The flora and fauna of Lake Peipsi are rich in species
Lake Peipsi is one of the largest lakes in Europe. The lake has an area of about 3,543 km2, a length of about 135 km, a width of 48 km, an average depth of 8 m, and a maximum depth of 17.6 m [1]. The lake is divided into Lake Peipsi (Suurjärv), Lake Pihkva, and Lake Lämmijärv. The basin of Lake Peipsi covers 47,802 km2 – it is larger than the territory of Estonia, because a large part of the catchment basin is also located on the territory of Russia. More than 200 rivers, streams, and ditches flow into the lake. Water flows out only through the Narva River.
Despite the fact that due to strong waves, Lake Peipsi lacks vegetation in quite large areas on the north-west and north shores, the flora and fauna of Lake Peipsi are still rich in species. 122 species of macrophytes (large plants) have been found in the lake, to which nearly 20 more species can be added which grow in flooded coastal areas. In total, 70% of all Estonian freshwater plant species grow in Lake Peipsi. There are many reed beds, and also the arrowhead, water horsetail, flowering rush, and water-plantain. Several rare aquatic plants also grow in Lake Peipsi, such as the narrowleaf water-plantain, small pondweed, water awlwort, Elatine hydropiper, Potamogeton rutilus, spiny quillwort, and Sparganium gramineum [2].
The algal flora of Lake Peipsi is also rich in species – more than 1,000 phytoplankton taxa have been found, about half of which are diatoms, among which there are also many rare species. Blue-green algae and green algae are also important. Approximately 270 taxa of zooplankton have been found. Rotifers dominate in number, but water fleas and copepods dominate in terms of biomass [3].
More than 400 species of benthic fauna have been found in Lake Peipsi. The most species-rich groups are nonbiting midges, molluscs, and Oligochaeta. Among molluscs, there are many zebra mussels, which is an alien species in Estonia [3].
37 species of fish have been found in Lake Peipsi, in addition one Cyclostomata species – the brook lamprey. Rich fish stocks have shaped life on Lake Peipsi through the centuries. Fishing has been one of the main livelihoods here. The main fish being caught are the European smelt, vendace, pike, zander, perch, bream, burbot, and Peipsi whitefish. The protected species are the grayling, asp, spined loach, weatherfish, wels catfish, and European bullhead [2].
266 bird species have been seen on the shores of Lake Peipsi, of which 180 are hatching birds. 71 species of birds have been found only stopping and feeding on their migration route, and 15 species have ended up here accidentally. Lake Peipsi is a stopping place on their migration route for such bird species as the long-tailed duck, common goldeneye, greater scaup, tufted duck, Eurasian wigeon, goosander, red-breasted merganser, etc. More than a million migratory birds use the lake as a resting place [2].
Amphibians are represented on the shores of Lake Peipsi by nine species: the smooth newt and northern crested newt, garlic toad, common toad, European green toad, common frog, moor frog, pool frog, and common water frog. Of the amphibians living in Estonia, only the natterjack toad does not live in Lake Peipsi or its coastal area [3]. Among the mammals, beavers, otters, muskrats, water shrews, and water voles live in and near Lake Peipsi [2].
The state of Lake Peipsi
The condition of the lake is affected by the actions of the approximately 1 million people living on both the Estonian and Russian sides of the catchment basin in household activities, agriculture, forest management, and other economic activities. The main problem is the eutrophication of the lake, i.e. the enrichment with nutrients (especially phosphorus and nitrogen compounds). Increased nutrients are causing changes in the lake’s ecosystem, the declining of fish stocks, the deterioration of water quality, and also the proliferation of blue-green algae. The seasonal concentration of cyanobacterial toxins in water has repeatedly exceeded the limit value for bathing water [4]. As a result of the proliferation of algae, fish breeding grounds have become muddy and their breeding conditions have deteriorated. There is also an overgrowth of the lower parts of the lake, an increase in the number of bacteria and ciliates, and a decrease in the species diversity of flora and fauna, benthic fauna, and fish [5, 6].
Due to its shallowness, Lake Peipsi is very vulnerable and its ecological status depends not only on human impact, but also on the weather conditions of a particular year [7]. For example, in water-poor years, nutrients are released from the bottom, causing algal blooms. This, in turn, can lead to nocturnal oxygen deprivation and the release of ammonia into the water, leading to fish mortality [8]. Therefore, the assessment of the ecological status of Lake Peipsi should be based on longer-term trends [7].
Another important factor is the crustacean Gmelinoides fasciatus, introduced into the lake in the 1970s, which, as an omnivorous animal, has become a strong dominant in most of the littoral zone and displaced most other large invertebrate species [9].
The status of Lake Peipsi in 2022 was mainly influenced by the higher water temperatures and low water levels. Although the ecological state of Lake Peipsi in 2022 was moderate, the chemical status was poor and due to this, the overall status of Lake Peipsi in 2022 was poor as well [10].
Last modified: 12.11.2021
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[1] EELIS: https://register.keskkonnaportaal.ee/register/body-of-water/8380546
[2] Peipsi järv (2012). Infoleht. Peipsi Infokeskus: https://peipsi.ee/wp-content/uploads/2017/11/peipsi_A5_12-lk_EESTI.pdf
[3] E. Pihu, A. Raukas. 1999. Peipsi. Tallinn. Keskkonnaministeeriumi Info ja Tehnokeskus.
[4] Riigikontroll. 2012. Peipsi järve seisundi parandamise meetmete tulemuslikkus. https://www.kalateave.ee/et/teadus-ja-arendustegevus/uurimused/150-2012-uurimused-arhiiv/1096-riigikontroll-peipsi-jarve-seisundi
[5] Nõukogu direktiivi 91/676/EMÜ, veekogude kaitsmise kohta põllumajandusest lähtuva nitraadireostuse eest, täitmine Eestis 2004-2007. (2008). Tallinn. Keskkonnaministeerium: https://www.digar.ee/arhiiv/et/raamatud/21808
[6] Keskkonnaülevaade 2009. Eesti keskkond. Toimetaja: Karmen Kaukver. Keskkonnaministeeriumi Info- ja Tehnokeskus, 2009. Tallinn: https://www.digar.ee/arhiiv/nlib-digar:54185
[7] O. Tammeorg, L. Tuvikene. 2020. Peipsi järve hüdrobioloogiline seire. Lõpparuanne. Tartu https://kese.envir.ee/kese/downloadReportFile.action?fileUid=22689459&monitoringWorkUid=19093975
[8] E. Kuht. 2006. Õitsev vesi Peipsis hirmutab suplejaid. Virumaa Teataja. https://virumaateataja.postimees.ee/2290039/oitsev-vesi-peipsis-hirmutab-suplejaid
[9] M. Kerr, A. Kovtun-Kante. Eesti pinnaveekogumite seisundi 2020. aasta ajakohastatud vahehinnang. Seletuskiri veemajanduskomisjonile. Tallinn, 2021.
[10] Pinna- ja põhjavee seisund. Keskkonnaagentuur - https://kaur.maps.arcgis.com/apps/MapSeries/index.html?appid=fd27acd277084f2b97eee82891873c41 (17.11.2023)