6/06/2017  |   09:00 - 09:15   |  306B

SIMPLE, TIME-SCALE BASED APPROACHES FOR EXPLAINING PHYTOPLANKTON DYNAMICS Time scales and their ratios represent a convenient tool for capturing multiple disparate processes, placing them in a single comparable currency, and collapsing partial differential equations into intuitive, graphical representations of just a couple variables. Despite their simplicity, time scale based relationships work well in describing and explaining the drivers underlying a wide range of observed patterns in phytoplankton across space and time. I will present examples of how time scale relationships have been used to explain and collapse complex dynamics observed in nature and depicted by more intricate numerical models. One such example, which focuses on the relationship between phytoplankton biomass and residence time, reveals the somewhat unintuitive tripartite relationship between those two quantities: phytoplankton biomass can increase, decrease, or not change at all as residence time increases. The particular relationship that occurs is determined by the relative rates (or, inversely, time scales) of phytoplankton growth and in situ loss. Processes operating and competing in the vertical dimension (which are particularly relevant to the dynamics of cyanobacteria) may also be described by relationships of physical and biological time scales.

Lisa Lucas (Primary Presenter/Author), U.S. Geological Survey, llucas@usgs.gov;


Janet Thompson ( Co-Presenter/Co-Author), U.S. Geological Survey, jthompso@usgs.gov;


Larry Brown ( Co-Presenter/Co-Author), U.S. Geological Survey, lrbrown@usgs.gov;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   09:15 - 09:30   |  306B

DROUGHTS, INTERNAL AND EXTERNAL NUTRIENT SUPPLIES, AND TOXIC CYANOBACTERIA OUTBREAKS IN POTABLE SOURCE WATERS OF THE SOUTHEAST Many potable source waters in the southeastern U.S. are being threatened by excessive droughts as accelerated global warming progresses. These waters are also being degraded with excessive nutrients (nitrogen, phosphorus) that are stimulating toxic cyanobacteria outbreaks and exacerbating their impacts. We considered several potable source waters in the Southeast, including their water residence times, nutrient levels, recent climatic forcing from droughts, hypoxia/anoxia in their water columns, evidence of sediment nutrient pumping, and what is known about the status of their cyanobacteria blooms. Key environmental factors that are most conducive for cyanobacteria in these systems were evaluated to forecast how they will change as accelerated climate change continues. The analysis indicates that both inorganic nitrogen and inorganic phosphorus will need to be decreased significantly, back to limiting levels, to reduce recurring toxic cyanobacteria blooms; that there will be a substantial lag in system response due to reduced flushing rates and nutrient sediment pumps; and that toxic cyanobacteria outbreaks will continue to increase until excessive phosphorus and nitrogen supplies are reduced and flushing is increased.

JoAnn Burkholder (Primary Presenter/Author), North Carolina State University, jburk@ncsu.edu;


Elle Allen ( Co-Presenter/Co-Author), North Carolina State University, ehallen@ncsu.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   09:30 - 09:45   |  306B

FINDING A WAY – CYANOBACTERIA BLOOM IN NUTRIENT-ENRICHED LOWLAND BLACKWATER SYSTEMS Coastal Plain blackwater ecosystems are not the most hospitable environments for hosting cyanobacterial blooms. The DOM-enriched dark water color attenuates light rapidly, and large Piedmont rivers entering the lowlands carry high suspended sediment loads that further attenuate light. Regardless, nuisance and toxic blooms of cyanobacteria have apparently been on the increase in nutrient-enriched blackwater systems in recent years. In the lower Cape Fear River blooms of Microcystis form on the surface to avoid light limitation and potentially have first chance at atmospherically-borne nutrients. These blooms have been constrained to years when high flushing did not occur. Blackwater Greenfield Lake is a eutrophic urban system in Wilmington, North Carolina, that previously suffered from dense surface cyanobacterial blooms leading to severe hypoxia. Installation of Solarbee mixers in 2005 substantially reduced the occurrence of surface blooms. However, the blooms morphed from surface habitats into massive Anabaena blooms that permeate the water column, with average chlorophyll a concentrations increasing from 19 to 34 ppb since addition of the mixers. Thus, unless nutrient inputs are strongly curtailed, cyanobacterial blooms will continue to infect such ecosystems.

Michael Mallin (Primary Presenter/Author), University of North Carolina Wilmington, Center for Marine Science, mallinm@uncw.edu;


Bradley Saul ( Co-Presenter/Co-Author), University of North Carolina Chapel Hill, Department of Biostatistics, saulb@live.unc.edu;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   09:45 - 10:00   |  306B

ANALYSIS OF TOXIC CYANOBACTERIA OCCURRENCES IN THE LOWER HAN RIVER, KOREA In 2015, severe harmful algal bloom occurred in the lower section of the Han River, that passes through Seoul City, the capital of Korea. Intensive analyses were carried out to investigate characteristics of the issue, possible reasons and counter measures for the problem. The study site can be divided into upper stream drinking water intake area and downstream wastewater discharge area. Peak occurrences of diatom, green algae and cyanobacteria were found in early spring, early summer and late summer, respectively. While reduced discharge from the Paldang Dam, the headwater for the study site, due to drought was considered to be one of the major reasons for the problem, effects of other factors such as pollutant loadings from boundaries or instream structures can contribute to the water quality problem as well. However, no significant correlation could be found for cyanobacteria cells/ml with Chl-a concentrations and also with other factors such as nutrient concentrations or temperature. Non-toxic cyanobacteria were dominant in the upper stream area where water quality is cleaner while toxic cyanobacteria were dominant in the lower part of the stream.

Dongil Seo (Primary Presenter/Author), Chungnam National University, seodi@cnu.ac.kr;


Jaeyoung Kim ( Co-Presenter/Co-Author), Chungnam National University, xth0218@naver.com;


Tongeun Lee ( Co-Presenter/Co-Author), Chungnam National University, kail11@naver.com;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   10:00 - 10:15   |  306B

WESTERN LAKE ERIE ECOSYSTEM MODEL: AN OPERATIONAL MODEL FOR THE SCIENTIFIC AND MANAGEMENT COMMUNITY Over the last five years LimnoTech has worked to develop the Western Lake Erie Ecosystem Model (WLEEM) to assist researchers and managers with answering complex questions regarding sediment and phosphorus fate and transport and connections to HABs in Western Lake Erie. This presentation will review recent applications of the model as part of the Annex 4 modeling group for the Great Lakes Water Quality Agreement, to the 2014 CSMI year for Lake Erie, and a recent confirmation of the performance of the model with 2015 conditions. The model is a powerful data integration and interpretation tool and can help managers and scientists isolate specific loading sources and identify key nutrient cycling pathways. When updated on a periodic basis the model can help to monitor lake responses to watershed nutrient reduction efforts and test new scientific hypothesis. Operational ecosystem models, such as this one, complement existing monitoring programs very well and help to reduce uncertainty for managers that must make decisions regarding ecosystem responses to specific and often costly actions.

Todd Redder ( Co-Presenter/Co-Author), Limnotech, tredder@limno.com;


Edward Verhamme (Primary Presenter/Author), LimnoTech, everhamme@limno.com;


Joseph DePinto ( Co-Presenter/Co-Author), LimnoTech, jdepinto@limno.com;


John Bratton ( Co-Presenter/Co-Author), LimnoTech, jbratton@limno.com;


Presentation:
This presentation has not yet been uploaded.

6/06/2017  |   10:15 - 10:30   |  306B

HISTORICAL CHANGES IN WATER QUALITY, TEMPERATURE REGIMES, AND CYANOBACTERIA DENSITIES OF 20 MIDWESTERN USA RESERVOIRS Water quality and cyanobacteria densities from 1989-2015 were compiled for 20 Midwestern USA reservoirs. Maximum summer cyanobacteria densities increased over the last 7-15 years of the record, with greatest increases typically observed in reservoirs with low watershed forest cover. In 2015, greater summer maximum cell densities were associated with decreased watershed forest cover, and 17 reservoirs had densities posing high probabilities of human health risks (>100 million cells/liter). Summer months had little increase in surface water temperature over the 26-year record, but May temperatures increased, particularly in reservoirs with low surface area to volume ratios (1–2 degrees Celsius/decade). In one reservoir (analysis of others in progress), mean dissolved oxygen in May decreased in the hypolimnion (5.4 to 2.9 mg/L) and increased in the epilimnion (8.3 to 10.8 mg/L) since 1989. Earlier seasonal warming of reservoirs likely contribute to changes in stratification regimes and may interact with increasing nutrients to affect cyanobacteria blooms. Ongoing analyses seek to link environmental change and reservoir characteristics with cyanobacteria abundances and to inform future management of algal blooms.

Nathan Smucker (Primary Presenter/Author), U.S. Environmental Protection Agency, smucker.nathan@epa.gov;


Jake J. Beaulieu ( Co-Presenter/Co-Author), United States Environmental Protection Agency, beaulieu.jake@epa.gov;


Christopher Nietch ( Co-Presenter/Co-Author), U.S. Environmental Protection Agency, nietch.christopher@epa.gov;


Jade Young ( Co-Presenter/Co-Author), U.S. Army Corps of Engineers, Jade.L.Young@usace.army.mil;


Megan Higgs ( Co-Presenter/Co-Author), Neptune and Company, Inc., mhiggs@neptuneinc.org;


Will Barnett ( Co-Presenter/Co-Author), Neptune and Company, Inc., wbarnett@neptuneinc.org;


Presentation:
This presentation has not yet been uploaded.