Dr. Haijun WANG (left) and Academician Jiankang LIU and Prof. Hongzhu WANG 

In January 2009, Academic Degrees Committee of Hubei Provincial People’s Government and Hubei Provincial Department of Education announced the results of 2008 Hubei excellent dissertations, among which 109 papers were ranked as excellent doctoral dissertations. The paper “Predictive Limnological Researches on Small-To Medium-Sized Lakes along the Mid-Lower Yangtze River”, written by Dr. Haijun WANG from the Research Group of Benthology at IHB was ranked as one of 2008 Hubei excellent doctoral dissertations.  

The Yangtze flood plain is one of the most important wetlands of the world. Over the past few decades, many lakes in this region have suffered from a variety of problems including fishery over exploitation and man-made eutrophication. The basis for solving these problems is to establish a general and quantitative platform of lake ecosystem management.  

Though mostly in the traditional limnology, scholars often conduct medium or small-sized system analyses on certain water body and they have significant value in terms of ecological mechanism, the results obtained are still limited, especially in the aspect of extrapolation of quantitative relations, and they lack of the understanding on the macroecological rules of complex ecosystem. Compared with traditional limnology, predictive limnology aims at exploring universal rules through large-scale comparisons.  

Aiming at solving the problems of excessive utilization of fishery sources and eutrophication, Dr. Haijun WANG conducted field survey of 46 small-to medium-sized lakes along the mid-lower Yangtze River under the instruction of Prof. Jiankang LIU, also CAS academician and Prof. Hongzhu WANG. He systematically conducted predictive limnological researches on shallow lakes along the mid-lower Yangtze River for the first time in China and proposed his doubt on the traditional N/P (ratio of nitrogen to phosphorus) hypothesis.  

Traditionally, total nitrogen or total phosphorus is extensively used to discriminate lakes as N- or P- limited. Nevertheless, through analysis of over 40 small and medium-sized lakes along the Yangtze River, Dr. Wang’s paper revealed that phosphorus is the key factor determining phytoplankton growth regardless of concentrations of nitrogen.  

He also proposed the views that planktivorous fishes (silver and bighead carps) failed to neither control the total amount of phytoplankton nor improve water quality. Previously, there has long been a controversy on whether planktivorous fishes could effectively control total phytoplankton. The controversy is mainly due to the fact that all the experiments were too small in spatio-temporal scales and difficult to reflect the real ecosystems.  

Through large-scale comparative researches, Dr. Wang reveals that the fish fail to decrease chlorophyll a and also fail to improve water transparency. Furthermore, he establish a series of simple but practical models such as key-time model of submersed macrophyte biomass, predictive models of epiphytic snailson submersed plants, predictive models of standing crops of benthos standing crops, maximum yield models and an optimal stocking model of Chinese mitten crabs.  

He introduced a unique way of modeling and new concepts of key-time models. His research gives explicit and quantitative suggestion for lake management and also promotes the research strategies of limnology.