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A non‐classical biomanipulation experiment in G onghu B ay of L ake T aihu: control of M icrocystis blooms using silver and bighead carp
Author(s) -
Guo Longgen,
Wang Qing,
Xie Ping,
Tao Min,
Zhang Jing,
Niu Yuan,
Ma Zhimei
Publication year - 2015
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/are.12375
Subject(s) - silver carp , bighead carp , biomanipulation , zooplankton , phytoplankton , fishery , plankton , biology , zoology , hypophthalmichthys , eutrophication , environmental science , nutrient , ecology , fish <actinopterygii>
Summary A non‐classical biomanipulation experiment was carried out in G onghu B ay of L ake T aihu in 2009. Silver and bighead carp were stocked in a large fish enclosure to control cyanobacterial blooms. Water quality, plankton abundance, and the intracellular and extracellular microcystins ( MC s) in lake water were investigated monthly in 2009. The concentrations of nitrogen nutrients were significantly lower in the fish enclosure than in the surrounding lake, while phosphorus (especially total phosphorus) concentration was higher in fish enclosure. During the blooming period, C yanophyta contributed to more than 90% of the phytoplankton in the surrounding lake, whereas it represented only 40–80% in the fish enclosure. The phytoplankton and crustacean zooplankton biomasses and the zooplankton/phytoplankton ratios were all significantly lower in the fish enclosure than in the lake. This result suggested that silver and bighead carp can effectively suppress the phytoplankton biomass with the initial stocking density of 7.5 g m −3 for silver carp and 1.1 g m −3 for bighead carp, despite a simultaneous decrease in the grazing pressure of the zooplankton on the phytoplankton. During the blooming period, the intracellular and extracellular MC s in the fish enclosure were reduced by 93.8% and 69.8% compared with the surrounding lake. MC s content varied from 0.34 to 18.8 ng (mean 4.8 ng) MC ‐ LR eqg −1 wet weight in the muscle sample of silver and bighead carp in the experimental enclosure, which suggested that these fish were safe to consume for human. However, the long‐term effects of MC s on aquatic ecosystem and on public health cannot be overlooked.