Highly eutrophicated fishpond – effect of the past nutrient and current high fishstock – results of 20 years of monitoring

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F25173154%3A_____%2F15%3A%230000430" target="_blank" >RIV/25173154:_____/15:#0000430 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Highly eutrophicated fishpond – effect of the past nutrient and current high fishstock – results of 20 years of monitoring

Original language description

Proceeding in: VYMAZAL, J. 2015. 9th International Workshop on Nutrient Cycling and Retention in Natural and Constructed Wetlands. Třeboň. Pp 7. ISBN 978-80-905483-2-9. For centuries, more than 20000 fishponds (man –made shallow lakes) of size <1ha to 490ha form important hydrological system of the inland country Czech Republic. During the 20th century, most of fishponds became eu- to hypertrophic both due to external nutrient loading (agriculture runoff, municipal waste water) and fishery management (fertilizing, feeding). Fish stock and production rose and fish yield reached 1000kg/ha and even more. Mean concentrations of total nitrogen and phosphorus increased form less than 1 to 3mg/l and from 0.05 to 0.3 mg/l, respectively. Fertilizing of fishponds with mineral P stopped in 1970th and was replaced by manure which was reduced from 1990th. Fertilizing of agriculture fields declined in 1990th and waste water treatment plants are constructed. Despite of that fishponds remain heavily eutrophic. High phytoplankton biomass results in reduction of water transparency to less than 0.5m. Size of zooplankton decreased although total biomass of zooplankton remains high. High fish stocks combined with weed fish affect negatively structure of plankton. Internal nutrient loading keeps high trophic level. Regular development of cyanobacteria results in low food chain efficiency which is sometimes compensated for by additional feeding. Data collected during last 20 years from c. 40 fishponds are presented.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

GL - Fishery

OECD FORD branch

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Project

<a href="/en/project/TA04020123" target="_blank" >TA04020123: Technological process of recycling nutrients from the fishpond sediments using suction dredger, integrated station for flocculant dosing and geotextile bags for local application in micro-catchment</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2015

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů