LAKES LINGANORE & ANITA LOUISE STUDY UPDATES Hannah Zinnert Gabrielle Troutman
LAKE ANITA LOUISE Gabrielle Troutman
Why Study Lake Anita Louise? • Last winter, a bloom of toxic algae, Planktothrix rubescens , turned the lake pink and raised concerns about water health
Planktothrix rubescens • Species of filamentous cyanobacteria that may produce microcystin • Microcystin is a hepatotoxin (a chemical substance that damages the liver) • Exposure to hepatotoxins may cause nausea, vomiting, diarrhea, and in some cases, acute liver failure • Humans can be exposed through the mouth and skin while swimming, drinking water, or showering in water that has been contaminated
Lake Anita Louise Study Goals Is Planktothrix rubescens still present in Lake Anita Louise at excessive levels? • Determine if P. rubescens is persisting in the lake • Determine if current levels of microcystin exceed the safe limit set by the World Health Organization (WHO) • Consider possible solutions to decreasing the presence of P. rubescens
Study Recap • Hood’s robotic boat used to map bathymetry • Located cold, deep point to sample • Conducted bi-weekly sampling visits • Samples tested for: dissolved oxygen, temperature, conductivity, pH, turbidity, dissolved inorganic phosphorous, chlorophyll, and phycocyanin levels • Samples examined under microscope to identify algal species present • Maryland Department of Environment conducted toxin analyses and reported microcystin levels
GIS-Generated Bathymetry Map • Created using Hood’s robotic boat and GIS software • Generated to determine areas where Planktothrix may be persisting • Sampling location chosen based on deepest point
The Stratification of Lakes Credit: Dr. Drew Ferrier
Changes in Temperature (°C) Temperature 0 5 10 15 20 25 30 0 While the surface 5 of the lake and Thermocline the oxycline 6/10/2016 10 7/6/2016 Depth (ft) warmed over the 8/1/2016 course of the 15 summer, the For reference… bottom of the 20 lake remains a 0° C = 32° F constant 25 temperature of Continuously cold temperatures 20° C = 70° F indicate that there may be a ~8-9° C groundwater-fed spring in the bottom of the lake http://clipart.coolclips.com/480/vectors/tf05163/CoolClips_vc009608.png http://images.clipartbro.com/254/sun-with-sunglasses-clipart-transparent-panda-free-254001.png
Changes in Conductivity Conductivity (µs/cm) 0 200 400 600 800 1000 0 Ions from spring at bottom of the lake are diluted by the • Conductivity has time they reach the surface 5 remained fairly constant at the Mixing between surface and surface and bottom bottom water is creating 6/10/2016 10 variance in conductivity 7/6/2016 of the lake Depth (ft) 8/1/2016 throughout the 15 summer Higher benthic conductivity • Freshwater systems may be due to incoming 20 groundwater in the bottom can have a of the lake conductivity 25 anywhere between 100-2,000 μ s/cm
Changes in Dissolved Oxygen (mg/L) Dissolved 0 2 4 6 8 10 12 14 0 Oxygen -The oxygen available 4 reduced drastically Oxycline between June and Jul/Aug. 8 Depleted oxygen 6/28/2016 -The depleted oxygen 7/20/2016 Depth (ft) zone is indicative of Increased oxygen 12 8/1/2016 heterotrophic organisms consuming oxygen, while the 16 increased oxygen may indicate an algal Below this point, the water bloom. Algae are 20 is hypoxic – this is a harsh autotrophic and environment for organisms produce oxygen as a that require oxygen product of photosynthesis. 24 http://www.clipartkid.com/images/6/generic-fish-clip-art-at-clker-com-vector-clip-art-online-royalty-azdyOh-clipart.png
Changes 70 in Turbidity Spike in turbidity in beginning of August 60 • Turbidity is a 50 measure of water Turbidity (NTU) 40 clarity. The higher Surface the turbidity, the Oxycline 30 less clear the water Max Depth appears. 20 • Turbidity is impacted by 10 sediments, algae, and decomposing 0 6/29/2016 7/9/2016 7/19/2016 7/29/2016 8/8/2016 plant matter. Date
Changes in Blue-green algae ratio of 0.7 Phycocyanin 0.6 to Chlorophyll Ratio of phycocyanin:Chlorophyll 0.5 • A high phy:chl ratio is 0.4 indicative that the algae Surface is composed mainly of Oxycline 0.3 blue-green algaes Max Depth Green algae 0.2 • The photo provided supports that the oxycline water sample 0.1 from the end of June with a high phy:chl ratio was 0 5/30 6/9 6/19 6/29 7/9 7/19 7/29 8/8 composed of more blue- Date green algae than other species of algae.
Predominant Algae June July August
Toxin Analysis Results Microcystin (ppb) WHO Drinking Water 1 Recommended Accidental Ingestion 2 - 4 Limits Moderate Risk 20 January 352 February 160 March >100 Lake Anita Louise April 32 May 34 June (surface) 1.08 June (max depth) 33.6
Concerns for the Future… • Planktothrix continues to persist in the lake • While surface microcystin levels have dropped to near the WHO limit, levels at the bottom of the lake remain nearly 33x greater than is recommended • Fall turnover will mix the contents of the lake and winter will decrease the temperature, creating a perfect environment for Planktothrix to thrive • Anita Louise feeds into Lake Linganore and could transfer microcystin
Possible Remediation Action at Lake Anita Louise • Reduction of nutrient inputs into the lake • Have your soil tested to find out if fertilizers containing phosphorous are necessary • Create a buffer zone – don’t mow right up to the edge of the Lake and plant shrubs along the edge of properties • Install rain barrels at homes to collect rain water and decrease runoff • Peroxide application during winter when Planktothrix is at the surface of the Lake • Addition of barley straw to the water in the spring to inhibit growth • Draining the lake to allow bottom water to receive full sunshine
Any Questions?
LAKE LINGANORE Hannah Zinnert
Goals • Is Lake Linganore at risk for harmful algal blooms? If so, what can be done to improve the health of the lake? • Investigate multiple water quality parameters over the course of the lake’s growing season • Determine predominant algae species found throughout the growing season • Understand the amount of nutrient flux occurring in the lake and how it interacts with other water quality parameters
What is a harmful algal bloom (HAB)? • Occur when colonies of algae grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds • Microcystis sp. • A type of freshwater blue-green algae that can form HABs • Can produce hepatotoxins • Liver toxins that can cause nausea, vomiting, and acute liver failure
Methods • Bi-weekly sampling at 5 sites on the lake • Collected vertical profile data at all 5 sites • Collected water grab samples at sites 1,2, & 4
Methods • Collected multiple water quality parameters for each vertical profile site • Including temperature, dissolved oxygen, light intensity, and conductivity • Analyzed water sample grabs at surface, middle, and max depth • Chlorophyll and phycocyanin fluorescence, active chlorophyll a concentrations, pH, and turbidity
Water Quality Site 1 Temperature Site 4 Temperature • Temperature Temperature (° C) Temperature (° C) • Dissolved 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 Oxygen 0 Thermocline 5 5 10 10 Thermocline Depth (ft) 15 15 Depth (ft) 20 20 25 25 30 30 35 17-May 13-Jun 18-Jul 17-May 13-Jun 18-Jul 35 • Generally, the water warms from surface to bottom throughout the • In the deeper sample site, the increasing temperature trend is the summer same • By mid July, a thermocline is set up and the water column is more • However, a thermocline is set up by June and gets even larger by stratified July
Water Quality Site 1 Dissolved Oxygen Site 4 Dissolved Oxygen • Temperature DO (ppm) DO (ppm) 0 5 10 15 20 25 0 5 10 15 20 25 • Dissolved 0 0 Oxygen 5 5 Supersaturated DO 10 10 Depth (ft) Depth (ft) 15 15 20 20 25 25 30 30 2 ppm hypoxia 2 ppm hypoxia cutoff cutoff 35 35 1-Jun 18-Jul 3-Aug 1-Jun 18-Jul 3-Aug • High levels of DO in surface waters • DO decreases as you move deeper in the water column • As summer progresses, the area of the water column containing little to no DO moves higher
Nutrients (MDE 2014 Data) Dissolved Inorganic Nitrogen (DIN) Dissolved Inorganic Phosphorus (DIP) 3.000 0.0120 2.500 0.0100 0.0080 2.000 DIP (mg P/L) DIN (mg N/L) 0.0060 1.500 more 0.0040 1.000 0.0020 0.500 water 0.0000 0.000 20-Apr 10-May 30-May 19-Jun 9-Jul 29-Jul 18-Aug 7-Sep 27-Sep 17-Oct 20-Apr 10-May 30-May 19-Jun 9-Jul 29-Jul 18-Aug 7-Sep 27-Sep 17-Oct Sampling Date Sampling Date DIN Surface DIN Bottom DIP Surface DIP Bottom • Much higher concentration of Dissolved Inorganic Nitrogen (DIN) than Dissolved Inorganic Phosphorus (DIP) • Concentrations of DIN in surface and bottom remain elevated throughout the growing season • Bottom DIP remains elevated (and even increases some), while surface DIP reduces to trace amounts
Nutrients (MDE 2014 Data) • Phosphorus is released from the sediment in the lake during summer months when the lake is stratified and there is little oxygen in the bottom
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