Lena River Delta (Russia)

Abstract

The Lena delta is one of the world’s largest river deltas (32,000 km²) with average annual discharge of 513 km³, 6,500 km of distributaries and about 30,000 lakes (predominantly of thermokarst and erosion origin). Mires consist mostly of vast areas of bogs with low-centered polygons and rarely, hillocky string bogs. Rivers, lakes, and bogs are normally interconnected by means of shallow tributaries and runoff troughs at the time of high water and spring to form a unified wetland complex. The coastal area abounds in small bays, while its lowest areas hold salty water lagoon lakes and foreland meadows. In coastal waters, materials washed away and carried over by distributaries have formed 0.5–5.0 m deep sandbars. The number of species of higher vascular plants, Bryopsida, lichens, fish, birds, and mammals is estimated at 316, 95, 51, 109, and 29 respectively. The endemic Salvelinus jakuticus inhabits the delta. Some species are presented by several ecological forms, e.g., four forms of the muksun Coregonus muksun are identified to occupy various ecological niches and have marked morphological differences. In 1985, the state natural zapovednik “Ust-Lenskyi” was established with a total area of 14,330 km². The delta has been included in the Ramsar shadow list. Being a place of fish reproduction and fattening, it supports the long-term viability of significant populations or stocks of the Siberian sturgeon Acipenser baeri and 12 salmonid species. Fishing technologies applied currently in the area are accompanied by mass take of the whitebait. The salmonid harvest has decreased 2.5 times from the 1940s up to the late 1970s.