Harmful Algal Blooms. A newly emerging pathogen in water. Juli Dyble. NOAA Great Lakes Environmental Research Lab Ann Arbor, MI

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1 Harmful Algal Blooms A newly emerging pathogen in water Juli Dyble NOAA Great Lakes Environmental Research Lab Ann Arbor, MI

2 Harmful Algal Blooms (HABs) Harmful: : produce toxins Algal: : planktonic, photosynthetic Bloom: : high concentration of cells, often at surface Prolific throughout the world

3 Algal blooms In waters used for drinking, fishing, recreation

4 Red tides Frequent on FL coast Usually late summer and fall Aerosolized toxins burning eyes, asthma-like respiratory distress Neurotoxic shellfish poisoining Fish kills Karenia brevis

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6 Great Lakes as an aquatic resource Largest supply of freshwater in the world 80% of US freshwater supply Drinking water supply for 40 million US and Canadian citizens Used extensively for recreation

7 Common cyanobacterial HAB genera in the Great Lakes Microcystis Aphanizomenon Oscillatoria Anabaena Cylindrospermopsis

8 Microcystis in the Great Lakes Lake Erie, Put-In-Bay, Sept 2006 Lake Erie, South Bass Island, Sept 2006

9 Why worry about cyano HABs? Degrades water quality Taste/odor issues Loss of recreational and fishing value to affected waters Hypoxia/anoxia, may lead to mortality in benthic invertebrate community and fish kills Alters food webs Unpalatable to many zooplankton grazers Toxin producer (neurotoxins, hepatotoxins, dermatotoxins) Toxic to zooplankton, shellfish, fish, animals, humans

10 Bioaccumulation Health food supplements Exposure to toxic cyanobacteria.. Boating/ recreation Drinking water reservoirs

11 Real problem is with people like this.

12 What makes a cyanobacterial bloom toxic? Shift in community composition Mostly non-toxic Mostly toxic strains Stimulation of toxin production by environmental factors Light Nutrients Temperature Trace metals Not producing toxin Producing toxin

13 Environmental factors influencing growth and toxin production in Microcystis NUTRIENTS LIGHT WATER TEMPERATURE HAB GROWTH MICROCYSTIN PRODUCTION RESIDENCE TIME GRAZING

14 Factors favoring cyanohabs nutrients from runoff N, P Salinity <15 psu Low flow/ High residence time hypoxia Reduced grazing Temp >20 C PO 4 NH 4 sediments

15 Nutrient controls Total nutrient load N, P enrichment promote blooms N:P ratios Cyanos rare or absent when N:P > 29 N:P < 15 supports N 2 fixers Specific form of N, P may be important Selects for different phytoplankton species Possibly important in toxicity Metals (Fe, trace metals)

16 Sources of nutrients wastewater treatment facilities septic tanks sewer overflow animal waste runoff fertilizer runoff laundry and dish detergents atmospheric deposition

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18 Microcystis in the Great Lakes 1970 Dominant member of phytoplankton community Blooms frequent and abundant High P input to system (detergents, fertilizers, septic) 1980 P abatement programs (Great Lakes Water Quality Agreement) Present Limit P content in laundry detergents Decrease in chlorophyll, increased water clarity Blooms rare Dreissenid mussel introduction P removal (chemical precipitation) implemented at sewage treatment plants discharging to Great Lakes Return of Microcystis blooms up to 90% phytoplankton community Extensive Microcystis blooms, July Sept

19 Impacts of zebra mussels on Microcystis promote growth of toxic Microcystis strains Grazing pressure selective rejection of toxic Microcystis strains consume more palatable species Nutrient excretion provide sufficient energy for growth of toxic strains rapid nutrient cycling

20 Management strategies Physical disruption Bubblers Increase flushing rate/ reduce retention time Chemical manipulation Add algicides (copper sulfate) Reduce nutrient input (often both N, P) Alter N:P ratios Biological additions Remove zebra mussels Introduce algal grazers Add lytic bacteria or viruses

21 Drinking water treatment Cells Filtration/ Flocculation may cause cell lysis Toxins Chlorination Ozonation PAC/GAC require sufficient concentration and contact time can be negatively affected by dissolved organic matter and high ph may produce toxic by-products Ultrafiltration subject to fouling