Use of visual and echo sounding surveys: case study of submerged aquatic vegetation of lake Kenon (Eastern Transbaikalia)

Abstract

The paper presents the results of studying of the aquatic vegetation of Lake Kenon based on the integrated use of traditional methods of visual survey with an echo sounding. The use of echo sounding surveys makes it possible to study better the features of the distribution of submerged aquatic plants. It allows you to speed up the process of sampling in the field, and also facilitates office processing of the received data. Based on the measurement results, a bathymetric map was built, and the boundaries and areas of dominant phytocenoses were determined. It was revealed that at present the total area of thickets is 489 hectares, which is 33 % of the lake area. The maximum depth of plant growth was 5.1 m. The data obtained is higher than the percentage of overgrowth in 1993, but lower than the values for the 70s and 80s. At present, as in previous years, Chara algae are leading in terms of overgrowing area. The decrease in the distribution area of Nitella flexilis and Potamogeton crispus was revealed.