Occurrence of Toxic and Odorous Algal Metabolites in Irrigation and Stock Ponds

Non-Technical Summary:<br/>
Climate change is predicted to increase the surface temperatures and change precipitation patterns leading to decreased water supplies and increased algal bloom occurrences. It has been shown that warmer temperatures and higher nitrogen and phosphorus (nutrient) levels promote growth of toxic cyanobacteria. Cyanobacteria, are photosynthetic, unicellular bacteria found in most surface waters around the world. Throughout their life cycle, they produce and release various metabolites which can be just taste-and-odor compounds or may be toxic and cause adverse health effects. The microcystins are the most common cyanobacterial toxins detected in the surface waters around the world. They are highly water soluble and are on the USEPA Contaminant Candidate List III. Cyanotoxins have been found all across the world including in Colorado and related poisonings have been reported in 50 countries and at least 36 states in the US while most of these poisonings affected animals. Irrigation and stock ponds providing higher levels of nutrients and stagnant conditions are highly vulnerable to algal blooms especially during warm spring to fall months. The recent studies reported that algal toxins may adversely impact the germination of seeds, and affect the growth, quality and productivity of crops. Exposure of several crops such as lettuce, rape, ryegrass, and rice to various concentrations of microcystins indicated that photosynthesis was reduced by 50%, root development was inhibited, especially in rape. Also several studies as well as many news articles reported the death of cattle and pets due to cyanobacterial toxin poisoning. Death of 4 cattle in southern Georgia in 1997 prompted investigations and again the cause of deaths was identified as toxins released by the massive algal bloom in the stock pond. The number of deaths was confined to only four as the herd was moved away from the pond immediately. There are no current research studies on occurrence and effects of toxins on cattle poisoning and crop growth in a full scale system, however this is an emerging area to be studied to be able to prevent tragic poisoning events of cattle and loss of food sources. It should also be noted that safe algae bloom prevention and pond management practices should be determined and adopted for the irrigation and stock ponds as some chemical algal inhibitors may impact the growth and quality of the crops. The objective of this project is to check the occurrence of toxic and odorous algal metabolites in agricultural ponds in Northern Colorado through instrumental analysis of water samples collected over summer, fall and spring months, and to assess their impacts on the irrigation water quality, crop growth and cattle health. The data will inform the researchers and hence the farmers of the likelihood of such issues and will enable them to take action before the problems are exacerbated. Guidance will be provided by the researchers on how to manage the ponds to prevent algal blooms and release of their metabolites. This way loss of cattle and produce will be prevented.
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Approach:<br/>
During May to October 2011, occurrence of odorous and toxic algal metabolites in 52 sites in Northern Colorado were monitored. Odorants were detected at significant levels in most sites, and Barr Lake was confirmed to have considerable levels of a potent algal toxin: microcystin-LR that ranged from 0.83 to 1.43 ug/L. For this proposed project, the main sampling locations will be Barr Lake and Milton Reservoir with less frequent sampling locations of Riverside, Jackson and Empire Reservoirs. Suggestions for other sampling locations from the review committee will also be considered and included for this project. Based on the initial results from sampling efforts prior to the start of this project (during May, June and July 2012), water samples will be collected from the indicated locations in a weekly or bi-weekly basis. The sampling will be continued until December 2012 (with a reduced frequency) and will be started back in April 2013 until the termination of this project. If the compounds of interest are detected, the frequency of sampling will be increased to be able to catch the trend in the release of the metabolites. Water samples will be collected from the center of the water body 3-4 ft below the surface with a 1 L amber glass bottle, headspace free, and will be immediately stored on ice in a cooler, in the dark. Concurrent samples will be collected by Dr. Stednick's group to test for nutrients, dissolved oxygen, pH and algae strains from Barr Lake and Milton Reservoir. For the samples obtained from other locations, same water quality analyses will be performed to obtain uniform data. All of the samples will be analyzed for algal metabolites within 24 to 48 hours. The samples will be screened for common microcystin variants (LR, RR, YR, LA) using a specific enzyme linked immunosorbant assay (ELISA). The samples that are determined to contain microcystin will further be analyzed and quantified by liquid chromatography coupled with mass spectrometry (LC/MS/MS) which is a highly sensitive method for toxin analysis. The odorant, geosmin, will be measured with solid phase micro-extraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS). Specific standards will be obtained and used to quantify the compounds of interest. If a sampling site is identified to contain algal toxins and odorants, permission to analyze the plants including the crops such as any vegetable, corn, small grains and/or forages, for such compounds will be sought from the owner of the farm. The plants will be processed to extract and quantify the toxins and the odorants. The microcystins pose a threat when they reach 4 to 6 ug/L in the water and the odorants become problematic at very low levels of 10 to 20 ng/L. The data obtained will be compared against these standards to be able to assess the condition of the ponds studied. This is a survey study to determine the occurrence of the studied contaminants, and the framers and other stakeholders will be guided on how to prevent the algal blooms through formal seminars/workshops as it is necessary to control the blooms to solve the toxicity and crop growth problems.
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Progress:<br/>
2012/07 TO 2012/12<br/>
OUTPUTS: NOAA has declared 2012 as the hottest year on record in the USA and further climate change is predicted in the upcoming years that are expected to increase the surface temperatures and change precipitation patterns leading to decreased water supplies and increased algal bloom occurrences. Cyanobacteria are photosynthetic unicellular bacteria found in most surface waters around the world, and are known to proliferate when water temperatures are warmer and the nutrients (phosphorus especially, and nitrogen) are abundant. Throughout their life cycle, cyanobacteria produce and release various metabolites which can deteriorate surface water quality. These metabolites can be just nuisances (taste-and-odor compounds) or may lead to adverse health effects (cyanotoxins). It was shown that when odorants were detected in surface waters, cyanotoxins were also detected in more than 80% of the sites tested. Cyanotoxin poisonings have been reported in 50 countries and at least 36 states in the US and most of these poisonings affected animals. Irrigation and stock ponds providing higher levels of nutrients and stagnant conditions are highly vulnerable to algal blooms especially during warm spring to fall months. Providing high quality and enough quantity of vegetables and fruits is essential for the health and welfare of the public. Farmers and researchers focus on methods to improve the nutritional quality of the crops and to increase the productivity of their plants. However, changing climatic conditions may lead to deteriorating water quality conditions in the irrigation ponds which may alter the productivity of the crops. Recent studies reported that algal toxins may adversely impact the germination of seeds, and affect the growth, quality and productivity of crops. Exposure of several crops such as lettuce, rape, ryegrass, and rice to various concentrations of cyanotoxins indicated that photosynthesis was reduced by 50%, root development was inhibited especially in rape. Increased toxin levels and exposure time increase the damage occurred to the crops. This means that if the agricultural and stock ponds are not maintained to be free of cyanotoxins, there might be a significant economic loss due to loss of crops and livestock. In order to understand and monitor the occurrence of algal odorants and toxins in selected Northern Colorado agricultural and stock ponds, water samples were collected during the end of May through mid-November in 2012. The samples were taken from Barr Lake and Milton Reservoir in bi-weekly intervals during May and August and then monthly until November. Monthly samples were also collected from Jackson and Riverside Reservoirs. Occasional samples were obtained from an agricultural ditch in Lakewood, CO as well. As proposed, the samples were analyzed for algal odorant geosmin and cyanotoxins. Other water quality parameters such as total phosphorus, total nitrogen, dissolved oxygen and pH were also measured. The data generated by this project will be uploaded to Colorado Data Sharing Network as the algal metabolites are not only a concern for the farmers but a major concern for the drinking water utilities as well.
<br/>PARTICIPANTS: Dr. Pinar Omur-Ozbek is the PI of this project and oversaw the sampling collection and analysis. Dr. John Stednick helped with the sample collections from Barr Lake and Milton Reservoir. Graduate student Mr. Glenn PArr collected samples from Jackson and Riverside Reservoirs. Dr. Kimberly Catton oversaw the phyto- and zoo-plankton analyses. Graduate student Mr. Patrick Brice as well as Mr. Glenn Parr conducted the instrumental and chemical analyses to characterize the samples.
<br/>TARGET AUDIENCES: The main target audience is the farmers who utilize the agricultural and stock ponds for irrigation and their livestock. In the case of occurrence of algal toxins, it is likely that crop production will be adversely affected and the risk of poisoning of the livestock will be increased. The other group who may be interested in these findings are the drinking water utilities. The changes in the surface waters, especially release of algal metabolites are a concern for the water utilities. Odorants, even though not a health concern, alarm the consumers and hence the utilities spend billions of dollars to treat those off-flavor compounds and to handle consumer complaints. In case of elevated levels of toxins, public officials need to inform the people who may get in contact with the surface waters to prevent adverse health effects.
<br/>PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
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IMPACT: This study is investigating the occurrence and release of detrimental algal metabolites in agricultural ponds in Northern Colorado. The findings generated throughout the duration of the study as well as previous monitoring efforts are not only used to assess the conditions and levels of toxins and odorants at the time of measurements but will also be used to predict future conditions if the toxins and odorants are detected in the agricultural and stock ponds being studied. One of the two main study sites Barr Lake, as well as Jackson Reservoir were also monitored in 2011 between May and October. Detectable levels of cyanotoxin microcystin-LR ranged from 0.83 to 1.43 ug/L in Barr Lake during this period. Geosmin levels varied between 0 to 2.7 ng/L in Barr Lake and did not correlate with microcystin-LR levels (i.e. higher geosmin concentrations did not occur during higher microcystin-LR concentrations). Jackson Reservoir samples in 2011 contained 0 to 4.3 ng/L geosmin, however no cyanotoxins were detected. During 2012 sampling efforts, mostly covered by this study, samples were collected between end of May and mid-November. Nine samples were collected from Barr Lake and Milton Reservoir, five samples were collected from Jackson Reservoir, and four samples were collected from Riverside Reservoir. Geosmin levels varied from 0 to 6.7 ng/L for Barr Lake, 0 to 3.9 ng/L for Milton Reservoir, 0 to 7.6 ng/L for Jackson Reservoir and 0 to 5.3 ng/L for Riverside Reservoir. No detectable cyanotoxin levels were determined for the samples analyzed. Comparing the climatological conditions between 2011 and 2012, 2012 was a much warmer and drier year. It was expected to observe higher levels of algal blooms and hence higher release of algal metabolites. During late summer months, starting in late July, high levels of algal blooms were observed, especially in Barr Lake. The detected geosmin levels were increased with increased algal blooms, as expected. However, geosmin production and release did not correlate with the cyanotoxins. Even though the conditions were favored for algal growth, no cyanotoxins were produced or released during this sampling period. Continuation of sampling efforts during the summer of 2013 will help understand the production and release of the algal metabolites studied and will shed light on the conditions that may promote algal blooms and metabolite release and prediction of future conditions. Statistical analyses as well as modeling will be possible for the replicates of the data for the two consecutive years. The interpretations will be strengthened with the limited results from 2011 samples. In the case of detection of concerning levels of toxins (> 5 ug/L) during the upcoming sampling months in 2013, the study will be expanded to investigate the growth, health and condition of the affected produce. If the algal metabolites are determined to be at concerning levels, the farmers will be informed of the findings and prevention techniques through a seminar style workshop.