Phytoplankton associations in a small hypertrophic fishpond in East Hungary during a change from bottom-up to top-down control

Borics, Gábor and Grigorszky, István and Szabó, Sándor and Padisák, Judit (2000) Phytoplankton associations in a small hypertrophic fishpond in East Hungary during a change from bottom-up to top-down control. In: 11th Workshop of the International-Association-of-Phytoplankton-Taxonomy-and-Ecology (IAP), 1998. augusztus 15-23., SHREWSBURY, ENGLAND.

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Phytoplankton species composition and abundance of a shallow hypertrophic fishpond (Mézeshegyi-tó, East Hungary) was studied for the period 1992–1995. The pond showed a pronounced algal periodicity. High-diversity phytoplankton assemblages occurred in spring and autumn. During the winter period, low diversity values were related either to stable community states, when K-strategist species dominated the plankton, or to a large bloom of r-strategist species. In summer, the stable environment led to low-diversity, high-biomass phytoplankton assemblages, dominated by Cylindrospermopsis raciborskii. At this time, the growth conditions for Cylindrospermopsis were akin to those prevailing in a continuous fermentor. The overwhelming dominance of this species lasted for more than four months, during which time, the phytoplankton resembled that of one in the tropics. In August, 1993, an unsuccessful chemical treatment for reducing the algal bloom succeeded in killing the pond’s entire population of fish. The large fish-stock comprised the planktivorous silver carp. Although the summer of 1994 was one of the warmest summers of this century, the expected Cylindrospermopsis bloom failed to develop probably because of a higher grazing pressure by large zooplankton. In spite of the fact that the temporal and spatial pattern of the phytoplankton is influenced principally by bottom-up effects, changes in cascading trophic interactions may also considerably influence the species composition and biomass.

Item Type: Conference or Workshop Item (Paper)
Subjects: Q Science / természettudomány > QE Geology / földtudományok > QE08 Hydrosphere. Hydrology / hidroszféra, hidrológia
Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia
Q Science / természettudomány > QK Botany / növénytan
Depositing User: Erika Bilicsi
Date Deposited: 06 Nov 2012 14:25
Last Modified: 06 Nov 2012 14:28

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