Long-term changes in the water quality and fish community of a large boreal lake affected by rising water temperatures and nutrient-rich sewage discharges – with special emphasis on the European perch

Voutilainen, Ari; Huuskonen, Hannu

doi:10.1051/kmae/2010017

Cited by 7 publications

(7 citation statements)

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“…On the other hand, biomasses of small copepods related positively to chlorophyll a concentration. As nutrient levels in Lake Pyhäselkä have always been quite low indicating oligo-or mesotrophic conditions, despite the high nutrient inputs from municipal and industrial sources especially between the late 1970s and early 1980s (Voutilainen and Huuskonen, 2010), it has been thought that changes in trophic status do not play a leading role in structuring plankton community of Lake Pyhäselkä.…”

Section: Discussionmentioning

confidence: 99%

“…In Lake Mjoesa, for instance, vendace and smelt preyed on Daphnia galeata, not on D. cristata, although the latter one was abundant (Sandlund et al, 1987). The abundance of perch, on the other hand, has clearly increased in Lake Pyhäselkä since the 1970s (Voutilainen and Huuskonen, 2010). As juvenile perch prefer large cladocerans (>799 μm) as food , increase in their abundance will without doubt reflect as strengthened predation pressure on cladocerans.…”

Section: Discussionmentioning

confidence: 99%

“…In years when the nutrient emission had its maximum (1977−1978), the average total phosphorus (TP) and total nitrogen (TN) concentrations in the lake water were 21 and 586 µg·L −1 , respectively. The plants that treat pulp mill effluents from Enocell and municipal sewage from the city of Joensuu were modernised in 1987 and 1992, respectively, which decreased considerably the nutrient loadings into Lake Pyhäselkä in the 1990s and helped the lake to start recovering towards its pristine water quality (Voutilainen and Huuskonen, 2010). Nowadays, the lake is oligotrophic again (TP 11 µg·L and TN 444 µg·L −1 in 2010).…”

Section: > Study Areamentioning

confidence: 99%

“…For a more detailed description of water sampling and analyses see Pietiläinen and Niinioja (2000) and Voutilainen and Huuskonen (2010). Analyses of phytoplankton primary production (standard SFS 3049) and chlorophyll a concentration (SFS 5772) have been carried out continuously since 1973 and 1977, respectively.…”

Section: > Sampling Proceduresmentioning

confidence: 99%

“…We wanted to use expressly the SOM clustering because the data in question have proven to be too complex for many conventional methods. Previous to the present study we have managed to analyse the data in scattered parts (e.g., Voutilainen and Huuskonen, 2010) but never as a coherent set. The SOM allowed as to project more complicated hypotheses and to build a matrix which included entire data.…”

Section: Introductionmentioning

confidence: 99%

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Analysing a large dataset on long-term monitoring of water quality and plankton with the SOM clustering

Voutilainen

Rahkola-Sorsa

Parviainen

et al. 2012

Knowl. Managt. Aquatic Ecosyst.

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Key-words:boreal lake, chlorophyll, phytoplankton, Self-Organizing map, water temperature, zooplanktonThe Self-Organizing Map (SOM) proved to be the method of choice for analysing a large heterogeneous ecological dataset. In addition to distributing the data into clusters, the SOM enabled hunting for correlations between the data components. This revealed logical and plausible relationships between and within the environment and groups of organisms. The main conclusions derived from the results were: (i) the structure of early summer plankton community significantly differed from that of late summer community in Lake Pyhäselkä and (ii) plankton community in late summer was characterized by two functional groups. The first group was formed mainly by phytoplankton, rotifers, and small cladocerans, such as Bosmina spp., and driven by water temperature. The second group was formed by small copepods and the abundant generalist herbivorous cladocerans Daphnia cristata and Limnosida frontosa, which, in turn, associated with chlorophyll a concentration. Biomasses of Bosmina spp. and D. cristata showed decreasing monotonic trends during a 20-year study period supposedly due to oligotrophication. Versatile possibilities to cluster data and hunt for correlations between data components offered by the SOM decisively helped to reveal associations across the original variables and draw conclusions. The results would have been undetectable solely on the basis of unorganised values. RÉSUMÉAnalyse d'un large ensemble de données de surveillance à long terme de la qualité de l'eau et du plancton par classification SOM Mots-clés :lac boréal, phytoplancton, carte auto-organisatrice, La carte d'auto-organisation (SOM) s'est avérée être la méthode de choix pour l'analyse d'un large ensemble de données hétérogènes écologiques. En plus de distribuer les données en grappes, la SOM permet la recherche de corrélations entre les composantes des données. Cette étude a révélé des relations logiques et plausibles entre et au sein de l'environnement et des groupes d'organismes. Les principales conclusions tirées des résultats étaient les suivantes : (i) la structure de la communauté planctonique du début de l'été diffère significativement de celle de la communauté de fin de l'été dans le lac Pyhäselkä et (ii) la communauté planctonique en fin d'été a été marquée par deux groupes fonctionnels. Le premier

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: > Study Areamentioning

confidence: 99%

Section: > Sampling Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysing a large dataset on long-term monitoring of water quality and plankton with the SOM clustering

Voutilainen

Rahkola-Sorsa

Parviainen

et al. 2012

Knowl. Managt. Aquatic Ecosyst.

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Impacts of climate warming on the long-term dynamics of key fish species in 24 European lakes

et al. 2012

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10.1007/s10750-012-1182-1Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. form, nor will it be during the first three months after its submission to Hydrobiologia."Corresponding author: Erik Jeppesen (ej@dmu.dk)We dedicate this paper to the late Prof. Jürgen Benndorf, a true pioneer and mentor in lake and reservoir management oriented research, who inspired a number of us to initiate longterm comprehensive experimental ecological studies on lakes and reservoirs. AbstractFish play a key role in the trophic dynamics of lakes. With climate warming, complex changes in fish assemblage structure may be expected owing to direct effects of temperature and indirect effects operating through eutrophication, water level changes, stratification and salinisation. We reviewed published and new long-term (10-100 years) fish data series from 24 European lakes (area: 0.04-5648 km 2 ; mean depth: 1-177m; a north-south gradient from 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 4 Sweden to Spain). Along with an annual temperature increase of about 0.15-0.3 °C per decade profound changes have occurred in either fish assemblage composition, body size and/or age structure during recent decades and a shift towards higher dominance of eurythermal species.These shifts have occurred despite a reduction in nutrient loading in many of the lakes that should have benefited the larger-sized individuals and the fish species typically inhabiting cold-water, low-nutrient lakes. The cold-stenothermic Arctic charr has been particularly affected and its abundance has decreased in the majority of the lakes where its presence was recorded. The harvest of cool-stenothermal trout has decreased substantially in two southern lakes. Vendace, whitefish and smelt show a different response depending on lake depth and latitude. Perch has apparently been stimulated in the north, with stronger year classes in warm years, but its abundance has declined in the southern Lake Maggiore, Italy. Where introduced, roach seems to take advantage of the higher temperature after years of low population densities. Eurythermal species such as common bream, pike-perch and/or shad are apparently on the increase in several of the lakes. The response of fish to the warming has been surprisingly strong and fast in recent decades, making them ideal sentinels for detecting and documenting climate-induced modifications of freshwater ecosystems.

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The hub of the wheel or hitchhikers? The potential influence of large avian herbivores on other trophic levels in wetland ecosystems

et al. 2023

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Goose and swan populations have increased concurrently with environmental degradation of wetlands, such as eutrophication, vegetation losses, and decrease in biodiversity. An important question is whether geese and swans contribute to such changes or if they instead benefit from them. We collected data from 37 wetlands in southern Sweden April − July 2021 to study relationships between geese, swans and other waterbird guilds, macrophytes, invertebrates, as well as physical and water chemistry variables. Neither goose nor swan abundance was negatively correlated with other trophic levels (abundance, richness, or cover). On the contrary, goose or swan abundances were positively related to abundances of surface and benthic feeding waterbirds, cover of specific macrophytes, and to invertebrate richness and abundance. Moreover, invertebrates (number of taxa or abundance) were positively associated with abundance of several waterbird guilds and total phosphorous with surface feeders, whereas water colour was positively (surface feeders) or negatively (benthic feeders) related. We conclude that waterbirds are more abundant in productive wetlands and that geese and swans do not show clear deleterious effects on other trophic levels included in this study. However, patterns may be masked at the species level, which should be addressed in further studies, complemented with experimental studies of grazing impact.

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Long-term changes in the water quality and fish community of a large boreal lake affected by rising water temperatures and nutrient-rich sewage discharges – with special emphasis on the European perch

Cited by 7 publications

References 39 publications

Analysing a large dataset on long-term monitoring of water quality and plankton with the SOM clustering

Analysing a large dataset on long-term monitoring of water quality and plankton with the SOM clustering

Impacts of climate warming on the long-term dynamics of key fish species in 24 European lakes

The hub of the wheel or hitchhikers? The potential influence of large avian herbivores on other trophic levels in wetland ecosystems

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