Comparative analysis of nutrients, chlorophyll and transparency in two large shallow lakes (Lake Taihu, P.R. China and Lake Okeechobee, USA)

Abstract

This article compares limnological attributes of two of the world's largest shallow lakesLake Okeechobee in Florida, USA and Lake Taihu in P.R. China. Both the systems support an array of ecological and societal values including fish and wildlife habitat, public water supply, flood protection, and recreation. Both have extensive research programs, largely because of concern regarding the lakes' frequent cyanobacterial blooms. By evaluating these systems together, we compare and contrast properties that can generally advance the understanding and management of large shallow lowland lakes. Because of shallow depth, long fetch, and unconsolidated mud sediments, water chemistry, and transparency in both the lakes are strongly influenced by resuspended sediments that affect light and nutrient conditions. In the central region of both the lakes, where depth is the greatest, evaluation of limiting factors by a trophic state index approach indicates that light most often limits phytoplankton biomass. In contrast, the more sheltered shoreline areas of both the lakes display evidence of nitrogen (N) limitation, which also has been confirmed in nutrient assays conducted in earlier studies. This N limitation most likely is a result of excessive levels of phosphorus (P) that have developed in the lakes due to high external loads over recent decades and the currently high internal P recycling. Comparisons of these lakes show that Lake Taihu has higher N than, similar total phosphorus (TP) and similar light conditions to that of Lake Okeechobee, but less chlorophyll a (CHL). The latter may be as a result of lower winter temperatures in Lake Taihu (around 5°C) compared to Lake Okeechobee (around 15°C), which could reduce phytoplankton growth and abundance through the other seasons of the year. In these systems, the important role of light, temperature, and nutrients in algal bloom dynamics must be considered, especially due to possible adverse and unintended effects that might occur with projects such as sediment removal, and in the long term, in regard to buffering lake responses to external load reduction.

Autotrophic Growth of Bacterial and Archaeal Ammonia Oxidizers in Freshwater Sediment Microcosms Incubated at Different Temperatures

“…Due to the lasting and intensive inputs of nutrients such as nitrogen and phosphorus, this lake has been experiencing accelerating eutrophication over the past 3 decades. Total N load in Lake Taihu has been estimated to be 28,658 tons year Ϫ1 , which is more than 350% higher than eutrophic Lake Okeechobee (32). Ammonium concentrations as high as 0.2 to 0.4 mM are common in the lake (unpublished data).…”

Correlations between algae and water quality: factors driving eutrophication in Lake Taihu, China

“…The worsening condition of Lake Taihu has prompted researchers and government officials to seek mitigation strategies. The large regions of the lake and its watershed have limited previous research investigations to local scales not encompassing the entire watershed (Dong et al 2008;James et al 2009), to limited water quality indices using data from a small number of monitoring stations (Chen et al 2003;Zhu 2008), or to remote sensing analyses over short time periods Wang and Shi 2008). The spatiotemporal distributions of and interactions between algal concentrations and water quality indices based on long-term monitoring data that encompass the entire watershed area and the key driving factors over season need to be further studied (Paerl et al 2011a).…”

The Fluctuation of Arsenic Levels in Lake Taihu

“…Taihu is a huge shallow freshwater lake located in the contiguous area of Jiangsu and Zhejiang province in east China, the most developed area of the country [18]. Serious eutrophication with annually seasonal algae blooms happened in Taihu in the last decade due to the very dense population and rapid development of industry around the area [19,20]. Studies on the sources and effects of eutrophication in Taihu have been vastly reported; however, the mechanisms of algae bloom in Taihu are quite unclear up to date [21][22][23][24].…”