Abstract
The algal record from Lake Ringsjön covers a period of more than 100 years. Towards the end of the 19th century, the lake had a well-functioning commercial fishery, when a brownish mess began to appear in the water, clogging-up the fishing nets and making fishing difficult. This was the first record of algal problems in the lake. Following complaints from the fishermen, the algal flora was investigated and the mess was stated to be a mass development of diatoms belonging to the genus Melosira ( Aulacoseira). Diatom maxima then appeared regularly in spring and autumn, whereas blue-green algae only occurred occasionally and in low abundances. Between 1900 and 1950, nutrient concentrations slowly increased in the lake. Algal blooms of Anabaena lemmermannii and Gloeotrichia echinulata began to appear in summer. Between 1960 and 1980, the lake developed into a hypertrophic status with extensive blooms of blue-green algae from May to October, including high biomasses of mainly Microcystis spp. This severe pollution started with increased usage of the lake, increased tourism and recreation, intensified farming with the introduction of artificial fertilization, and also the diversion of sewage water from a sewage treatment plant. In 1968, cattle death was reported and in 1981, algal toxicity was verified by mouse bioassay. After a period of extremely poor water quality, the lake began to show signs of improvement as a result of the nutrient and fish reduction programmes. The very heavy blooms of blue-green algae decreased and the duration of blooms became shorter. The Microcystis species were to a certain extent replaced by Anabaena and Aphanizomenon species, and biodiversity of algae increased. With respect to the algal community, the lake has improved considerably, but is still eutrophic and suffers summer blooms of toxic blue-green algae.
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References
Andersson, A., 1948. Näringstillgång och planktonutveckling i några skånska sjöar. Vattenhygien 4: 9–21.
Bergman, E., 1999. Changes in the nutrient load and lake water chemistry in Lake Ringsjön, southern Sweden, from 1966 to 1996. Hydrobiologia 404: 9–18.
Bergman, E. & E. Bergstrand, 1999. Lack of a top-down effect on the zooplankton community after a cyprinid fish reduction. Hydrobiologia 404: 77–87.
Björk, S. & U. Lettervall, 1968. Bolmen-Lagan-Ringsjön. Resultat från en 2-årig limnologisk undersökning i samband med projektering för Skånes framtida vattenförsörjning. Sydvatten. Limnologiska Institutionen, Lund, Sweden (In Swedish).
Cleve-Euler, A., 1938. Våra sjöars Melosira-plankton. Bot. notiser 4: 143–163.
Cronberg, G., 1982. Phytoplankton changes in lake Trummen induced by restoration. Folia limnol. scand. 18: 1–119.
Cronberg, G., 1983. Ringsjöområdet ekosystem i förändring. Förändringar i Ringsjöarnas växtplankton under 1900-talet. Institute of Limnology. University of Lund, 56 pp (In Swedish).
Hamrin, S. F., 1999. Planning and execution of the fish reduction in Lake Ringsjön. Hydrobiologia 404: 59–63.
Hansson, L.-A., M. Enell & E. Bergman, 1999. Lake Ringsjön: its catchment area, its history and its importance. Hydrobiologia 404: 1–7.
Lemmermann, E., 1904. Das Plankton schwedischer Gewässer. Arkiv för Botanik 2: 1–209.
Lundh, A., 1951. Studies on the vegetation and hydrochemistry of Scanian lakes. Bot. notiser 3: 1–137.
Skulberg, O., 1979. Giftvirkning av blågrönnalger-första tillfälle av forgiftning i Norge. Temarapport 4 NIVA.
Trybom, F., 1888. Bottenprof från svenska insjöar. Geol. Fören. i Stockholm Förhandl. 10: 491–497 (In Swedish).
Trybom, F., 1893. Ringsjön i Malmöhuslän dess naturförhållande och fiske. Medd. Kongl. Lantbruksstyr. 4: 14–42 (In Swedish).
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Cronberg, G. Qualitative and quantitative investigations of phytoplankton in Lake Ringsjön, Scania, Sweden. Hydrobiologia 404, 27–40 (1999). https://doi.org/10.1023/A:1003757504155
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DOI: https://doi.org/10.1023/A:1003757504155