Total phosphorus thresholds for regime shifts are nearly equal in subtropical and temperate shallow lakes with moderate depths and areas
Article first published online: 1 APR 2014
© 2014 John Wiley & Sons Ltd
Volume 59, Issue 8, pages 1659–1671, August 2014
How to Cite
Wang, H.-J., Wang, H.-Z., Liang, X.-M. and Wu, S.-K. (2014), Total phosphorus thresholds for regime shifts are nearly equal in subtropical and temperate shallow lakes with moderate depths and areas. Freshwater Biology, 59: 1659–1671. doi: 10.1111/fwb.12372
- Issue published online: 1 JUL 2014
- Article first published online: 1 APR 2014
- Manuscript Accepted: 10 MAR 2014
- National Natural Science Foundation of China. Grant Number: 30900194
- 973 Programs. Grant Numbers: 2008CB418006, 2002CB412309
- Chinese Academy of Sciences. Grant Number: KZCX1-SW-12
- State Key Laboratory of Freshwater Ecology and Biotechnology. Grant Number: 2011FBZ14
- regime shifts;
- subtropical lakes;
- TP thresholds;
- turbidity thresholds
- Published research suggests that the total phosphorus (TP) thresholds for the regime shifts between a clear-water state dominated by submersed macrophytes and a turbid-water state dominated by phytoplankton in shallow lakes vary with forms of lake basins and climates. However, such hypotheses remain untested by direct field evidence. We therefore tested the hypotheses with empirical data from subtropical lakes on the Yangtze floodplain and also from other lakes in temperate to tropical zones.
- TP thresholds were found to vary little at moderate depths, but to decrease notably when depth exceeds a level of probably 3–4 m, and increase sharply when depth is below a level of around 1–2 m.
- TP thresholds were found to be nearly equal in shallow lakes (1–2 m <mean depth <3–4 m; c. 0.1 km2 <area <at least 350 km2) from temperate to subtropical (probably to tropical) zones, being 80–120 mg m−3 for the forward shift from a clear-water state to a turbid-water state and 40–60 mg m−3 for the backward shift.
- The threshold of turbidity for the forward shift was found to be higher than that for the backward shift, amending the previous hypothesis of the equality of turbidity thresholds for both shifts.
- Our findings suggest that according to the subequality of TP thresholds, similar target concentrations for in-lake TP can be set in most shallow lakes world-wide to mitigate eutrophication.