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Changes in Internal Phosphorus Loading and Fish Population as Possible Causes of Water Quality Decline in a Shallow, Biomanipulated Lake
Author(s) -
Boros Gergely,
Tátrai István,
György Ágnes Irma,
Vári Ágnes,
Nagy Alex Sándor
Publication year - 2009
Publication title -
international review of hydrobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 1434-2944
DOI - 10.1002/iroh.200811090
Subject(s) - macrophyte , biomanipulation , environmental science , water quality , phosphorus , nutrient , mesocosm , biomass (ecology) , population , fish kill , eutrophication , population dynamics of fisheries , biota , ecology , fish <actinopterygii> , biology , fishery , chemistry , algal bloom , phytoplankton , demography , organic chemistry , sociology
Impacts of internal nutrient loading and the role of biota in phosphorus (P) dynamics were studied in a shallow, hypertrophic, biomanipulated lake. Reduced fish stock resulted in clearing water and the development of a dense submerged vegetation by 2005. However, an abrupt shift occurred in 2007, seven years after the fish manipulation. Simultaneously, water quality deteriorated which became obvious in elevated chlorophyll‐ a concentration in lake water, associated with increased biomass of fish and decay of a previously extended macrophyte cover. There were no significant differences in lake water P concentrations between the two periods (2005–2006 and 2007); however, peaks of different P forms were markedly higher in 2007 than in 2005–2006. At the same time, P content of sediment pore water declined considerably in 2007. Our mesocosm experiment, carried out in the manipulated lake, emphasize the positive role of the dominant fish species (roach) in P regeneration. We suggest that fish manipulation should be carried out every 5 year to maintain clear water conditions permanent, until the total removal of redundant nutrients accumulated in the lake ecosystem. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)