extension outreach response to livestock mortality events associated with algal toxin production in...
DESCRIPTION
Proceedings available at: http://www.extension.org/67606 Excessive nutrient enrichment in watersheds can create harmful algal blooms (HABs) in aquatic systems, including ponds, which are frequently used to water livestock. Harmful algal blooms are typically dominated by cyanobacteria (commonly referred to as “blue green algae”) many of which produce toxins that can be harmful to fish, wildlife and humans. In May 2012, our laboratory began receiving reports of cattle mortalities associated with HABs. We began an outreach effort to screen and identify algal species and toxins in water samples submitted by private citizens from ponds throughtout Georgia. Prior to this effort, no state or federal laboratories offered such a service. Private laboratories conduct these services, however the collection protocols and analytical costs preclude the average citizen from utilizing them. Rapid detetion of a HAB is critical for farmers so that access to the water source can be restricted. We recognized the need to provide such a service and to educate the public regarding exposure effects, preventative measures, and treatment of HABs.TRANSCRIPT
Extension Outreach Response to Livestock Mortality Events Associated With Algal Toxin Production in Georgia Farm Ponds
Waste to Worth – Denver, ColoradoApril 2013
Susan B. Wilde, Rebecca Haynie, David Kissel, Leticia Sonon and Uttam Saha
Background
• “blue-green algae”
• can photosynthesize but more similar to bacteria than true algae, existing as prokaryotic cells • reclassified as
cyanobacteria
• fix nitrogen, survive in inhospitable environs
• Nonmotile, can be single, colonial, or multicellular
Background
Eutrophication – the addition of nutrients (i.e. Soil erosion, Nitrogen, Phosphorus, Chemicals, Fertilizers, etc.) to an aquatic system
Additional Nutrients Increased Productivity Algal Blooms (some Toxic!)
Influenced by drought High summer temperatures
Toxin Production
Common genera that produce toxins:• Anabaena• Aphanizomenon• Cylindrospermopsis• Microcystis• Oscillatoria• Planktothrix
Three primary toxins:• Microcystins- liver• Anatoxin-a- nervous system• Cylindrospermopsin- liver, kidneys
Toxicity
Concentration in water (ppb)
Microcystins Anatoxin-a CylindrospermopsinHuman recreation uses 0.8 90 4Subchronic water intake, dog 2.0 100 10Acute water intake, dog 100.0 100 200Subchronic water intake, cattle 0.9 40 5Acute water intake, cattle 50.0 40 60*Office of Environmental Health Hazard Assessment (OEHHA), California EPA 2012
Action Levels for selected scenarios
• Subchronic- Multiple day
• Acute- Single day
• Human drinking water < 1 ppb(World Health
Organization)
Microcystis aeruginosa
Stone Lab, Lake Erie Colonies can be almost macroscopic and form a thick floating scum.
Aphanizomenon flos-aquae
Anabaena
Cylindrospermopsis raciborski
Lyngbya wollei
Case Study
• May 2012
• Report of 4 cattle deaths in Gwinnett County, GA
• Attending veterinarian suggested testing pond because it was “bright green”
Clinical Signs
• Weakness & extreme weight loss
• Confusion, loss of coordination • Flaccid or rigid paralysis• Pale colored mucous
membranes & excessive salivation
• Bloody diarrhea• Sudden collapse and death• Green stains on muzzle
Clinical signs are not diagnostic!
Site conditions
• Agricultural runoff pond • <1 acre
• Annual fertilization • Poultry litter
• Unrestricted access
Gwinnett County, GA
Site Assessment Protocol
May 30, 2012• 4.4 x106 cells/mL• TEST: >5 ppb microcystin• ELISA: >142 ppb microcystin
• Identify and count algal species microscopically
• Toxin assays:• Quick field test strip• ELISA kit
Treatment and Response
May 30, 2012 (4.4 x106 cells/mL) • Conservative: 1 gal Cutrine+
June 19, 2012 (3.7 x106 cells/mL)• Fourth cow death• Maximum: 3 gal Cutrine+
June 25, 2012 (1.2 x106 cells/mL)• Appearance of diatoms and
green algae
July & August• Microcystin >5 ppb• Increase in cell density
Media Blitz
• TV and newspaper coverage
Cattle pond samples from:• Dade• Grady• Gwinnett• Johnson• Monroe• Morgan• Spalding• Tift
Dead cow and algae summer extravaganza!
Assessment Results
Cattle pond samples from:• Dade• Grady• Gwinnett• Johnson• Monroe• Morgan• Spalding• Tift• Stephens
RED = reports of cattle deaths
Ponds Investigated14
Ponds w/ Microcystis11 of 14
Microcystins > 5 ppb7 of 9
Ponds in Drought13 of 14
Drought Conditions
USDA (droughtmonitor.unl.edu)
8/7/2012
• News flash: Animals are not that smart
• Cattle, dogs will consume cyanobacterial crusts/mats
• Affinity for water with cyanobloom
Lopez and Costa 1999
Additional considerations
Management Recommendations
• Algaecide and/or water conditioning products
• Aeration• Implementation of BMP’s• Restrict access• Vegetated buffer
• Change fertilization regime• Limit phosphorous
Management Recommendations
Livestock watering options• Limited • Rely on pond
State/federal agencies strongly discourage watering in creeks
Statewide Screening Initiative
Investigate• Landowners send samples via
UGA Ag testing service• Contract basis (pay/sample)• Provide for each sample • Species list• Toxin analysis• Recommendations
Educate• Participate in short courses
Acknowledgements
Dr. Lee Jones, UGA Veterinary Diagnostic Laboratory
Dr. Gary Burtle, Dr. Lawton Stewart, UGA Cooperative Extension Specialists
Brad Bartleme, Jamie Morgan, Graduate Research Assistants
Dr. Mark Risse, UGA Agriculture and Environmental Science
Questions?