduce their ability to restore heat-denatured proteins, including contractile proteins of the heart, which usually leads to a rapid drop in HR in mollusks from polluted sites.