Determining critical light and hydrologic conditions for macrophyte presence in a large shallow lake: The ratio of euphotic depth to water depth |
| |
| Affiliation: | 1. Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. School for the Environment, University of Massachusetts Boston, Boston, MA 02125, USA;1. Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China;2. School of Earth Sciences and Engineering, Hohai University, Nanjing 210098, China;3. Key Laboratory of Digital Earth Sciences, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;1. Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway;2. School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK;3. Department of Biology, University of Oslo, PO Box 1066, 0316 Oslo, Norway;4. Limnologische Station der TU München, Hofmark 1–3, 82393 Iffeldorf, Germany;1. State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the University of the Chinese Academy of Sciences, Wuhan 430072, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;1. School of Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA, UK;2. School of Environmental Sciences, University of Liverpool, Liverpool, L69 3GS, UK |
| |
| Abstract: | Light determines macrophyte distribution, community composition and biomass in shallow lakes. Therefore, it is vital to determine the critical underwater light climate thresholds for macrophyte degradation and recovery. In this study, we first proposed a novel index, defined as the ratio of euphotic depth (Zeu) to water depth (WD), as a measure of the underwater light supply for macrophytes. The underwater light environment in Lake Taihu (a large, shallow, eutrophic lake) was then characterized based on this index (Zeu/WD) using field measurements collected from 2006 to 2013 (8 years × 4 seasons × 32 sites). The distribution of the macrophyte presence frequency (MPF, the number of investigations that identified macrophytes divided by the total number of investigations) was greater than 0.70 in Xukou Bay and East Lake Taihu over the 32 investigations, followed by the other sites distributed in East Lake Taihu. The proportion of macrophyte coverage increased with the increase in Zeu/WD. A significant relationship was observed between Zeu/WD and MPF for the 19 sites with macrophytes (r2 = 0.48, p < 0.001, n = 19). In the region with high nutrient concentrations and serious water pollution, better underwater light conditions are required for the growth of macrophytes. A Zeu/WD value of 0.80 can be regarded as the critical underwater light threshold for the growth of macrophytes in Lake Taihu. The region with Zeu/WD ranging between 0.57 and 0.80 was usually covered by sparse macrophytes; this region should be vital for macrophyte recovery and environmental management in Lake Taihu. The distribution of Zeu/WD was further obtained using MODIS satellite-derived Zeu from June to October in 2003 and 2013. Xukou Bay and Guangfu Bay in the southern part of Lake Taihu could be regarded as potentially crucial regions for the recovery of macrophytes from the perspective of underwater light and nutrient levels. |
| |
| Keywords: | Underwater light Euphotic depth Water depth Macrophyte Shallow lake |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
