Long-term dynamics of vegetation cover of Lake Manzherokskoye (Republic of Altai) under high antropogenic load on the reservoir and its basin

Abstract

In the second, third and fifth years after implemented dredging and bottom sediments removal (August 2020, 2021 and 2023), species diversity of aquatic and semi-aquatic vegetation, type and degree of lake Manzherokskoye overgrowth, productivity of dominant species were studied, and the indices of species diversity and saprobity were calculated. Based on literature data, the long-term (almost for 60 years) dynamics of vegetation cover and the features of lake overgrowth were defined. Particular attention was paid to studying water chestnut (Trapa natans), a species included in the Red Book of the Republic of Altai. In the fifth year after dredging, a partial restoration of macrophytes diversity was noted. Further clearing of the lake’s bottom and its shores in 2023 caused the destruction of the floating mats complex and the reduction in the number of floating mats-forming species. In 2023, water chestnut dominated in terms of overgrowth area and price-formation. A massive appearance of polymorphic multi-leaf forms of water chestnut, forming rosettes with 40 or more leaves, occurred. Analysis of the water chestnut population dynamics for a long period (including one after dredging) showed the high potential for self-recovery of this species. In the case of implementation of special measures on mitigation of recreational load impact on the areas of Trapa natans distribution, in the next 5 years the return of the lake importance as its main habitat, and, consequently, the preservation of the natural monument “Lake Manzherokskoye” is expected.

Keywords

• anthropogenic transformation
• water chestnut trapa natans
• productivity
• biodiversity indices