Successful restoration of a tropical shallow eutrophic lake: Strong bottom­up but weak topdown effects recorded
Zhengwen Liu
Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou, 510632, Guangdong, China
Jinrun Hu
Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou, 510632, Guangdong, China
Ping Zhong
Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou, 510632, Guangdong, China
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Keywords

Lake restoration, Biomanipulation, Implantation of macrophytes, Tropical lake

How to Cite

Liu, Z., Hu, J., & Zhong, P. (2018). Successful restoration of a tropical shallow eutrophic lake: Strong bottom­up but weak topdown effects recorded. Journal of Environmental Pollution, (4). Retrieved from http://scopuseu.com/scopus/index.php/jep/article/view/214
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Abstract

Fish manipulation has been used to restore lakes in the temperate zone. Often strong short­term
cascading effects have been obtained, but the long term­perspectives are less clear. Fish manipulation
methods are far less advanced for warm lakes, and it is debatable whether it is, in fact, possible to
create a trophic cascade in warm lakes due to the dominance and high densities of fast­reproducing
omnivorous fish. However, removal of benthic feeding fish also reduce disturbance of the sediment,
which not only affects the nutrient level but also the concentration of suspended organic and
inorganic matter with enhanced water clarity and potentially better growth conditions for submerged
macrophytes. We conducted a biomanipulation experiment in one of the basins in Chinese Huizhou
West Lake that have remained highly turbid after extensive nutrient loading reduction. Another basin
was used as control (control­treatment pairing design). Removal of a substantial amount of planktibenthivorous
fish was followed by planting of submerged macrophytes and stocking of piscivorous
fish. We found strong and relatively long­lasting effects of the restoration initiative in the form of
substantial improvements in water clarity and major reductions in nutrient concentrations,
particularly total phosphorus, phytoplankton and turbidity, while only minor effects were detected for
crustacean zooplankton grazers occurring in low densities before as well as after the restoration. Our results add importantly to the existing knowledge of restoration of warm lakes and are strongly
relevant, not least in Asia where natural lakes frequently are used extensively for fish production,
often involving massive stocking of benthivorous fish. With a growing economy and development of
more efficient fish production systems, the interest in restoring lakes is increasing world­wide. We
found convincing evidence that fish removal and piscivores stocking combined with transplantation
of submerged macrophytes may have significant effects on water clarity in warm shallow lakes even
if the zooplankton grazing potential remains low, the latter most likely as a result of high predation
on the zooplankton.

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