Long-term nutrient trends and harmful cyanobacterial bloom potential in hypertrophic Lake Taihu, China

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• 作者：Hai Xu ; Hans W. Paerl ; Guangwei Zhu ; Boqiang Qin ; Nathan S. Hall…
• 关键词：Eutrophication ; Lake Taihu ; Microcystis ; Chlorophyll a ; Nitrogen ; Phosphorus
• 刊名：Hydrobiologia
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：787
• 期：1
• 页码：229-242
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Freshwater & Marine Ecology; Ecology; Zoology;
• 出版者：Springer International Publishing
• ISSN：1573-5117
• 卷排序：787

文摘

Rapid economic development in China’s Lake Taihu basin during the past four decades has accelerated nitrogen (N) and phosphorus (P) loadings to the lake. This has caused a shift from mesotrophic to hypertrophic conditions, symptomized by harmful cyanobacterial blooms (CyanoHABs). The relationships between phytoplankton biomass as chlorophyll a (Chla) and nutrients as total nitrogen (TN) and total phosphorus (TP) were analyzed using historical data from 1992 to 2012 to link the response of CyanoHAB potential to long-term nutrient changes. Over the twenty year study period, annual mean Chla showed significantly positive correlations with both annual mean TN and TP (P < 0.001), reflecting a strong phytoplankton biomass response to changes in nutrient inputs to the lake. However, phytoplankton biomass responded slowly to annual changes in TN after 2002. There was not a well-defined or significant relationship between spring TN and summertime Chla. The loss of a significant fraction of spring N loading due to denitrification likely weakened this relationship. Bioavailability of both N and P during the summer plays a key role in sustaining cyanobacterial blooms. The frequency of occurrence of bloom level Chla (>20 μg L−1) was compared to TN and TP to determine nutrient-bloom thresholds. A decline in bloom risk is expected if TN remains below 1.0 mg L−1 and TP below 0.08 mg L−1.