Long-term effects of extreme weather events and eutrophication on the fish community of shallow Lake Peipsi (Estonia/Russia)

Abstract

The fish kill in lake Peipsi (Estonia/Russia) during the extraordinarily hot summer of 2010 evoked an investigation into the effects of environmental extremes and long-term eutrophication on the fish community of the lake. Current data on lake Peipsi indicate that temperature extremes and synergistic interactions with eutrophication have led to a radical restructuring of the fish community. Commercial landings of lake smelt, <em>Osmerus eperlanus eperlanus</em> m. <em>spirinchus</em> (Pallas), the previous dominant species of the fish community, have decreased dramatically since the 1930s, these declines being coupled with summer heat waves coinciding with low water levels. Gradual decline in smelt stock and catches was significantly related to a decline of near-bottom oxygen conditions and to a decrease in water transparency. The first documented fish kill in 1959 occurred only in the southern, most shallow and eutrophic lake (lake Pihkva). Recently, summer fish kill have become more frequent, involving larger areas of the lake. In addition to the cold-water species, <em>e.g. </em>smelt and vendace <em>Coregonus albula </em>(L.), the abundance of bottom-dwelling fishes such as ruffe <em>Gymnocephalus cernuus</em> (L.) and juvenile fish have significantly decreased after the 2010 heat wave probably due to hypoxia and warm water temperatures. This study showed that fish community structure in large shallow lakes may be very vulnerable to water temperature increases, especially temperature extremes in combination with eutrophication

Climate change impacts on lakes: an integrated ecological perspective based on a multi-faceted approach, with special focus on shallow lakes

“…The harvest of whitefish (Coregonus spp.) has declined substantially in Lake Vät-tern as well as in Lake Peipsi in Estonia (Jeppesen et al, 2012a;Kangur et al, 2007;Kangur et al, 2013). In the UK and Ireland, a decline in the coregonid pollan (Coregonus autumnalis) in recent decades has also been attributed to warming (Harrod et al, 2002).…”

Consequences of size-selective harvesting and changing climate on the pikeperch Sander lucioperca in two large shallow north temperate lakes

“…This collapse has certainly and markedly affected both the development of fisheries and the population dynamics of the pikeperch. Moreover, the smelt populations in large Estonian lakes have also declined to historically low levels (Kangur et al, 2007a(Kangur et al, , 2013a. In such situations, inferior small fish (e.g., ruffe Gymnocephalus cernuus, roach Rutilus rutilus, and white bream Blicca bjoerkna) constitute the most important part of the adult (Kangur et al, 2007c) and juvenile (Ginter et al, 2011) pikeperch diet.…”

“…Pikeperch prefer to prey on slender-body fish such as smelt (Osmerus eperlanus) and vendace (Coregonus albula) when such fish are available in the lake (Pihu, 1966;Kangur, 2000;Kangur et al, 2007c). Vendace was previously an important species in Lake Peipsi both for commercial fisheries and as a prey of pikeperch, but the vendace stock collapsed in the early 1990s (Kangur et al, 2013a). This collapse has certainly and markedly affected both the development of fisheries and the population dynamics of the pikeperch.…”

Weather conditions influencing phosphorus concentration in the growing period in the large shallow Lake Peipsi (Estonia/Russia)

“…Despite being fragmentary, long-term monitoring records of the large shallow body of water that forms Lake Peipsi have been of great importance for understanding those factors affecting the functioning of that lake's ecosystem (Haldna et al, 2008;Kangur and Möls, 2008;Haldna et al, 2013;Kangur et al, 2013). In the present study, we applied advanced statistical methods for Weather conditions influencing phosphorus concentration in the growing period in the large shallow Lake Peipsi (Estonia/Russia) N o n -c o m m e r c i a l u s e o n l y analysing the long-term series of TP to ascertain the roles of water temperature (T), water level (L), mean and maximal wind speed (V, Vmax), and photosynthetically active radiation (PAR) in causing TP anomalies appearing as deviations between observed and predicted TP concentrations.…”