Related Experiment Video
Updated: Dec 21, 2025

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading
Published on: March 6, 2014
Do bigheaded carp act as a phosphorus source for phytoplankton in (sub)tropical Chinese reservoirs?
Qiuqi Lin1, Qinghang Chen1, Liang Peng1
1Department of Ecology, Jinan University, Guangzhou, 510632, China.
Abstract:
Stocking of bigheaded carp (mainly Hypophthalmichthys nobilis and H. molitrix) is commonly used in (sub)tropical Chinese reservoirs to control phytoplankton, but with ambiguous results. Whether these carp act as a phosphorus (P) source or sink for phytoplankton is debated. We compared the trophic structures in twenty-three reservoirs with different nutrient concentrations in the flood season (after bigheaded carp introduction) with the dry season (after bigheaded carp harvesting). Fish biomass was positively related to TP, and the slope of the relationship showed no difference between seasons. Bigheaded carp harvesting exceeded the amount introduced, which may explain an observed lower intercept of the relationship and fish biomass to the TP ratio in the dry season. Fish predation pressure on zooplankton (fish: zooplankton biomass ratio as a proxy) was highest in the flood season and increased with TP in both seasons. Accordingly, zooplankton grazing effect on phytoplankton (zooplankton: phytoplankton biomass ratio as a proxy) decreased with fish biomass. Furthermore, both the zooplankton biomass and the zooplankton: phytoplankton biomass ratio were among the lowest reported in the literature for the nutrient range studied. Fish grazing effect on phytoplankton (fish: phytoplankton biomass ratio as a proxy) was also highest in the flood season and decreased with TP in both seasons. Nanoplankton was the dominant phytoplankton group in oligotrophic to mesotrophic reservoirs, while filamentous cyanobacteria dominated in eutrophic reservoirs. Chlorophyll a increased with TP and fish biomass, whereas the yield of chlorophyll a per TP (Chla: TP ratio) increased with fish biomass. Accordingly, both chlorophyll a and the Chla: TP ratio were highest in the flood season. We conclude that bigheaded carp act as P sink at the ecosystem level but as P source for phytoplankton, and enhance the yield of chlorophyll a per TP and thus eutrophication.
More Related Videos
10:28Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
Published on: June 13, 2020
12:24Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout Salvelinus namaycush from Its Prey
Published on: August 29, 2014
Related Concept Videos
Primary Production
The Phosphorus Cycle
Red Algae