Lake Ladoga ecosystem

• Category: Inland Aquatic Biomes.
• Geographic Location: Europe.
• Summary: This large Russian freshwater lake has high primary productivity and is known for its wide variety of fish and a native inland seal species.

A freshwater lake in northwest Russia, Lake Ladoga is the largest lake in Europe, with a surface water area of 6,908 square miles (17,891 square kilometers) and a volume of 201 cubic miles (837 cubic kilometers). The lake is home to about 660 islands with a combined total land area of 168 square miles (435 square kilometers), including the Valaam Archipelago. Several of the islands, such as Kilpola, are large enough to contain lakes themselves.

Lake Ladoga is part of the Neva River catchment; it is sited in a generally flat, low-lying, and marshy region. There are tens of thousands of much smaller lakes and ponds throughout the area, in many cases linked by some of the thousands of rivers and streams. Three such rivers are the main inlets of water to Lake Ladoga. The Vuoksi River flows in from Finland to the west; the Volkhov River flows in from the south; and largest of all, the Svir River, flows in from the east.

The Neva River drains Lake Ladoga, sending waters to the Gulf of Finland and thence to the Baltic Sea. The lake is part of both the Volga-Baltic Waterway and the White Sea-Baltic Canal system; by a series of navigable natural rivers, lakes, and manmade canals, this network links the Baltic, the Arctic Ocean, and the Caspian Sea—a fact that has brought about opportunities for many species to migrate and settle into new habitats, with some impacts both negative and beneficial to various plants and animals.

Lake Ladoga has generally strong layering in its water column, with warm surface temperatures developing seasonally, but a benthic or deepwater layer that stays in the range of 34–39 degrees Fahrenheit (1–4 degrees Celsius) year-round.

Biodiversity

The Ladoga ecosystem is home to a wide variety of fish—some 48 species, including an endemic (found nowhere else) species of smelt, and the endangered European sea sturgeon, usually found in saltwater and brackish coastal regions. The caviar trade was one of the contributing factors to the sturgeon’s endangerment, and overfishing in general has been a problem in Lake Ladoga in the past. Commercial fishing in the lake has declined considerably because of overfishing early in the 20th century. Fish farms and recreational fishing remain widespread. Roach, carp, bream, European perch, ruffe, and salmon are among the leading types of fish in the lake. Lake whitefish dwell quite comfortably in the colder waters of the central lake portion—except for the Valaam whitefish, an endemic species that prefers the southern shallows.

The Ladoga seal, a subspecies of the ringed seal, is a hallmark endemic animal in the lake. As one of the extremely few freshwater seals on Earth, the population of this pinniped was decimated in the 20th century; highly protected now, the few thousand members of the Ladoga seal community are still jeopardized by side-effects of industrial fishing and shipping, as well as poaching.

Muskrat, beaver, river otter, and flying squirrel are quite numerous along the shores, on the many islands, and in the reedy wetlands in the fringe areas of the lake. As the core freshwater feature of the region, the Lake Ladoga biome also supports elk, sika deer, wild boar, brown bear, European lynx, pine marten, red fox, and European wolf in the bogs and woodlands around the lake proper.

At least 250 identified bird species dwell or migrate through the Lake Ladoga biome. Swamps along the east and south of the lake attract golden plover, jack snipe, redshank, curlew, black-tailed godwit, and osprey. Shorebirds in particular find nesting zones across the southern portion of the lake, where the three main tributary rivers have their mouths. Rails, terns, gulls, ducks, and grebes congregate here—and must remain vigilant under the hungry eyes of osprey, marsh harrier, and white-tailed sea eagle.

The shallow areas of the lake offer favorable reed and rush stands for crustaceans and mollusks. Through a succession of mud flats, fens, and wet meadows, these habitats transition to the typical shrub meadows and mixed coniferous-deciduous forests.

Threats and Conservation

Ladoga is a eutrophic lake: Excessive nutrients have led to extremely high primary productivity, that is, the production of organic compounds from carbon dioxide, principally through photosynthesis—in this case, by the lake’s algae. This productivity hurts water quality and reduces the amount of dissolved oxygen—a key factor in marine health, particularly for marine fauna and microfauna. Pollution in general, while improved in the last ten years, still harms the lake. Since the 1970s the lake has experienced elevated nutrient concentrations, its trophic state changing to mesotrophic. The total concentration of phosphorus has also risen, increasing 2-5 fold since the 1960s.

Climate change is in evidence here, as spring temperatures have been arriving earlier—with potential stress delivered to the region’s food chain through altered plant germination schedules; changes in migratory bird arrivals, breeding and hatching patterns; uneven availability of nutrients and natural fertilizers; and related factors. These impacts will require many species, both flora and fauna, to adapt and/or migrate elsewhere.

The Nizhnesvirsky Nature Reserve is a 161-square-mile (416-square-kilometer) reserve established by the former Soviet Union and given its highest level of protection: zapovednost, a term that doesn’t translate well into English, but amounts to a nature reserve intended to be kept forever wild, with human use restricted to limited amounts of scientific research or educational display. (The term zapovednik refers both to the nature reserve itself and to the staff assigned to manage and protect it.)

Nizhnesvirsky occupies the eastern shore of Lake Ladoga, covered principally in the same Scotch pine as many of the islands, and is home to many of the migratory birds that stop to feed and drink from the lake’s waters. The presence and size of the untouched reserve—nearly as much land as there is in Lake Ladoga’s islands—are important features of the ecosystem.

Bibliography

Anokhin, V.M. et al. "Current State and Problems of Anthropogenic Transformation of the Ecosystem of Lake Ladoga in a Changing Climate." Russian Academy of Sciences, Sept. 2021. DOI: 10.12731/978-5-907366-50-3. Accessed 6 Nov. 2024.

Kudersky, Leonid K., Juha Jurvelius, Markku Kaukoranta, Pekka Tuunainen, and Kyosti Makinen. “Fishery of Lake Ladoga: Past, Present, and Future.” Hydrobiologia 322, nos. 1–3 (1996).

Pozdnyakov, Dmitry V.; et al. “Multi-year Satellite Observations of Lake Ladoga's Biogeochemical Dynamics in Relation to the Lake's Trophic Status.” Journal of Great Lakes Research, vol. 39 no. 1, 2013, pp 34-45, doi.org/10.1016/j.jglr.2013.05.002. Accessed 6 Nov. 2024.

Rukhovets, Leonid and Nikolai Filatov. Ladoga and Onego: Great European Lakes. New York: Springer, 2009.

Saarnisto, Matti and Tuulikki Gronlund. “Shoreline Displacement of Lake Ladoga: New Data from Kilpolansaari.” Hydrobiologia 322, nos. 1–3 (1996).

Sparks, T. H., F. Bairlein, J. G. Bojarinova, O. Huppop, E. A. Lehikoinen, K. Rainio, L. V. Sokolov, and D. Walker. “Examining the Total Arrival Distribution of Migratory Birds.” Global Change Biology 11 (2005).