National Science Foundation     |     Directorate for Engineering  (ENG)
Division of Chemical, Bioengineering, Environmental, & Transport Systems  (CBET)
CBET Award Achievements (Nuggets)
Notable Accomplishments from CBET Awards
Ensuring Sustainability of Large Lakes
Hans Paerl    University of North Carolina at Chapel Hill

Background:  Man-made nutrient over-enrichment (eutrophication) in freshwater systems has led to a global proliferation of harmful blue-green algal (cyanobacterial) blooms (CyanoHABs) which foul waterways and water intakes, disrupt food webs, fuel hypoxia, and produce secondary metabolites that are toxic to water consumers and users, including zooplankton, fish, shellfish, cattle, domestic pets, and humans.  This problem is exacerbated by global warming, which favors CyanoHABs (Paerl and Huisman, Science 320:57-58 (2008)).  CyanoHABs are now threatening the use and sustainability of the world's largest lake ecosystems, including the Great Lakes, Lakes Okeechobee, Ponchartrain in North America, the large lakes of Africa, Asia and South America, and drinking water reservoirs worldwide.  Particularly affected are the rapidly developing regions of Southeast Asia, typified by China's 3rd largest lake, Taihu, a previously pristine, revered lake supplying the drinking water needs of over 20 million people.
In recent years, Taihu has experienced CHABs so severe that human water use has had to be curtailed, leading to a highly publicized drinking water crisis in 2007 (Image 1).  This project employs an interdisciplinary (ecology, toxicology, management), international (USA-China) team to assess, control and mitigate CyanoHABs threatening the sustainability of this lake.  Seasonal in situ nutrient dilution bioassays are determining which nutrient(s) (nitrogen, phosphorus) promote toxic CyanoHABs, and nutrient input reductions are needed to bring the lake below the bloom threshold.  The additional role of climate change, specifically warming, in CyanoHAB dynamics is being investigated.  Lake Taihu serves as a "looking glass" for formulating nutrient input reductions and long-term management strategies in large lake ecosystems threatened by proliferating CyanoHABs.

Results:  During two research trips to Taihu in 2008, Dr. Paerl established protocols for bioassay deployment and analyses with research collaborators at the Nanjing Institute of Geography and Limnology (Chinese Academy of Sciences) (NIGLAS) (Image 2).  Preliminary results of seasonal bioassays indicate that both nitrogen (N) and phosphorus (P) are being supplied in excess, leading to "runaway" blooms of the toxic genus Microcystis.  In 2009, bioassays will test a range of nutrient dilutions aimed at establishing a bloom threshold.  Parallel diagnostic pigment, toxin and molecular assays will monitor CyanoHAB community responses to clarify the ecological basis and rationales for mitigating CyanoHABs and to ensure that certain CyanoHABs are not replaced by other harmful species once wastewater and agricultural/industrial nutrient reduction efforts, and hydrologic modifications, including flushing of the lake with nearby Yangtze River water, are implemented.  This research project provides a scientific basis for long-term CyanoHAB management in large lakes worldwide.

Hans Paerl 1
Image 1.  Principal Investigator Hans Paerl sampling the bloom from Lake Taihu.

Hans Paerl 2
Image 2.  P.I. Hans Paerl and Chinese colleagues preparing bioassays in Lake Taihu.  Bioassays are designed to assess nutrient impacts on CyanoHAB bloom potentials in October 2008.
Credit for Images 1 & 2:  Hans Paerl, University of North Carolina at Chapel Hill, Institute of Marine Sciences
This project addresses the NSF Strategic Outcome Goals, as described in the NSF Strategic Plan 2006-2011, as follows:
Primary Strategic Outcome Goal:        (1) Discovery:  This research program is focused on transforming the knowledge base of US researchers on developing response strategies to the proliferation of cyanobacterial harmful algal blooms (CyanoHABs) in US water supplies.  Through collaborations with and observation of efforts by the Chinese Academy of Sciences, the intent is both a discovery and learning process that will provide currently unavailable infrastructure to deal with future CyanoHAB events in North America.  These efforts will help researchers investigate and document approaches to dealing with massive scale CyanoHAB events that are anticipated to ultimately impact the overall use, ecological integrity and safety of North American surface waters.
                                                                     (1) Discovery Category:
                                                                            - International Collaborative Research
                                                                            - Biological Sciences
                                                                            - Engineering Research
                                                                            - Geosciences: Earth, Atmosphere, and Ocean Sciences
                                                                            - Mathematical & Physical Sciences
                                                                            - Social, Behavioral, & Economic Sciences

Secondary Strategic Outcome Goals:  (2) Learning and Research Infrastructure:  Secondary strategic goals are to develop sustainable resource management approaches that will prevent efforts (outlined in the primary goal) from pressing natural resources beyond a "tipping point" where one Cyanohab species is replaced by another potentially harmful (or even more harmful) species.  The development of such strategies is currently not part of the educational and research efforts used to develop science-based HAB mitigation strategies and management approaches.
                                                                     (2) Learning and Research Infrastructure Categories:
                                                                            - K-12 Education
                                                                            - Teacher Education and In-service Professional Development
                                                                            - Undergraduate Education and Undergraduate Student Research
                                                                            - Postdoctoral Education, including International Postdoctoral Fellowships
                                                                            - International Research Experiences for Undergrad & Graduate Students
                                                                            - Postdoctoral Education
                                                                            - Public Understanding of Science and Lifelong Learning
                                                                            - Other Infrastructure and Research Resources

In terms of Intellectual Merit, this work is notable in developing a process-based, ecologically and economically-sound approach for long-term control of CyanoHABs, which have caused massive problems for industry, recreation and tourism and has disrupted regional drinking water supplies.  While events in China may seem half-way-around-the-world relative to local concerns, they are in fact a potential foreshadowing for North American waterways.
Moreover, dramatic responses planned by the Jiangsu Provincial EPA and the Chinese National EPA represent novel opportunities to test mitigation and control approaches to CyanoHAB events that cannot currently be tested in North America (since there are no events of this scale, yet).  This project will evaluate these approaches by deploying in situ bioassays and examining communities with advanced molecular biological tools to determine nutrient input thresholds below which CyanoHAB growth and proliferation can be controlled in a regime of changing climatic conditions.

In terms of Broader Impacts, this work is notable because the project is seeding numerous collaborations and interactions between established US researchers at the University of North Carolina-Chapel Hill (NSF Pre-graduate Research Experience Program), The University of Tennessee-Knoxville (an EPSCoR institution), and those at NIGLAS, other branches of the Chinese Academy of Sciences and Chinese Universities.  Exchanges between American and Chinese labs will foster new understandings of how science as a process is undertaken in different cultures, and provide novel opportunities for students and researchers.  Outreach includes the development of components of this program to incorporate motivated undergraduate students in research.  Moreover, the inclusion of students focused on Environmental Science and Studies (UNC-CH's Institute for the Environment) and Science-Journalism (UT's School of Journalism) will facilitate rapid and wide spread dissemination of the materials to all levels (K-12, collegiate and general public).

This research is Transformative.  This program of research, education and partnership with Chinese researchers is providing a novel "looking glass" into how future CyanoHAB events might be dealt with in North American systems.  The program will collect valuable information needed for the long term sustainability of North American water supplies, and will foster further development and strengthening of the global partnership between American and Chinese researchers.  This program will provide researchers with the opportunity to examine potential CyanoHAB scenarios for North American surface water supplies that are predicted to occur 10 - 50 years in the future.

This research represents Broadening Participation.  This project directly broadens research participation of underrepresented groups by supporting a PI and students in an EPSCoR state institution (The University of Tennessee).  This study will allow for students to participate in state-of-the-art research in ecology and molecular biology, while further their understanding of how science functions in other countries.

Existing or potential Societal Benefits of this research:  The single most valuable natural resource of any country, especially in North America, is an ample supply of water for its citizens.  In the United States surface water resources are critical to supplying of potable, industrial, transportation and commercial needs.  This research directly addresses the maintenance and protection of this resource by addressing the single most significant threat to this resource, thereby providing incalculable benefits to society.  This project further supports a deeper collaboration with Chinese researchers, benefiting residents of both countries as we strive towards a better understanding of our managed natural resources.

Program Director:
Bruce Hamilton
CBET Program Director - Environmental Sustainability
NSF Award Number:   0826819
Award Title:
  Collaborative Research: Evaluating Nutrient Reductions to Control Cyanobacteria and Ensure Large Lake Sustainability: Lake Taihu (China) as a Model for North American Systems
PI Name:   Hans Paerl
Institution Name:   University of North Carolina at Chapel Hill
Program Element Code:   7643, 7731
NSF Investments:
  - Climate Change
- Human and Social Dynamics
- Sensor Research
- Environment (including the importance of fresh water and dynamics of water processes)
- Understanding Complex Biological Systems (including the
      interfaces of life, physical, and computational sciences)
CBET Nugget:

  FY 2009

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This Nugget was Updated on 28 September 2009.