Аssessment of surface and water transport impacts on the biological resources of mountain rivers in the national park “Yugyd va”

Direct and indirect impacts of various types of transport such as motor cars, allterrain vehicles and aircushion ships and motor boats on the ichthyofauna and zoobenthos of rivers in the National Park “Yugyd va” are shown. Direct noise impacts produced by boat engines or aircushion ships on fish were not revealed. The model species (European grayling) remained active when feeding even in close proximity to noise-making objects (transport). However, with a boat getting closer, fish stopped feeding and swam away from it independent of the level of the noise produced by the boat engine. When passing across the river, aircushion ship “Khivus” - “The Arctic” produces almost no effect on European grayling's food activities. At the same time in shallow waters with a depth 0.3-0.6 m. the movement of the ship causes turbulent flows directed towards the bed. As a result, water mixing and tearing off algae and moss growing in water- course boulder-pebble soils take place. After the air-cushion ship “Khivus” had passed across the river, the content of biomass of plant residues (primarily fila- mentous alga, occasionally freshwater alga and moss) in bottom invertebrates drift samples increased almost 30 times. As such, bottom invertebrates leave their habitats. The larvae of stone flies, mayflies and chironomids especially sharply response to physical effects produced by the air-cushion ship “Khivus”, after the ship had passed across the river, their number in drift samples in- creased more than 20-100 times. The key factor of negative impact on river zoo- benthos in the areas of unimproved transport crossings is the increased content of suspended substances in the flow after the ship has passed. There is a clearly observed plume of turbid water (1.5-2 km long) along the riverbed. In areas pol- luted by erosion materials reduction in the zoobenthos species diversity and de- crease in number and biomass of invertebrates, the basic objects of fodder base of fishes, is marked. The environmental efficiency of anti-erosion measures - construction of bridge crossings over watercourses - is shown. Restoration of the previously disturbed zoobenthos structure and number in mountain rivers crossed by automobile roads takes 5-6 years after the construction of a bridge crossing.